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  1. #1

    Default What to expect from this motor?

    I just picked up a motor with the following specs wonder what to expect for performance?Fresh bottom end 5.2 rods .060 overOval head factory valves .450 hydraulic roller camHead shaved .140 ARP bolts in bottom end Previous owner had 5 races on this setup said he ran 8200 rpms? Rpm seems hard to believe? Would this engine benefit from a larger cam lift? It appears the cam is a custom grind the numbers on the cam are the following:PC-HRT-9509-9508-11.115 2020R. Thanks you guys are great

  2. #2
    Join Date
    Dec 2012
    Posts
    22

    Default

    Years ago, valve lift was a decent predictor of an engines performance. In these days, mild factory engines usually did not exceed .450 valve lift, and the hottest factory engines were never over about .500 lift. The figure that does, and always has mattered in predicting engine performance is camshaft duration at .050 inch lift. Cams are now available that have very large duration numbers while still having stock or near stock lift numbers. An example of these camshafts would be one of the many "lift rule" cams that are marketed by Howards. Other than camshaft duration, the other biggest limiting factor in engine potential power is total intake flow of the cylinder head. Some stock cylinder heads fall on their faces at 3500-4000 rpm, an example of this would be the gm truck heads produced from 1987-1995. Some factory cylinders heads have very high performance and rpm potential, and example would be the fuelie(a.k.a. camel hump) heads from the late 1960's. The fuelie heads were the stock cylinder heads on high performance g.m. small blocks. I would a few cam companies and ask them if this is their part number. To me, it kinda looks like a Howards Camshafts part number, I could be wrong. In order to turn 8200 rpm, I would expect a .050 lift duration number that was at least 235, probably 245 or higher.
    Last edited by dirtdobberrr; 11-22-2020 at 09:56 PM.

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