RFP for the Engine Build for the Missile
First of all Im not looking for validation, as those of you who know me will say, that's not what drives this project. I really am up to other approaches, If you said a flux-capicitor would do the trick and you could provide one, we would sit down and talk.
Secondly 12 valve, that was a very concise and easy to understand explanation.
Thanks again guys.
Andrew
I wasn't intending to ruffle feathers with my word choice so my apologies. But you're being told by various people (some that have been there) that the parts choices either "may not" or "won't" do what you want within the restrictions given.
For what it's worth here are my changes and why I chose them. If you don't want to accept this flux capacitor it's entirely your choice:
1. Any cam that will enable the rpm window you're looking for will need to be solid tappet. You simply will not get the 285HL to rev to or make power at 7500. Especially against a 1.6 rocker and the associated spring you'll need to run. The sim programs don't take lifter collapse or springs into account because in order to plot a linear curve they simply assume it will keep performing at a certain percentage. Do asearch for dyno plots from real engines and watch the power peak drop at a specific rom - ususally between 5500 and 6K, some might get as high as 6500 with the beehives and 1.5s. But they drop off a cliff because the valve control is lost. in order to chose a cam you have to look at the head flow data and the end result you want. Providing Ryan can get what he says (I have little doubt he can't) then you need to see at what lift the heads flow 300cfm or more. Then cam it to keep the valves open long enough and far enough to feed it in that area. From my limited info those heads are not really moving air until .400, and they don;t see higher than 300cfm until .500. So you will need a solid roller (provides the most area under the lift curve) of at least .650 lift (that opens the valve far enough past .500 after lash to reach the bigger flow numbers), and you'll want the duration @ .050 to be in the 270 range (in order to give the cylinder enough time to use that high flow rate). 600HP and 7500rpm does not come from street cams or street engines. It comes from race cams in race engines. Again - talk to Dave (DJV) and review his threads. Especially the one where he swaps heads and top ends.
Checking your lash will need to be done roughly twice a season and should be checked prior to any race event. It takes about 20 minutes and as long as you have the procedure down and dont overtighten the valve cov ers it costs nothing. It's easier and faster than changing spark plugs with big tube headers in an A body and that will enable you to make a tamer 600hp engine.
2. The dynamic you're looking to run - If you're using a dished piston and a 63cc chamber, you should be running a tight quench distance. With steel rods and a 7500rpm redline and road racing I'd be looking at .040" head to piston clearance. With a tight quench and aluminum heads, plus the associated larger cam you have to run to make the real 600hp level, the dynamic compression can be raised to 8.75:1. I've built more than a few 4" stroke small blocks this way and they run on pump 89 with 10% ethanol with no detonation. With larger cams they run on 87. If you're planning to run pump premium you have lots of room for improvement with the DCR and you don't need to be afraid of it.
3. The intake manifold for a street car is drastically different than an engine that is expected to produce big power naturally aspirated. you're looking for close to 1.5hp per inch. The best dual plane will struggle to make that, if it can at all, and porting is only so good unless they are cutting the top off and then welding it back up because they can reach everywhere. The dual plane simply is not the best intake for your specific need. It's the best
compromise intake. Again, for what you want and expect, a compromise may not deliver as good a result (meaning less power as a properly sized single plane. The intake port extends from the back of the valve to the carb butterfly. Great heads can be squelched with a mismatched intake. Big numbers don't come from mismatched parts.