AETC Conference Day 2: Pistons, Gaskets and Engines

The eagerly awaited second day of the AETC conference got underway with a schedule of Hall of Fame engine builders, award winning product engineers and even a College Professor of Mechanical Engineering from Clemson University.  Like the conference promoters promised, “The industry’s key thinkers” sharing technical information.

Leading the batting order on the second day was National Sprint Car Hall of Fame Engine Builder, Gary Stanton of Stanton Racing Engines.  Stanton has fielded cars with a who’s who list of drivers over the years including Al Unser Jr., Jeff Gordon, Dave Blaney, Brad Doty and Steve Kinser.  In addition to winning Championships and being inducted into the Sprint Car Hall of Fame, in 1997, Stanton was selected by Mopar to develop an aluminum sprint car engine.  The engine turned out to be a championship winner and the partnership between Mopar and Stanton has continued since then.

Gary Stanton, National Sprint Car Hall of Fame Engine Builder.

Gary Stanton – Advanced Midget, Sprint and Short Track Engine Building Techniques

Stanton started his presentation explaining that his success in sprint car engine building stemmed from his love of sprint car racing.  He was emphatic about needing passion in order to become a great engine builder.  According to Stanton, the passion that you get from engine building will allow you to do incredible things.  For example, when Stanton was asked by Mopar to build their Midget engine, Stanton started with a blank sheet of paper and less than 33 weeks later, had the finished version of the two time USAC Championship winning engine.

Stanton claimed that the keys to success in creating the Mopar Midget engine lay in four areas:

  • A great manufacturing partnership between Stanton Racing Engines and Mopar.
  • Great geometry in the engine, primarily the bore and stroke ratio and a shorter engine deck.
  • Weight.  Less weight and a resulting lower roll center.
  • Manufacturing a great cylinder head for the engine.

Stanton continued by breaking down what he had done differently despite the reality that “there are no secrets in building a successful motor.”  According to Stanton, “Cheap parts never pay off.  Always use quality parts, and select parts that work together.”   He also explained that cylinder bore to ring interface is critical, “Ring development has come a long way.  You have to consider the style of piston ring, radial depth, coatings and finishes.”

Stanton explained that bore finish is extremely critical and bore finish and ring matching make the difference in an average engine and an exceptional engine.  “This is part of watching all the details” he said.

He felt that “Current pushrod engine design is non competitive” and that is why they designed their own heads that featured an overhead camshaft.  Stanton claims that there is a distinct RPM advantage, valvetrain stability and reliability with the OHC design.  “All this and it’s a lighter overall package,” he said.

Stanton explained that the new Mopar AS1 engine will be legal in USAC competition next year, and it will be “the next generation of Midget engine.”

Next Year’s Advanced Engineering Technical Conference Topics

Before the next speaker started his presentation, Brian Reese and Tammy Holland of AETC announced that next year’s Advanced Engineering Technology Conference would cover general topics from multiple disciplines.  Many in the audience felt that this move toward general engine building would promote a wholesale sharing of engine technology between all forms of racing.

Stephen Golya, Principal R & D Engineer for JE Pistons.

Stephen Golya – Advanced Analysis of Piston Design and Leading Edge Technology for Circle Track Race Engines

Stephen Golya, Principal R & D engineer for JE Pistons, took the stage in a much anticipated discussion on piston design. Golya focused his presentation on the development of a 410 sprint car piston design, however, the process of designing a piston is identical for all types of racing piston design, so it translates to engine builders from all aspects of motorsports.

Golya started by saying that he was challenged to design a 410 sprint car piston that could produce ten more horsepower.  In order to develop more horsepower, Golya started with data acquisition by looking at the current model of piston for the 410 sprints.  According to Golya, the piston was designed for circle track engines developing up to 750 horsepower, and featured a full round skirt with box style pin bore struts.

His goal in the new piston design was to develop ten more horsepower, but he also wanted to redesign the piston to meet areas prone to weak spots. In order to achieve these lofty goals, Golya plotted values for material fatigue and temperature into a CAD program and began to simulate run cycles based on the data he acquired from deconstructing the old style pistons, failure analysis, and other empirical data collected over the piston’s manufacturing run.

According to Golya, the data collected and studied gave him some strategies in designing the new piston:

  • Increase strut stiffness and reduce compressive stress concentrations.
  • Reduce crown stresses, especially where the valve pockets meet.
  • Improve pin bore contact stresses.
  • Maintain skirt contact pressure.
  • Reduce reciprocating weight.
  • Make the design forgeable and cost effective.

With these strategies in place, Golya said that he started changing pin bore bridges and braces looking to “take advantage of geometry features to design for strength.”  With each change, Golya ran 14 separate iterations looking for temperature and stress loads.  In doing the design work with computer aided design programs, he was able to “take material from one area and move it to where it was needed.”

After Golya had made changes and evaluated all the data, he began running cycles on the models “looking for uniform wear and how the loading was distributed.”  Other design considerations were then given to the placement of wrist pin oilers, before working on the piston skirts.

Golya moved forward with the piston skirt design much in the same fashion but more time was spent studying the primary motion of the piston.  After studying the motion of the piston in the cylinder, Golya performed thermal profiles and stress profiles to isolate the expansion of the piston skirts.  According to Golya, he was looking to design a skirt that would be stable, wear evenly but also trap some oil to create a hydrodynamic film between the skirt and cylinder wall.

Golya hit his taget with a sprint car piston that achieves greater horsepower and lasts hundreds of laps longer than previous versions, but he warns would be piston designers; “Changing form is very effective, but you have to be careful in the changes you make.”

Greg West, Fel-Pro Gasket's Product Engineer.

Greg West – Gasket Designs and Installation Considerations for Circle Track Race Engines

One of the highlight speakers of the day was Fel-Pro Gaskets‘ Greg West. West has been responsible for the design of gaskets in the Fel-Pro Performance line and has been awarded three patents for head gasket designs.

West explained that the “wire-ring head gasket was the first head gasket designed specifically for high performance engines and was the gasket of choice for many years.  But when horse power levels increased, the wire-ring gasket reached it’s limits.”  Although the high horsepower engines are beyond the capabilities of the wire-ring gasket, West said “There are many applications where the wire-ring gasket is a good choice.  It’s compatible with rougher surface finshes and lower horsepower performance engines.”

West continued by introducing the MLS gasket to the audience. “The MLS gasket features functional layers, between one and four layers, a stopper, sealing beads, primary and secondary coatings.”  According to West, the functional layers have a rubber coating on the outer layer with 2,3 or 4 embossed layers attached.  Between the embossed functional layers are distance or shim layers that are used to control the overall thickness of the gasket.

West told the audience to think of the embossed bead as a valve spring. “As you compress the gasket, you are compressing the ‘spring’. When the gasket is compressed, gasket loading is increased. As each cylinder fires, the cylinder head is lifted off the deck of the block. The lifting motion causes the emboss bead to compress and uncompress as the engine runs. The gasket must maintain sufficient loading during head lift to provide a good combustion seal.”

West explained the testing technique that Fel-Pro uses to evaluate their gasket designs. “Not all MLS gaskets are created equal,” he continued, “Head lift is an important consideration in head gasket design.  The gasket can only do so much to overcome head lift.”

One of the high points of West’s presentation was when he proclaimed that “Oil on head bolt threads is not recommended.”  West went on to say; “Remove the black oxide coating off of the threads and thrust face of the fasteners.  We suggest using CMD #3 grease on the threads and thrust faces of the nuts and washers.”

According to West, when you tighten head bolts, you should “cycle bolts just as you would do with rod bolts. Put them on, let them sit for some time, then remove and reinstall them a couple of times.”  This will help the bolts maintain the clamping load.

Conclusion

It was obvious that the speakers at the conference had kept up with the changing environment and technology in race engine technology. What’s most important about these speakers is that they are willing to share their information and technical advances through conferences like the AETC. What’s clear to this author is: If you miss this conference, you are missing some information that is cutting edge and will change your race engine program.  The tips, tricks and explanations of how products are developed are invaluable in understanding how to get the most from your engine program.

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
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