Raising Compression Ratio?

breathegood · 08-19-2009, 11:26 AM

There isn't much info on this topic for the 3V that isn't related to forced induction. If I wanted to stay naturally apspirated, what would I need to do to raise the compression ratio just high enough to still be safe on 91 pump gas?

I am about to put CNC'd heads on the mod list for my tuner, and I'm thinking now might be the time to think about bumping the CR.

Is it as simple as a thinner head gasket and surfacing the deck, or am I opening up a new can of worms with pistons and rotating assembly?

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2007VistaBlueGT · 08-19-2009, 08:10 PM

Don't even bother, especially if you want to stick to 91 octane. Get the CNC heads and you need to find the best cams for natural aspiration, tranny and rear gear choice.

foolio2k4 · 08-20-2009, 12:50 PM

I understand the direction you are going in. Depending on what CR you are bumping up to you will need diff pistons as well. I think your question is better suited to very experienced engine builders. Let me know how it works out. I would be interested as well.

breathegood · 08-20-2009, 02:52 PM

After my experience with STS, I don't want to mess with F/I on this car anymore. I already have intake, cams, and headers in hand, and my tuner told me he could get my heads CNC'd for $1800......Since I'm not going F/I, I thought this would be a good time to look at the CR, but if it's going to involve pistons and/or rotating assembly, I'll just wait until I know whether or not I want to really build a N/A beast.

SirKnightTG · 08-20-2009, 08:22 PM

You could go 11:1 just fine, possibly even 12:1.

If it were me, I'd just call up Livernois and ask them about compression ratios for a N/A beast and have them build you a block with all the goods. Check out what they have online too.