Hey peeps,
This question is for any of you who have bored their block, or raised their compression. See I am boring my block to a 2.2 and also raising my compression and I wanted to know what the best compression ratio should be. I was thinking 11 to 1 but I want more. I am planning on getting a turbo as well so I don’t want to go too high, but that’s like a year down the road. Any help would be greatly appreciated

>Hey peeps,
> This question is for any of you who have bored their block,
>or raised their compression. See I am boring my block to a 2.2
>and also raising my compression and I wanted to know what the
>best compression ratio should be. I was thinking 11 to 1 but I
>want more. I am planning on getting a turbo as well so I
>don’t want to go too high, but that’s like a year
>down the road. Any help would be greatly
>appreciated
>

You can't bore out our blocks to a 2.2 because there isn't enough room. The only reason people bore out our blocks is to make sure the cylinders are perfectly round and free of any wear. The amount of material taken off is very insignificant as far as any power gains are concerned. You can however get a stroker crank and some pistons with the wrist pin moved up to get a 2.2.

As far as compression is concerned, if you are going turbo and want 11:1 or higher compression, then get ready for an assload of problems. I wouldnt even attempt to do that without a standalone system like the Haltech. If you want good compression, my recommendation to you is to buy some JE 8.8:1 pistons, have the block decked and have the head milled. That should bring you to around 9.4:1 or so leaving you with relatively high compression for a forced induction car, and reasonable to tune. There is a good reason why most sub-10 second turbo cars use 9:1 compression or less .

Matt
1995 Eclipse GS
2.0L, S16g Turbo, 8 Injectors, 26psi

1998 Eclipse GSX
2.3L Stroker, AEM EMS Converted to Speed Density, FP3065 Turbo, 35psi , and so on...

Yea man. I am getting the strocker kit Im sorry i forgot to put that one in there. I on the other hand am not getting a turbo for awhile so I was thinking about going 11:1, or more compression and then as soon as i get the turbo ARD said i can just slap a bad ass head gasket on there. Do you think thats kool or no? I want the most amount of compression now and then when i get my turbo I will lower it of coarse.
Thanks,
DJTJ

I'm not a huge fan of headgasket shims. Some people have real good luck with them and some don't. I definately wouldn't get a shim that lowers the compression more than 1 point though because with constant use on the street with a turbo, the gasket will leak after awhile. If you use 11:1 pistons with that setup, it will still leave your compression at 10:1 after shimming the head up with a thick headgasket. 10:1 is still a bit high for me, but it is definately more reasonable then 11:1 or higher. If you know for a fact that you are going to go turbo, then I would still try to stay away from higher compression. You will be happy you did once you have the turbo on there. If I were in your shoes, I would rebuild with pistons close to 9:1, resurface the head, deck the block, and slap the turbo on. Going any higher than 9.5:1 with significant amounts of boost is just asking for trouble in my opinion (at least without a standalone system).

When I was breaking my motor in with 8.6:1 pistons and no boost, I couldn't tell a difference in performance from the stock 9.6:1 pistons using the butt-o-meter. The amount of performance that you will gain with higher compression while you are NA won't be worth the tuning hassles you will have when you are turbo. I say that if you are definately going turbo, build the motor the way a perfect turbo motor should be built without any headgasket shim and the proper compression and you will be glad you did in the long run. But that's me

Matt
1995 Eclipse GS
2.0L, S16g Turbo, 8 Injectors, 26psi

1998 Eclipse GSX
2.3L Stroker, AEM EMS Converted to Speed Density, FP3065 Turbo, 35psi , and so on...

Yea that is one way I didnt think of. I am curious though what if i get the pistons and everything and make the compression like a 10.5:1 and raise it to an 11:1 by putting a thin head gasket on. and then when I go turbo i will put that little bit bigger than stock gasket in there and it will be like a 9.5:1, or soemthing like that. I dont know though b.c i havnt jacked around with the turbo thing yet. Shoot I havnt even driven a turbo eclipse GS so I am not to sure!! Thanks,
DJTJ

Let's face it, if a headgasket was as good at holding compression as a block, then the motor would be made out of the stuff they make headgaskets out of.
Just do it once, or pay for it twice.
-=B-=

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Man, if you want to make a lot of easily tunable power through turbo boost, run less than 9:1 compression. Run any more, and you're just going to end up damaging your bottom end.

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'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



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