Dave Buschur Of Buschur Racing
The hot topic in the Evoltion/DSM 4G63 tuning community right now is making power on lower octane fuels. When we started racing the 4G63 DSMs in 1989 we ran what we found at the corner gas station. I was new to turbocharged cars then and the cars I owned before had low enough compression to not even consider running anything other than normal pump fuel.
One day while at the track with my father and his turbo Buick, I tried some of the magic sauce he was running. I believe it was 112-octane Sunoco. At the time I was running around 20 psi of boost on pump gas with a stock ECU and absolutely no way to monitor knock or air/fuel ratios. As soon as I dumped the 112 octane in the car, the vehicle responded and dropped about a half second of e.t. and picked up around 5 mph. From that point on, I was sold. For the next few years we'd run the highest octane fuels we could find, since we were still limited to the stock ECU with a TMO chip and the HKS VPC/GCC for tuning. This combination led us to continue to set records and break the 12-, 11-, 10-, 9-, 8- and 7-second barriers using the 4G63 engine first. My tube chassis rear-wheeldrive 2G Eclipse ran a best of 7.81 at 175 mph and won the IDRC East Coast, Central, and National Championship in Pro Import-all with this "poor" tuning method.
As time progressed I had to become computer savvy and move to a stand-alone engine management. Our choice was the AEM EMS as they made a plug-and-play ECU for Evos/ DSMs. The hardest part of tuning for me was just learning how to use a computer. Since 2003, all I've done is tune stand-alones. I've tuned hundreds upon hundreds of cars and continued to set records, but now much more reliably.
It's funny because before to make big power, we were committed to running highoctane fuels. Over the last two years though things have been changing. It started when I was asked to use E85 to tune a good customer's Evo. I was hesitant but decided to do it as a favor. The fuel is unbelievable. We were able to make over 500 whp on a stock shortblock. Now, two years later, this car is still running and has never had a problem.
Tuning on the E85 led me to thinking about pushing the limits of standard pump fuel sooner. Where everyone had once thought 22 to 23 psi of boost was the limit, I'd tune a car and push that limit a pound or two higher. It wasn't long before 30 psi on 93- octane fuel was an easy chore. I've now turned out quite a few 500-plus-whp Evos that run on nothing but 93-octane fuel. There's no octane booster involved, no alcohol injection kits, just straight cheap pump gas.
One of our employees here, Trent, drives his Evo 61 miles each way to work, that's 122 miles minimum per day. The car has been tuned to 525 whp for over a year and put on almost 10,000 miles without a single problem. This fullweight Evo has run a best of 10.6 at 135 mph.
My latest effort on another Evo belonging to Peter put down an astonishing 585 whp on our dyno at 31 psi of boost. This street Evo weighs a mere 2,860 pounds with a driver. This translates into 9.7 e.t.'s at around 148 mph, all on pump gas. It's actually quite mindboggling. This same car at 43 psi on C16 put down 655 whp. The gains from pump gas to race gas with 12 additional psi of boost have made the owner of the car stick to running pump gas only, for now.
There's a key to this. Tuning is, of course, a major part of making this power and -Dave keeping the car together. Be warned: Every single car out there cannot run this kind of boost on these octane levels. The parts combinations play a huge roll in the equation. The exhaust is a key element to being able to do this. A small-diameter exhaust or an exhaust full of reducers and resonators isn't going to cut it. The intercooler cannot be some cheap undersized unit. The turbocharger plays a large roll and he larger the turbine wheel/ turbine housing, the easier it is to tune the car at high boost and keep it detonation free. The camshaft grind also plays a large part in this. Basically, the air needs to get into the engine with as little restriction as possible. It needs to stay cool and then it needs to pass out of the engine with little or no backpressure.
It's nice to be at the cutting edge of tuning, and make large unexpected power after all the years we were stuck using stock ECUs and piggy-backs. Maybe pump gas actually is the race gas of the future?