Anyone running 11.5 CR?
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,613
Likes: 0
From: Winston Salem NC
Anyone running 11.5 CR?
It looks like there's a crack in a sleeve. So the engines coming out.
Current:
Stock cubes
228/228/112 cam
flycut intake
Z06 heads 2.055/1.57 milled .18(about 10.9CR)
Plan:
Forged flycut flatops
.045 Cometic for .038 quench
Heads milled another .030 for total of 11.5 CR
Should be around 11.5CR. Any thoughts?
Do rocker bolts need to be shortened?
Suspect the Fast valley cover bolts need to be replaced with flathead bolts?
Do heads need to be angle milled for intake manifold to fit? If so, what issues are created?
Rockers need to be shimmed .035? Currently getting about 1-11/2 turns after preload.
If heads are angle milled, does shimming change?
Bottom line, is it worth doing 11.5CR. Or might less be better?
228
228
112
112
2 IVO
46 IVC
46 EVO
2 EVC
112
4 o'lap
__________________
382HP............Best 1/8th...7.199 95.79 1.571
407HP 374Tq...Times to come
Mods: ,PT4000,3.90 gears,Eastcoast deep pan,B&M transcooler,Z06exhaust, Vram,Z06stylescreens,siliconecoupler,Fas tintake ,NWilliams 90mmTB,LS1edit,EFIV7,TechedgeWB,TEAstg2. 5 Z06heads,HSrebuiltrockers,93Pony228/588/212 cam,FLPheaders,Rollmaster2Xrollerchain,A SP UD pulley,Magnecorwires,NGKiridiumplugs,30# SVO inj.,PCVmod,180thermoshim,Hurstlinelock.
Current:
Stock cubes
228/228/112 cam
flycut intake
Z06 heads 2.055/1.57 milled .18(about 10.9CR)
Plan:
Forged flycut flatops
.045 Cometic for .038 quench
Heads milled another .030 for total of 11.5 CR
Should be around 11.5CR. Any thoughts?
Do rocker bolts need to be shortened?
Suspect the Fast valley cover bolts need to be replaced with flathead bolts?
Do heads need to be angle milled for intake manifold to fit? If so, what issues are created?
Rockers need to be shimmed .035? Currently getting about 1-11/2 turns after preload.
If heads are angle milled, does shimming change?
Bottom line, is it worth doing 11.5CR. Or might less be better?
228
228
112
112
2 IVO
46 IVC
46 EVO
2 EVC
112
4 o'lap
__________________
382HP............Best 1/8th...7.199 95.79 1.571
407HP 374Tq...Times to come
Mods: ,PT4000,3.90 gears,Eastcoast deep pan,B&M transcooler,Z06exhaust, Vram,Z06stylescreens,siliconecoupler,Fas tintake ,NWilliams 90mmTB,LS1edit,EFIV7,TechedgeWB,TEAstg2. 5 Z06heads,HSrebuiltrockers,93Pony228/588/212 cam,FLPheaders,Rollmaster2Xrollerchain,A SP UD pulley,Magnecorwires,NGKiridiumplugs,30# SVO inj.,PCVmod,180thermoshim,Hurstlinelock.
Melting Slicks
Joined: Sep 2003
Posts: 2,458
Likes: 105
From: Northville Michigan
Joe,
You won't be able to run 11.5:1 compression ratio on pump gas, unless you significantly retard the timing.
11.2:1 is about as far as you can safely go with 94 octane pump gas, if you want to run the appropriate timing. And, you need a set of heads with very smooth combustion chambers and valve faces. No spark points in the chamber between the two valves.
.
.
You won't be able to run 11.5:1 compression ratio on pump gas, unless you significantly retard the timing.
11.2:1 is about as far as you can safely go with 94 octane pump gas, if you want to run the appropriate timing. And, you need a set of heads with very smooth combustion chambers and valve faces. No spark points in the chamber between the two valves.
.
.
Safety Car
Joined: Mar 2002
Posts: 4,928
Likes: 1
Cruise-In V Veteran
St. Jude Donor '09
Hey Joe!!
Sorry about your beast and it's need for enhancements....uhh.....repairs.
I'm running the LPE/SCCA LS6 heads that are milled .055" (59 - 60 cc). LPE hand sanded/finished them and installed Rev 2.02 and 1.57.
Pistons are flycut so I picked up 1 cc there.
Stock 2002 GM Gasket - compressed thickness ~ 0.060".
The 90 mm Fast didn't require adjustment ( stock LS6 intake did). I used the Fast Kit bolts. Your insight made this job/install a heck of a lot easier.
7.350 pushrods if I remember correctly - 7.400 = stock?
Yella Terras - no shims.
I've never had a problem with knock (Great.....I think I just jinxed myself!!!!)...it gets into the high 90's low 100s here - some.
I run TR-6s in the summer.
My cam bleeds off some cylinder pressure (239/251, 106 LSA and ICL ). Intake valve closes at 45.5 * ABDC.
33* overlap.
joel
Sorry about your beast and it's need for enhancements....uhh.....repairs.
I'm running the LPE/SCCA LS6 heads that are milled .055" (59 - 60 cc). LPE hand sanded/finished them and installed Rev 2.02 and 1.57.
Pistons are flycut so I picked up 1 cc there.
Stock 2002 GM Gasket - compressed thickness ~ 0.060".
The 90 mm Fast didn't require adjustment ( stock LS6 intake did). I used the Fast Kit bolts. Your insight made this job/install a heck of a lot easier.
7.350 pushrods if I remember correctly - 7.400 = stock?
Yella Terras - no shims.
I've never had a problem with knock (Great.....I think I just jinxed myself!!!!)...it gets into the high 90's low 100s here - some.
I run TR-6s in the summer.
My cam bleeds off some cylinder pressure (239/251, 106 LSA and ICL ). Intake valve closes at 45.5 * ABDC.
33* overlap.
joel
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,613
Likes: 0
From: Winston Salem NC
Joel,
I am getting conflicting advice. Plumba is not alone in his opinion.
It looks like you're running around 11.5CR. If I do what's outlined, it would be just about a total of .055, also. I wonder what the difference in result is considering your overlap versus mine. The cam difference is huge.
Joe
I am getting conflicting advice. Plumba is not alone in his opinion.
It looks like you're running around 11.5CR. If I do what's outlined, it would be just about a total of .055, also. I wonder what the difference in result is considering your overlap versus mine. The cam difference is huge.
Joe
Safety Car
Joined: Mar 2002
Posts: 4,928
Likes: 1
Cruise-In V Veteran
St. Jude Donor '09
Joe,
I guess it comes down to DCR, VE (as in Volumetric Eff) and head design (aren't LS6 heads similar to Fastburn?).
I would talk to someone with realworld LS1/LS6 experience ...if it was me. Ed Potter @ LPE. Julio or Dave at Cartek. One of the Vette Doctor Gurus?
Please let me know what you come up with?
joel
I guess it comes down to DCR, VE (as in Volumetric Eff) and head design (aren't LS6 heads similar to Fastburn?).
I would talk to someone with realworld LS1/LS6 experience ...if it was me. Ed Potter @ LPE. Julio or Dave at Cartek. One of the Vette Doctor Gurus?
Please let me know what you come up with?
joel
Melting Slicks
Joined: Oct 2002
Posts: 2,200
Likes: 0
Originally Posted by Bink
Joe,
I guess it comes down to DCR, VE (as in Volumetric Eff) and head design (aren't LS6 heads similar to Fastburn?).
I would talk to someone with realworld LS1/LS6 experience ...if it was me. Ed Potter @ LPE. Julio or Dave at Cartek. One of the Vette Doctor Gurus?
Please let me know what you come up with?
joel
I guess it comes down to DCR, VE (as in Volumetric Eff) and head design (aren't LS6 heads similar to Fastburn?).
I would talk to someone with realworld LS1/LS6 experience ...if it was me. Ed Potter @ LPE. Julio or Dave at Cartek. One of the Vette Doctor Gurus?
Please let me know what you come up with?
joel
Static compression simply does tell the whole story. The DCR is effected by VE, cam over-lap, etc... There are several good threads over at LS1tech.com on the subject...
Good Luck,
Safety Car
Joined: May 2000
Posts: 4,827
Likes: 352
From: Albuquerque NM
11.5:1 is very do-able. 
I'm running 11.4, on the street, have for years, with a cam much like a Z06 stocker (218/218, .558", 114 LSA). The more overlap in the cam, the more CR you can and should run. At sea-level I was running on 93 gas, no problem, and here, at altitude, on 91 octane.
I'm running 11.4, on the street, have for years, with a cam much like a Z06 stocker (218/218, .558", 114 LSA). The more overlap in the cam, the more CR you can and should run. At sea-level I was running on 93 gas, no problem, and here, at altitude, on 91 octane.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,613
Likes: 0
From: Winston Salem NC
Thanks for all your input. I've decided to be a little conservative and go with 11.2CR and .038 quench. It will only cost me about 5 more HP and in the NC heat and humidity, 11.2 will be enough for me. It also does away with possible fitment issues.