with all 4bbl upgrade on my 4.3 i am now turning 5200 rpms with a 3 blade ss prop pitch is 19. I was thinking of trying a 21' revolution 4 mercruiser says they are great for v6 boats. but I have heard that you need to be turning alot of horsepower to turn a 4 blade prop well. what do you guys think or hopefully some one has tried one of these props on a v6.

Going from a 19P to a 21P 3-blade will cause you to drop to 4800rpm. Going to a Rev 4 21P will cause you to lose another 200-300. You may want to consider a 19P Rev 4.

according to mercury you can use the sme pitch it will not drop rpm's much.

Yes, that's a rule of thumb. Experience specifically with the Rev 4 in most applications has yielded a 200-300 rpm drop with the same pitch. If you want to make sure you keep the same rpm's, try an Offshore (don't worry that Mercury says it's for outboards).

yep/Darin

I lost 300 rpm going from a 19 3 blade to a Rev4. But i picked up 2-3 mph