Question regarding L89 pistons...
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 962
Likes: 13
From: Camarillo California
Question regarding L89 pistons...
This question is purely academic, but something I've been wondering about....
The '69 L89 Corvette engines used open-chambered heads (#3946074). In order to maintain an 11:1 compression ratio like the L71 (which I believe in 1969 still used the older iron closed-chambered heads), what pistons were used in the '69 L89? Were they unique to that engine and how big were the domes? Obviously the L88/ZL-1 pistons with a 12:1 CR had larger domes made for open-chambered heads, but I don't recall ever seeing a Chevrolet 11:1 piston with a dome shaped for open chambers.
Anyways, I grew up with these cars and this is something I've never really thought about until recently. I'm hoping to finally bring an L89 Corvette into my life in the foreseeable future....
The '69 L89 Corvette engines used open-chambered heads (#3946074). In order to maintain an 11:1 compression ratio like the L71 (which I believe in 1969 still used the older iron closed-chambered heads), what pistons were used in the '69 L89? Were they unique to that engine and how big were the domes? Obviously the L88/ZL-1 pistons with a 12:1 CR had larger domes made for open-chambered heads, but I don't recall ever seeing a Chevrolet 11:1 piston with a dome shaped for open chambers.
Anyways, I grew up with these cars and this is something I've never really thought about until recently. I'm hoping to finally bring an L89 Corvette into my life in the foreseeable future....
Drifting
Joined: Nov 2016
Posts: 1,963
Likes: 579
From: Pittsburgh PA
This question is purely academic, but something I've been wondering about....
The '69 L89 Corvette engines used open-chambered heads (#3946074). In order to maintain an 11:1 compression ratio like the L71 (which I believe in 1969 still used the older iron closed-chambered heads), what pistons were used in the '69 L89? Were they unique to that engine and how big were the domes? Obviously the L88/ZL-1 pistons with a 12:1 CR had larger domes made for open-chambered heads, but I don't recall ever seeing a Chevrolet 11:1 piston with a dome shaped for open chambers.
Anyways, I grew up with these cars and this is something I've never really thought about until recently. I'm hoping to finally bring an L89 Corvette into my life in the foreseeable future....
The '69 L89 Corvette engines used open-chambered heads (#3946074). In order to maintain an 11:1 compression ratio like the L71 (which I believe in 1969 still used the older iron closed-chambered heads), what pistons were used in the '69 L89? Were they unique to that engine and how big were the domes? Obviously the L88/ZL-1 pistons with a 12:1 CR had larger domes made for open-chambered heads, but I don't recall ever seeing a Chevrolet 11:1 piston with a dome shaped for open chambers.
Anyways, I grew up with these cars and this is something I've never really thought about until recently. I'm hoping to finally bring an L89 Corvette into my life in the foreseeable future....
Thread Starter
Burning Brakes
Joined: Mar 2002
Posts: 962
Likes: 13
From: Camarillo California
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,089
Likes: 4,446
From: Marlton NJ
My 454 LS6 tribute has 10.55 CR with 074 heads. 116 CC chambers. .039" gasket. 27CC domes. +.030"
Somewhere I thought I read that the L89s came with closed chambers just like the L72s. And only the late '69 L88s, '69 ZL1s, and '71 LS6s used the 074s.
Somewhere I thought I read that the L89s came with closed chambers just like the L72s. And only the late '69 L88s, '69 ZL1s, and '71 LS6s used the 074s.
Last edited by leigh1322; Jan 26, 2020 at 10:04 PM.
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
L89's were closed chamber. Basically an L71/L72 shortblock with aluminum heads.
JIM
JIM
Last edited by 427Hotrod; Jan 26, 2020 at 11:35 PM.
