Whats up offshore, i recently bought my first speed boat. its a 91 fountain fever powered by a single 540 ci with approx 640 hp, according to the previous owner. on the back i have a 25p rev4 bolted to a bravo x drive 1.5:1 with imco shorty lower.

i got to ride her a couple times last season but i am very excited for next spring to come. i never met the previous owner in person and he was very vague over the phone as to the specs on the motor. i dont kno what the max rpm for the motor is or really anything about the internals either. i do kno the internals are forged, with canfield aluminum heads, merlin intake manifold, holley double pumper, and i think cmi exhaust.

i was told the boat topped out at around 75-77mph. the question i have is if this sounds accurate with that set up or should i be at least in the 80's. thanks.

Welcome to OSO!!

Nice 1st boat good luck with it!high 70's low 80's 640 hp I'd guess you'll just have to find out this spring

good luck withyour fountain.have fun and be safe.

Congrats on your new ride.

http://www.go-fast.com/Prop_Slip_Calculator.htm

Just guessing and plugging in some numbers

Assuming 5400 rpms and 12% slip = 75, 5600 rpms = 77mph.

Where did you buy the boat from? Anywhere in MI by chance?

I think that shorty is hurting you. My one friend has a 27 and we tried one and it slowed it down. His slip went up...It could not carry the bow as well.I bet that is the reason why it has that rev 25.That prop is like the 4 blade version of the mirage plus.Some times it works better than the bravo one.Fountain use to put them on the 29 fever with a single 525.You might want to try a five blade......

thanks guys for your responses and knowledge. i purchased the boat in nj. i thinking of trying a maximus 5 blade in the spring. i figured im gettin 21% prop slip in my midrange. im doing 50 mph at 4000 rpm. also i do get some porpising from time to time if trimmed up a bit too high. to run level my right tab is at 1 my left at 3 and my drive 3-4 on the indicators.

Is that a one inch or 2 inch shorty? maybe try a one inch spacer.I think the hydromotive px5 might work better right out of the box.