I have been looking to replace the HP500EFI in my Cougar. Well I fell into a very good start for a 540. Dart big M, CNC AFR335s, 4340 Scat crank and H beam rods. Plan on using Mahle flat tops for about 9.3 cr. and EZ EFI2.0. Premium fuel is not available so it has to run on 87 octane as well.

I am looking for a bulletproof 600-650hp. so it doesn't shred the drive. I have been thinking about using a crane 168741 with 114 degree centres rather than the 112.

Comments and suggestions please.

22MTR

You could go with 6-8 degrees more duration or so and a Dart Tunnel Ram(lol).....shift your power up the rpm range a little.
Your boat won't need mountain moving torque and your drive obviously won't like it anyway.

Sounds like a good foundation you have. Those cubes and those heads want to be fed - so feed them.

wanna see this thread... subscribed.....

I'd call a couple cam guys / grinders and see what they come up with.

Marine kinetics, cam motion, crower etc. and let them know what you're doing and how you plan on using the boat. (Be as accurate as you can. GI = GO )

Before we ordered my cam we talked to the three I referenced above and they all specified cams that were remarkably close.

http://www.offshoreonly.com/forums/g...o-results.html

Ultimately after some tuning , ^^^ this combo made around 680HP if I recall with only 9:1 static, and pushed a 35 mistress to upper 70s, with the 741 Crane cam. Those valvetrains lasted quite some time as well. This was 12 years ago.

That's interesting to see the link above. I built pretty much the identical engine except with 305 heads(thought incorrectly that I had 315 heads) and peaked with 660 @ 5700 and I don't believe it left the dyno quite as dialed in as it could have been.

My builds pushed my Mistress to 73, looks like some dyno time for me this winter to see WTF I am missing, going off dyno sheets of my old engines these don't have the TQ I need....

if my engines were in a lighter boat I bet the results would be better...

I should start the most TQ 540 thread lol

Thanks for the thread. Looking at it, it is 315 heads. Wondering how much the 335s will move things up the rpm band. Also what is max input RPM for a bravo XR??

This is the dyno sheet from the link mild posted. The photo is mine. I don't have my cam specs on hand, but it's a mild hyd roller. Other than that you're seeing the difference between the 305 and 315 heads.
*edit- well for some reason I can't copy and paste the chart from the link. Oh well

Do you want a cam that simply makes a good number on the dyno pull, or a cam that opens and closes the valves gently, can be run with less spring pressure, less lift with longer spring life, and maybe sacrifice a few HP to do so?

Theres more to a good cam choice than the dyno number the engine makes, or where it makes its peak power.