The competition at this year’s World Time Attack Challenge was fierce as teams ventured from across the globe to compete at Australia’s Eastern Creek Raceway. In the end, only two powerhouses were left standing. Sierra Sierra Enterprises and Cyber EVO pulled out all the stops as the battle raged on, with only one claiming the championship title. Follow along with our very own Eric Hsu, as he reveals an exclusive behind-the-scenes diary of the action that unfolded—drama and all—at WTAC.
Prerace Preparations
Whenever I visit Sierra Sierra Enterprises (SSE) to work on Christine (SSE EVO’s nickname), I get to stay in the small town of Minden, NV. Located just one hour south of Reno, Minden is central to some of the greatest outdoor networks of rivers, mountains, lakes, and all kinds of awesome activities, but unfortunately, I never get to partake in any of that. When I go to SSE, I’m there to do one thing and one thing only: to make sure Christine is running at her maximum potential.
BorgWarner
Back on May 5, 2011, I returned to SSE to finalize the turbo sizing with Brock Fraser from BorgWarner and, of course, team members Mike Kruszewski, Jethro Austin, Richard Raeder, and Ron Parks of SSE. The last time Dave Empringham drove Christine on track was in November of 2010 for Super Lap Battle. We won the event and set the SLB at Buttonwillow Raceway record on Hankook D.O.T. tires while running a BorgWarner EFR 8374 turbo. The problem was that we were running the turbo at its extreme limit. BorgWarner lists the EFR 8374’s maximum speed at 128,100 rpm, but we were approaching 141,000 rpm at SLB. While it doesn’t sound like much of a difference, think of it this way: it’s like revving an engine designed to rev to 9,000 all the way to 9,900 rpm. Sure it can do it once in a while, but keep over speeding it and something’s going to break. Luckily we didn’t have any failures at SLB. The solution? Use a larger EFR turbo. BorgWarner has been a huge help in the turbo department to date. Of course, Sierra Sierra also provided a huge amount of real-world testing that BorgWarner also needed for their newly released line of EFR turbochargers.
We performed a series of tests with several different EFR turbos on SSE’s in-house Mustang all-wheel-drive chassis dynamometer. We got the best performance out of an EFR 9180, which is the largest turbo in the EFR lineup. With some minor adjustments made to the exhaust camshaft timing, the Cosworth 2.2L 4G63 engine had no additional lag even with the larger turbo. This can only happen if there’s either an open exhaust or a very good exhaust system. Kruszewski and Raeder designed the new exhaust system in 3.5-inch stainless steel, and it was working damn well. The reduction in pre-turbine backpressure meant that we had to install stiffer wastegate springs to bring the boost pressure back up. The awesome thing about the Turbosmart Comp-Gate40s is that it only takes a minute to change a spring.
Anti-lag System
Fast-forward to June 16, 2011, two days before Christine was to be placed in a shipping container to journey to Sydney. The boys at SSE had gone through the entire car to make sure she was in tip-top shape for the WTAC. They did an awesome job putting the car together using tricks and details that only experienced race car mechanics and builders do. After pouring in the last quart of Royal Purple XPR 20W-50 oil, we were back on SSE’s chassis dyno to break in a brand-new Cosworth 2.2L 4G63 engine. This new engine has larger rod journals and even uses rod bearings from one of Cosworth’s past F1 engines. Also on the list was to test the anti-lag strategy (ALS) that I’ve implemented in the Cosworth Pectel SQ6 ECU. Kruszewski installed a rally cross–style anti-lag valve that allows fresh air into the engine when the throttle is shut. With an added dose of fuel cut and a ton of ignition retard, the raw fuel ignites inside of the glowing hot orange turbocharger during deceleration and causes the turbo speed to skyrocket. The idea was that when Emp (Empringham) would crack the throttle open to power out of a turn, the turbo would already be at full speed and there would be absolutely zero turbo lag. That super loud bang-bang noise the cars make in WRC when a driver is off throttle is the ALS; the only difference is that I was trying to implement ALS on a turbo three times the size of a WRC turbocharger with an engine that was only 200cc larger. Spooling up an extra-large turbo with less potential energy is challenging, but nobody said my job would be easy.
After breaking in the new engine, we did some full throttle tests to make sure everything was good. Then, we tested the ALS. After some ECU adjustments, the turbo shaft speed increased after I closed the throttle. We didn’t get to finish the ALS testing 100 percent due to time constraints, but we figured we could do the rest on track in Australia. We were confident the car would go considerably quicker than last year at Eastern Creek Raceway, despite not having been on a racetrack since November 2010—we just weren’t too sure about the Cyber EVO and the Revolution RX-7.
Sydney, Australia
Fast-forward again to Wednesday, August 3, 2011, and I’m in Sydney, heading out to the World Time Attack Challenge event.
ECR is only 30 minutes outside of the city, which probably makes it the most convenient racetrack in the developed world. It is a world-class FIA racetrack that has hosted world-class races in the past, such as A1GP and Australian Supercars. There are large grandstands, large concession areas, indoor bathrooms, and plenty of garage spaces. ECR is not only competitor friendly, but it’s spectator friendly as well. The track is technical with two tricky decreasing radius hairpins and some off-camber turns while being fast with a big, long front straight and two smaller straights.
Sizing up the Competition
While waiting for the SSE team to show up at the track to unload Christine, I immediately looked for the Revolution RX-7 and the Cyber EVO. Looking at the RX-7 in detail, I began to worry. The Mazda was a beautifully prepped Super GT GT300 race car! Everybody told me the car would be questionable when it came to applying rules and regulations, but seeing it in person was another thing. There weren’t too many visible changes on the Cyber EVO since the aero wasn’t prepped yet, but I did see six-piston Audi R8 Brembo monoblocks on the front. The SSE guys showed up and we unloaded the container and prepped our garage for the rest of the day.
Later that afternoon I saw the Unlimited Works (the shop that maintains the Cyber EVO) mechanics unloading some ultrawide Advan A-050 tires from their container. I asked Tarzan, “How wide is the new tire?” He replied, “Oh, it is new, 295.” I asked Raeder to borrow his tire durometer gauges, and asked Tarzan if it was OK to measure. He said yes, and I measured a 46. Last year’s Advan tire measured 51. Our 295-wide Hankook Ventus TDs measured 51 this year. This meant that the Cyber EVO would be on softer tires than us this year. Never mind the 400-pound weight advantage the Cyber EVO had over Christine. Damn, another car to worry about.
Day 1 Practice
Thursday, August 4, 2011, was open practice for all WTAC competitors. Emp suited up and re-familiarized himself with ECR and Christine outfitted on the Hankook Ventus TD C71 tires (different than the tires we usually use in the United States). Japanese and Australian time-attack rules mandate that tire surfaces must have two thirds of the surface covered by tread grooves. We spent most of the day doing checks and making suspension adjustments. Raeder and Emp wanted to verify that the center differential changes Raeder made to the car since last year were working well at ECR. They worked wonders at Buttonwillow, but ECR is a whole different track. I spent the day looking over data and getting used to the motorsport-grade Australian grain-based E85 fuel. In America, we use corn-based E85. Overall, I’d have to say that the Australian E85 was pretty damn good. Before the end of the day, Emp did a timed lap at “low boost”, which was 1.6 bar or 23.2 psi and clicked off an unofficial 1:30.25 second lap. That was faster than Cyber EVO’s winning lap time from 2010, but Emp knew there was more in the car. Tarzan and the Cyber EVO team seemed to have spent most of their day making adjustments and practicing segments of the track. In typical Tarzan fashion, he kept you on your toes thinking.
WTAC Competition
Friday, August 5, 2011, was the first day of WTAC 2011. The format is that every session is an official time-attack session. You could theoretically go out and blast a crazy fast lap, pack up, and win the event after one session, but since WTAC has the fastest time-attack cars in the world, it’s never going to be that easy. Everybody is constantly pushing the limit of the driver, the team, and the cars.