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F54 compression ratio?


zeiss150

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Hey guy's Im about ready to put together my F54 N42 combo and im worried about the CR. I have a 20 thou over bore and with the standard head gasket I get 9.92:1 but with the 2mm HKS head gasket I get a CR of 9.2:1.

So my question is this... Which one is better for a daily driver?

Ill be using SU's with sm needles a stock cam and header with 2 1/2inch pluming and an electric dizzy

I really need some advice on this one guys, I don't want to do it twice:ermm:

Matt-

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Oops, must have missed this one in all the new posts.

With a stock cam I think I'd stick with the lower compression. If you plan on upgrading the cam in the future, either one will work.

With 9.9:1 you'd want to run at least 91 octane, and that could run into a bit of change with the way the gas prices keep going up.:ermm:

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Thanks 2manyz's

Do you think that i would get a smooth every day driver with the lower compression? I just want an every day driver that pull like a bat out'a hell. YOu wouldn't by chance happen to know what kind of torque and HP i can expect with my setup?

Thanks again 2manyz's

Matt-

P.S. how do I put a picture on here?

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zeiss150

Hey guy it is going to be just as smooth either way with proper tune up.

The differential is performance.

Higher compression, more Horse power.

Also, higher cost of operation due to the need for hightest fuel.

I am opting for the the near 10:1 using a P-90 head, cut .080, on a flat top piston block. the biggest difference will be that I am using an aftermarket Cam with increased overlap, which will allow a higher compression without detonation problems. This is what 2manyZs was referiing to, when he asked if you were planning to change cams. (I am also making additional changes on both the intake and exhaust sides to better utilize the compression and cam.)

So the real question is: "are you satisfied with a slight increase in compression and horsepower, or do you want more". At this point, it is your call, mainly based on $$$, maintenance and fuel costs. Remember, smoothness will be solely a product of the final state of tune!

ecp48

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I would go with the lower CR. You will be able to burn regular gas and go. The higher will put you on the edge and gain you a wopping 5 HP or so plus the cost of premimum gas. Since the rest is stock and your DD build it that way and enjoy it.

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Thanks lance,

I think you were reading my mind, that was my next question, how much horse power would I gain from the extra CR.

Thanks to every one that replied, Im going with the 9.2:1, ill let you guys are know if my set up works bitch'n or sucks.

Matt-

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