compression ratio - Nitrous Oxide Forum

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compression ratio
Friday, August 19, 2005 1:40 PM
Hey guys im getting some forged pistons and was wondering which compression ratio to run. I have the choice of 8.5 or 10.1. Im also running nitrous. Thanks alot.


vrooooom

Re: compression ratio
Friday, August 19, 2005 2:22 PM
you want high compression with nitrous, but too high will lead to reliability issues.

low compression is used for boost.

so, basically if your using only nitrous and that's all you want to run in the future, then go with the 10:1





Re: compression ratio
Saturday, August 20, 2005 7:28 PM
10:1 is gonna be cool. n2o doesnt mind moderate compresson


Re: compression ratio
Monday, August 22, 2005 6:35 PM
What would 12:1 do with everyday driving conditions? Would there need to be any other things to replace once you went with 12:1 pistons?


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Re: compression ratio
Tuesday, August 23, 2005 1:28 PM
12:1? You'd be driving around on race gas... that or your engine will knock until you spin a bearing.
Re: compression ratio
Thursday, August 25, 2005 2:24 PM
so what would be a decent compression for boost AND n2o....?


12's......here i come
Re: compression ratio
Thursday, August 25, 2005 6:12 PM
^^^^^ what he said


vrooooom
Re: compression ratio
Thursday, August 25, 2005 9:11 PM
10:1 or lowwer would be my guess since stck ecos are at 10:1 and you can boost them with decent results and many guys spray them as well. But the eco does have a better designed head than a 2200 then again nothing a little machining and porting would be able to help out with. Just my.02




Re: compression ratio
Monday, August 29, 2005 9:57 PM
If I was building an engine for boost and nitrous, I'd just build it for boost, and then use a very small amount of spray. Infact, I probably wouldn't run both but if I was going to I'd stick with a lower compression ratio. In your case I'd go with the 8.5 to one, CC the heads and maybe mill them if you want to go a little higher, perhaps 9:1?
Re: compression ratio
Tuesday, August 30, 2005 12:11 AM
Quote:

you want high compression with nitrous, but too high will lead to reliability issues.


It really doesn't matter about nitrous when it comes to reliability. If you build your motor with a high compression like 11:1 with forged pistons and rods, than you have nothing to worry about but fuel and ignition timing. The problem is maintaining a car with 11:1 compression by itself.

Quote:

so what would be a decent compression for boost AND n2o....?


As far as compression goes WITH boost, the lower it is, the less chance of detonation, that's why people say you should lower it. Once again, the nitrous part depends on how strong your internals are, fuel & ignition timing (for the most part). Honestly, if your running boost and have strong internals, I wouldn't bother with nitrous or not a huge shot. I would keep use of upping the PSI than upping the shot of nitrous just for the fact that the power is always there when needed instead of it being temporary.

OP wrote:12:1? You'd be driving around on race gas... that or your engine will knock until you spin a bearing.


Those are the biggest issue when it comes to running high compression...what gas to use and how your computer will handle having high compression pistons. If you really wanted to run an all motor setup on high compression pistons (on a daily driver with no type of stand alone) I'd go 10.5:1 or MAYBE 11:1 hoping that the computer will be nice to me.

OP wrote:If I was building an engine for boost and nitrous, I'd just build it for boost, and then use a very small amount of spray. Infact, I probably wouldn't run both but if I was going to I'd stick with a lower compression ratio.


Agreed.

OP wrote:In your case I'd go with the 8.5 to one, CC the heads and maybe mill them if you want to go a little higher, perhaps 9:1?


Agreed...I'd probably go with 9:1 though depending on how much boost (PSI) I plan to run.



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