I've seen quite a few dyno sheets for 2000 model S2000s, and on Dynojets stock S2000s generally record anywhere from 195 to perhaps 202 hp, with most of them putting down right around 198-200. When I baselined my car prior to installing the Mugen header, it delivered a hair over 198hp to the wheels. Below is the dyno sheet from that installation.
Again, bear in mind that the car no longer has the Mugen header installed, so for this test the subject car was bone stock except for the throttle body coolant line bypass.
Due to the involved nature of the installation of the V2, I decided to reverse the normal order of our dyno testing procedure. In other words, we went to the dyno with the V2 already installed, made a few passes, and then temporarily uninstalled it and then reinstalled the stock airbox to measure the difference in performance. Since the dyno time for these tests is provided courtesy of Dynolab of Marietta, GA it was only fair to be as efficient as possible with the provided time. In theory, this method should be no different than had we tested in the "normal" order. The car remained strapped to the rollers, and it took less than 10 minutes to reinstall the stock intake and make the next round of passes.
To ensure consistency in the numbers, as always we used an OBD-2 scantool to monitor the engine coolant temperatures and also to monitor the intake air temperatures. In our testing, the car's cooling system was very consistent, easily keeping the coolant at a rock steady 181F to begin each run.
After making the first pass, I was pleased with the numbers that flashed up on the monitor. 209whp and 142 lb-ft of torque. We made 3 more passes to ensure that the numbers were stable, and each of the runs netted very consistent results, actually within about 0.5hp and 1 lb-ft each time. Based upon the numbers from my previous (2000) dyno session, this result was actually slightly better than I had expected. AEM advertises gains of around 8hp on their website and our own Shawn Church has verified these gains on several different S2000s he's tuned at Church Automotive, so the numbers weren't too surprising.
What came as a huge surprise, however, was the numbers the car delivered when it was taken back to the stock airbox configuration. Just out of curiosity, I made one pass with the stock filter on the stock intake, but I removed the airbox. This resulted in 201.2 hp and 135 lb-ft at the wheels. I expected to see a similar result when I fully reinstalled the stock airbox, but to my astonishment, the first pass with the full stock intake system registered just over 207 hp to the wheels(!) Scratching my head, we made two more passes, both registering right at 207hp to the wheels and about 137.5 lb-ft of torque.
What gives? According to these new dyno sheets, in the tested stock form the car has gained nearly 9hp since the last time it was dyno tested in stock configuration. It's widely believed that the S2000's F20C continues to loosen up through the first 10000 miles or so, but could it gain NINE hp in that amount of time? We looked through several other S2000 dyno tests that were performed at Dynolab, and all of the baselines fell within the "normal" range mentioned earlier in this article.
Stock airbox reinstalled for reverse baseline