sc2dave wrote:is there a formula to determine plenum size?for instance, to determine where you want your power at intake?
man, all these numbers sound confusing! i'm using stock cams,i just want more lower range power. what if i just lengthen the runners,and maybe make them smaller diameter?
sc2dave wrote:max stock power is at 5600. all i want to do is try to make more power where i drive at, under 4000 rpm. i've heard these cams are not the adjustable type.this manifold is one runner per cylinder,then the head has 2 intake valves per cyl. there is nothing that the ecm controls on the manifold.
sc2dave wrote:..so, how then can i know what length and diameter runners to use so that i can lower peak power and bring it down to where i want it at?
BillyShope wrote:I would agree that it's really silly to manifold tune for an rpm which you won't even "see" after the WOT shift out of first gear. I say this even though I was at Chrysler when they did exactly that with their long branch intake manifolds. My boss in the Vehicle Performance Department tried to point this out at the time, but he didn't have enough clout. The bean counters were given rides in the early project cars and they were impressed and that's all it took. After it was too late, a "drag race" was surreptitiously arranged, at the proving grounds, between a Chrysler with the "ram" manifold and another identical car with the conventional dual quad setup. The conventional "ran off and hid" from the ram.
But, with the throttle blades upstream of the plenum, the ram did give a very good part throttle "feel," which is why the bean counters were impressed. So, I'm sure there are those who would opt for the ram, even though WOT performance was actually poorer.
As far as WOT performance is concerned, you'd want to tune for an rpm midway through the range seen in an intermediate gear. (Unless, of course, you're building a Bonneville car, in which case you'd want to tune for the horsepower peak.)