6/1/2001
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Pushing Into High Performance Frontiers
By Ken Weber
Engine Technology is the Talk of the Town at SuperFlow’s 11th Annual ATEC
One of an engine builder’s biggest challenges is staying current with advancements and developments in the industry. Information passed down from manufacturers of equipment and components, is one of the key ingredients, and networking with key personnel at the manufacturing level and leaders in the application of new technologies in the industry is the ultimate method to obtain that information.
For the last 11 years, Superflow Corp., of Colorado Springs, CO, in partnership with the University of Colorado, has hosted its Advanced Engine Technology Conference.
I don’t know of any other format where you can find people of this caliber, in a relaxed casual environment, who are willing to answer questions and share their vast experience and knowledge with anyone. The titles of some of the programs may make you think you need a master’s degree in mechanical engineering to understand the presentation, but that’s not the case at all. While the material is naturally of a technical nature, it is usually presented in a manner that is simple and understandable.
The first day of speakers at last year’s conference consisted of presentations on "Atmospheric Effects on Engine Power Production" by Dr. Dean Hill of New Mexico State University; "Manufacturing Challenges of Motorcycle Engine Testing and Development" by Gary Valine of Buell Motorcycle Company; "Cylinder Head Development and CNC Production Process" by Mike Chapman of Chapman Racing Heads; "Programmable Ignitions and Application Techniques in Engine Research and Development" by Steven Masters of MSD Ignition; and "An Update on Material Application and Selection for Racing Engine Components" by Ai Wood of Detroit Racing Components.
Hill gave all the low altitude "flatlanders" a lesson in why they feel light headed and dizzy just walking to the restroom at the 6,200 foot altitude of Colorado Springs, and also why their vehicle feels like it’s pulling the race car trailer. In airplane lingo, it’s called density altitude, caused by a combination of temperature and altitude, and it’s why correction factors are necessary when doing dyno work.
Gary Valine, of Buell Motorcycle Co., detailed the process of meeting drive-by noise emissions certification with his company’s bikes. The problem is to effectively muffle the exhaust, intake, and mechanical noise emissions. In the Buell, the problem is compounded by the fact that a V-twin emits lower frequency sound waves than the higher revving engines of a four-cylinder bike. Since the sound absorbing material must be the thickness of the wavelength to be effective, this means the muffler must be either bigger or more restrictive, or both. Valine went on to cover Buell’s development of digital fuel injection for off-road racing.
Mike Chapman discussed cylinder head and manifold prototyping, and the process he uses from concept design through finished product. Using stereo lithography and wet flow testing, combined with Solgen rapid prototyping, he can build, test and dyno a cylinder head design in two months to 10 weeks. If necessary, it takes about a day to make a major change to a port, and retest it.
In the area of tidbits to take home, Chapman pointed out the current trend towards steeper intake valve seat angles — as steep as 58° — and large volume ports. He also had slides showing the use of spray Dykem during flow bench testing to simulate wet flow patterns. He pointed out that a head with less swirl will generally have a broader, flatter torque curve.
MSD’s new programmable ignition system was detailed in the presentation by Steven Masters. Using MSD’s new Windows-based, Pro Data Plus software, which can be downloaded from the company’s Web site (www.msdignition.com), this system offers individual cylinder timing adjustments and timing retards for each gear. A fiber optic number one cylinder pickup eliminates the need for a cam sensor. Primarily drag racing oriented, this system offers the next step in individual cylinder tuning capability.
In the final session of the day, Ai (Woody) Wood, of Detroit Racing Components in Ortonville, MI, (DRC is a supplier to Formula 1 and CART), discussed the mechanical properties and benefits of AMC 225xe, an aluminum matrix composite, suggestions for failure analysis and current coating technology.
Since aluminum-beryllium ($600/lb) alloys have been outlawed in Formula 1, they have been replaced with new application-specific alloys such as AMC 225xe. This alloy is being used in pistons, pushrods and other components.
In discussing failure analysis, Wood advised not fitting the broken pieces back together, since the fracture may be your best clue to the actual cause of failure. Different styles of fracture are typical of different types of failure. A cup-cone fracture is typical of tensile failure, the clamshell is a symptom of fatigue failure, and a faceted surface shows high temperature failure.
Regarding coating technology, Wood pointed out that coatings are materials on materials, and are effective as protective surfaces, thermal barriers, friction reducers, corrosion barriers and lubrication enhancement. One coating discussed is Apticote 2000. Used in IRL engines, it has dramatically reduced wear, shown superior oil retention (giving more horsepower from friction reduction) and allows finer bore finishes which further reduces friction. Cylinders can be run for three races without rehoning, Wood said.
In the future, with a trickle-down from aerospace technology, we can expect new material introductions at a faster pace than in the past. There will be an emphasis in some circles (Formula 1 for instance) on application-specific material developments, and coatings will continue on a strong development path. With the increase in computer power, Finite Element Analysis will become more common, and machining technology will see big improvements.
The third day of the conference opened with "Coolant System Flow in a NASCAR Winston Cup GM SB2 Engine" presented by Steve Wilson of Richard Childress Racing and Jim Covey of GM Racing.
This presentation detailed the investigation of the two center exhaust seat temperatures on the Chevrolet NASCAR SB2 cylinder head and how cooling flow restrictors in different locations affected the spread of those temperatures. Tiny thermocouples were installed at key locations in the heads and in the coolant exits from the heads to record responses to changes in flow.
Several different combinations of restrictors in the coolant exits and flow paths for the coolant from the block past the two exhaust seats were tried. Data was collected in the last 2 seconds of a 6,500 to 8,500 rpm dyno pull, and then later in actual track testing. The final optimized flow was around 30 to 35 gpm, with a 310° F maximum head temperature. Using a 22-24-lb. cap, resulted in 40 lbs. of pressure in the block and a 20 lb. differential between the block and the radiator. A more detailed account of the test is available as SAE paper # 983024.
Velocity is the focus of many of the top engine builders today. Velocities on the track to be sure, but in this case, we heard about air velocity through the ports and valves in the manifolds and heads. Darin Morgan, manager of cylinder head research and development for Reher-Morrison Racing Engines, provided a lesson on basic cylinder head dimensions and port sizes, and illustrated the superiority of oval ports by comparing specifications on Dart Big Chief 14° square port and 14° oval port heads.
Starting with intake valve area, Morgan explained that the correct valve size is between 52.5 percent and 54 percent of the cylinder bore diameter, such as a 2.450˝ valve in a 4.600˝ bore. The actual size used is a matter of experience for the application and the head used, butit is better to undersize than oversize. An undersized valve moves the power band down in the rpm range, while an oversized valve produces poor performance throughout the rpm range. The goal is to move the maximum air through the minimum area. A sharp-edged orifice will flow 146 cfm per square inch. Comparing the flow coefficients for different sized valves and ports will give you a measure of their relative efficiencies.
When developing an intake port, shoot for 100 percent coefficient at the pushrod reduction or approximately 2 inches up from the start of the short turn. The port throat under the valve seat should be a maximum of 91 percent of the valve diameter, and the cross sectional area at the apex of the short turn should be 105 percent to 110 percent of the valve throat. Above the pushrod restriction, the port should taper at a 2°-4° angle to the entrance to the runner.
In the comparison of the oval port and square port Big Chiefs, Morgan explained that the relatively sharp corners of the square port create turbulence which impedes the flow in the corners of the port, whereas the large radius of the corners of the oval port provide much lower flow gradients across the cross section of the port, and therefore more flow per square inch of port area.
The only reason to use small corner radii (square shapes) is to increase port volume when the port is too small. In a head where you have ample port volume, use the largest corner radius possible, to minimize turbulence. Morgan did caution that a round port tends to develop a vortex that screws up mixture distribution, so avoid the temptation to make your port perfectly round.
On the exhaust side, Morgan stated that the port throat should be 88 to 89 percent of valve area in low lift applications and 90 percent for higher lifts. Some Pro Stock heads are using up to 95 percent.
Brian Scollon, general manager of GRP Connecting Rods, discussed some of the features of his line of billet aluminum connecting rods. He pointed out that his production time for an order of connecting rods is approximately five hours, that they frequently ship same day, and all of his sales are manufactured as custom orders.
The surprise hit of the 1999 conference, Rafael Fuentes, import project manager for Moroso Performance Products, was back, accompanied by Kevin Brown, Product Development Engineer for Moroso. The pair continued 1999’s discussion centered on oiling systems.
Oil system failures in popular import engines have become a problem for high output applications. The crank snout-driven oil pumps in these engines are prone to failure from several specific issues that vary from engine to engine: the pumps are built to close clearances; the geroter operates off a fixed eccentricity; and the crank nose deflects under high stress loads, causing interference and binding between the pump gears and housing. The result is catastrophic pump (and engine) failure. In addition, Honda B and D series engines have the same oil pump design using a cast aluminum backing plate that flexes under high loads. Honda H series pumps have an extra fastener located to prevent flexing and adding longevity to the system.
After some background on the principles of fluid flow and the differences between gerotor and spur gear types of pumps, the duo detailed a list of design criteria to use when setting up an oiling system for an engine, and the advantages of wet and dry sump systems.
After this session, attendees were treated to a tour of the SuperFlow facility, including dyno testing of a Honda/Acura turbo 4 cylinder that made 765 horsepower on racing gas and 22 lbs. of boost. While enjoying the tour and snacks, I took advantage of a networking opportunities by discussing computer engine simulations with Audie Thomas of Audie Technologies, and some points of cam design with Billy Godbold of Comp Cams.
On Wednesday, day four, W. Kurt Dobson presented a project to use a computer program to design and fabricate headers for an Altima powered by an injected twin turbo small block Chevy and intended to compete in the Silver State Classic Challenge.
Dobson and his brother developed a high tech 3D computer program to determine all of the bends and cuts needed to make all of the tubes in a set of headers so that they will clear all of the chassis components and each other, yet end up at the right location and be very close to the desired length. Dobson stated that the exhaust tubes for this car were measured and designed in about 30 minutes, and both sides of the system were fabricated and welded in one day. Having built many a set of headers, I can testify that a program like this would definitely take the guesswork out of many projects.
Javier Gutierrez, a self-proclaimed graduate of BYU (Back Yard University), and owner of JG Engine Dynamics, specializes in high output small displacement import engines. He is the builder of the Honda/Acura engine that was on the dyno the night before. In building one of these 2500 cc screamers, Gutierrez starts by machining the top of the block and fabricating and installing a matching plate that supports the top of the free standing cylinders. He then inserts high nickel content sleeves through the deck plate, providing a very rigid cylinder – a necessary step, he says, because these motors tend to destroy cylinders under high boost conditions.
A lot of attention is paid to the cylinder head porting and the piston shape. The chambers are welded to reduce the volume and add two quench areas. Compression is 11:1. The pair of intake valves flow 289 cfm and the exhausts flow 238, giving an 85 percent intake/exhaust relationship. The intake valves use a full radius seat while log type manifold with radiused entrances to the runners. Because of flow variations, an offset inlet to the manifold was developed. The exhaust system uses short equal length runners into the turbo. Javier says the compressor outlet temp runs about 250° F before the intercooler, and exhaust temps are around 1500° F for a drag motor and 1200°-1300° F for an endurance motor.
Gutierrez revealed that he has built some R & D engines that have made nearly 1000 hp from 2500 cc.
After the break, Richard Maskin, owner/president of Dart Machinery, gave us some insight into the world of Pro Stock engine component development. In the discussion of the evolution of the Pro Stock engine, he pointed out that these engines have matured from 1000 horsepower to around 1280 horsepower since 1982. In spite of the increases in power, a major part of the Pro Stock ET improvement has come from acceleration, not horsepower. In the evolutionary process, the "weak link" circle is a constant companion. Fix the weak crank and the rods fail. Fix the rods and the pistons fail, and so on. The lightweight cranks were short lived until Maskin started using cranks made from EN30B by Randy Winberg. Larger base circle cams help strengthen the camshaft, but lifter hang out becomes a problem. He has valve springs wound to his own specifications to work with the .930.
Recent efforts have resulted in around a 15 hp improvement. Maskin indicated that the revised firing order relates to improved flow distribution in the intake manifold. Piston ring seal is first and foremost and involves properly preparing the block — which includes vibralax treatment with the heads and main caps installed, and the rings and the piston ring grooves — which are cut to fit each ring. Pistons are coated to retain combustion heat, and coating the bearings makes them more forgiving of debris.
The final presentation of the conference, titled "Spintron Data Interpretation and Analysis of Dynamic Valvetrain Behavior," was by Thomas Griffin of Comp Cams. Griffen detailed the relationships between mathematically modeling valvetrain behavior and then collaborating the mathematical model experimentally on a Spintron. He used an example of a situation in NASCAR to illustrate the importance of Spintron testing. Several years ago, Chevy engine builders were adding more and more rocker ratio to their engines to achieve higher lifts and more rpm. The Ford camp found out about it and followed suit. After all, they reasoned, if it worked for Chevy, and all the pieces were the same, it should work for Ford, right? Wrong. The barrel size of the two camshafts and the geometry of the valvetrain components are different, and severe valve bounce resulted with the attending failure of valve springs.
As always, I came away from the conference with a notebook of information and a pocket full of business cards from new contacts. During the times between presentations, at the luncheons, and the closing banquet, I had the opportunity to develop new contacts, renew old ones, and discuss my own engine building ideas and concerns with people who very willingly provided answers to my questions. Sometimes, just listening to conversations between others is very informative. I feel the personal contacts made during the week are as much benefit as the presentations themselves.
For more information about the 12th Annual Advanced Engine Technology Conference, to be held Nov. 10-14, 2001, visit www.superflow.com.
You may e-mail Ken Weber at kweber@engine-builder.com