2008 Ultimate Street Car Challenge Emissions - The Results

Finally, someone took my advice and shot for the lead by dominating the emissions test. But it didn't work out as planned. Setting the curve by having a super clean OEM car will put you ahead, but having a filthy gross polluter will also push the rest of the pack up. And that's exactly what happened. Alison's GT-R came in and, even with its secondary cats removed, still managed to come out cleaner than anything else in USCC history. This also includes the brand-new Sienna support van that we borrowed from Toyota.

Just like the man, we also clamped down on the emissions standards for this year's USCC. The old rule, that allowed five minutes for contenders to plug up a catalyst bypass, was outlawed outright. The point is to make the horsepower numbers better reflect what real streetcars should make. However a car ran on the dyno was how it ran for our EMS five-gas emissions sniffer. We even had each team representative step out of their car prior to their last dyno pull, to ensure that no tuning changes were made to the cars prior to the emissions test.

We also threw another curve ball in this year and did the emissions test on the dyno. Tailpipe emissions were sampled at idle, like previous years, and now at an unloaded steady state 25 mph on the dyno in Second gear. Idle emissions hurt cars with cams and big injectors as both tend to dump a lot of raw fuel out of the exhaust at such a low-engine speed. The 25mph dyno test made it harder on NOx emissions, since the inertial load of the dyno would raise combustion temperatures and show what real road NOx emissions would be. Turbo cars would fair better because there would be little boost under the minimal load, but supercharged cars would suffer the biggest penalty as air/fuel mixtures richen when the supercharger started boosting.

Even with the dyno emissions curve ball, this year's contestants proved to be the cleanest bunch ever. Apparently, contenders have caught onto the value of emissions points. With a few exceptions, most cars had NOx and HC emissions in the hundreds of rpm range, instead of the thousands that we've seen before. The only car to run without a cat was the Tuning Technologies prepped Evo VIII, which still ran so clean that we had to peek underneath the car to make sure there really wasn't a cat.

What killed the GT-R's clean sweep victory was the BMW. By scoring so low with its partially tuned super rich mixture, the Groma Fab BMW basically pushed the rest of the cars so far up in the points that they made up for the immaculate emissions performance of the R35. -Jay Chen