Ken: Never seen a "Miller Cycle cam". Sounds like this cam is a wide LDA design, like Tony said, that is dependent on the induction pressure of the boost, to raise or "stabilize" the CR. This can be done, but in cam selection it is a balancing act between late intake closing for "maximum" top end power, without the problems associated with spark knock or detonation.
It all comes back to the octane thing. You want an engine that will run decently, idle OK, and yet get up an GO! Naturally aspirated, or blown, an engine needs to be manageable, yet maintain decent/compatable design to octane sensitivity.
The octane demand goes down with -
1.cam timing retarded (later intake closing)
2.cam ground with wider LDA
3.ignition timing is retarded
This is the hard part of engine building, these judgement calls, when it comes to cam choices on an engine, like the one you have.Cam choices are based upon: the cam design parameters, and, head flow CFM volumes, ( both intake and exhaust), and, shape of the combustion chamber, and, the type of induction system used on your engine, (FI or carb).
I realize that as air density rises (supercharging), the demand for octane will increase. The static compression ratio: 8.5 to 1 as an example, might produce a dynamic compression of say 150 PSI, with a compression gauge, and also might be comfortable to run on 87 octane gas. But with the correct cam design, it will change/influnce, and balance, against flow, velocity, and pressure differentials, to actually bleed off some intake pressure so as not to make it ultra octane sensitive, maybe not combatable with 87, but would run on 92 octane pump gas.(I'm talking about a blown 8.5 to 1 example, but not running the high pressure boost you are talking about, maybe something in the range of 4 to 6 psi)
I am of the opinion that if that was my 292, I would build up the bottom end, basically stock. Spend the bucks on the forged slugs. You can't go wrong there. Stick with stock rods, be sure everything is magged and resize rods. Spend your money on the HEAD!! Lots of porting and flow work to get that baby breathing! New valves, new seats, blend the short sweeps to the runners. Open up the exhaust side a bunch. Smooth out that combustion chamber. Weld up, and smooth all the sharp corners of the chambers also. You will gain much more for your dollars here, than in anything else you do, guaranteed! Proper porting and flow work to the chambers can gain 30% to 50% increase over stock CFM flowrates, no kidding.
I do not know if you already have the Whipple, or not? Repost and let me know, and I will give you imput/responces, my 0.02 cents.
Think Chevy!
:rolleyes: :p
