Earlier today at the Source Interlink 2010 Superlap Battle, we (team Sierra Sierra) smashed the previous Buttonwillow CW13 time attack lap record with a 1:41.046 lap time. Emp cranked out this damn near perfect lap in the Sierra Sierra EVO 8 (Christine) during his very first hot lap in the first time attack session today. The previous Buttonwillow time attack record in the 13CW configuration was a 1:43.34 that we (team Sierra Sierra again) ran in practice at Redline Time Attack's 2010 season opener back on March 28. We tried a larger turbo that we've never run on track before in the 2nd time attack session so I had to freestyle the ECU tuning. Luckily the Cosworth Pectel SQ6 ECU has an excellent data logging platform that makes freestyle tuning really quick and accurate for me. Then we backed up our quick lap in the third and last time attack session with a 1:41.185 (we need a bit more track time with the larger turbo for evaluation). That once, seemingly unattainable old Taniguchi/HKS CT230R EVO record of 1:43.527 is easy for us now. I remember watching how smooth and effortless Taniguchi executed the 1:43.527 back in 2007. That's how it looked when Emp dished out the 1:41.046 in Christine this morning. In fact, Emp cranked out a 1:47.xx during a WARM UP lap on only half warm tires and brakes with less than 2 seconds of accumulated full throttle.
In a previous test at Buttonwillow about a month ago we ran a 1:43.2 on two step harder Hankook C51 tires and a low boost setting of 1.6 bar with the new BorgWarner EFR 8374 turbo. We did not have a chance to turn up the boost that test day, but we didn't expect a 1:41.0 by turning up the boost (2.2 bar) and changing over to C91s today either.
We made leaps and bounds developing the EVO these past couple of months with front, center, and rear differential changes, the BorgWarner EFR turbo, Turbosmart CompGate 40 wastegates (BTD write up coming soon), and of course the evolution of the Cosworth 4G63. As the Cosworth representative on the Sierra Sierra team, you can bet your ass I was glad that there was no cylinder head removal necessary at the track today or yesterday. Tyler, Clayton, Lyon, Magnus, Martin, and myself's efforts at Cosworth to improve 4G63 cylinder head sealing at higher power levels are definitely working. The diff and engine changes are internal information so asking me what they are in the comment box below would be useless since I'm unable to discuss them at this time.
We tried a tire change after our first hot lap in the first session, but it took a little too long. We probably need to practice our NASCAR skillz and add fuel next time. Actually Mike, Jet, Don, and Richard did all the work. I just offloaded data and held some fans while they did the hard work.
2nd fastest overall was Billy Johnson in the FXMD NSX that ran a 1:41.949. Unfortunately the NSX suffered from engine problems in the last time attack session. Were we worried that Billy would come out and beat 1:41.0? Hell yeah we were. A mid-engined V-6 turbo car with crazy aero, an experienced team, and a quick ass driver like Billy would have you worried too.