Prop Selection
 

The boat is a 25 outlaw 7.4 mpi 310 hp Bravo 1 1.50 ratio. running a 21p mirage plus (Wot 4600-4700)
I am adding a procharger 5psi bringing the crankshaft hp from 340 to 500... I was told by procharger that the kit will not add any rpms I dont no if thats true or not, however I am looking find a good place to start prop wise. A procharger tech said that you would typicaly go up 4 sizes after adding a procharger and another company said No way go up two sizes. So at this point I have no idea what to do, should I wait until I install the procharger and run the 21p and see what I get for rpm then adjust or should I just start with a bigger prop? Does anyone have any ideas as to what I should run?
Thanks,
Derek

Try a 25 Mirage

We have a Hammer with a 454mag mpi and run a 25 mirage up to 4900rpm at 72mph, best conditions. Un labbed it did 70 at 4700rpm. What is your best speed stock?

3 people and a full tank 55-56 ......4600rpm

I would check the internals of that engine before putting a Procharger on it......also I would take anything a "tech" at Procharger says with a grain of salt....just saying...:coolcowboy:

My 25 Ol just last week with a carb 7.4 480 hp 64.1 gps still tuning the engine. With 25p Ballistic prop. Will try the B1 24p next week.

I understand what you are saying about the internals being cast and all but the procharger is getting bolted on next week and when the motor pop's which it will, the question is when???? At that point I will do a total repower.
I was told similar things about the procharger people so I figured I would to turn to the oso members for advice. Surely someone out there has the similar set up.

When they say it will not add RPM, they are referring to the operating RPM range. If you do not change the prop when you supercharge it, the engine will undoubtedly increase the RPM it reaches.

26p bravo 1. Maybe a 24. Good handling and will give u great acceleration. Call blades and rent one get a baseline.

I agree, 25 mirage +. General rule, if you boat can get out of the water with a 3 blade it will be faster than a 4 blade 9 times out of 10.