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Discussion Starter #1 (Edited)
I am buiding my engine this Winter, and thought that our engines don't have good response... so what we can do to make it more responsive...smaller turbo=x no, so more compression=O yes.

HOWEVER, I have no idea where makes 8.5CR pistons for our car... mmm.

Does anyone know? I guess I should phone up those piston guys and find out..
 

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Why not go with some forged pistons for the n/a cars, do a little head work to drop the compression ratio a bit to about 9.0-1, and then use upgraded components to compensate for the extra pressure. You would probably be able to run up to 15 pounds of boost without too much trouble. Or have some specialy made pistons fabricated. Have you thought about using nos to help spool up those turbos? Just make sure the fuel system can take the mods. Good Luck!
 

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Discussion Starter #3
Ya, but I think using the correct pistons with higher CR would make more sense. so, I hope that I could find one.

I will try.

thanks for the idea, though.
 

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maybe you should consider a lightweight flywheel and driveshaft? And gutting cats/w exhaust should help out with response. If you are rebuilding the engine anyway, then bumpin up the displacement a wee bit could be helpful.
 

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I think bumping up the CR is a great idea. I can get you custom forged pistons any size shape CR for around $800. send me an email.
 

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Discussion Starter #7
Hey Black95TT,

How is the response compared to the stock pistons?

It's much better right? I think I will do that, I remeber when I drove my friend's Skyline.. he had 8.7:1 or something like that with new piston, he didn't like it even with 8.5:1, but I think I will stay with 8.5:1 because I am planning to push my engine a little. so.

so matt, I will email you.
 

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Discussion Starter #8
Hey Black95TT,

I see that you have 93mm pistons, but have you had any problems so far? and how much air are you pushing?

Man that is quite big bore, isn't it?

I guess I haven't heard so much trouble about that, yet, so I might go with it.
 

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No problems yet. I'm running 15 psi right now and will soon be running 30 at the track and 20-25 on the street.
 

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Just boring out to 3.1 and using the same depth pistons will kick you up to about 8.3 or 8.4. If you are pulling the engine and all ... well there you go. :D
 

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i know i might sound like an idiot but i gotta find outa anyway sooner or later. what exactly is broing your engine? and i was also wondering fi you get pistons with a 8:1 CR and others with a 9:1 compression rations which piston s are actually bigger in size? just a question.

U might be wondering why i am also so interested in the lowere compresion pistons and boring and all that, seeing as how i have an na, the thing is that i wanna supercharge my car, but before i even thi nk about doing that i am going to change my internals so that it can handle a good amount of boost. thanx for the info guys
 

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luisitol said:
i know i might sound like an idiot but i gotta find outa anyway sooner or later. what exactly is broing your engine? and i was also wondering fi you get pistons with a 8:1 CR and others with a 9:1 compression rations which piston s are actually bigger in size? just a question.

U might be wondering why i am also so interested in the lowere compresion pistons and boring and all that, seeing as how i have an na, the thing is that i wanna supercharge my car, but before i even thi nk about doing that i am going to change my internals so that it can handle a good amount of boost. thanx for the info guys
Boring out the engine is just increasing the size of the cylinders themselves, usually done by a qualified engine builder. It has to be done just right, to big or small for your pistons and your engine will leak air/oil or seize. Also to large of a bore can weaken the cylinder walls by making them too thin. This will cause them to flex, causing leak and possibly damaging a number of internals.
The compression doesn't necessarily tell you how big a piston is as far as diameter, although generally larger diameter yeild slightly higher compression. Bore size gives you the diameter of a piston. I don't know what the stock bore is on these cars but I believe that the most common overbore for our cars is .050" which gives you 3.1L (someone correct me if I'm wrong).
The main thing that effects compression is the geometry of the top of the piston. Some pistons have flat tops. Some have dome tops which will increase compression, come have dish tops that lower compression.
Ok, enough now, I'm sure that's more than you wanted to know, just thought you should know, oh but one last thing. The higher the compression a piston creates, the more power it can make ie, a 10:1 CR yeilds much more power than a 8:1 CR. But when you have an engine with boost, you want lower compression so that the boost doesn't blow your engine to bits. Of course you can still run boost with high compression, you just have to use low amounts of boost. Email if you have any questions.
 
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