piston delimma
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: May 2006
Posts: 564
Likes: 0
From: IN A VAN, DOWN BY THE RIVER!
piston delimma is there anyway i can get a streetable compression on a 408 with 5cc dome pistons, and still keep the quench tight?
(by streetable i mean pump gas)
(by streetable i mean pump gas) A HUGE combustion chamber. I think the biggest you can get is around 76cc's. That's not gonna cut it! If the pistons have a solid dome you could have the dome machined off. Not a great choice, but a possibility. Of course, then you'd have to re-balance the rotating assembly. Bottom line, new pistons are in order here.
Ok, I will stand corrected here. Based on a 4.060" bore and 4.0" stroke with your 5cc domed pistons at zero deck with .052" gaskets and a 76cc combustion chamber you'll be at 11.34:1. With a 72cc chamber you'll be at 11.87. With a good tune you could get away with pump gas. I think the LS7's around 11.5:1. Sorry to get you all fired up without doing the calculations before I posted!
Oh yeah, one more thing, that's static compression. You DCR (dynamic compression ratio) is going to play a big role in how well it'll run on pump gas. Without your cam specs I can't help ya with that one!
Oh yeah, one more thing, that's static compression. You DCR (dynamic compression ratio) is going to play a big role in how well it'll run on pump gas. Without your cam specs I can't help ya with that one!
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: May 2006
Posts: 564
Likes: 0
From: IN A VAN, DOWN BY THE RIVER!
lol whew! thanks man, i knew about the dynamic / static roles. i haven't picked a cam yet so i wanted to see just how high it actually was. but thanks for the info man.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
FormerVendor
Joined: Nov 2001
Posts: 3,065
Likes: 6
From: Houston, Tx.
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: May 2006
Posts: 564
Likes: 0
From: IN A VAN, DOWN BY THE RIVER!
Sorry for the delayed response, but yes, a true flat top with no valve reliefs and a 67cc chamber will be that same as your 5cc dome and 72cc chambers. 11.87:1 based on what I posted above. That's on the ragged edge in my opinion. If you're going that route I'd try to get a 76cc chamber to bring the scr down a little more. Bear in mind that a flat top piston will produce a more efficient combustion chamber than the dome and have more detonation resistance. You're certainly going about dropping your compression the right way, increasing chamber size as opposed to using thicker gaskets, but I'm still leaning towards swapping pistons in this case. Of course, that's just my opinion. The work involved is certainly greater, but it'll be the cheaper route in the end. A set of heads will run ya over 2 grand while a set of pistons, related components and a good balance shouldn't run more than $1500.