Copyright © 1998

Porsche Club of America Out For A Spin September, 1998 Bruce Corwin Bruce968@PorscheNet.com

In my June column, I promised that I would tell all the "secrets" of the upgrades to my 968 and how I was able to beat Charlie Learoyd and Steve Ross, two very formidable autocross competitors. Some of what I learned is car specific, but most of it can be applied to any model.
 
The most important element in a car's competitiveness is the driver. I was undefeated during the 1995 and 1996 autocross seasons, but was taken down last year when Charlie Learoyd moved into my class and beat me at 2 of the 4 events I attended, leaving me in second place for the year. After serving as the autocross chairman for two years, it turned out to be a good time to hand the reigns over to Patrick Branagan. Autocrossing is a sport that requires concentration and focus, which is hard to achieve when you're running the event. For example I was always too busy to walk the course, which is very important. So my first upgrade was to study the sport, read books by the experts and focus on winning.
 
Next it was time to upgrade the car. I was fortunate that my car has the rare M030 sport suspension package which includes 17" wheels, bigger brakes, limited slip, adjustable shocks and other upgraded suspension components. I wanted to run in the "stock" class, so I carefully read the autocross series rules to first determine which modifications I could make that would fall under the "free modifications" category. Anything you do to your car beyond "free modifications" could potentially put your car into a "modified" class.
 
The first modification was to upgrade the car's wheels and tires. I had been using R1 tires 235 front, 255 rear on the factory wheels. I upgraded these to Hoosier autocross compound A3S02 tires, 245 front and 275 rear. Autobahn Performance is a Kenisis dealer and set me up with lightweight K20 three piece wheels. Despite the bigger wheels and tires, there was an unsprung, rotating mass weight savings of a few pounds per corner. The Hoosiers are too soft to drive on the street, so it means having to change tires before and after the event, which is a pain, but part of the cost of winning.
 
 Last year I had a custom four-wheel alignment done to the car to establish a compromise setting for camber and such. It is my daily driver so I didn't want the handling to get too squirrelly. The car was also lowered a small amount. Lowering ride height too much on 944/968s can cause accelerated wear in front end components. Corner balancing the car, which I have not done yet, would be a further improvement. This helps when, for example, a car sits level, but all the weight is on the left-front and right-rear wheels, which would result in poor handling.
 
For engine modifications, I started with a baseline dynamometer test. Next I had a B+B muffler, Autothority chip and Magnacore wires installed. According to Autothority, B+B and PowerHaus, the muffler and chip should give somewhere between 19 and 31 additional HP. A second trip to the dyno showed almost no change, a very slight gain here, a very slight loss there with maximum HP down from 205.6 to 203.8 at the rear wheels. So much for truth in advertising! However, the chip does give me an extra 200 RPM before the rev limiter kicks in, the red wires look nice and the muffler saves about 10 pounds and sounds real cool.
 
The next thing to try was replacing the catalytic converter with a test pipe. Perhaps this would free up the restriction in the exhaust and allow me to take advantage of the B+B muffler. This raised the sound level from real cool to almost obnoxious. Back on the dyno, I found a gain of about 5-10 HP between 2900 and 3300 with max HP now down to 200.7 from the original 205.6. I wondered if a K+N or other air filter might help, so while it was on the dyno, I also tried with no air filter which didn't do much other than bring max HP up to 203.9.  Then I tried disconnecting the intake box and letting it just breathe the air under the hood, which was open and had a big fan blowing on it. This gave a little more power in the high RPM range with max power reaching 208.3.  Seems like a lot to go through for a gain of 2.7 HP from the stock configuration.
 
So this is what I learned. Porsche knows what they are doing when they design a power plant. If you have a turbo or want to make major modifications to your engine, you can take that route (which often leads to reliability problems). Otherwise, your best bet is to focus your efforts on (1) improving your driving skills, (2) mounting the fattest, stickiest tires possible on lightweight wheels, and (3) optimizing the suspension, including alignment, ride height and corner-balancing.