Quote:
Originally Posted by matt f
this is covered on pgs. 501 & 502 of "porsche 911 enthusiast's companion" by adrian streather and bentley publishing
their findings using the dyno concluded " no improvements" , claims of 6-8 hp gain are not substantiated
they did note there was improvement in the sound of the engine
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You can't believe everything you read just because someone printed it in a book. My experience is also that European chassis dynos are not very accurate or consistent. Dynojets are though. When in doubt, just test it yourself. The following was from some tests we did on Tyson Schmidt's '93 C2. Car is stock except with a primary bypass. Chip files were unaltered for the test comparisons. The blue and violet runs are without the airbox cover, the green and red ones are. The runs were alternating back and forth with about 5 minutes between runs. The first run with the airbox was run #12, the red curves. Next the cover was removed and the result was run #13, the blue curves. We went back to the airbox cover and the result was #14, the green runs. About a half hour later we tested it again without the airbox cover and the result is #21, the violet curves. The numbers shown are power at the wheels, so divide by 0.85 to approximate power at the engine.
