highest CR for turbos - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

BplumCrazy-SS · 12-11-2015, 09:15 AM

what would be the highest CR you would go to with a E-85 setup boost around 20-25

Unreal · 12-11-2015, 09:33 AM

No good answer.

Could be 10:1 or 15:1. Depends on overall setup. Cam, heads, turbos, intercooler, dynamic compression, timing, etc.

You could run a tiny cam and restrictive heads just to get boost up which would have less cylinder pressure than some crazy head/big cam setup at 5psi.

BplumCrazy-SS · 12-11-2015, 09:48 AM

my setup goal is around 1200hp...thinking about selling my heads and getting some LS9 heads to drop CR .........sorry about that

Unreal · 12-11-2015, 10:21 AM

I would at least do an aftermarket thick deck head for 1200rwhp. If you are just talking 1000rwhp (1200ish crank) then ls9 heads would be fine.

AGP Turbo · 12-11-2015, 11:23 AM

I would go ~11.0:1 if I could pick anything. But even if it's higher, just pick a cam that bleeds off a little pressure. And go a little extra big on the exhaust side of your turbo.

SSeniorMoment · 12-11-2015, 11:56 AM

Quote:

Originally Posted by AGP Turbo

I would go ~11.0:1 if I could pick anything. But even if it's higher, just pick a cam that bleeds off a little pressure. And go a little extra big on the exhaust side of your turbo.

What's meant by a cam that bleeds off a little pressure?

willhe64 · 12-11-2015, 12:38 PM

Cam overlap. More overlap means that both intake and exhaust valves are open for a period around top dead center.

AGP Turbo · 12-11-2015, 12:39 PM

The timing of when the valves open and close in relation to piston location can bleed pressure off into ether manifold. Or valve overlap when both valves are open at the same, the pressure will move from low to high.
OP has a TH400 and I'd assume a loose converter so lag is not an issue at all. So by going with a really low back pressure turbo and having a little valve overlap, it will blow a little off the dirty burnt air out the exhaust valve when both valves are open. Make for a super efficient set-up with turbos. Like 1000whp at 13-14psi

12-11-2015, 09:15 AM	#1
BplumCrazy-SS Drives: 416 w/TH400 Join Date: Mar 2012 Location: Houston Posts: 697	highest CR for turbos what would be the highest CR you would go to with a E-85 setup boost around 20-25 __________________ ERL 416 - 12.5 cr, TH400, Custom VVT Cam, PRC 255 heads, NW 102 TB, Aeromotive stealth fuel system, Fast 102 plumbed with a nitrous express direct port kit, BMR 15" conversion kit

12-11-2015, 09:33 AM	#2
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	No good answer. Could be 10:1 or 15:1. Depends on overall setup. Cam, heads, turbos, intercooler, dynamic compression, timing, etc. You could run a tiny cam and restrictive heads just to get boost up which would have less cylinder pressure than some crazy head/big cam setup at 5psi. __________________ Nick Corvette Z06 -1200ish rwhp

12-11-2015, 09:48 AM	#3
BplumCrazy-SS Drives: 416 w/TH400 Join Date: Mar 2012 Location: Houston Posts: 697	my setup goal is around 1200hp...thinking about selling my heads and getting some LS9 heads to drop CR .........sorry about that __________________ ERL 416 - 12.5 cr, TH400, Custom VVT Cam, PRC 255 heads, NW 102 TB, Aeromotive stealth fuel system, Fast 102 plumbed with a nitrous express direct port kit, BMR 15" conversion kit

12-11-2015, 10:21 AM	#4
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	I would at least do an aftermarket thick deck head for 1200rwhp. If you are just talking 1000rwhp (1200ish crank) then ls9 heads would be fine. __________________ Nick Corvette Z06 -1200ish rwhp

12-11-2015, 12:38 PM	#7
willhe64 Drives: 2012 45th Vert, 2011 4x4, 9sec Vega Join Date: Mar 2012 Location: Canada Posts: 2,188	Cam overlap. More overlap means that both intake and exhaust valves are open for a period around top dead center. __________________ I feel it only fair to warn you, I have a black belt in CAPS LOCK.

12-11-2015, 11:23 AM	#5
AGP Turbo Drives: All things Turbocharged Join Date: Dec 2010 Location: AZ Posts: 1,199	I would go ~11.0:1 if I could pick anything. But even if it's higher, just pick a cam that bleeds off a little pressure. And go a little extra big on the exhaust side of your turbo.

12-11-2015, 12:39 PM	#8
AGP Turbo Drives: All things Turbocharged Join Date: Dec 2010 Location: AZ Posts: 1,199	The timing of when the valves open and close in relation to piston location can bleed pressure off into ether manifold. Or valve overlap when both valves are open at the same, the pressure will move from low to high. OP has a TH400 and I'd assume a loose converter so lag is not an issue at all. So by going with a really low back pressure turbo and having a little valve overlap, it will blow a little off the dirty burnt air out the exhaust valve when both valves are open. Make for a super efficient set-up with turbos. Like 1000whp at 13-14psi