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avalaugh

Compression ratio help required.

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Im currently running 6psi on a totally stock engine, it dyno's at 309BHP, I want to run more boost, Im planning on fitting some ARP head bolts and a MLS head gasket, I'd like to know what thickness to purchase to get to the optimum compression ration, aiming to run 16psi at max RPM. Fueling etc has already been taken care of.

The stock gasket thickness is 0.030 I believe, my MLS thickness options are :-

.070

.080

.098

.120

.140

Advice would be greatly appreciated.

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No head block all stock, never been apart.

As for target compression ratio I'm guessing around 9:1 would be the ideal ?

But please advise accordingly as this is fairly new to me, lowish boost high ratio builds do produce good power though, but with the way the SC produces boost I'm looking for the best compromise

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In all honesty, I couldn't/wouldn't tell as I wouldn't want to be responsible for a bent rod, and also I do not know what you'd need :-).

However, I would advise that you remove the head and measure the CC of each combustion chamber vs. the swept volume of each cylinder + combustion chamber volume when you are ready. Think of how much air can physically fill the cylinder at atmospheric pressure vs. how much it compresses by.

First off, determine the power output you want, then the boost required for it, followed by the compression ratio required.

From then you can work out the compression ratio you already have by measuring your current engine, AND THEN, you can think about what size head gasket you require. You may or may not require some different pistons/head skim to really fine tune what compression ratio target you are setting out to achieve.

Sorry this is only the partial answer, and may not be what you want to hear, but that's how I'd attack it.

 

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Well yes that's the correct way haha

I've not got time for that, once I get a bit of time I'm going to trawl the web and find all the stock measurements and presume they're correct.

Then using an online comp ratio calculator I'll just try a few calculations and see what gets me somewhere I'm happy with.

It's only a toy, if it breaks I'll just fix it, always been my philosophy [emoji12]

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