Targa Miata
March 28, 2010 - Time for some more dyno testing!
One nice thing about the individual throttle body setups is that I can change out the air horns and alter the intake runner length. In theory, a short runner should trade off low rpm torque to gain high rpm power - and a long one should do the opposite. But if they're way off, then you just plain lose. Since I have a collection of horns, I'll simply do some back-to-back testing and see what happens. It's always interesting to simply install a pipe that's 1" longer and see a power bump.
I had the chance a while back to talk with Bill Schenker, a national-level CSP autocross competitor about his engine. It makes very good horsepower - similar peak power to my engine, but with less torque - and it's all come from hundreds of dyno runs, testing one slight change against another. One thing he told me was that the length of the intake tube running from the stock intake manifold to the filter had a big effect. Again, a 1" change made a notable difference. Of course, he was talking about naturally aspirated power so it wasn't a 15 hp difference, but if you can find 10 places to gain 1.5 hp, there's your 15 hp gain.
So, bring on the air horns!
entry 736 - tags: testing, intake, air horns, IRTB