KWright

Yes but focusing on the rpm range of peak torque and what you need to do to extend it 400- 600 rpm would be more beneficial. When we were working on my engines, Tim Hogan redid our intake runners and plentum's, 3 times before we had the curve where we wanted it. And although the torque curve moved up and broadened, peak HP and rpm dropped.

KWright

Not always.

sutphen 30

yeah,,maybe in a 330,,but any built big headed bbc w/ like a big cam.and theres exceptions to the rule but generally,,bigger cam w/ supporting hardware makes big power na.

sutphen 30

sounds like your cam was wrong.

what was your engine build?

KWright

With out getting off topic. Tim's concern's were to get more top end out of his boat. So to do that he has to be able to spin his prop faster. Raising his curve by 400-600 rpm would do that. Just a suggestion not trying to step on anyone's toes or challenge anybody's engine building ability.

bck

When my engines were rebuilt the increase in top end hp came at the cost oflow to midrange tq. I was initially concerned about this but the further testing with carbs/ intakes/ spacers improved the tq considerably. Also, peak hp only moved up 200 rpm while peak tq moved up about 600 rpm iirc. So a noticeable move up for pk tq.

MILD THUNDER

iTrader: (3)

How much torque did you gain with those changes?

I have no doubt, that if Tim had dyno'd with some 2.25" full length dyno headers, his torque would have been higher, as well as his HP on the dyno sheet. Problem for him, he doesn't run 2.25" dyno headers in his boat. On a 700HP N/A engine, running with an exhaust system that is simply not the exhaust you will be utilizing, its hard to know what the combination likes best, when you take away the scavenging effect. The exhaust is no different than any other part of the combination. A cam that might work awesome with some big dyno headers into a 4" collector dumping into 5" flex pipe, might not work so well, with a short runner manifold, with 3.5" gas pipes with water in them.

bck

I don't remember the exact #s. I lost some tq at all lower rpms. I'd say the new motors had less tq all the way to the old motors tq pk of 4600. After 4600 the new motors kept building to 5200. I've got 2 1/2 primaries on the boat so I figure might not be much difference going from dyno headers to boat headers.

KWright

Exactly thats why you dyno in full boat trim[ATTACH=CONFIG]563519[/ATTACH]

SB

iTrader: (1)

ID 2.5" ? If so, yikes !