PatriYacht

The alum. heads are worth about 100 hp n/a and about 150 hp with 8 lbs of boost. Speed costs money, how fast do you want to go?

jdnca1

[QUOTE=Chris Sunkin;2355212] My point is this- He's not going to be near the 800 hp mark with 8psi on pump gas and probably will be turning this motor about 6000 rpm. QUOTE]

You are simply wrong here, he should be well over 800hp with 8# of chilled boost...even with stock GM heads ~@5800rpm. . If he's still running the stock 500EFI stick, that is the limiting factor, slide a Crane 651 in and its there...actually closer to 850 @6100. We did it on a set of 500's as above with 8# of non chilled "roots" boost and carbs. still together and still going strong....

Chris Sunkin

You are simply wrong here, he should be well over 800hp with 8# of chilled boost...even with stock GM heads ~@5800rpm. . If he's still running the stock 500EFI stick, that is the limiting factor, slide a Crane 651 in and its there...actually closer to 850 @6100. We did it on a set of 500's as above with 8# of non chilled "roots" boost and carbs. still together and still going strong....[/QUOTE]

8 lbs boost on 8.75 CR pistons and no intercooler? 850 hp on pump gas?

jdnca1

8 lbs boost on 8.75 CR pistons and no intercooler? 850 hp on pump gas?[/QUOTE]


Yes sir, 8-71 blower shop at that on 93octane. I'ts definately "on the edge", but the cylinder pressures are under control and its a big blower turing slow...not for everyone.

f311fr1

I made 825 on Nickerson's dyno with Merlin tall deck 540, Hampton 10-71 and Merlin CI heads. 8 lbs boost, no intercooler and 8.75 CR. Dean did the twin 850's. I backed the boost down to 6 lbs when I put them in the boat. Ran good for several years until i went back to NA and EFI.

Chris Sunkin

On 91 octane and 35 degrees of timing lead? Few more cubes in there but that's only 50 or 60 hp.

Back4More

13.5:1 final CR....that would be over the edge.

cobra marty

Get AFR 305 or 315 heads, ARP head studs, cometic gaskets and RMBuilder to do a cam for you and then you need someone like Tyler Crocker to dyno it and reprogram the computer. How much power do you want? Stock engine and 8 pounds will give you 700-725 HP. With heads and cam and 8 pounds you will have 850HP and if you build a 540 you can see 950+ HP. What drive are you going to break?

jdnca1

8.75:1 with 8# of boost is right there....

Chris Sunkin

I tend to like to look at what other successful builders are doing and follow that direction. When you look at Sterling, Zul, Cobra and others, their engines making the kind of power you're talking about are 100 cubic inches larger and constructed out of the absolute top-of-the-shelf components.

Now I've heard the argument about how Merc is so ultra conservative but it seems to be a trend among those builders that have been around a while. Unless you have an unlimited budget, are willing to own 3 sets of engines and do preventative majors on a regular basis, reliability becomes part of the equation.