Competing in the 25 Hours of Thunderhill race has been our major goal for all of 2014. We knew going in that we were going to be up against teams that were faster, more heavily funded, and had larger crews than we did. Midway through the year we decided we wanted to compete in ES rather than E0.
The cars current power to weight ratio made it fit into E0 without ballast or detuning. The reason we chose to enter in ES was because we knew in the future we would have time time to build a higher power engine and we wanted to get some experience with the open fueling and car preparation rules in ES. This decision required us to make some big major changes to take full advantage of the open rules and to make sure we were competitive with the other cars in our class. We designed and built a custom 44 gallon fuel cell that mounted in the stock location. This was a very difficult task, we first created the can maximizing the size as much as possible within the given location. This fuel cell with dry break filling and centralized mass allowed us to drive the car over 4 hours without stopping. We filled the car in about 30 seconds and in reality the driver changes took longer than the fueling ever did. The centralized location of this 270lbs of fuel helped keep the car manageable to drive when full of fuel and kept the handling predictable whether we were full or empty. We really believe this was our biggest advantage over our competitors who carried less fuel and stopped about twice as often.
Our car had some unusual features: a full carbon fiber splitter, flat bottom and diffuser made entirely at Pavlov Racing and Lang Racing Development. Our trunk mounted radiator, associated plumbing, cooling ducts was fabricated entirely at Pavlov Racing Service. The rear mounted radiator proved to be quite a challenge, we had to quickly fabricate the large carbon fiber scoops on the sides and quarter windows to feed more air volume to the radiator. Plumbing also proved challenging and had to be modified several times in the weeks before the race to make sure the car ran cool enough and that the electric water pump and mechanic pump functioned together correctly.
While we did have one of the smallest crews at this event, we had an even smaller driver line up. We decided that finding qualified drivers for our fairly high powered car that lacked ABS would be difficult given our time constraints so about a month before the race we made the call to just plan on doing a 2 driver line up of Andrew Lang and Steve Pavlov. We chose to drive approximately 3.5 to 4 hour stints switching at each fuel stop. This proved to work quite well and gave us sufficient time to recover before having to get back in the car again.
Our race was going surprisingly well up until about midnight. Our fuel strategy had been paying off and we had climbed up to 6th overall despite our lap times being about 15 seconds slower per lap than the leader (a prototype car in ESR). Being classed in ES meant we were up against some pretty stiff competition, like a heavily modified Porsche Cup Car that had won this race overall several times already. Around 1am we had a wheel to wheel incident with another BMW which broke our tie rod and sent us off track. We managed to replace the tie rod and do a rough alignment in about an hour. Getting the car back on track for just a lap we had to be towed in as a problem that had been developing with our newly rebuilt transmission finally came to a head. We had been having trouble shifting from 4th to 5th and finally the car was stuck in gear and we couldn’t get the car rolling again when we were fully stopped on track due to a red flag incident. At 2am we decided we had to replace the transmission and with no spare available we had to spend some time sourcing one from another team. Our driver Andrew Lang along with several exhausted crew spent the morning hours removing and reinstalling the transmission to get us back out at 5am. We had a trouble free race up until just about 30 minutes before the checkered flag. Our VANOS line had cracked creating a high pressure leak that drained about half of the oil from our oil pan in a single lap. The car was limped into the pit, the VANOS line was crimped shut, and the car was sent back out to take the checkered.
While we finished much further down than we could have if we had a trouble free race, we were happy to complete the race with a car that was just recently finished. The engine we built for this race was broken in on Wednesday on the dyno and again at Friday qualifying, it literally had 3 hours on it. While Andrew said he was confident the motor would last, it is always a risk bringing in a fresh engine right before a long race. We knew we were taking a big risk but we knew we wanted a fresh motor custom built for this race to help demonstrate that the wider rod bearing solution for the S54 could take the abuse of a race like this. The motor we used had our modified crankshaft to accept a wider rod bearing as well as custom lightweight Carrillo rods and high compression pistons running race fuel. Our cylinder head was what we might call a Stage 3+Lang Racing cylinder head complete with Supertech valves and valve springs, and 52mm throttle bodies. The rocker arms, and rocker arm rails were all WPC treated to reduce friction and extend their life. We were happy to say that despite having almost no oil pressure for a full lap the engine was able to survive being raced for that many hours with nothing more than an occasional oil top off.
Our results this year give us a lot to look forward to next year. The reliability problems we had this year should be easy to resolve and we still have plenty of seconds left in the car to start catching up with some of the faster paced cars. We’re happy to head home, tear the car apart, and begin fine tuning our aero and suspension setup, which we never had time to do before this event. Our fuel strategy proved to be our biggest asset so we will attempt to perfect that during the 2015 season at WERC.
Were it not for our fantastic volunteer crew taking care of our severely complicated tire strategy, fueling, and pitching in to do the last minute work all night long that we needed to get done to get the car on track Saturday morning this event would have been impossible. We owe a huge debt to Kieth Calcagnie, Matthew Delaney, Daniel Kertson, Brian Andrus, Kyle Massa, Ryan Osinga, and several others who came together as a team to make this event happen. We also have to thank Beau Brown over at AEM Electronics who saved us by tuning the car at the last minute up at the track and got this motor to make power reliably throughout the entire race.