Performance Improvements possible with newer 4 stroke outboards

[twzted]

There is a big difference between running in a oval boat race and seeing the best top speed. The oval boat race is about the fastest lap time not the fastest speed. Tom runs against stock 2 stroke motors. The top runners in the class have good acceleration and hit over 61 mph on the straight. Tom can match their acceleration with a 19 pitch prop. Problem is they have the extra mile or two top end. When Tom runs his 65 mph prop they have superior acceleration and he cannot catch them.
To be Honest Tom does not get the best clock starts and is usually not the first boat to the first turn. When he has, he has been tough to catch. I think with a 21 pitch and a good start he can win.

Yea i knew it was a higher pitched prop not best for oval racing, im not racing but i do long runs down in the Florida keys 100+ miles ( all straight ) sold my supercharged waverunner and am building this boat, i plan to go with all the skis i used to ride with so i want to try and keep up. I have a 12x22 labbed Merc cleaver for it. Like i said i dont plan on racing but want the best performance i can get out if it, I was really just seeing your thought on the engine in perticular performance wise. whats the difference between the T750 boats and the 850? i know most are 70+ hp but whats the speed difference like?

[Hounddog]

Yea i knew it was a higher pitched prop not best for oval racing, im not racing but i do long runs down in the Florida keys 100+ miles ( all straight ) sold my supercharged waverunner and am building this boat, i plan to go with all the skis i used to ride with so i want to try and keep up. I have a 12x22 labbed Merc cleaver for it. Like i said i dont plan on racing but want the best performance i can get out if it, I was really just seeing your thought on the engine in perticular performance wise. whats the difference between the T750 boats and the 850? i know most are 70+ hp but whats the speed difference like?

The T750 boats are 55 to 67 hp. The T850 altered 56 OMC ‘s are 100 hp plus. Speed wise the T750 record is over 65 mph. Our best T850 recorded speed is 80 mph while the UIM T850 record is 68 mph. Overall all the feedback I get about the 60 is positive. Interesting that you have a 12 x 22 Mercury prop. The original model of that prop is liked by many T guys. With your boat you may find it is too much prop. I would not be surprised if an 11.5 x 18 works better. One last comment....I had a fellow running a 1998 59 cubic inch 2 stroke Mercury switch to the 4 stroke. The 2 stroke acceleration was better, but the 4 stroke was only 1 mile an hour slower. So for a non race application...equal!!

[twzted]

The T750 boats are 55 to 67 hp. The T850 altered 56 OMC ‘s are 100 hp plus. Speed wise the T750 record is over 65 mph. Our best T850 recorded speed is 80 mph while the UIM T850 record is 68 mph. Overall all the feedback I get about the 60 is positive. Interesting that you have a 12 x 22 Mercury prop. The original model of that prop is liked by many T guys. With your boat you may find it is too much prop. I would not be surprised if an 11.5 x 18 works better. One last comment....I had a fellow running a 1998 59 cubic inch 2 stroke Mercury switch to the 4 stroke. The 2 stroke acceleration was better, but the 4 stroke was only 1 mile an hour slower. So for a non race application...equal!!

Cool, yea i may need to drop some pitch and or diamiter but i know i could sell the 12x22 easily as they are very good on the f4s boats, i may try one of Mr Hills props if it dosent work or trade mine for another merc cleaver.