The third and final day of the 2010 Advanced Engineering Technology Conference (AETC) ended with a couple of high notes. The final speaker of the conference light the house up with his stories about burning things and a roundtable session with some of circle track’s greatest living engineering legends. When it was all said and done, almost everyone agreed that this year’s conference was one of the best in the 21 year history of the event.
Leading the final day session was Dr. Andy Randolph from Earnhardt-Childress Racing. Dr. Andy, as he likes to be called, holds a PhD in Chemical Engineering from Northwestern University which probably explains why he likes to watch things burn. A true firebug, Dr. Andy held the audience’s interest with stories about burning various things over the years. Randolph definitely found the perfect job as a combustion expert at ECR.
Dr. Andrew L. Randolph – The Advanced Science of NASCAR Cup Engine Optimization
Dr. Andy started off by explaining the typical engine that he works with now, the NASCAR Sprint Cup engine, which is a small block V8 with cast iron block and aluminum cylinder heads. He explained that they are limited to a 12.0 max compression ratio with a single Holley 850 four barrel carburetor. Randolph says that these engines develop 870 horsepower and 560 ft-lbs of torque in the open engine configuration and 490 horses and 380 ft-lbs of torque with the restrictor plate. That is, depending on the restrictor plate size.
Summarizing the engine, Randolph said; “It’s pretty remarkable. We’re using 1960’s architecture with 2000’s materials and coatings. For old stuff, we’ve polished that turd pretty good by now, but there’s still power left to find.”
Randolph explained the best way to go about gaining more power was to consider the V8 engine as “Eight individual engines that share a single crankshaft.” According to Randolph, each of the cylinders must be optimized to obtain maximum performance. “When you optimize each cylinder to it’s peak performance, that’s free power.”
He went on to explain that there were several problems with getting each cylinder to the same level. “Individual cylinder air-fuel ratio maldistribution also reduces total engine peak power.” By his measurements, this maldistribution costs about 7 horsepower when global spark timing is used and about 4 horsepower when individual cylinder spark is used. “Individual cylinder spark optimization will help you recover some of what you lost.”
Another issue that Randolph addressed was thermal efficiency loss. “Because the center cylinders are surrounded by the outer cylinders, you will experience some loss of thermal efficiency. In addition to thermal efficiency losses, there are other efficiency losses in volumetric efficiencies, and mechanical efficiencies. Volumetric efficiencies, as he explained, “are losses through intake or exhaust restrictions, charge [air-fuel] dynamics, and mechanical dynamics [valve train].”
In order to achieve the most from your engine, Dr. Andy explained that you must improve the thermal efficiency, volumetric efficiency and mechanical efficiency to their optimal levels. Randolph went on to state that the current Sprint Cup engine is only achieving 35% efficiency. Backing that statement up by saying that these engines are using 2430 horsepower of potential energy to produce 860 horsepower actual at the output. For engineers that are trying to find more horsepower in these engines, Dr. Andy says; “The good news is: we all have jobs for the next few years.”
Randolph went on to breakdown the losses in great detail. Heat to water costs 150 horsepower, heat to oil costs 35 horsepower, unburned fuel costs another 145 horses. Remarkably, in Dr. Randolph’s testing, blowby only cost 2 horsepower from the total potential horsepower numbers.
According to Dr. Randolph, “567 horsepower of losses are via mechanisms that can be addressed through engineering innovation.”
Following Dr. Randolph’s presentation, all speakers from the conference along with a couple of selected guests, held a roundtable question and answer session where the audience could present any question to the panel. The roundtable discussions alone were worth attending the conference. COMP Cams Scooter Brothers addressed the panel and audience, getting everyone to think about the future of racing as we know it, and the things that we can do to spread that passion. Brothers particular concern was how to make racing “relevant” to the OEM companies and the population as a whole. That is a dilemma whose time has come, and according to Brothers, “If we don’t start addressing it now, we might not like the way the future plays out for racing.”