low compression with no boost
10-17-2006, 07:31 PM
#11
5th Gear Member
Join Date: Apr 2005
Location: South Jersey
Posts: 2,489
RE: low compression with no boost
ORIGINAL: Mark99GT
How much power would I lose if I used a forged short block with low compression (8:1) that was designed for f/i but ran it n/a? Reason I ask is I need a new motor and a forged short block is looking like the only viable option.
I really want to add a blower but dont have the money now. It would suck to have a block with 9+:1 compression built then want to f/i it later. Its one of those do it once, do it right things. So what would I lose if I had a low compression motor n/a and drove on that until I had the money to f/i it?
How much power would I lose if I used a forged short block with low compression (8:1) that was designed for f/i but ran it n/a? Reason I ask is I need a new motor and a forged short block is looking like the only viable option.
I really want to add a blower but dont have the money now. It would suck to have a block with 9+:1 compression built then want to f/i it later. Its one of those do it once, do it right things. So what would I lose if I had a low compression motor n/a and drove on that until I had the money to f/i it?
10-17-2006, 07:32 PM
#12
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
RE: low compression with no boost
ORIGINAL: ShadowDrake
You can still run boost with higher compression... whoever tells you that you can't is wrong. Compression = power, that's all there is to it.
I can't say exactly how much power you'll lose with the lower compression, you'll definitely notice it feeling weaker, especially down low... I want to say somewhere around 10% power for 2 points of compression but don't hold me to that at all. You'll be fine driving around N/A with a low compression block, though, you'll get better gas mileage and more power with a higher compression one.
You can still run boost with higher compression... whoever tells you that you can't is wrong. Compression = power, that's all there is to it.
I can't say exactly how much power you'll lose with the lower compression, you'll definitely notice it feeling weaker, especially down low... I want to say somewhere around 10% power for 2 points of compression but don't hold me to that at all. You'll be fine driving around N/A with a low compression block, though, you'll get better gas mileage and more power with a higher compression one.
The general rule of thumb is as follows
8.1-8.7:1 = Great for high boost
8.8-9.7 = Great for moderate to low boost
9.8 and above = Great for N/A engines
10:1 and above = ONLY for N/A engines unless you plan on running drag fuel.
10-17-2006, 07:35 PM
#13
5th Gear Member
Join Date: Apr 2005
Location: South Jersey
Posts: 2,489
RE: low compression with no boost
ORIGINAL: Armydad
I don't want to hijack thread but i am going through the same angst but in reverse. I want to run higher comp and boost, but every one with certain exceptions say it's a bad idea. Why? What is supposed to happen? Too much heat build up? In the old days we were always trying to get comp up, shaving heads, domed pistons etc. comp does = power ( lower end gruntage)
ORIGINAL: ShadowDrake
You can still run boost with higher compression... whoever tells you that you can't is wrong. Compression = power, that's all there is to it.
I can't say exactly how much power you'll lose with the lower compression, you'll definitely notice it feeling weaker, especially down low... I want to say somewhere around 10% power for 2 points of compression but don't hold me to that at all. You'll be fine driving around N/A with a low compression block, though, you'll get better gas mileage and more power with a higher compression one.
You can still run boost with higher compression... whoever tells you that you can't is wrong. Compression = power, that's all there is to it.
I can't say exactly how much power you'll lose with the lower compression, you'll definitely notice it feeling weaker, especially down low... I want to say somewhere around 10% power for 2 points of compression but don't hold me to that at all. You'll be fine driving around N/A with a low compression block, though, you'll get better gas mileage and more power with a higher compression one.
10-25-2006, 12:41 AM
#14
6th Gear Member
Join Date: Jan 2004
Location: United States
Posts: 12,575
RE: low compression with no boost
ORIGINAL: Mark99GT
Ok...so If ive got this right, a stock compression ratio would be fine for a streetable f/i car (99+ pi) making about 400-450rwhp with forged internals and 93 pump gas? Im not looking for anything over 450rwhp out of this car...but I want to run it on pump gas. Any really serious hp numbers would require the lower compression and massive ammouts of boost which is not what Im after...correct?
Ok...so If ive got this right, a stock compression ratio would be fine for a streetable f/i car (99+ pi) making about 400-450rwhp with forged internals and 93 pump gas? Im not looking for anything over 450rwhp out of this car...but I want to run it on pump gas. Any really serious hp numbers would require the lower compression and massive ammouts of boost which is not what Im after...correct?
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