Compression ratio suggestions?
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
Compression ratio suggestions?
What would you run on a forged LS2 with a ZR1 cam? I'll be running the Vortech Si-Trim with a 3.4" pulley so that will probably work out to around 13PSI or so. The car will remain a pump gas daily driver (I am adding meth/water injection but don't want to rely on it too much) so it has to be a "safe" combo.
The reason I'm posting is because everyone I talked to (Lingenfelter, my builder, some tuners) is suggesting 9.5 - 9.8:1, but I wanted to go higher, 10:1 - 10.5:1. I know you *can* run even the stock engine (10.9:1) with that much boost but I'm wondering what others have found to work...
The reason I'm posting is because everyone I talked to (Lingenfelter, my builder, some tuners) is suggesting 9.5 - 9.8:1, but I wanted to go higher, 10:1 - 10.5:1. I know you *can* run even the stock engine (10.9:1) with that much boost but I'm wondering what others have found to work...
Racer
Joined: Jan 2009
Posts: 405
Likes: 1
From: SPRING CREEK NEVADA
I am running 9.6 at 14lbs on 91 octane with meth injection, I put alot of miles on my car as you do and I would rather be on the safe side as you never really know what kind of fuel you are getting in some places. we don,t have 93 in most places out west. with the power you will be making I don,t think the extra compression is really necessary for street use. especially down low where you would notice it. 
Melting Slicks
Joined: May 2008
Posts: 2,121
Likes: 2
From: CT
What would you run on a forged LS2 with a ZR1 cam? I'll be running the Vortech Si-Trim with a 3.4" pulley so that will probably work out to around 13PSI or so. The car will remain a pump gas daily driver (I am adding meth/water injection but don't want to rely on it too much) so it has to be a "safe" combo.
The reason I'm posting is because everyone I talked to (Lingenfelter, my builder, some tuners) is suggesting 9.5 - 9.8:1, but I wanted to go higher, 10:1 - 10.5:1. I know you *can* run even the stock engine (10.9:1) with that much boost but I'm wondering what others have found to work...
The reason I'm posting is because everyone I talked to (Lingenfelter, my builder, some tuners) is suggesting 9.5 - 9.8:1, but I wanted to go higher, 10:1 - 10.5:1. I know you *can* run even the stock engine (10.9:1) with that much boost but I'm wondering what others have found to work...
Safety Car
Joined: Oct 2001
Posts: 4,945
Likes: 0
From: Dallas/Valley Ranch TEXAS!!!
when we build mine I will be shooting for 9.5-10/1 with 9.75 being glodielocks... I believe your builder is spot on, however I also believe for your goal 10-10.5/1 would also be spot on, however, you never "think" you'll want more but you will, and mid to high 9's will be better for the future, and possibly resale...
Pro
Joined: Sep 2005
Posts: 593
Likes: 5
From: Murphy TX
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Drifting
Joined: Jun 2008
Posts: 1,778
Likes: 3
From: PNW
wait wait, ill say this again since I own a ZR1:
93 octane fuel, 10psi of boost, 9.5:1 SCR, and 26degrees of timing at 11.5:1 AFR.
People werent reading the fact tht you will be using the ZR1 cam, and how much different the DCR can be from SCR. Now again with the ZR1 cam, 10 to 10.5 should be perfect. Taking into consideration I personally had very good experience with high compression and centrifugals. Now if you had a PD supercharger, or TT im guessing lower compression would be better since you "could" have boost everywhere in the RPM band.
93 octane fuel, 10psi of boost, 9.5:1 SCR, and 26degrees of timing at 11.5:1 AFR.
People werent reading the fact tht you will be using the ZR1 cam, and how much different the DCR can be from SCR. Now again with the ZR1 cam, 10 to 10.5 should be perfect. Taking into consideration I personally had very good experience with high compression and centrifugals. Now if you had a PD supercharger, or TT im guessing lower compression would be better since you "could" have boost everywhere in the RPM band.
Last edited by zeshawn; Dec 9, 2009 at 07:26 PM.
Burning Brakes
Joined: Jul 2008
Posts: 754
Likes: 3
From: port Orange FL
I run 10.3 with that cam with meth and 16 lbs of boost with great results, if you use meth and a good tuner no problem. I wasn't even worried at all because Doug (ECS) was tuning my car. My C5 I ran 11lbs on 11.1 CR but that was probably pushing my luck. Good luck and let us know how it turns out.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Your cam choice may dictate your ideal/max comp ratio. I don't have a clue how dcr and scr relate considering valve events. A different cam may allow a higher comp ratio. With your vette being a d/d, a higher scr has big value. Even with a gonzo right foot, you're in boost only a small percentage of the time you're on the road.
Drifting
Joined: Aug 2009
Posts: 1,412
Likes: 0
From: Texas 1,002rwhp/928rwtq
St. Jude Donor '09-'10
You will make more power from boost than you will from adding a half point of compression. After you forge the engine, you should be able to pulley for max impeller speed on pump gas with methanol without breaking a sweat. Max boost will increase your throttle response and ramp the torque curve much earlier in the rpm range. As a side note, you may as well upgrade to a Ysi while you are at it.
Last edited by aTX427; Dec 9, 2009 at 09:57 PM.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
You will make more power from boost than you will from adding a half point of compression. After you forge the engine, you should be able to pulley for max impeller speed on pump gas with methanol without breaking a sweat. Max boost will increase your throttle response and ramp the torque curve much earlier in the rpm range. As a side note, you may as well upgrade to a Ysi while you are at it.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 6,149
Likes: 11
From: Greater Detroit Metro MI, when I'm not travelling.
It'll be a while... When I come back from Australia it will be early January and by then we'll be in the middle of winter here... I picked up a BMW 328I as a DD, so my goal is to be done in time for spring... I am guessing by the time the engine comes back, I install it, get the meth kit in, new clutch, Z06 fuel pump, etc etc it will be mid to late February?
