[Mark O'Neal]

Well, we do a fair amount of these things, and I would state your practical limit at 572ci. (with an early block) That's at .080 over, although most of the blocks we've sonic'ed would be perfectly happy at 4.500".

We did one (for a truck) that was 572ci with Blue Thunder heads, that were ported on the exhaust side only.

It made 680 HP and aroung 650 ft lbs.

There are only two rules. Tune it so it doesn't detonate or lean out, and understand that it's a big block, so it isn't going to 8,000 in these combinations.

I wouldn't get too awfully tied up in these arcane ratios. They mostly serve for drunken conversation and to start arguements.

99 percent of dead engines are killed by lousy tuneups (once you established it was screwed together correctly). Anybody can get stupid tuning, driving, or building motors, but they seldom kill themselves.

I've put tham in Cobras, boats, cars, and fifth wheels (wanna pull Donner Summit at 55 in cruise control?), they don't have any more problems than any other engine.