help understanding props
 

I run a 31' v hull, twin 454, 415 hp, stock bravo 1's, 1993 variety, engines and out drives are 2 years old. Just had the pain done, it looks FAST, now I get it to perform as good as it looks...

Max speed is upper 50's generally, have gotten to 60 with empty tank and great water...

I am thinking I should be able to get quite a bit more speed, running 25p three blade mirage props. I would like to get to mid 70's if possible. Max RPM's I can turn is 4400. I am also thinking I should be able to handle much more speed in that boat.

Someone told me a four blade gives more lift in the rear, I have quite a bit of bow rise.

If fours will do that, what about five bladed screws?

To get RPM's up closer to 5000 should I try and run a higher pitch? Should I focus on something besides screws and RPM?

I am not trying to get to 90 mph, but at the poker run this weekend I got smoked by some boats with much less HP than I have, I did not get trashed, finished in the middle of the pack, but want to come in closer to the front, and you know how that goes...

Thanks in advance for the help....

P.S. - the guy who won was in a 46' sonic with twin, blown big blocks. He SCREAMED by everyone else, I know he has a lot of HP, but damn, he is pushing a lot of boat too.....

Re: help understanding props
 

What boat are you running? Weight? Are your engines reworked to get that hp from a 454? Stock 454's are either 300 at the prop or 350hp(mag carb) at the prop. You'll hear 330 and 365, but that's not at the prop. EFI's are 310 and 385 at the prop. 502 carb is 390 and 502efi is 415. Check here for specifics. http://www.outdrives.com/merc/sternspecs.html

If you want to increase rpm's, you have to drop pitch. Try 23" 3 blade props or 24 4 blade props. That's the common prop selection for your size boat with stock 454's.

Also, check out the bam site prop slip calculator for help to dial in... 4 blades will help lift you and decrease slippage.. Be sure to read their link to prop slip definition and what percentage you should look for...
http://go-fast.com/Prop_Slip_Calculator.htm

Good luck!!!