Originally Posted by ThisIsLivin (Post 4031172)

I was going to start a thread myself on this topic. I'm looking to upgrade to a bigger boat and I want a minimum of 800hp ea and would like to stay away from a blower. I was considering a 572 with some custom heads, 10:1 compression, tunnel ram, solid cam, and lightning headers. I didn't consider dry sump although I have thought about using extractors to reduce crankcase pressure or even a vacuum pump. I currently have a 524 running just shy of 700 with a hydraulic roller cam at .623/.612 lift and 242/252 duration at .050". It took every bit of tweaking to get that, I know the stretch to 800 and still have drive ability is going to be tough, but I really like the rumpity rump of a big cam. I checked out AFR's heads, I currently have the 315's, while AFR makes a bigger port, they don't flow more than the 315 until they hit .700 lift and they all flow worse below .500. Anybody have any recommendations on heads that flow really well from .200 to .700?

Haxby, some of the new throttle bodies say they will support 900hp but require 9" of vacuum to function properly. I have been thinking about using throttle bodies on a tunnel ram to make more power through more complete atomization. What are your thoughts?

Originally Posted by bobl (Post 4031306)

Here is a video link of the dyno run for the engine I built for my personal boat.

http://www.youtube.com/watch?v=1deXRs-g51g

598 with AFR 335 heads,9.8:1 compression, hydraulic roller cam, Dart tunnel ram with 4 x 2bbl throttle bodies, efi w/mefi3 ecm.
It's been running great for several years. Idles at 800 RPM and very well mannered. I believe targeting much more HP than this you'd give up a lot of durability and drivability staying naturally aspirated.

Bob Lloyd
Full Throttle Marine

Originally Posted by Tinkerer (Post 4031830)

haxbypeed - After doing some thinking I think the best thing to do is go supercharged. Most people feel the Procharger I the way to go. If I go with a supercharger what would you suggest? My thoughts are to buy one that will be able to feed a 1000 + HP engine that will work on my existing 509 until I build the new short block. My 509 has 10 to 1 compression and I was thinking about running it on E85. Could I run E85 at 10 to 1 and run 7 lbs boost???

Originally Posted by HaxbySpeed (Post 4031849)

That'll work. I agree, to make 1000 reliable HP with a 509 you'll need a centrifugal SC or a turbo, with the centri being much cheaper and easier to do. I'd go with an M3sc, It'll make 1000hp now, and support up to 1200 if you upgrade to a 540 down the road. The M3 along with your compression will make a ton of torque in the midrange.

Originally Posted by GPM (Post 4031859)

Any chance the M4sc might be better for future HP, http://www.procharger.com/marine/M_tech_specs.shtml