We've got guys in T/S making 350RWHP+ with GT-40P heads (unported), GT-40 intakes, shorty and .500" cams. One has susposedly made 378RWHP in carbureted form. It doesn't take an expensive motor to do it. Last years champ did it on stock block (+0.030), stock crank and rods, with TRW replacement pistons. No fancy lightened cranks, polished rods, none of that. Now if he's making 350RWHP, that would be in excess of 400 at the crank.
If you're talking 347 with AL heads, .560" cam, LT headers and Edelbrock intake and you can't make 450HP from it, then something's wrong. Careful selection of parts and good tuning should get you there real easy. The tuning is the tough part. It takes time, runs at the track or dyno, and some money but as the forty-niners used to say..."There's horsepower in that there engine!"
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Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH
Chambers Racing Team