Idle quality, displacement and cam choice...
Idle quality, displacement and cam choice... I've been hearing that a larger displacement motor can take a bigger cam with much less issue than smaller displacement motor. Tuning a larger motor with a big cam is supposedly easier than tuning a smaller motor with that same big cam. Suppose you take a cam spec'd at 236/236 @ .050, .600/.600 lift, 112 LSA and stick it in a 5.7L LS1 and the same exact cam in a 402 stroker (6.6L). Is is really true that a 402 stroker would idle close to stock with a cam such as the MS3 simply because of the torque advantage of the longer stroke, bore, or both? How different would the powerbands look and how different would the idle sound like?
Does anyone here have idle clips of the same cam in motors of varying displacements? I'm curious to hear what the MS3 would sound like in an otherwise stock cube LS1 to a stock 6.0L all the way up to something like a 402 stroker, or heck, an LS7...
Does anyone here have idle clips of the same cam in motors of varying displacements? I'm curious to hear what the MS3 would sound like in an otherwise stock cube LS1 to a stock 6.0L all the way up to something like a 402 stroker, or heck, an LS7...
I don't think it is so much of a sound difference as efficiency. Cam will have no less of a choppy idle at low rpm's sound but it will be much more efficient in making power with the added cfm of air the larger displacement engine is pulling in.
well think about it in a simplistic say. the larger the engine, the larger its demands for air are, no matter in the rpm's are. a cam, put simple, controls how much air flows through the motor, or at least plays a part in it. big motors just swallow up more air.
for example, i came across a 496 (as we know, and ls1 is 346 ci)big block el camino today that made 670hp on an engine dyno, n/a, pump gas. carbureted, with a solid roller. it idles like a 230* ish cam would in an ls1. i didnt ask cam specs, but i would assume i was something 249/255 on a 110 lsa, possibly more.
for example, i came across a 496 (as we know, and ls1 is 346 ci)big block el camino today that made 670hp on an engine dyno, n/a, pump gas. carbureted, with a solid roller. it idles like a 230* ish cam would in an ls1. i didnt ask cam specs, but i would assume i was something 249/255 on a 110 lsa, possibly more.
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forgot somethin.. I ran identicle cams in both a 318 and a 360 dodge years ago. Same car, heads, carb, etc. cam was something like a 232 @ .050 w/ .484" lift. Mild cam compared to what i see nowdays, but was a very lopey beast for the 318, and noticeably smoother in the 360. Still a lope, but not as rampant.
The 360 has a bigger bore and stroke than the 318, and would still be curious to see how it would behave in a 340, which shares same stroke as the 318. But alas, after i bought a '79 t/a 6.6 my days of tinkering with old mopars had gone.
*edit* Generally speaking, if you look at stock run of the mill engines (not HP versions), the bigger the CID, *generally* the bigger the cam specs. A mild grind for something like a 454 would likely be not so mild in say a 350.
The 360 has a bigger bore and stroke than the 318, and would still be curious to see how it would behave in a 340, which shares same stroke as the 318. But alas, after i bought a '79 t/a 6.6 my days of tinkering with old mopars had gone.
*edit* Generally speaking, if you look at stock run of the mill engines (not HP versions), the bigger the CID, *generally* the bigger the cam specs. A mild grind for something like a 454 would likely be not so mild in say a 350.
Last edited by chux77; Dec 30, 2008 at 09:39 PM. Reason: forgot somethin..
