ok i've been researching on this topic but i still haven't found a solid anwser yet. i hear two different stories. high compression with a turbo will be better and faster. on the other end of the search low compression is better. im really confused, can anyone please tell me what the difference is and what each one is for?

 

high compression good tuning more pwr. 10:1 flat top piston is the way to go...

 

when people refer to high or low compression...turbo...that range is between 8:1 upto like 9.8:1...what you give up is power (before the turbo spools) when you go low low compression...but then you are able to boost more. But with the higher compression turbo pistons...anything above 9.4:1..you gain more power when you are not boosting...plus there are more gains also when the turbo is boosting. Cylinder temperatures do greatly I mean GREATLY increase with every bump of compression. But hey if you have a fully built motor, sleeves, and great tuning...I wouldnt mind running close to 10:1 c/r. Thats what i think.

 

if you are running on an almost stock motor then low compression is best

 

High comp is good if you tune the car well and are not cheap. FULLY BUILT MOTOR, great standalone, and allot of time tuning. Also you will need higher octane gas to boost to higher levels. If you want a car streetable and want it to be moderate priced get low compression. If you have the money to resleeve, buy all new internals, standalone, allot of tuning time, and good money for high octane gas. Go high compression. On a seperate note. I have Brand new JE pistons pro series. If they are for a b16 the compression is 9.3 -1 which is perfect in the cars i have done. If you are doing a b18c the compression will be 10.2-1 which is high like you are asking = ). heheh . rayk83@yahoo.com.

 

WITH TURBOCHARGED

high compression =low boost
low compression=high boost

in other word if ur gonna be doin some serious boostin go low compression even with stock engine internals you could stay with ur current c/ratio but once you do some 10-12 psi of boost you better replace your piston c/ratio to atleast 9.0to1


hope this help




[Modified by shifthard, 8:00 PM 6/6/2002]

 

definitely!

 

Thats what i tell my vw friends. they cant believe how low my boost is with the drag3. they buy 1 bar chips.

 

Say it again Viren! The way to go!

 

wait till the methanol 10:5:1 compression motor is done. We are just gettting it all straightened out right now 2.1 liter 10:5 to 1 35 pounds of boost should hit right under 800hp.

 

12:1 CR with 25-30psi is best for max spool and power!

(SaRcAsM)

 

I don't get it. Is that big or small? bahahaha anyway...

I think High vs. Low compression kind of boils down to "What's better? Lots of power or not so much power?" It's just what you can afford. I think for unlimited budget a high compression turbo would be better for the street, it wouldn't be a slug down low, which isn't an issue at the track. Right?

 

well said... how much power do u want is the question... u want more power... go with higher comp

 

higher compression = more power..vewwwy vewwy simpaauuuuu!!

 

high comp with high octane juice and fine tuning

 

QUOTE
well said... how much power do u want is the question... u want more power... go with higher comp

wtf...i thought we're talking about turbocharged
if so how can a high c/ratio equal more power
you cant have high c.ratio and highboost and not run into trouble with that engine..
correct me if im wrong


[Modified by shifthard, 9:30 PM 6/6/2002]

 

i want a lot of power, around 400hp and be streetable. the engine is going to be fully built. so should i go with high or low c/r. if i go high can i use 93octane?

 

ok... can u show me an exmaple of a motor that has high hp and that doesnt run into trouble??? i always believed in the saying "if ur not breaking anything... ur not makeing power" and its the damn truth!!! power and reliability dont go well in the same sentence... a 10:1 motor with a decent sized turbo is fine as long as u tuneit right...

as for what is high comp exactly... most people consider 10:1 a high comp when it really isnt.. its such a normal comp to have nowadays... anything lower really serves no purpose unless whoever is tuning ur car really doesnt know what they are doing

to some people 9:1 is good... thats all they need... they're not trying to make high hp... as for why higher comp makes more power... u try to spool a decent turbo which will make power with a 8:1 piston... good luck cuz it wont really work

 

you can make high hp with 9.1 comp pistons.

 

dont u just love this question?

 

QUOTE

you can make high hp with 9.1 comp pistons.....my point exactly


i never said 10 c/r is high either
all im saying is ur better of boosting with with a low c/ratio
if you think 10 is low good for you but personaly i prefer 9 to1 c/ratio
when i boost 12 psi....

 

10.1 is to high to be street driven espically if your running a large amount of boost. you have to run high octane juice all the time. now if you have the $$$$ to do that go ahead you should have a problem. but if you dont the end result is kaboom!!!!!

 

what about a stock motor with a greddy 3mm headgasket? I just had my head rebuilt and am running an almost brand new block (30000 kms)...ran 10 psi before the rebuilt, should i stick with 10 or do you think I could bump it up to 12 PSI? I have a d16 turbo, intercooled with just a votec FMU and holley intake fuel pump...

 

you will make more hp at a given psi of boost with the higher compression piston ALWAYS. So if you have a goal of say 400hp and you run 10:1 pistons you wont have to run NEAR as much boost to get that same 400hp out of a motor with 9:1 pistons. Less boost also means lower intake temps. If you are worried about the bad gas situation get a J&S knock sensor and wire it up to a Hondata or AEM EMS. The "higher" compression ratio piston will require more tunning and have less of a "window" for error, but if you are shooting for 400hp, a good standalone and tunner will solve that problem also. I run 9.7:1 FI rollerwave pistons.

 

BOOOOYAH!