cmcnitt

I thought it did pretty good except the torque peaks way early.

10:1 c/r
crower 10404 cam(292 int, 303 ex dur, 110 lobe center, about 600 lift)
dual plane manifold
GMPP oval port aluminum heads (110cc)
Demon 850 dp carb

I'd like to see the torque peak closer to 4500, would a single plane intake help much?

articfriends

iTrader: (1)

I'm surprised the tq peak is at 3600 rpm's,most big blocks similar to yours are around 4400. What is cam duration at .050? Smitty

RumRunner

Do you know what the correction factor was when you dyno tested?

cmcnitt

RR, see attached.

I just got this boat and it seems real sluggish after about 4500 rpm (half throttle). Anything over half throttle doesn't seem to add much speed, it ran about 70mph at 4800 (just over half throttle) and slowly creeped up to 77 at full throttle. It wouldn't bother me so bad if it was more responsive but it is too d#$! sluggish the way it is.... I just don't know what the best bang for the buck would be at this point.

Thanks!
Chris

PatriYacht

The heads are the culpret here. You could have some porting done or you could crutch the heads by using a cam with a little more duration. More duration means more overlap ( time when both valves are open) and that could mean reversion. With an engine that size I would definatly use a single plane.

articfriends

iTrader: (1)

I agree,something is a definate restriction here,the cam isn't all that small. Do you have any flow #'s on the heads? Smitty

RumRunner

Have you pulled a plug yet?

cmcnitt

I haven't had the heads flowed, they are stock gmpp part number 12363392. I couldn't find any numbers on them. The plugs look good, I ran the boat today with an o2 sensor and it runs around 12.5 afr. The boat jumps right out of the water but runs out of steam after about 4300 rpm. It sounds like I need to swap the heads and intake..

Chris

Kidnova

GM heads part no. 12363392 are oval ports, designed for 396 through 502's. 2.19 I, 1.88 E stainless steel valves. Probably not enough flow for a 540.

Hope this helps.

Bulldog

I may be wrong, but oval ports sound small for a 540.