Dan74

I have a 33 Fountain Executioner which I'm re building the engine's and would like to get some more speed. The boat now runs approx 75-80 mph @ 5000-5200 rpm. I would like to keep the same props as they are hard to find and run up to 5500 - 5800. (It has speedmaster 2's)

The current engine combo has been in for 5 years no problems with water reversion or oil temps etc.

Gen 6, 450hp 502 crate engines (stock) iron rectangular port 118 cc heads, forged crank, forged pistons 8.75 :1,
Power flow Exhaust Maniflods & stainless risers
MSD Billet distributor with Msd 6m box and rev limiter.
Standard dual plane manifold & 800 Holley.

This is what Im thinking of doing, JE 9.5:1 pistons, camshaft crane 731 or similar ? The heads are getting a clean up and 3 angle job and will be match ported to a new hp 500 single plane style manifold and fit roller rockers.

Will this get me to 5500-5800 rpm or shall I go bigger on the cam?
Shall I keep the hydraulic lifters or go solid?
I have to replace one crank & rebore both so I was thinking to make them both 540's using eagle cranks and rods with Je's
The speedmaster legs can take the extra hp what about my transmissions ?

Thanks.

1BIGJIM

From those numbers it sounds like you have a great setup already. Is the 75-80 mph GPS?

I always have RMBUILDER (do a search) grind mine per the application. Well worth the extra money.

If you plan on running 9.5 CR with iron heads you better make sure you have good gas available or you will have problems.

Big question, what exhaust are you running?

As per going to a 540 that just depends on how deep your pockets are $$$$. If you only need one crank I would replace the one crank. Otherwise you are looking at new cranks and rods and you have the block machined for the additional stroke. I have built three stroker motors and love them. Again its on how much do you want to spend.
I think you would be money a head putting on some AFR heads and a custom grind roller

Good Luck

KAAMA

I agree. I would at least have RMBuilder/Bob Madara of Marine Kinetics design a cam for your engines. He will custom design a cam for YOUR specific application and what you want. You will get a custom ground cam for about the same price for what you would pay for an "off the shelf" cam. Bob is an excellent consultant on marine performance stuff. Bob's number is 585-654-8583 in N.Y.

Dan74

The Exhaust's are imco powerflow manifolds and stainless riser's, which for now we will run with. We always use premium 96. As for the speed we run a solid 75 most days which I checked with a handheld gps a few years back when I installed a new speedo. Lightly loaded on a good day up 80. I forgot about getting the block machined for the stroker. thanks

PatriYacht

You'll need to get to 600 hp if you're going to gain that much speed. 540's and the 741 cam will get you close with the iron heads. The 731 and 502 ci will make a little over 500 hp. Not nearly enough. Btw the No.2 Speedy is not very strong. Be gentle with 600 hp.

R Addiction

No substitute for Cubic inches........But I have seen some stout 502's built that run realllll good!! Do what you can afford but do it right either way.

Griff

You need to gain about 80-100hp for 500rpm gain. I think you will be close with boring to 509's and without stroking it with the other mods you posted. I would also go with a 741 cam or similar for a 509. Stay with a hyd roller.

Dan74

Thanks for the Info guys, have been in contact with Bob and will be getting him to do cam for me for sure. Before I decide need to find out more about strengh of the speedy no 2's. PatriYacht any more info would be great how gentle?.

PatriYacht

The Speedy No. 2 uses all the internals from the TRS. I would guess it can handle up to 600 hp with a fair degree of reliability. But just like a Bravo, flying the boat or doing holeshots will kill it in a hurry.

sandcraft

I would never stroke to 540 using a standard deck block. To much rod angularity. Tall deck only. 509 as griff pointed out would be the way to go. And go with aluminum heads for the amount you would save on a stroker crank.