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Old 03-31-2006, 09:15 AM
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454, Long Rods, and Nitrous, oh my

Hello all. I've been lurking here for a while now, just never needed to post much because a little research on here usually answered my questions. However, I am now in a quandry and need some educated opinions and experience.
My 454 is currently in the process of being rebuilt. I haven't selected a camshaft for sure yet, but I'm going to go with a hydraulic roller, something in the 240-ish @ .050 range. Comp Cams recommended their Extreme Energy 294HR (242,248 @ .050). I've already purchased a new 4340 crankshaft, but I have hit a snag when it came time to purchase new rods. I've been reading a lot about the long vs short rod debate, and I'm currently thinking of going with a .250 longer con rod (6.385 vs 6.135). It is my understanding that in theory this should help with mid to upper rpm power, at the cost of low speed scavenging somewhat. I also understand, I think, that since the longer rod dwells at TDC longer, it would be possible for a long rod to develop more cylinder pressure, and since the piston will be moving slower, I would be able to reduce overall ignition advance without losing power. However, what concerns me is nitrous. I fully plan on using just a 'tad' of nitrous on this motor (fully forged 4340 crank and rods,forged pistons, stud kit on mains, deck and heads surfaced just enough to make sure they are flat, and good head bolts). With a long rod and nitrous, would cylinder pressure be uncontrollably high? The pistons I'm looking at running with the long rod also have thin (1/16) rings. Should I be overly concerned about using nitrous at all on this motor combination? What should I limit myself to applying? If I go the long rod route, any recommendations on the camshaft? Call Comp again and see what they recommend?
If I went with a short rod, I should be able to apply even more nitrous, since cylinder pressure wouldn't be as high, right? How much nitrous can be injected before I start running into other problems due to cylinder pressure? Either way, the nitrous system will have it's own fuel delivery.
Finally (I think), I'm looking to build static compression ratio at 10:1. Is there anyway this can be run on 93 octane pump gas? I read once, I can't remember where, that a long rod is theoretically capable of allowing a little higher compression ratio since the amount of ignition advance is reduced. Am I on the right track at all, or have I wandered down the unbeaten path?
Thanks for all your help, advice and opinions.

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Old 03-31-2006, 09:26 AM
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Nothing you do will makea dang bit of difference what rod you use. I doubt you can get a off the shelf cam that would benefit you long rod theory. I would use the longer rod to make the piston lighter so it's easier on the crank. Do a search on rod lenght, grab a snack, and a comfortable chair.
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