Endurance racing is without a doubt the ultimate test of man and machine as cars, drivers, and teams battle for hours on end for nothing more than bragging rights and that all important sense of accomplishment. The last time you saw the Yost Autosport E92 M3 endurance race car turning laps around a race track was six months ago at the 2014 NASA 25 Hours of Thunderhill, but the car you see here today is much different. Sure the livery is different, but the entire car was torn down to the chassis and rebuilt from the ground up. The 2015 version is lighter, stronger, faster, and more efficient, all things necessary for success in endurance racing.
We were able to shed 200 lbs. of weight thanks largely to a long list of small weight reduction improvements and a few big ones in the form of carbon fiber doors and roof. Aerodynamics were also improved by adding side windows and redesigning the underside, front splitter, and rear diffuser on the car with the help of APR Performance. Some areas of the car were only slightly changed, for instance in the suspension department we simply switched over to BC Racings new ZR Series Triple Adjustable coilovers and some aftermarket sway bars. Some areas of the car werent changed at all, like our CSF Racing cooling system. All-in-all, the car is simply a much better, more optimized version of the one we ran at last years 25 Hours of Thunderhill and this racing season provides us with a whole new list of challenges to overcome, starting with the first race of the year for us, a 3-Hour enduro at Buttonwillow Raceway.
Since weve already proven we have a car that can run for 25 hours, a 3 hour race should be a walk in the park correct? Under normal circumstances yes, but this race was anything but normal. For this race we were faced with 108+ ambient temperature, the blinding light of a setting sun, and a host of other challenges.
Our first challenge was Qualifying and Practice, which was one in the same. Both myself (Mike Bonanni) and team principle Jordan Yost were set to be the only two drivers for the 3 hour race. Although both of us had plenty of experience around Buttonwillow Raceway, neither of us had any experience driving the track in the opposite direction, counter-clockwise, which is how the race would be run. So essentially both Jordan and I had one single solitary 25 minute session to get used to the newly rebuilt car, get used to the new track configuration, and put down a good qualifying lap. I went out first, getting about 4 laps in before coming in to hand the car over to Jordan. After a quick driver change, Jordan was out for his laps. At the end of the short session, neither of us were 100% confident in our performance but we knew that wherever we qualified we would have 3 hours to make it up on-track. Jordan set the fastest lap between the two of us, qualifying us 9th out of 38 cars, 3rd in class.
It was up to me to start the race and do the first stint. The plan was to drive the car at a comfortable and fast pace until we hit the hour and a half mark or needed to come in for fuel, whichever came first. The green flag flew at 6:30pm and we were off. I quickly settled into a groove and started strategically moving my way through the pack up to the other cars in our class. The heat inside the closed cockpit M3 was building quickly and before long I had lost communication with the pits, we are guessing due to overheating the base unit for the radio inside the car.
Without communication with the pits all I could do was glance over at pit wall each lap to see if they were waving me in. As I settled into my pace we ran into what we believe to be an oil starvation problem which would cause the car to go into limp mode costing us precious time. Unfortunately this problem re-occurred a few times during my stint but fortunately it was a problem that I could fix on my own without coming to the pits by cycling the ECU. With the ECU problem I knew the strategy needed to be focused on making it to the hour and a half mark. Our competitors were going to have to make 2 pit stops during the race and if we could get away with one then we could gain a lot of time back. I started driving with fuel savings in mind and just plugged away as many consistent laps as I could. As the sun started dipping low enough to shine directly through the windshield it began to heat the inside of the car up even more and after a while it just got un-bearable. I started showing signs of heat stroke and decided to pull the car into the pits and get Jordan in the car.
After what felt like an eternity, I pulled into the pits and the pit crew got Jordan in the car with a full tank of fuel while I tried desperately to get my wits back about me and cool off. I was devastated to learn that I had only been out there for an hour before I came back in meaning our chances at a one-stop strategy were over. Even though the sun was now starting to set and the temperature outside starting to drop I was convinced that Jordan wouldnt be able to be in the car for the remaining two hours, but to my surprise he pulled through and finished the race driving into the night before taking the checkered flag at 9:30pm. Fortunately for Jordan, the ECU problem seemed to have gone away for his 2 hour stint and in heroic fashion he was able to make up all the time lost during my stint and then some, battling back up to 7th overall and 2nd in the highly contested ES class, giving our car and team our first podium finish. Now well into the night and after coming in for a splash of fuel, with about 30 minutes to go, the heat started really taking its toll on Jordan as well. We were in a comfortable position with a few laps separating us from competition ahead and behind and it made no sense to come back and do another driver change so Jordan dialed it back and cruised the car home to the checkered flag. When he got out of the car his drink bottle was completely dry and he could hardly stand from heat exhaustion.
While the 25 Hours of Thunderhill was an epic challenge, so to was this Buttonwillow 3-Hour simply due to the extreme heat for both the car and the drivers. Fortunately for us, outside of our ECU issue the car performed flawlessly yet again. Our CSF Radiator and coolers kept everything in operating temperature range even with the heat and our BC Racing ZR Series coilovers were as consistent as ever. The car was as predictable at hour 3 as it was at the drop of the green flag. The drivers, I am not sure I can say the same for. We will now retire back to the garage to re-think our driver cooling and prepare for our next race, a 6-Hour enduro at Miller Motorsports Park in Utah!
Word by Yost Autosport driver Mike Bonanni
Photos and Video BC Racing NA