“We didn’t know what was going on. We didn’t think we changed anything,” remembers Russ O’Blenes, manager of GM Racing and Advanced Projects. “Turns out they all had the same failure where they lost an exhaust lash cap.”
The team talked to engineers, conducted breakaway tests and came up with a quick-fix solution involving Loctite and silicone—literally chemically bonding the cap to the retainer—and both cars finished the race. But that band-aid remedy didn’t identify the underlying source of the problem, let alone offer a permanent solution. It would take more than garage diagnosis and quick thinking to unravel this mystery. It would take a village, of sorts, paraphrasing the classic African proverb.
Welcome to the new GM Powertrain Performance and Racing Center, a spectacular showcase of high-tech engine-building tools, striking design elements and rich racing history. It’s also a stronghold of innovative thinking and go-fast spirit. This is where horsepower is not only produced, but problems are solved.
Super highway of information exchange
The 111,420-square-foot center brings together more than 80 engineers, builders and support staff with the latest and sometimes top-secret development and test equipment to build or help improve engines for NASCAR, NHRA, IndyCar, IMSA and other racing series. The racing center is located adjacent to the massive GM Global Powertrain Engineering Center in Pontiac, Michigan, where the automaker develops engines, transmissions and electric/hybrid/fuel cell components for its cars and trucks. It’s all part of GM’s vision to effectively leverage technology resources that have been stockpiled from decades of competition and automotive manufacturing.
I’m a kill-it-dead kind of guy.–Russ O’Blenes, GM racing
Not the least of officials looking for the fast lane on this expressway is O’Blenes.
“We’re excited about having a relationship with the CAE (computer aided engineering) guys,” says O’Blenes. “Because we’re at such a high end of engine speed and cylinder pressure, if you look at production engines they’re heading in that same direction. So these guys are really hungry to develop processes they can use to develop production engines by using our data.
“We can instrument engines for them, then they can work on what it takes to correlate their models at higher cylinder pressures, higher engine speeds, faster combustion,” adds O’Blenes. “We’re able to bring their competency up and also benefit because we’re going to get to use those tools.”
Ten engine-build bays
The race center was previously located at the Wixom Performance Build Center that was probably best known for sponsoring customer builds on LS7 and LS9 engines for Camaro and Corvette owners. The customer build program was moved to Corvette assembly plant in Bowling Green, Kentucky, while the racing operations relocated to the new facility in Pontiac as part of GM’s $200 million investment in the sprawling powertrain campus.
“This facility has the ability to get the final degrees of efficiency and performance,” promises Jim Campbell, GM’s VP of performance vehicles and motorsports.
Although only about half complete, the new racing center was opened in early February for a media preview. A sampling of the center’s capabilities include full CNC machining, engine builds, electronics and telematics, design release, dyno validation and track calibration. Engines the center will either have full or share some technical responsibility include the 358ci NASCAR R07 V8, the IndyCar 2.2-liter twin-turbo that was co-developed with Ilmor, the COPO Camaro V8 engines for NHRA Stock and Super Stock, the Cadillac ATS-V.R twin-turbo V6 and the 5.5-liter V8 used by the Corvette Racing C7.R team. Additionally, high-performance crate engines and crate powertrain systems offered in the Chevrolet Performance catalog will be developed at the new facility.
Some of the facility highlights include 10 engine-build bays, complete machine shop with nine CNC machines, laser scanners and a 3D printer, an electronics lab for design and calibration of control systems and four state-of-the-art AVL engine dynamometer cells. Included in the dyno section are two engine dynos, a driveline dyno and a new electric driveline dyno. The driveline dynos are used to test differentials or the electric dyno could be set up to spin the engine for valvetrain tests. And if four dynos aren’t enough, the race center could have access to one of the more than 80 dyno cells in the global powertrain center.
Have a club meeting there!
Finally, there’s an interactive lobby and meeting space that officials say will be open to clubs, suppliers or race teams and could support up to 125 people for private functions.
“We expect the center to be fully operational by July of this year,” promises Nicolson.
The driveline testing capabilities of the new racing center are likely to be quite busy.
“You know that some of the things we have in NASCAR are somewhat antiquated,” quips NASCAR driver Ryan Newman, who visited the center on media day. “We use the old style gears and locker. It has a lot of moving parts, which in turn makes it challenging to get the vibrations out. That’s one of the biggest things we work on is getting the vibration out, especially in the rpm we’re running.”
Newman also looks forward to when his team at Richard Childress Racing can connect with ECR Engines at the center.
“They have to come together at a place like this to work on optimization,” says Newman. “It’s a unique situation that [the center] gives us.”
Getting back to the opening storyline, a driveline dyno is exactly what the Corvette team needed to track down the misbehaving lash caps at Sebring.
“To figure out how it actually happened, we instrumented an engine with exhaust sensors and also cut away part of the valve cover for a high-speed camera that takes 100,000 frames a second,” continues O’Blenes, who started at GM building engines for Jimmy Johnson’s stadium truck before the brash off-roader started winning championships in NASCAR. “What we found out watching the video was that every time the valve closed, the lash got taken up on the rocker arm. So the valve would close and the lash cap would actually float. The video also showed a spring surge.”
Eliminating the problem
Then the team started comparing other data and discovered that the lash caps always rocketed off the valve stem during a shift.
“This was our first race with paddle shifts,” recalls O’Blenes. “There was a pressure pulse in the exhaust port. It correlated with a spring surge and it actually lifted the valve off the seat because it overcame the available spring load and allowed the lash cap to pop off.”
Next the team started analyzing shift data, because torque reduction in the engine is needed to allow the transmission to shift. Turns out the method of torque reduction caused a “pop” in the exhaust.
“And there’s a certain split second where everything could line up wrong,” explains O’Blenes. “If you got it on the negative side of the spring surge and there was a big enough pop to overcome it, you could spit the cap off. So we redid the shift system. Some of the analysis that figured into the solution came from the driveline tests. In the past we had done all of our engine durability in engine-only mode. Now, every year we at least do one full durability run with the driveline dyno just to make sure we never get bit by something like that.”
And to truly ensure the problem never surfaces again.
“Also, I’m a kill-it-dead kind of guy,” admits O’Blenes. “So we also developed an exhaust valve that didn’t need a lash cap.”