260Velocity

BB. I see ur from Bel Air Md. I know Tony down at CMS in Middle River and that is where I will be navigating when done... Just an FYI.

As for the motor, I should not need to spin it past 5500. I want to keep a hyd roller in it and that is getting up there for them and rocker studs with out girdles as u mentioned..

Any thoughts on intake ? I know a single plane but what is good for a marine where low and mid range torque are needed?

GPM. I do have the complete motor set up. From 14 qt off shore pan to the billet 2/ 4 air cleaner. Dual 750 4 corner idle circuit carbs,
Are u interested in it? I was going to use the block and heads over and sell all the loose parts. Marv Martin out of spring grove re did the heads couple years ago and have never been run. Cost me 750 for that. Has new bearings, rings and oil pump..

GPM

I'm just wondering why you would give up the Blower motor for a N/A motor, what is there to gain ?

Black Baja

iTrader: (2)

I know Tony. Honestly if you know Tony he's a very solid guy and will set you in the right direction. With today's lifters and springs 6,000 rpm isn't an issue with a hydraulic setup. I know Tony is running Hydraulic stuff in his race boat with big lift numbers and the proof is definately in that pudding. If your only going to spin 5500 rpm I think the 750hp goal is going to fall short. Spin it over 6000 and I think you will be pleasantly surprised that you will go over your goal. The bottom end isn't the issue with these builds and big cubic inches it's the valvetrain and oil control. When it comes to single plane intakes there is no magical intake they are what they are I would try to find one that will match heads without a lot of effort and that can easily be found out by making a few phone calls...

260Velocity

GPM. I have a goal of 85 to 90 with my 260 velocity. I would like to do that in the most reliable way. I know blowers produce heat and high IA kills motors. I do not want to buy a 2K intercooler for it and then worry about cleaning it and it leaking into the motor. I will be navigating in Brackish water of the Chesapeake bay.
I am just looking for reliable trouble free. (Haha I know it's a boat and that won't happen ) power.

GPM

Like I said I was just curious, I have a friend running a Tyler Crockett 502 blower motor for 18 years now with only oil changes and a carb rebuild. I have to wonder if the inner cooler and a closed cooling system may be worth a little consideration. Just a thought, good luck with what ever you decide.

SB

iTrader: (1)

How about getting a better SC, a good cyl head porter, and a cam to match ?

SB

iTrader: (1)

Hah ! Didn't see this 2nd page. Looks like alot of us are on same page.

MILD THUNDER

iTrader: (3)

A 509, with the right blower and cam, will do 750hp on snooze at 5500rpm with those RHS heads . Your stock crank and rods will also be fine there. Theres a thousand merc 500's with whipples out there running around at that power level without breaking a sweat.

A buddy of mine is running 509's with 8-71 mooneyhams, merlin iron heads, flat top JE pistons, chevy steel cranks and dimple rods, mild .630 lift hydraulic cam from bullet cams, made right at 800HP at 5600rpm in a 38 Cigarette, and they idle just fine and dock just fine. Going on 5 seasons now with them. Prior to that, they had 250 blowers, and a single 1050 dominator, and a slightly smaller cam, they made 700HP with 7lbs of boost.

I could tell you that a 10-71 blower on a 540ci, with no intercooler, see's 130-140* degree air temps at 6000rpm and 6-7lbs of boost. Many of us run blowers without intercoolers and no issues. Pick a blower you can run around 1:1 ratio give or take 10%, and you'll be much better off than the 250 blower setup.

FIXX

iTrader: (2)

4.380 crank only gives you a 557...you will ned a 4.500 crank for a 572... thats a lot of stress on those cylinder walls..might want to get the block sonic checked first if its been a marine block its whole life..

GPM

4.560 x 4.375