Thanks Jeff!

I think the head flow is equivalent to the GM Fast Burn... I had all of this documented here at home but my computer crashed and I I lost it all. 230/170 @ .500 seems to ring a bell.

I'm eager to see what you come up with... I've read about some 355 combos with less compression and a notch down on the camshaft work out to somewhere in the low 400 hp range. I think I'm going to have a real drive buster here.

Thanks!
Tom

Tom I ran the numbers last night. I used a 383 with 750 CFM carb, dual plane intake, and flat tappet hydraulic lifters. I found the numbers on a vortec head but the valves are the 1.94/1.5 but I'm able to adjust the valve size. Since you have your heads ported we'll see how close thes numbers are.


Your Extreme Marine Cam: 2000-172 HP/ 450 Torque, 2500 217/455, 3000 262/458, 3500 305/458, 4000 339/445, 4500 361/422, 5000 363/381.

Extreme Energy Cam: 2000-159/417, 2500 206/433, 3000 252/441, 3500 299/449, 4000 343/451, 4500 380/443, 5000 401/421.

It looks like its a good cam for the upper revs. Althought there is still a ton of torque down low it gives up a fair amount to the extreme marine. The extreme marines torque is flat as a board all the way up until it gets almost to its max operating rpm. Where the EE doesn't start to drop off until later. I guess is all in where you typically run at. Hope this helps.

Wow, that's a major slide in torque when comparing the two.

Since the boat is heavier than a comparable go-fast and since I'll be spinning a bigger prop maybe I should stick with the 262 or maybe up it one notch in the marine category?

Could you run these numbers for me? This is Comp's XM-270-H which is the next rung on the ladder.

270*/276*, 226*/236* @ .050, .480"/.489", 112* LSA

I guess I'd like to see the flat torque curve with a little more horsepower. I would rather not have to beat the crap out of the motor to get up on plane and keep it there. If the other cams are requiring that then I'll stick to what I have for now. How do you tihnk one of the other cams would run (XE-274 and the XM-270)?

Any suggestions?

Thanks!

Tom here are your numbers.

2000 162 hp/426 ft/lbs.
2500 207 hp/434 ft/lbs
3000 251/439
3500 297/446
4000 340/447
4500 375/438
5000 398/417

Looks like is a wash between the two.

I figured as much...

Do you think that the more aggressive cam will be driveable? I think I'll stick to it and give it a try (nothing to put another cam in it if I need to).

Here's a thought... maybe the lower torque of the more aggressive cam will help to save the drive from major destruction? Yeah that's it!

Anything has to be better than the old 355 was so I guess it'll do.

Lower torque?, I hate to tell you your alpha is going to hate you anyway. Youre idle is probably going to suffer, but like you said switching the cams is no big deal. Looking at all the numbers, such as overlaps and IVO EVO, and that kind of stuff, it isn't too far off the Exteme Marine. So I would think it would behave similar.

But you have to admit, that Extreme Marine is a pretty good cam, down low. Cams are cheap. Someone should invent a break away coupler. If you get close to toasting a drive, it gives first.

39 days and the cover comes off.