John became president of AERA in October of 2003 rejoining an industry that he had briefly left to finish his Ph.D. in Engineering Management. His career in engine rebuilding began in 1980 back in Salt Lake City Valley where he opened an automotive machine shop specializing in foreign cars. After four years of shop ownership, he then began his career in machine tool sales working for Sunnen Products as a field engineer working his way up to sales manager in 1996. His entrepreneurial spirit led him to begin Five Star honing equipment and abrasives in 1997 where he imported the first metal bond superabrasive connecting rod honing machines for our industry. He then sold Five Star to Peterson Machine Tools and became a honing development engineer for the Kansas Instruments division. John then developed and created a market for flexible nylon abrasive brush tools that eventually led to new patents and used as the preferred standard for finishing cylinder bores after honing with conventional and superabrasives. These developments landed him at Osborn International to further the brush tool technology.

John then entered the OE arena becoming the director of Advanced Technology for Micromatic-Textron. Here John developed new standardized statistical methods for studying and evaluating manufacturing tools, abrasives, coolants, fixtures and honing processes. After Mircomatic was sold, he took the position at AERA.

At AERA, John led the association through many changes of efficiency and professionalism. Having a professional technical guy at the helm for the last 9 years has been very beneficial for our association.

John states: “At some point, I knew this day would come. It happens to everyone and now, retirement is happening to me. As with any event you don’t want to think about, you just bury it away and go about your business. But I am told with age comes wisdom and I thought it wise to move my concentration away from career and focus on Shirley (my wife) and grandchildren. Life doesn’t often give one a second bite of the apple but retirement can do just that. So, without looking back, Shirley and I decided that on June 30, 2012, I should retire from a beloved industry that has given us so many good friends and memories. Given past history, I will stay active and still have a few things to contribute, but family gets the lions share.”

Staff, members and associates of AERA would like to thank John for his years of service and wish him and his family a great retirement.

An engine’s rotating assembly obviously includes the crankshaft, connecting rods, pistons and pins, piston rings, rod bearings and main bearings (as well as damper and flywheel/flexplate in the case of externally-balanced setups). While many engine builders prefer to design their engines using specific components (brands and versions of components with which they’ve had previous success, etc.), the option of purchasing a rotating assembly “kit” offers a time savings, as well as potential cost savings.

A pre-packaged rotating assembly (available from a variety of aftermarket crank and rod manufacturers) provides a level of convenience by offering a system that has been pre-determined to suit specific goals, in terms of engine displacement and compression ratio. Want to build a 347 stroker Ford starting with a 302 block? Naturally, you’ll need a 3.400” stroker crank and 5.400” rods, along with the appropriate piston CD to accommodate your block deck height requirement. A pre-designed system will include the necessary crank stroke, bore-diameter-appropriate pistons, required rod length, as well as suitable rings for the included pistons, and main & rod bearings for the application (simply specify stock or suitable undersize). As far as compression is concerned, the rotating assembly supplier will provide a reference chart which easily allows you to match-up the pistons to the head that you plan to use in order to obtain your desired squeeze ratio. If you’re not picky about brand of pistons, rings and bearings, you’re able to obtain the assembly that you want by ordering a single part number, as opposed to flipping through catalog pages or perusing numerous websites.

In addition, suppliers offer in-house balancing services. Depending on the individual supplier, the specific rotating assembly and the price level, precision balancing will either be already included in the assembly price or available as an option. Again, this is yet another advantage, if for no other reason than to save time at your end. The goal of a pre-packaged rotating assembly is to provide convenience, essentially to produce a “plug n’ play” bottom-end.

Depending on the specific rotating assembly part number, you’ll be able to customize your kit according to your wishes (cast, forged or billet crank, forged or billet rods, I-beam or H-beam rods, hypereutectic or forged pistons, style of rings, style/performance level of bearings, etc.). Most rotating assembly suppliers understand that builders require certain choices, and offer variant levels of their systems accordingly. Basically, you decide displacement, compression ratio and level of component “strength” (race or street), and the supplier handles the details for you.

PROS AND CONS

Pros: A rotating assembly “kit” provides a matched system without the need to purchase individual parts. This saves both time and money.

Cons: If a builder prefers to create his own system by cherry-picking specific brands/models of components, and/or prefers to use his own design ideas (re: rod length, piston CD, ring spacing, bearing clearances, piston dome design, etc.), buying a complete pre-packaged system simply doesn’t make sense.

POPULAR STROKER COMBINATIONS

While a pro engine builder (especially one who builds competition engines) may likely opt to piece his own system together, the ready-availability of pre-packaged rotating assembly combinations make it easy to obtain the customer’s desired displacement and compression package by simply ordering a single part number. Especially in the area of stroker builds, the aftermarket performance crankshaft makers make this easy.

While a wide variety of combos can be had (either by purchasing individual components or by ordering a pre-coordinated rotating assembly), following is a sample list of available stroker packages, which will include the crankshaft, connecting rods, pistons and pins, rings, rod bearings and main bearings. This list is courtesy of Ohio Crankshaft, but similar packages are available from most crankshaft manufacturers. Note that additional stroker/displacement combos not listed here are also available from other suppliers)

• SMALL-BLOCK CHEVY: 434, 421, 377, 383, 408, 434, 428, 421, 447
• BIG-BLOCK CHEVY: 509-540, 555-565, 496, 605, 620, 572, 582, 588, 598, 632, 698, 706
• GM LS: 403 – 416
• SMALL-BLOCK FORD: 302 – 347, 351w – 408, 302 – 331
• BIG-BLOCK FORD: 514, 533, 545, 557
• PONTIAC (400/455): 463, 468, 501
• MOPAR: 360 – 428, 360 – 408, 440 – 500, 440 – 511, 440 – 493, 440 – 541, 440 – 572, 426 – 472

Of course, even if a particular stroke/bore/rod/piston combo isn’t listed as a package, most makers can create a rotating assembly package for a specific set of requirements.

Crankshaft makers who offer complete rotating assemblies naturally feature their crankshaft in a rotating assembly kit. If that maker also manufactures connecting rods, naturally their rods will be included (choices in cranks and rods are common, between cast and forged cranks, forged or billet I-beam or H-beam rods, etc.). As part of the “kit,” the crank maker will include pistons, rings and bearings of various brands (they may offer choices of brands). For example, pistons of choice might include Mahle, JE, SRP, KB, Wiseco, Arias, Carrillo, Diamond, CP, Ross, Probe, etc. Bearings might be from Mahle Clevite, Federal Mogul, King, etc., while rings may be sourced from Mahle Clevite, Total Seal, PBM, Federal Mogul, Hastings, etc. many assembly suppliers offer a choice of specific component brands. The use of specific pistons, rings and bearings might be based on either performance or pricing factors, depending on the level or intended application. In any case, the quality aftermarket crank makers take advantage of the highest quality in terms of completing their rotating assemblies. In other words, if you stick with the leading suppliers of rotating assemblies, you’re not gonna get stuck with junk pieces.

PRICE COMPARISON EXAMPLES

What’s the approximate cost difference, if any, between buying a rotating assembly kit as opposed to piecing-together a system using the same/similar components? We wondered that as well, so I took a look at one of the big box parts discounters websites (using their pricing merely as a representative example). Merely for the sake of illustration, I chose three popular systems — one for the 383 stroker Chevy small-block, one for the 347 stroker Ford small-block and one for the 408 SBC. Again, just for the sake of providing examples, I referred to one of Eagle’s rotating assembly for the Chevy, one of Scat’s rotating assembly for the Ford and one of Callies assemblies for the 408. Note that the first two examples include packages that feature cast cranks. Both Scat and Eagle, for example, offer cast and forged cranks, as well as hyper and forged pistons, with prices varying depending on selected components.

SMALL-BLOCK CHEVY 383

An Eagle rotating assembly for a small-block Chevy 383 was offered at $838.95. This kit included a cast 3.75” stroke crank, 4.030” hypereutectic pistons, Eagle I-beam 5.700” rods, plasma moly rings, main and rod bearings, and a damper and flexplate. The brand of pistons, rings, bearings, damper and flexplate wasn’t listed, so I made my best guesses with regards to those components. Piecing the kit together, purchasing all items individually, I came up with a total of $996.95, a savings of about $158.00.

Big box parts discounter prices per item:

• Eagle cast crankshaft $165.95
• Eagle I-beam forged rods 228.95
• Speed Pro hyper 4.030” pistons 127.60
• Speed Pro rings 38.95
• Clevite H-series main bearings 89.95
• Clevite H-series rod bearings 71.60
• TCI flexplate 93.95
• Damper 180.00

Total $996.95*
Rotating assembly price $838.95
Savings by buying kit $158.00*

SMALL-BLOCK FORD (302 STROKED TO 347)

One big box parts discounter offers a Scat rotating assembly for a 347 Ford that includes a Scat cast 3.400” stroke, Scat forged 5.400” rods, 4.030” flat-top forged pistons, plasmamoly rings, main bearings and rod bearings. The package sells for $872.95. Without knowing the brands of pistons, rings and bearings, I approximated using Speed Pro forged pistons, Speed Pro rings and Clevite H-Series bearings. When I added individual pieces together (again, citing one of the big box parts disounter prices as reference), I obtained a total of $1,128.00. Using these examples, that represents a savings of about $255.05 when buying the kit as opposed to buying parts separately.

The breakdown is as follows:

• Scat cast crankshaft (3.400” stroke) $242.95
• Scat forged rods (5.400”) 257.95
• Speed Pro forged flat-top pistons (4.030”) 319.60
• Speed Pro plasmamoly rings 111.95
• Clevite H-Series main bearings 99.95
• Clevite H-Series rod bearings 95.60

Total $1,128.00*
Rotating assembly price $872.95
Savings by buying kit $255.05*

CHEVY 408

One big box parts discounter lists a Callies rotating assembly for a 408 Chevy at $2,460.00, which includes a Callies forged crank, Callies forged Compstar H-beam rods, forged pistons, plasmamoly rings and main & rod bearings. Note that, according to Callies’ website, each rotating assembly also includes precision balancing, so we can also factor in that cost as well.

• Callies forged crank (4.000” stroke) $931.00
• Callies Compstar rods 662.00
• JE forged pistons (4.030”) 819.00
• Total Seal rings 115.95
• Clevite main bearings 178.00
• Clevite rod bearings 150.00
• Estimated balancing cost value 200.00

Total $3,055.95
Rotating assembly price $2,460.00
Savings by buying kit $595.95

* Disclaimer: Granted, without knowing exactly which brands and part numbers of rings, pistons, bearings, damper and flexplate that the rotating assemblies include in the above examples, the prices of individual parts and the resulting savings differentials may not be accurate. However, the sample comparisons still make it clear that purchasing a pre-packaged rotating assembly should represent some degree of savings as compared to piecing the system together.

COMPRESSION RATIO CALCULATOR

Rather than take space here to list a host of formulas, a very handy and easy to use calculator is available on Diamond Racing’s website. Simply plug in your numbers (deck height, stroke, bore diameter, gasket thickness, rod length, piston volume, chamber volume, etc.), and this calculator does the work for you in a heartbeat. This is a very handy reference to help you to make decisions relative to piston volume, gasket thickness, piston CD, etc., to help you to tune-in your desired compression ratio. Yes, some may view this as a form of cheating (it does the math for you), but it’s darned handy. Just go to www.diamondracing.net/tools. Once you start to play with this calculator, you’ll be hooked.

ROD RATIO… SOMETHING TO CONSIDER

Connecting rod ratio refers to the length of the rod in relation to crankshaft stroke. Rod ratio is determined by simply dividing rod length by crankshaft stroke. For example, a rod length of 6.700” mated to a crankshaft stroke of 4.500” will result in a rod ratio of 1.488:1 (6.700 divided by 4.500).

Rod ratio directly affects piston side-loading due to the maximum operating angle of the rod. As rod ratio is lowered (moving to a shorter rod with a given stroke, for example), the angle of the rod relative to the cylinder bore increases, which results in potentially increased piston skirt wear, increased friction (skirt and rings to cylinder wall) and resulting increase in heat. Basically, as rod ratio decreases, the rod (at its maximum angle) is trying to push the piston through the cylinder wall (“side loading”) in addition to moving the piston up/down. Obviously, if side-loading is excessive, this not only poses a threat to component longevity but also results in a horsepower loss due to the increase in frictional drag (as well as a potential change in bore geometry due to both frictional drag and elevated heat, which can affect ring sealing). Due to modern boring/honing technology (where cylinder bores are machined with greater concentricity) and modern piston design (stronger designs along with friction-reducing skirt coatings) reduces the potential for increased wear and drag, but we still need to consider rod ratio in order to maximize durability and power for a given engine application.

Side-loading increases as the rod ratio decreases, and the effect of side-loading decreases as rod ratio increases. Rod ratio should be considered when choosing rod length and stroke combinations.

According to Eagle, a rule of thumb is to stay above 1.45 or so for a street engine with modern pistons and boring technology. It is generally accepted that past 1.72:1 you won’t realize any significant gains (diminishing returns). The improvement from 1.40 to 1.50 is significant, but going from 1.75 to 1.85 won’t have much affect.

Following are a few examples of rod ratio in specific setups (courtesy Eagle):

• Ford 302 (5.090” rod / 3.000” stroke) = 1.70 rod ratio
• Ford 351W (5.956” rod / 3.500” stroke) = 1.70 rod ratio
• Ford 460 (6.605” rod / 3.850” stroke) = 1.72 rod ratio
• Chevy 350 (5.700” rod / 3.480” stroke) = 1.64 rod ratio
• Chevy 400 (5.565” rod / 3.750” stroke) = 1.48 rod ratio
• Chevy 454 (6.135” rod / 4.000” stroke) = 1.53 rod ratio
• Chrysler 440 (6.760” rod / 3.750” stroke) = 1.81 rod ratio

To avoid side-loading issues, many builders simply take the approach of using the longest rods that will fit with a given combination. The most popular range seems to be within 1.48 to 1.72. Stroker engines will typically feature a lower rod ratio.

DIMENSIONAL FACTORS TO CONSIDER

When choosing a complete rotating assembly, naturally one of the critical elements deals with dimensions in terms of making the reciprocating movement of the assembly fit the block in question. A nice feature of a pre-designed rotating assembly is that the supplier has already determined which stroke variations will fit a particular OE-design block (yes, some clearancing may be needed, but it’s do-able).

• Block deck height: Distance from the main bore centerline to the cylinder head deck surface. Note: We need to consider the finished block deck height, not a theoretical OEM or otherwise assumed deck height.

• Crankshaft stroke: The published stroke distance represents the crank’s total stroke (distance from the rod journal centerline at bottom-dead-center (BDC) to the rod journal centerline at top-dead-center (TDC)). For purposes of configuring connecting rod length and piston compression distance, you’ll only factor-in one-half of the published crank stroke….the distance from crank centerline to rod journal centerline with the rod pin at the top of its stroke (TDC).

• Connecting rod length: Distance from the rod’s big-end bore centerline to the small-end bore centerline.

• Piston compression distance (CD): This refers to the distance from the wrist pin bore centerline to the “flat” of the piston dome/deck.

Example: In order to achieve a “zero deck” (where the piston deck meets and is flush with the block’s deck), we need to determine crank stroke, rod length and piston CD dimensions that will add-up to equal the block’s deck height with the piston at TDC.

½-crank stroke + rod length + piston CD = block deck height.

For example, if we’re dealing with a block deck height of 10.210”, and assuming we want zero-deck, the distance from the centerline of the crank’s rod journal (when at TDC), the rod length and piston CD must equal the block deck height. In this example, using a crank stroke of 4.500”, a rod length of 6.700” and a piston CD of 1.260” will result in a zero deck. Note that one-half of the crank stroke is 2.250”.

½-Stroke 2.250 + rod length 6.700 + piston CD 1.260 = 10.210”

Let’s say that we prefer that the piston at TDC is located 0.015” below deck. Using the above example, we could reduce piston CD from 1.260” to 1.245” (by ordering a custom piston). By the same token, if we wanted the piston to protrude, say, 0.010” above deck, we would increase piston CD to 1.270”.

BALANCING

The need for crankshaft balancing should be obvious. After all, you wouldn’t want to run a fresh set of tires on a vehicle without first having the tire/wheel assemblies balanced. An out-of-balance condition would result in radial imbalance due to uneven centrifugal forces (vibrations/harmonic changes, etc.). Why would we risk an imbalance condition in an expensive engine assembly? A proper balancing correction eliminates unwanted stresses and harmonics, which helps to optimize engine longevity and horsepower. Eliminating this easily-correctable parasitic influence simply makes sense, even in a street build.

One annoying aspect is worthy of mention here. All too often, uninformed consumers confuse the terms “balancing” with “blueprinting.” It’s very common for a novice to boast that his engine has been “balanced and blueprinted,” when in fact a blueprinting has not been performed. The work involved in blueprinting an engine (optimizing every aspect of the build, in terms of clearances, dimensions, airflow, chamber volumes, etc.) adds mega-dollars to the build and realistically is only justifiable in all-out competition engines where every fraction of horsepower and optimized engine durability is absolutely critical. In other words, if a crank/rotating assembly has been balanced, that does not mean that the engine has been blueprinted.

Whether we decide to zero-balance, under-balance or over-balance (we’ll address these issues later in this article), the reciprocating components must be weight-matched. All piston and pin combinations must be of equal weight. All connecting rod big ends must match, all rod small ends must match, all total-rod weights must match, all rod bearings must match and all ring packages must match. In the “old days,” a set of pistons may vary in weight by as much as 5-8 grams or so, requiring the balance technician to weigh all pistons, determining which piston is the lightest. All remaining pistons must then be weight-relieved (by removing material from the pin boss areas) in order to achieve a set of weight-matched slugs. With today’s casting and forging technology, coupled with CNC machining, it is very rare to find the need to weight-correct any pistons made by any of the high-quality performance aftermarket piston manufacturers. The same holds true for connecting rods, where all big ends must weigh the same, all small ends must weigh the same and total weights must be equal.

When checking for equal/matched component weights, staying within about 0.5g (piston to piston, or rod-to-rod) is acceptable.

Again, due to close-tolerance manufacturing techniques used by today’s performance aftermarket rod makers, it is very unlikely that you’ll need to perform any weight corrections to a set of rods.

Nonetheless, you should never assume anything, even when using the highest quality components. It’s good basic practice to weigh each piston and each rod, if for no other reason than to obtain peace of mind and to create a detailed record of the build.

INTERNAL vs EXTERNAL BALANCE

Internal balancing relies on the crankshaft counterweights alone to handle the reciprocating mass of the rods, rod bearings, pistons/pins and rings (as well as anticipated clinging oil weight). External balance feature additional counterweights on the damper and flywheel to provide assistance to the crankshaft counterweights. Certain engines, largely due to limited room inside the engine block that may not be able to accommodate large-enough crank counterweights, must be assisted by the damper and flywheel (i.e. external weight) in order to achieve crank balance. Based on limitations of the room inside the block, this is true for some builds that feature longer strokes and larger bore diameters.

With an internal balancing job, the damper and flywheel are not considered (here we simply use zero-balanced damper and flywheel). With an external balance, the damper and flywheel must be attached to the crankshaft during the crankshaft spin balance check.

Internal balancing is always preferred, if you can get away with it. If the crank counterweights are too light, you can always drill and add tungsten (heavy metal, which is about 1.5 times heavier than lead), although this adds to the expense of the balance job, due to the high cost of heavy metal slugs, which can easily add $100 to $200 or more to the balance job). By maintaining the necessary counterweight closer to the crank centerline and within the confines of the block, you place less strain on the crankshaft. External counterweights apply more dynamic force at the ends of the crank, potentially inducing more crank deflection. For mild street applications, it really doesn’t matter, but for high-stress applications, internal is always a better way to go. This is especially true if you’re running a blower, where more stress will be applied to the crank snout. The less weight you have hanging out on the snout (weighted balancer as compared to a harmonic damper or pulley hub), the better.

By the way, when adding heavy metal slugs, while these may be placed on the outer face of the crank counterweights (90-degrees to the crank centerline), a preferred placement is through the counterweights (fore/aft), placing the drilling and weight parallel to the centerline. This eliminates the possibility of slinging the weights out during crank rotation.

OVER-BALANCING

While achieving a “zero” balance is the common goal, some builders prefer to intentionally over-balance. This means that you’re allowing a bit more weight on the crank counterweights than needed for zero balance. This theoretically moves the ideal balance point further out on the rpm scale (smoothes out more at higher rpm). For instance, instead of balancing a V8 crank at 50%, the crank is overbalanced by a few (for example 1 to 3 percentage points), 51 to 53%. This is done by making the balancing bobweights 1 to 3 percentage heavier when spin-balancing the crank. The theory is that you’re trying to compensate for higher dynamic forces (in addition to static weight) that occur at higher rpms. The engine may idle a bit rough, but will smooth out at a target high engine speed. Several builders I spoke with told me that “this is something that you can try…if it works out for you, great. If it doesn’t, at least you learned something.”

Mike Mavrigian has written thousands of technical articles over the past 30 years for a variety of automotive publications. In addition, Mike has written many books for HP Books. Contact him at Birchwood Automotive Group, Creston, OH. Call (330) 435-6347 or e-mail: mike@birchwoodautomotive.com. Website: www.birchwoodautomotive.com.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

A major part of any re-organizing, expanding or setting up a new machine shop is planning the floor layout.

The KISS principal (Keep It Simple Stupid) should be taken seriously by about 95% of shops. Unless you have a large facility that can justify using some type of electronic drawing program, ¼” to the foot squares on paper with cardboard cutouts made to scale is the best way to create a layout.

Graph paper with ¼” to the foot squares has always been available at office supply stores, but you can print the same squares on paper using Microsoft Excel. Look for the Excel template under “Graph Paper – Medium Rule”. Using the ¼” squares makes it easy to lay out most shops on a standard 8 ½ x 11 or even legal size paper. If your shop is larger, you can tape any amount of paper together to come up with the size or shape you need.

What seems to be one of the most complicated steps to get started is to accurately measure the shop floor area. Use a long tape measure (50 ft. or more) to eliminate errors in adding up inch measurements. Keep your drawing simple, but pay attention to the precise location of doors, windows, electrical boxes and outlets, compressed air outlets, drains etc. If there are hoists in place, their travel needs to be shown in the drawing.

Use a soft lead pencil to draw on the graph paper so mistakes can be easily corrected. After you have accurately drawn all the things that will not move you can go over the pencil lines with a Sharpie marker to make them stand out better.

Make the cutouts of all your machines, benches, trash cans, refrigerator etc out of light cardboard. Use the squares on the paper or a ¼” per foot ruler for sizing them. Don’t forget to include anything that sticks out from the machine. Now you can move the cutouts around the drawing until your final design is reached.  When you think you have it as perfect as possible, a light dab from a glue stick can hold the cutouts in place.

Obviously any shop employees should be involved from the start. Their daily movement and efficiency can be greatly affected by the location of equipment. Don’t be shy about soliciting ideas and opinions from others outside your business. Fresh ideas or questions can sometimes be a real eye opener and help.

The area for most shops seems to be always too small. One of the simplest ways to gain space is to use pallet racking for storing incoming or completed work. You are now making use of vertical air space that you are already paying for. Besides gaining space, pallet racking can really make a difference in the appearance of a shop being organized.

There is probably nothing that requires more compromise than organizing a shop, but there are some basic ideas that you should keep in mind.

1. Any machines that emit dust or dirt should be kept in a different room or as far away from the main shop as possible.

2. I like to use the 80/20 rule. Focus on making the flow for the majority of your work (the 80%) as efficient as possible.

3. If possible a designated area for receiving incoming (dirty) jobs should be defined. Isolating dirt is always a help to keep the rest of the business cleaner.

4. Also if possible have a designated area for customers to pick up their clean parts. Sometimes it has to be the same as the incoming area which makes it a challenge to maintain a clean environment.

5. Be certain there will be enough room to move equipment into the shop without taking down walls.

6. Sometimes existing drains are not located in the ideal location. With the disposal laws we have it might be better not to have an open floor drain except for washing the shop floor. Moving a floor drain can be costly but could pay dividends if it makes the shop more efficient.

7. For years, using a 3-ft. minimum aisle space has been the standard. Bigger might be better but generally having a minimum 3-ft. aisle provides efficient work movement.

8. Analyze what it will take to provide air and electricity to all equipment in your new layout. Add up the power and air requirements to be certain you have enough for your shop now and in the future.

If you have a larger shop, you should take the time to do a layout electronically. There are numerous drawing programs available, but unless you are doing a very large complete building design a 2D program is all that is needed. I’ve been using a lower end program called “Auto-Sketch” from the maker of the Auto-Cad drawing program. It works extremely well for doing simple or very complex drawings. There are all the colors and layers you will ever need and it can automatically dimension anything. It also allows you to export the drawing in many different file formats including most of the .dwg Auto-Cad file formats for higher end use. If you want to print out a large size drawing of your creation, companies like Kinko’s can take almost any file drawing from a memory stick or CD and print it out on really big paper.

Be prepared for a steep learning curve if you have never used an electronic drawing program. However there is a big advantage once you have conquered it. The ease of making changes is about as hard as using a word processor.

When an electronic drawing is done properly it should have many layers in it. An example would be drawing the electrical or plumbing on separate layers. You can then view all layers with the complete drawing or just have any layer show up by itself. Print out any single layer and now the electrician, plumber or anyone else can do their work with just the information they need.

Any layout requires patience and understanding of how work moves through the shop. Whatever time you spend planning a layout will come back many times in efficiency, which will relate to better profits.

Lyle Haley has been in the engine rebuilding industry since 1961. He currently does consulting and equipment sales as “The Shop Doc” at www.shopdoc.biz where an overview of his experiences can be found. You may contact Lyle Haley via email lyle@shopdoc.biz or call (763) 464-1286.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

In every class of motor sport, engine power is increasing in impressive leaps.

Even small displacement engines now produce horsepower that only ten years ago was considered the realm of highly refined and exotic mills hundreds of cubic inches larger. And sizeable cubic inch power plants regularly produce over 1,000 horsepower in street trim with a cast aluminum intake manifold and a single carburetor. There seems to be no end to the power potential.

Cylinder head technology, with increased air flow and combustion chamber design, has led the charge. Many of these advances have been accomplished by improving the performance of the valve train, achieved largely by state-of-the-art test and development equipment such as the Spintron, and also by the latest computerized machining centers.

The enthusiast community measures engine power in terms of horsepower and torque. But cylinder pressure read as BMEP and IMEP are more accurate indicators. These abbreviations refer to Brake Mean Effective Pressure and Indicated Mean Effective Pressure, which are more precise measurements since gas pressure in the cylinder varies from a maximum at the beginning of the expansion stroke to a minimum near its end. Also, these classifications can very accurately compare the power of engines of different displacements since it is the pressure per piston area that is being examined.

Recognizing that cylinder pressure is the true dynamic that creates horsepower compels one to consider the piston and the forces applied to it. In high performance and racing applications the piston needs to withstand and then transfer the cylinder pressure to the crankshaft while it also maintains its shape, provides a long service life, partakes in sealing the bore, and compliments and not detracts from the effectiveness of the cylinder head and combustion chamber. That’s a long list of tasks!

Over the years, the performance engine-building community has gone from using an original-equipment-style cast piston to a stronger forged design that also allows more freedom in manufacturing and a reduction in the reciprocating mass. High quality, advanced aluminum materials are employed and forged pistons are now available with outboard or with the narrower inboard pin towers. Additionally, they provide excellent load paths and rigid structures and attract an array of competent coatings to protect them.

However, the forged piston has one major shortcoming: infinite design potential. If, for example, a piston designer or engine builder or race team wishes to change the piston structure or adopt different load paths or experiment with different struts and buttresses, only a billet piston will accommodate these requirements.

NASCAR teams were quick to recognize the billet’s potential, taking advantage of its versatility. Piston manufacturers continue to develop and test new designs constantly. Nonetheless, bringing a cost-effective billet piston program to the general market turned out to be a formidable challenge—often cost prohibitive and, therefore, unsustainable. In fact, the program only became viable when manufacturers established a special department with dedicated engineering staff and equipment. Once the technique had been established, race engine builders no longer needed to work within the confines of a forging.

Many engine builders openly admit they felt they were on a short leash with any forged piston. Not being able to have it fully meet their requirements they compromised as best they could. Race teams not only openly embrace the freedom that billet pistons offer but also the ability to re-examine the cylinder head, combustion chamber and valve angle for further power gains. The possibility for another great leap in power is one of the most exciting aspects of the billet piston.

With regard to material strength there is no appreciable difference between the forging and the billet piston. As mentioned earlier, most of the NASCAR teams and the NHRA Pro Stock elite are already using billet and have proved its durability. Some NASCAR teams switched to billet pistons because they detected slight variations from forging to forging. Pro Stock and other high-rank drag racing teams longed for the opportunity to experiment with piston designs not possible with existing forgings. In addition, for highly competitive race teams, having access to a billet piston program provides them with much prized exclusivity—they prefer their secrets to remain safe.

With a forging program, the piston maker’s position is greatly compromised. When a new forging is needed he is compelled to invest in new tooling, often costing in excess of $10,000; obliged to wait months before receiving the forgings; and often required to purchase the first 500 slugs from the new tooling. Obviously, the piston-maker has to amortize the costs and as a result everyone benefits from the great idea, and exclusivity is minimal. However, a billet program eliminates the need for special tooling, associated delays, and minimum-order quantities. Now the great idea remains the property of the one who conceives it.

Usually machined from a solid piece of 2618 billet aluminum, the piston has an expansion rate slightly greater than its forged counterpart. Most users set the piston-to-wall clearance between .0065in to 0.008in. With regard to weight, the billet version is typically one to two percent lighter than a comparable forged piston for the same application.

Of course billets easily accommodate reduced skirt areas, which minimize friction and weight. They also permit the optional use of buttons instead of spiral locks. Buttons make it much easier and quicker to change pistons should the need arise. In addition buttons prevent the expander in the oil control ring from distorting around the half-moon openings in the back of the groove on the piston where the pin bores intercept the oil control ring groove. As already stated billet pistons are well-suited for teams embarking on new engine development programs. These programs often require last-minute design changes that can affect bore sizes, cylinder head configuration, valve sizes, valve pocket depths, pin boss dimensions or load paths.

Usually billet pistons are available in a range of finishes. Diamond, for instance, furnishes them in a natural finish or hard-anodized or with a ceramic crown coating and a moly skirt coating. Hard-anodized coatings help prevent scuffing and galling of the cylinder bores under extreme conditions.

In the early days of motor sport, slang for a piston was “slug”, a term that suggests a limited amount of engineering—how false that is. With the introduction of affordable billet pistons, engine development just took another huge leap forward.

SOURCE: Diamond Pistons, 23003 Diamond Dr. Dept EP, Clinton Twp, MI 48035 USA, (877) 552-2112 , www.diamondracing.net.

Ray T. Bohacz’s interests have always revolved around mechanical apparatus but he admits his true love is engines. It matters little if it is a Detroit Diesel-powered irrigation pump in the middle of a corn field or nitro-burning Hemi. His first byline appeared in 1995 and has since published over 1,200 in-depth technical articles pertaining to engines. He has also authored three books on engine systems. He is a member of SAE, American Society of Materials and the International Motor Press Association.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

New GM Ecotec 2.5L powers Chevrolet Malibu’s quest for quietness

The 2013 Chevrolet Malibu’s new 2.5L engine with direct injection is expected to be one of the quietest and most refined in the segment. It will be available in the new Malibu this summer.

The 2.5L development team reduced noise intensity by 40-percent of the Ecotec 2.4L engine, which was already a Ward’s 10 Best Engines award winner. It also passed subjective evaluations of what sounds good as the engine climbs through its rpm band. To Malibu’s passengers, that is expected to mean a quieter driving experience and a more refined sound as the engine revs to its 7,000-rpm peak.

The refinement and quietness of the 2.5L are impressive,” said Tom Slopsema, Noise and Vibration engineer. “No fastener, cover or internal engine part was left unexamined in our quest to make this an engine that surpasses the benchmarks in the industry.”

Specifically, the engine’s noise frequency signature was targeted, with the aim of pushing radiated noises into a higher frequency range well above 2,000 hertz, which is more pleasing to the ear – particularly in the high-load operating ranges where engine sound is the most intensive.

“Think of it as the difference between low-frequency, course noise, such as a vacuum cleaner, versus a higher frequency, precision noise, such as a sewing machine,” said Slopsema. “We focused on reducing the overall engine noise level and placing the remaining noise in a higher frequency range.”

The refinement-enhancing changes and improvements over previous Ecotec engines ranged from the comparatively simple – such as integrating a sound-absorbing cover into the intake manifold and specifying quieter drive chains – to more fundamental architecture items, such as relocating the balance shafts from the cylinder block to a cassette within the oil pan.

Engineers worked around core elements of the engine that they simply couldn’t change, namely its aluminum-intensive architecture and the use of other lightweight, composite plastics.

“Both aluminum and plastic are very effective radiators of noise, but their mass-saving advantages are a must for fuel economy,” said Slopsema. “That meant we had to be more creative in how we approached noise reduction, addressing individual components’ effects on overall N&V and how to counter them.”

So, engineers implemented 10 key elements fundamental to giving the 2.5L its segment-challenging refinement, ranging from major items such as rotating and reciprocating components within the engine to items as minor as the front cover bolts. Here’s a look at them…

1. Relocated Balance Shafts: The 2.5L’s balance shafts – which are commonly used in four-cylinder engines to reduce vibration – are located in a cassette in the oil pan. It’s a move from previous Ecotec engines’ cylinder block-mounted shafts, which helps reduce noise through three key design features: a shorter, quieter drive chain, precision shaft-to-shaft reversing gears and light drag torque from driving the oil pump.

The short drive chain eliminates the previous long, winding “bushed” chain that included driving the water pump. It uses a premium inverted tooth chain design instead of a conventional roller-type chain, for quieter performance. The shaft-to-shaft reversing gear set allows the drive gears of the shafts to mesh directly, eliminating the need for a chain to “back drive” the second shaft, which must rotate in the opposite direction of the first shaft. The second shaft also drives the oil pump, providing a light drag torque to pre-load the reversing gear teeth for smooth, rattle-free and quiet operation.

2. In-Pan Oil Pump Assembly: Another significant change from previous Ecotec engines is the relocation of the oil pump assembly from the front of the crankshaft to within the oil pan, where it is driven by the second balance shaft. This reduces noise from the front cover area – an aluminum-intensive area that radiates noise – and provides a small drag torque to ensure quiet balance shaft gear operation. Also, the oil-sump location minimizes the potential for pump cavitation noise.

3. Camshaft Drive with Inverted-Tooth Chain: Like the drive chain for the balance shafts, the camshaft drive chain uses a premium, inverted-tooth design that is significantly quieter than a roller-type chain. As its name implies, an inverted-tooth chain has teeth on its links – two-pin rolling pivot joints – that essentially wrap around the gear sprocket to take up virtually all the tension. This allows for smoother meshing of the chain links to the sprocket teeth, the cause of most noise in chain drive systems. The chain-to-sprocket tooth impact is greatly reduced with the inverted-tooth design (also known as a silent chain drive), which virtually eliminates noise and enhances durability.

4. Two-Piece Oil Pan: When it came to the oil pan, engineers faced a conundrum: Aluminum provides stiffening structure to an engine, but it radiates noise. Stamped steel, on the other hand, radiates less noise, but doesn’t offer the structural benefits needed for a stiff powertrain assembly. Their solution was to combine the materials to create a unique, two-piece oil pan that features a stiff aluminum upper section to support the engine’s structure – maintaining the Ecotec engine’s signature full-perimeter transmission mounting surface – and a stamped steel lower section to provide greater overall sound performance.

5. Structural Camshaft Cover: As a cast-aluminum part mounted on the very top of the engine assembly, the camshaft cover can be a significant source of noise. That’s not the case with the 2.5L, thanks to a new, structural cover design that is stiffer and mounts more rigidly to the engine. It features increased ribbing and additional attachment bolts down the center, all of which increase the cover’s stiffness to help push the engine’s sound frequency above 2,000 hertz. It also enables excellent oil sealing for valvetrain oil control passages integrated within the cover.

6. Acoustic Intake Manifold Cover: Like many engines in the segment, the 2.5L uses a composite plastic lightweight intake manifold. But plastic conducts noise, so engineers wrapped the intake with a clamshell-like isolating cover. It has a sound-absorbing “blanket” on the inside that snugs against the intake to provide isolation, plus the cover has a visually clean outer layer, which works as a noise barrier.

7. Forged Steel Crankshaft: Engineers selected a forged steel crankshaft for the 2.5L because, along with its strength and durability, it is stiffer than a conventional cast iron crankshaft. That reduces noise and vibration at mid- and high-rpm levels, enhancing the engine’s smoothness.

8. Iron Main Bearing Cap Inserts: Iron inserts are cast into the 2.5L’s aluminum cylinder block bedplate, enhancing the structure at the main bearings, for greater smoothness and quietness. The bedplate provides stiffness to the bottom of the cylinder block and incorporates the main bearing caps – components used to secure the crankshaft within the block. The iron insert material ensures close main bearing tolerances over a wide range of engine operating temperatures, for quieter engine lower-end noise.

9. Isolated Fuel Rail: Although not new to the 2.5L, its isolated fuel rail nonetheless helps achieve overall quietness. Like the Ecotec 2.4L and Ecotec 2.0L turbo, the 2.5L features direct injection, which employs a very-high pressure fuel system, including an engine-mounted fuel pump and complementing fuel injectors that “fire” with very high pressures directly into the combustion chambers. This can be a source of noise. The fuel rail is a tube-like component that supplies gasoline to the injectors. To reduce the noise associated with this efficiency-enhancing system, the injectors are suspended and the fuel rail is attached to the cylinder head with rubber-isolated, compression-limiting mounting provisions.

10. Structural Front Cover: Similar to the structural camshaft cover described above, the 2.5L’s front cover, which covers both the camshaft drive system and balancer drive systems, was designed with extra ribbing and secured with extra fasteners – including a new row of attachments down the middle of the cover. Like the camshaft cover, the result is a stiffer, more rigid, quieter cover that contributes to lower engine noise.

The new Malibu will be sold in nearly 100 countries on six continents. It is available in LS, LT, ECO and LTZ models in North America. Malibu will be built in multiple locations around the globe, including the Fairfax, Kan., and Detroit-Hamtramck assembly plants in the United States.

Dave Hagen, our Senior Technician, has over 36 years of experience in our industry. As an ASE-certified Master Machinist, Dave specialized in cylinder head work and complete engine assembly for the first 17 years of his career.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

There has never been a performance engine builder who isn’t constantly looking for extra horsepower. Until now, the dynamometer provided all performance data, but no longer. Combustion analysis (CAS) is now the ultimate measurement tool. While cylinder pressure measurement has been around for some time, it is only in the past few years the performance benefits have surfaced. In one baseline test, information can be revealed that can never be found in continuous dynamometer testing; information that can save many hours of trial and error.

A combustion analysis system (CAS) measures individual cylinder pressure every degree of crankshaft rotation, at any chosen rpm. Pressure is measured by one of two types of transducers, both extremely accurate. One is a special designed spark plug; the other is for permanent mounting. Pressure is normally measured over seventy five to one hundred engine cycles; one cycle being 720 degrees of engine rotation.

Why combustion analysis? It immediately tells which cylinder is producing the most horsepower and which is producing the least. Cylinder pressure produces torque, torque produces horse power. Contrary to popular opinion; on a multi-cylinder engine, each cylinder does not produce the same combustion pressure when running. Figure #1 (on the following page) displays measured individual cylinder pressure from a six cylinder engine, notice the variation. There can be many reasons for this; one could be where a percentage of the mixture burn took place.  Look at Figure #2, 50% mass burn of intake mixture at the exact crankshaft angle. Notice anything? Look at cylinder #2; 50% mass burn at slightly over eight degrees and it produced the most cylinder pressure. All other cylinders produced 50% mass burn at much later crankshaft rotation; the piston was farther down the cylinder! More cylinder volume, less pressure!  With pressure variations like these there can be huge torque differences between cylinders. A dynamometer cannot measure that. The dynamometer looks at the engine as a single unit; numbers the dyno produces are an average at best. Simulation programs are no better; they rely on someone else’s data or theory.  For optimum performance and efficiency each cylinder must be analyzed as a separate engine. CAS does that. The goal is to equalize all cylinders.

Not only that; but cylinder pressure referenced to valve motion is critical in determining optimum cam lobe profile, see Figure 3. The valve sequences are not exact but adequate for illustration. You can see cylinder pressure rise after the intake valve opens. Not good! Did the intake open too soon; the exhaust open too late? Additional information to answer these questions could be found in reviewing the pressure change at specific crank angles. These are but a few of many performance indicators measured and recorded.

Previously to benefit from collected data, complex mathematical heat release calculations were required or the utilization of MatLab or similar programs. Now, software programs have been developed to interpret all data; on an individual cylinder basis, and print a report showing both graphical and analytical results minutes after the test.

How do we analyze each cylinder?

As I have said before combustion is a misnomer; combustion analysis implies the involvement of thermodynamics, which it does, but only to a small degree. Individual cylinder pressure measurement is what we are dealing with.  A baseline test is the beginning of CAS engine development. The engine is mounted on the dynamometer, intake air is set for operating altitude and several “pulls” are made to establish operating temperature, torque and horsepower. Next, transducers replace sparkplugs and data is sampled at desired rpm; usually max torque and max horsepower. Sample time is 75 to 100 cycles. Data is downloaded and a report is printed in both graphical and analytical format. This requires approximately 10 minutes. I need to say now this report, format and all graphs are not standard. They are the results of a proprietary software program owned by iSystems, Inc; the sole purpose is to save time disseminating the data. Now we review cylinder pressure. We look at each cylinder in several ways; peak pressure, cyclical variation, pressure rate of rise measured in crank angle degrees, mass burn and IMEP, “indicated mean effective pressure”; the pressure that is pushing on top of the cylinder. The baseline test will show “traces”; lines if you like, of each cylinder during the test period. These can be displayed individually, collectively or in bar chart form. (See sample.) The desired goal is to have ALL traces coincide and horizontal; i.e. one flat line. How do we get there? Not to sound vague but there are many avenues; individual ignition trim, altering combustion chamber, piston dome, rod length, cam lobe profile or air fuel ratio to mention a few. There is NO one magic bullet! Depending on the degree of variation, one modification may be tried first; EX. The 50% Mass Burn graph shown previously, individual cylinder ignition trim would be a very good choice. Results would be instant. The most compelling testimony for cylinder pressure measurement would have to be the NASCAR open cup engine. That engine has 360 cubic inches, limited to 12:1 compression, 9300 rpm and breathes through one four barrel carburetor with specified venturi, a few teams have hit 900 reliable horsepower!

Combustion analysis is the quickest, least expensive, and the most accurate method of engine development! It allows the individual to analyze empirical data taken from a running engine that will be the basis of a blueprint for maximum efficiency and power.  It is beneficial not only to gasoline engines but also to diesel and alternative fuel.

Editor’s Note: This is the first of a multi-part series. The next will be a data review of an actual CAS test on an engine supplied to iSystems, Inc. For more information, call (406) 587-9369, e-mail iSystemsinc@gmail.com or go online: www.isystemsperformance.com.

Levon Pentecost is a graduate of Auburn University in Industrial Engineering. He has been involved in fields as diverse as manufacturing design systems to medical devices and engine design and development. He has been involved in motorsports since the 60s and has raced in IMSA, 24 Hours of Daytona and 12 Hours of Sebring. He has built and developed motors for high-profile clients such as the late Bob Snodgrass, president of Brumos Motorcars, and Jim Bailie, manager of Brumos Racing, as well as many others.

Cecil Stevens has been developing V8 push rod valve control systems for maximum performance for over 19 years. He brings expertise in in-cylinder combustion pressure, testing and analysis, and test equipment and software; and 16 years experience in NASCAR Cup racing with two teams. His achievements include: development of NASCAR Dodge and Toyota Motorsports engine valve train with combustion analysis, and 151 NASCAR Cup races without a single valve train failure.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

It’s the little things…
Oil galley plugs and how to attack them

Those darn balls, solid round plugs (iron/aluminum), and the old reliable threaded pipe plugs. Are they obstacles, or opportunities? Or just necessary little evils to reckon with, preventing comebacks.

Our approach to any head with oil galley plugs, regardless of style, is to first analyze the pulmonary system. Where does the oil enter the head and flow from there? How are the cams, lifters, variable cam timing, etc. fed? A visual inspection with a wire and small flashlight, or during rinsing after the prewash, you can force pressured water into the main feed hole observing output. You may need to use a few fingers while simultaneously blocking off some feed openings, to discover others. The use of a borescope also comes in ultra-handy. They are now inexpensive.

Second step is to strategically determine which plugs need to be removed (possibly all). I use the word strategic because we only remove those plugs necessary to thoroughly clean the head. As you may already know, it can take longer to remove and replace a few plugs than it does to machine 16 seats. If we can access or easily see behind a plug, we will occasionally use a can of carb spray with a straw attached. You can bend these straws into many shapes, allowing access to the hard to reach areas dissipating debris. After chemical washing and regardless of your cleaning method from this point, (glass bead blasting, soda blasting, ultrasonic cleaning or maybe you just stop after the chemical wash) the plugs just need to be removed.

More and more heads that enter our shop have come off of sludge engines. We have tried to clean these heads many different ways, only to discover that when we remove a steel ball, it is still packed with crud at the artery end. The head may not have lubricated properly, and then have risked debris coming loose, and possibly lodged in a hydraulic lifter, V-tech component, etc. Enough.

Third step is the removal/extraction of plugs. To remove threaded style plugs, a little heat goes a long way, easy. To remove solid aluminum plugs: we drill a hole, tap the center (usually 6mm), install a bolt or use a section of threaded rod that is attached to our slide-hammer vise grip. A few pulls and the plugs are removed. To remove ball style plugs: you can use an EDM machine to burn a hole in the plug, let cool and the plug will practically fall out on its own. The method we now use is super simple: with a TIG welder and stainless weld rod, we build the ball up to twice its size. This gives you something to grab onto using the vise grip slide-hammer. The plug will be loose in the hole, and with a few pulls, out they come. We save these plugs until the job is completed, for a measurable reference. (Note: After extraction, a small chamfer is placed around the hole, this helps installation.)

Fourth step is to fill the void. There are many situations where you can simply tap the hole to 1/16th or 1/8th pipe threads. This works well provided there are no intersecting oil galleys where the newly installed pipe plug would block off circulation to other vital areas. Protrusion of pipe plugs may also interfere with the machined mounting surfaces. To install an aluminum plug to be flush or below the surface, you first need to know the diameter of the hole. This can be done a few different ways. Measure the removed ball (it will be close to what you need) or use a ball micrometer. Another quick, simple way we determine hole size is with the use of a steel plug gage set. They come in .001 increments and we use the go-no-go method of determining hole size. Once the hole size is determined, we add .004+ press fit and select a plug from our assortment of common sizes. Special sized plugs are turned on the lathe using 7075 T6 aluminum material.

Installing the new plugs into the head: we first apply a thin layer of sealer to the inside of the hole. The sealant we use is Permatex #1 (tried and true). We have tried many other sealants, but with Permatex #1, we have never experienced a leak. Next, we use a driver in conjunction with a squaring sleeve on the outside. This starts them in perfectly straight. Now, pound in the plug, and then set the plug below the surface with a setting driver that is slightly smaller than the plug itself. DONE.

Bottom line…we do not charge enough for the service, but we DO CHARGE. Sometimes per plug, or the fee gets buried into the job itself. With profit margins as slim as they are, none of us can afford to rebuild the same head again. So… PULL YOUR HEAD OUT AND REMOVE THOSE BALLS.

Steve Schoeben is the owner and operator of HeadWerks, Inc., an automotive machine shop serving Minneapolis and surrounding areas since 1991. HeadWerks specializes in the repair of all types of cylinder heads, ranging from industrial applications and light diesel to motorcycles, antiques, racing and European autos. For more information, please call (952) 884-6306 or email info@headwerks.com.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

Additional income for your shop

We here at Republic Diesel have been using the thermal spray welding process for many years. I personally applied the coating for my first time in the mid 80’s and we haven’t slowed down yet. This process is something we do every day on a multitude of different components. It has actually become a very important part of our business and a well needed source of income.

Thermal spray welding, also known as metalizing or flame spraying, as it is sometimes referred to, was first performed around the start of the 20th century. In the 1920’s spray welding in the United States was seen mainly in coatings on Navy ships, railroad cars and on coal barges. The process was used mainly as a corrosion resistant coating. Several people believe that World War II gave flame spraying its biggest boost to date. As our Armed forces were sent overseas to protect our country their need to repair equipment and machinery in the field gave many businesses an opportunity to get into the thermal spray market. What followed was, as the old saying goes, necessity is the mother of invention.

There are several types of thermal spray processes. The most popular are the flame spray system and the arc type system, both of which we use many times each day. A few other types are Plasma, HVOF (High Velocity Oxy/Fuel) and Cold spray. Each process has different characteristics and performs differently. The flame spray system is perhaps the most versatile process to start with. It utilizes oxygen-acetylene as the fuel source and the powder is carried by another source, usually shop air or gravity. As the powder is dropped into the center of the flame, it turns into a molten state and the air pressure forces it onto the surface.

For years thermal spray welding had a bad reputation and was considered by many as Black Magic or Voodoo. This negative impact label has been a major hurdle for many shops to overcome. Some of the reasons for this may be due to the number of shops that had gotten into the field without proper training or equipment. The product these shops produced quickly failed and it was easier to find fault with the process than the people applying the coatings. The coating process is just that, a coating. It does not fuse itself to the substrate as conventional welding does. Thermal spray does not have much shear strength but under compression it can withstand a beating.

As I mentioned earlier, we find this process to be a great source of additional income. Some of the parts we apply the thermal coating to are cylinder block decks and main bore saddles. Some OEM’s (including Caterpillar) have actually approved this thermal spray process to restore material previously removed during the repair of components. As examples, crankshaft seal areas and connecting rod bores are also areas we apply the coatings. Some non-engine components we repair are transmission and torque pieces, driveline yokes and large heavy-duty brake parts.

To give you a little deeper understanding of the process I would like to walk you through the repair of a couple of components, a yoke and a crankshaft seal surface. I understand crankshaft seals can be repaired with a wear ring but when it comes to the large diesel crankshafts, the cost of the wear ring makes the application of the thermal spray a very economical, alternative process.

In this first picture you can see where the yoke seal surface has some grooves cut into the yoke. These grooves need to be repaired before the yoke can be put back into service. We have indicated the yoke in the lathe and applied the masking material. The masking material is a water soluble paint type material that will keep excess overspray from adhering in the splines, bolt holes and on non-functional surfaces. The masking material will help with the clean up when all machining has finished. We will next undercut the worn area about .015” per side to remove as much of the groove as possible. This undercutting procedure gives us a good clean line for the thermal spray coating to adhere to and it also prepares the surface for the coating. The surface preparation is extremely important; it needs to be clean and rough. The rough surface gives the coating more contact area to adhere to.

In the next picture we are applying the coating. We use the flame spray system for smaller parts. This system uses oxygen and acetylene as the flame. Once the coating powder is mixed with the flame it turns into a molten stage and air pressure forces it onto the part. While the flame could potentially melt the part, we do not allow the component to reach more than a couple of hundred degrees. There are several factors you need to take into consideration when thermal spraying components. The distance and angle you maintain from the spray gun to the part is as critical as the temperature you maintain, the amount of material you are applying per revolution, the speed the part is rotating and the exact mixture of gas pressures; all are equally important in the coating process.

As you look at the coated part in picture 3 you can see some excess material in the splines and at the base of the yoke. This overspray can be easily removed with nothing more than a good stiff wire brush. The part will need to cool before we can do our final machining as we do not want the temperature to affect the finish size of our component.

Pictures 4 and 5 are simple machine work, turning a part in a lathe. The coating is very abrasive but can be easily machined with several of today’s cutting inserts. On some parts we use a sealer to act as a lubricant for the cutting tool and also to seal any porosity in the coating.

Lastly you see the finished part, cleaned, polished and ready to return to the customer. The total time we spend coating the seal surface on a piece this size is somewhere around 45 minutes. We will use less than ¼ pound of powder to coat the part and the masking material in less than a ½ cup. When you factor in the gases and cutting inserts we will have around $20.00 to $25.00 in consumables. We find this repair to be profitable and when your customer has to replace the part he will find it very economical.

While I understand most shops do not have these yokes sitting around waiting for repair, there are many other components you could look into to increase your shop services. Small water pump shafts were an item we cut our teeth on in the early stages of developing our thermal coating department. Electric motor shafts are another source of small pieces you could consider as a new source of revenue. While there may not be a seal area to repair on these shafts, they are notorious for spinning bearings.

Thermal coating is not Black Magic, it is a very effective repair process used in the repair of heavy duty components. There are remanufacturing facilities using it every day to repair front covers and flywheel housings where pumps or covers have worked loose and fretted into the cover surface. It has become such an important part of our business that we have five machinists/technicians applying the coating every day for their entire shift. Those jobs do not even include the coating process we use in our engine component areas.

Born and raised in Louisville, Kentucky, Steve Edmondson began his 32-year career in 1979 at Republic Diesel, a leading specialist in medium to large diesel engine machining and spray welding. If you have any questions or concerns about spray welding your unique component, feel free to call Steve at (800) 292-5565.

For a PDF of this article (complete with photos), go to:
http://www.aera.org/ep/epQ112.html

Why attend?

Everyone owes it to themselves and their business to gain knowledge and network with other people within the same industry. AERA understands that traveling to national trade shows to gain this knowledge and networking opportunities is very expensive. Therefore, AERA has decided to help by teaming up with a regional host and offer these opportunities to different regions of our country and hopefully closer to your shop.

Along with the outlined technical programs, AERA is inviting leading manufacturers of engine building/rebuilding tools, supplies, services, parts and machinery to attend these conferences. Suppliers will have table-top displays that will be accessible all day long. Meeting these suppliers in a relaxed atmosphere is a great way to begin lifelong relationships that will help you prosper.

FEBRUARY 25, 2012
Hosted by SUNNEN & MAHLE at Citrus Community College, Glendora, CA
Click here for the SUNNEN & MAHLE Attendee Brochure

APRIL 20, 2012
Hosted by JOE GIBBS RACING, Charlotte, NC
Click here for the JOE GIBBS RACING Attendee Brochure

MAY 19, 2012
Hosted by LIBERTY, New England Warehouse, Worcester, MA
Click here for the LIBERTY Attendee Brochure

JULY 19, 2012
Hosted by EPWI, Denver, Co
Attendee Brochure - coming soon!

SEPTEMBER 27-29, 2012
Hosted by ROTTLER (In conjunction with the Rottler open house) Seattle, WA
Attendee Brochure - coming soon!

SEPTEMBER 28-29, 2012
Hosted by COMP CAMS, Memphis, TN
Attendee Brochure - coming soon!

DECEMBER 6-8
Hosted by AERA (In conjunction with the IMIS TRADE SHOW), Indianapolis, IN
Attendee Brochure - coming soon!

We will have more specifics coming your way via brochures, email, website and Engine Professional magazine in the coming weeks and months. Please mark these dates now and start making plans to attend a Tech & Skills Conference near you!

QUESTIONS? Call AERA toll-free 888-326-2372 or direct at 815-526-7600.

• FEBRUARY 25, 2012
  Hosted by SUNNEN & MAHLE at Citrus Community College, Glendora, CA
• APRIL 20, 2012
  Hosted by JOE GIBBS RACING, Charlotte, NC
• MAY 19, 2012
  Hosted by LIBERTY, New England Warehouse, Worchester, MA
• JULY 19, 2012
  Hosted by EPWI, Denver, Co
• SEPTEMBER 27-29, 2012
  Hosted by ROTTLER (In conjunction with the Rottler open house) Seattle, WA
• SEPTEMBER 28-29, 2012
  Hosted by COMP CAMS, Memphis, TN
• DECEMBER 6-8
  Hosted by AERA (In conjunction with the IMIS TRADE SHOW), Indianapolis, IN

AERA invites all suppliers to present their products and distribute literature on table-top displays at these one-day conferences. If you cannot attend, AERA will set-up your table-top display and be sure your literature is distributed. AERA associate members pay only $325 for one 6 ft. table. (Non AERA members pay $400.) Space is limited.

Click here for the 2012 Display Brochure and Registration Form

QUESTIONS? Call AERA toll-free 888-326-2372 or direct at 815-526-7600.