by crispone » Thu Oct 22, 2009 4:59 am
RON wrote:
Let us then assume that we modify Car A to produce 25 hp more at the flywheel (maybe a good head port and set of camshafts). The car would now produce almost 230 hub hp on the Dynapack, but on the Dynojet it would produce 217.5 hp. Same car, but the difference between the two dynos has grown from 10 to 12.5 hp, largely due to inertial effects.
^^^ That's EXACTLY the type of "variance" that I'm talking about and have experienced... although with motorcycles as opposed to cars. Specifically, the "inertial effects" on a DRUM DYNO with a motorcycle (which are SUBSTANTIAL when you figure RPM sweeps upwards of 12k~14k redlines) can net a PEAK that exceeds an eddy current steady state power rating which will be much lower, and on run over run basis... generally MUCH better repeatability, and control over a "tune" at that specific rpm point. Full tunes on the latter involve HOLDING the engine rpm at steady rpm's in various increments (250rpm/500rpm etc...) and then working through 0% 1/4, 1/2, 3/4 and 100% throttle position, etc... to dial in each intersection to an optimal exhaust gas target range while achieving maximum absolute power. A lengthy process to be sure.
Anyway... always good dyno chatter!
-crisp
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crispone - Immitagably Verbose Dude
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