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Straight to the Limit

A race car engine can be a real monster. Especially the NASCAR ones, which are designed to be more powerful, efficient and tuned than any “normal” car engine. Typically this means more robust, lightweight components to rotate, as well as higher compression ratios, a more aggressive valve vent and less rotating and reciprocating friction. Also important for achieving optimization is that parts are more accurate and have tighter tolerances.

The smell of oil lingers in the air as we enter the shop. All kinds of tools and parts are scattered around. ECR Engines is a highly specialized company for the NASCAR racing series in the United States. The North Carolina company produces race car engines for NASCAR’s top two series. For the IMSA series, it manufactures DPi Cadillac engines.

Quality Manager Jim Suth is responsible for supplier quality management, metrology, failure analysis and special project design.  

Problems lie ahead

The facts may be complicated but Jim Suth makes it all sound so easy: “In principle, our engine works the same way as a four-stroke pushrod V-8 engine found in a Chevrolet Corvette,” he says. But that’s where the similarities pretty much end. ECR engines are naturally aspirated and produce up to 750 horsepower. The quality manager talks about his engines as though they were close friends. He loves what he does.

The engines are specially built for NASCAR races and are thus completely custom-made. Very few components are standard off the shelf. Unlike production engines, engineers know exactly how long their engines must last, the speed they will operate at, and the fluid temperatures they will experience.  

Optimization is needed

To achieve this high standard, ECR engines are developed with computer simulation including Finite Element Analysis (FEA), Computational Fluid Dynamics (CFD), Computer Aided Design (CAD) and countless hours of dynamometer power and durability testing. Many race series change their base engine design and architecture quite often. NASCAR does not – they stick to their tried-and-true procedure.

“For example, our current base Chevrolet R07 engine debuted in 2007. For over ten years we have been optimizing every part for optimal efficiency, power and reliability for a 650-mile race. We are now working toward making these engines run for 1,300 miles without sacrificing power or reliability,” says Suth. He and his team adhere to NASCAR’s rules for all engine components.  

Oil temperature is key 

There are critical limits to engine speed, water and oil temperatures. Engine speeds have been designed to strict safety margins that permit historical or predicted speeds for a given racetrack and car gear selection. However, the engine must be able to withstand quick overspeed events seen during shifts, leaving the pits and early on a fresh set of tires. In NASCAR races, the latest trend has been to run the engines hotter for aerodynamic benefit.

In some cases the engines can experience over 290°F in oil and water temperatures for 600 miles. “We must also build in protections for the occasional hot dog wrapper on the car grill which has caused intermittent temperatures well over 325°F,” says Suth. 

The solution 

ECR mechanics build over 600 engines a year. The challenge are fast-paced development and the production cycles. “We must have reliable metrology and microscopy systems,” explains Jim Suth. “We cannot afford any downtime. This has been a problem in the past. With ZEISS we have a perfect track record.” The systems are tested in the ZEISS Lab to verify the incoming quality of critical components. The Failure Analysis investigations find the weak point in case there is an issue with one of the components.

In early 2017, ECR suffered a “bottom-end” engine failure during a test. This resulted in a fireball from the bottom of the engine in the test cell. A catastrophic failure with a lot of secondary damage to the components.

“We were able to pinpoint the cause of the failure using our microscopes to an accuracy of 50 to 100 micron foreign particles that were embedded in our bearings.” Suth’s engineers could also quantify the particle chemistry and determined the source of the particles, which came from an improperly manufactured assembly in the oil system. They did this within 24 hours. Suth says: “For the last few racing seasons, we have produced some of the most durable engines in all of NASCAR – with the best horsepower contributing to wins and championships.” The next race begins tomorrow. 

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