rob vanharten

So I have just completed converting my 1986 formula 357 to #5's on ext boxes. I have about 625hp a side for power. I am currently running a 25 pitch 4 blade 17 inch diameter prop and am having no trouble at all planning. Prop shaft are about 1 inch below running surface. I am running out of motor at about 4500 rpm's and 68 mph on gps. But my cruise speed it great at right around 55 at 3500 rpm's. Anyways what can be done to my current props to get me up to the 5600 rpm range were the motors make there power? And how would it change my cruise speed?

rob vanharten

Any input on this one Brett?

bbladesprops

It will be next to impossible to pull the additional 1100 rpm you desire and maintain efficiantcy.

I do have routes that can give you another few hundred rpm or a little more but changing pitch or gear ratio is going to be required if you truely want 5600. Changing blade area is one of the options and it will decrease cruise speed some.

Brett

bunky1957

I put a set of mild 540's in a '93 357 with bravo drives.First set of props I tried was stock Bravo 1 28 pitch. Planes easy, cruise is 43 mph @3200 rpm.Top speed is 71.5 mph @4850 rpm with a full tank and 2 guys.I have a set of stock 26 pitch Bravo 1 and a set of stock 26 pitch Hydro Quad IV that I will try this weekend to get closer to the 5200 rpm power peak.

buckknekkid

have you tried the QuadIV on your 311?

bunky1957

No,I have one engine out of the 311 for a refresh,but when finished it will be the first prop I try.