Re: 1988 nova xl prop help
Supercharged 502? That changes EVERYTHING...Sounds like maybe a custom built engine? I find it highly unlikely that 4,500 is anywhere near correct for that motor. For all we know this thing might be built to make its peak power at 6,500 or something ridiculous...
Just one random example, these guys reference 5,500 to 6,200 as an RPM target, depending on model:
http://www.htgracing.com/marine.php
Presumably after the engine build it was run on a dyno, or at least there are predicted stats from the engine builder that should identify an expected peak HP rpm.
Wherever this engine makes its peak HP, that is where you want to prop it. Depends entirely on how it's cammed, ignition curve, amount of boost provided by the supercharger, etc...
So if you let us know what specific RPM this engine needs to be run at for max power, then we can help you identify a prop that will get it into that rpm. I would STRONGLY suggest a discussion with the engine builder. If it's not set up to run higher RPMS, you could create a VERY expensive problem for yourself...
Alternately, if you can't talk to the engine builder, a one-speed boat run in smooth water is really just a huge and rather predictable dyno. So you can obtain a few identically designed props that will put the motor in different RPM ranges. Maybe get ahold of a 27, 25, and 23 that are all idenical in design to the current 29. Run them all and compare speeds and RPMS. If speed and RPM increase, as pitch decreases? That means you're getting the engine closer and closer to its peak HP rpm...as usually max speed will equals max HP output RPM on a performance boat...
Again, proceed with caution, within parameters of possible self-destruction...
