"Enlarged" TPI Runners
Thread Starter
Senior Member
iTrader: (1)
Joined: Sep 2015
Posts: 683
Likes: 19
From: Knoxville, TN
Car: 1988 IROC-Z
Engine: 350 TPI
Transmission: T56 swap ongoing
Axle/Gears: 2.77 9-bolt Posi
"Enlarged" TPI Runners
Found a set of polished TPI runners for a reasonable cost.
Only thing is, they've been "enlarged" 9%--most likely they ran one of those tools through the passages in order to remove dents before polishing.
Original diameter of TPI runners is 39mm, if I recall correctly, 9% would mean they're at 42.5mm....would this actually make any notable difference in the torque curve? Unlike many people working on a Camaro, I want to keep torque in the low/midrange as they were new, not interested in making it into a 7,000 RPM screamer.
I'm thinking since the length of the runners is unchanged, I'm not likely to notice much, of any of a difference, which is fine by me...am I thinking right, that there shouldn't be any issue?
Only thing is, they've been "enlarged" 9%--most likely they ran one of those tools through the passages in order to remove dents before polishing.
Original diameter of TPI runners is 39mm, if I recall correctly, 9% would mean they're at 42.5mm....would this actually make any notable difference in the torque curve? Unlike many people working on a Camaro, I want to keep torque in the low/midrange as they were new, not interested in making it into a 7,000 RPM screamer.
I'm thinking since the length of the runners is unchanged, I'm not likely to notice much, of any of a difference, which is fine by me...am I thinking right, that there shouldn't be any issue?
Joined: Feb 2001
Posts: 8,494
Likes: 414
From: Sophia, NC
Car: 2016 Camaro SS + 1986 Z28
Re: "Enlarged" TPI Runners
I agree.
....and beyond that, those "enlarged" runner auctions have been around on Ebay forever. -assuming you're talking about the ones where they run the steel ***** through them, and not actual "larger" aftermarket runners. I've always been skeptical of whether or not that's actual possible to stretch the runner. And even if it is, the flange at the plenum and manifold are cast, so how would THEY be larger? -although you could port that part.
....and beyond that, those "enlarged" runner auctions have been around on Ebay forever. -assuming you're talking about the ones where they run the steel ***** through them, and not actual "larger" aftermarket runners. I've always been skeptical of whether or not that's actual possible to stretch the runner. And even if it is, the flange at the plenum and manifold are cast, so how would THEY be larger? -although you could port that part.