Thread: 500 hp/550 lb-ft from a 390?

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Scat rods are on order and should be in soon.

Tech,
I just wanted to ensure that I'm on the same page here, the pistons that you mentioned are Speed-Pro's with a 4.070 bore (at least that's how I read it) and a .030 overbore was mentioned initially so wouldn't that require a 4.080 piston? If that's the case, I don't see that size readily available from Summit. I haven't had the machine shop check bore sizing yet but my initial measurements with the ol' Mitutoyo caliper shows that it might just be possible to get there from here. I've looked and a couple of companies make forged pistons in .030 over but the price is pretty steep. I really like the idea of forged pistons so I'd like to keep it that way....I realize that .010 isn't that great a change but I would value your thoughts on power production with that difference. Assuming I've got the math right anyway...

+0.030 is usually the first thing that pops out of my mind on these builds because a block will almost always clean up at 0.030", where it may or may not clean up at 0.020". I much prefer less cut on the cylinder walls, thinking that the walls should be left as thick as possible. In my opinion, the small amount of additional power gleaned from another 0.010" cut doesn't justify the thinner walls.