Intermission

Intermission

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A lot of issues had cropped up at my June 2002 race in Portland. Luckily, I had almost 10 weeks before my next race in August to work out the kinks. First, the engine had been misfiring. Second, my differential wasn’t so much leaking as it was Exxoning. Third, I had noticed a tendency for the coolant to overheat on warmer days. Finally, I had to deal with the pesky issue of keeping the car street legal (or not).

To fix the engine-missing problem, I did a number of things to the car. I swapped in new copper spark plugs (I’ve been told that the old engines don’t work well with the hotter, shorter duration platinum plugs), dumped a bottle of fuel injection cleaner into the gas, cleaned and re-seated all of the ground cables that run from the engine to the chassis, replaced the fuel filter and advanced the distributor timing. This wasn’t the best trouble-shooting technique, but since the problem required an hour or two of street driving to reproduce, I didn’t have a lot of easy options. The problem slowly dissipated and eventually disappeared, making it difficult to know what had fixed the problem. My best-guess was that it was either related to cruddy fuel, or an electrical resistance problem brought to a fore as the engine-bay heated (and wiring resistance increased). Both are long shots, but I just couldn’t pin the problem down. It wasn’t a satisfying resolution.

As a quick project one evening, I replaced the left differential output seal. I expected it to be a big pain. The Bentley manual’s directions were easy to follow. First I undid the eight allen-head bolts that hold the half-shaft axle to the differential. Then, using a dowel, I gently pried out the metal output shaft. It popped right out. Being careful not to mar the differential, I cut and pulled the old seal out. I used a big 36 mm socket to help drive the new seal in. I slipped the output shaft back into place, redid the bolts and took the car out for a test drive. No more leak. I tried not to let success go to my head.

In order to make sure the engine was “healthy,” I took the car to Carb Connection. They used a chassis dynomometer to measure the car’s torque output and air / fuel mixture under load. A chassis dyno is basically a giant roller the car pushes. The acceleration rate of the roller is compared against its known mass / resistance to acceleration. Since acceleration = force / mass, and both acceleration and mass are known quantities, the force produced by the car can be calculated. There are some nifty calculations to null gearing, but that’s the gist of it.

A chassis dyno produces a realistic picture of engine health, by showing whether there is a smoothly increasing curve through the RPM range. “Jaggies” in the curve can indicate a problem with the engine or engine management system. By advancing the spark timing on the engine slightly, we were able to increase the torque and smooth the curve. The engine felt stronger. Additionally, I learned that the air / fuel mixture looked good. This is important to make sure that the engine isn’t running “lean” (too little fuel) or “rich” (too much fuel). The optimum ratio is between about 12 : 1 and 14 : 1. Deviating from that ratio can reduce power or even destroy an engine.

The chassis dyno also told me that my car made about 96 peak horsepower at the rear wheels, which translated to about 110 hp at the engine output. Engine output, or “at the crank,” is how cars are rated. That might not be much in the big picture, but it was plenty to get me in trouble from time to time. It was also exactly what Mike Kolbet, my engine builder, had lead me to expect from his work.

Satisfied that my engine was in good shape, I worked on resolving the overheating problem. I bent, cut and glued a piece of sheet metal to work as a baffle. It fit down beside my radiator, where previously airflow had gone past, not through. The hope was that it would direct more air through the radiator. It worked. Just driving my car around my neighborhood, I could tell that my heating problem was solved. When people talk about "sorting" a race car, this is the kind of thing they mean – all of the tiny things that have to be done to get the mechanical systems to function properly at a level of stress that street cars are not designed for.

With the heating problem dealt with, it was time to see about reregistering my car and passing emissions. The emissions folks gave the car some funny looks. The numbers and roll cage were a bit of a give-away. Nobody looked very surprised when I failed by a mile. While I had still a factory exhaust and catalytic converter, I had done many things to tune the engine, even if only slightly. There was no way I was going to spend hours of work finding and detuning each of the tiny things I'd done over the last six months in order to pass emissions – especially since I now possessed a big-mean-green tow vehicle! I scratched my head and mulled over the possibilities. There was one good choice. The car would not be kept emissions legal – its days as a street car were over. It was a decision that opened up a realm of possibilities – but the first was obvious. If you can’t actually be fast and certainly don’t look fast, you might as well sound fast.

That morning I called and scheduled an appointment with Muffler King. Muffler King is an exhaust specialty shop that came recommended by other racers. The barn-like exterior of their building might be off-putting to some, but the quality of their work was very high. They clearly understood just how solidly a race car's exhaust had to be mounted to withstand a race environment. They mounted it closely to the bottom of the car, so that it would stay out of the airflow and not bottom out when I added race suspension.

I found that the car was much louder than it had been. No more driving around the neighborhood to make sure everything was still properly fastened together! At full throttle and high RPMs the car was uncomfortably, tick-off-your-neighbors, get-a-ticket loud. Not quite as loud as some of the race cars, but enough to be really unpleasant. I also noticed that with the heat shielding removed, the passenger floor heated up significantly. The engine seemed to rev more eagerly. Without track time, I couldn’t tell whether the exhaust would actually make me faster. I had my hopes that it would.

Time would soon tell. I carefully eased the car on to a tow dolly (a trailer that only lifts the car’s front wheels) and prepared to set out for another weekend adventure racing at Portland International Raceway. It would be my first time towing my race car to the races, and my first time with race exhaust.