Compression ratio change 3.5 v8

mcmental · Oct 23, 2023

I have a 9:35.1 and I’m curious what the ratio would change to if fitting composite head gaskets?
Currently deciding which way to go with the build as I have a supercharger that keeps looking at me from the shelf and whispering that it wants to get up close and personal with the V8

Henry_b · Oct 23, 2023

Composite gaskets will drop the comp ratio by about 0.3 - 0.6 on a 9.35:1 engine power loss is near enough unperceavable.

300bhp/ton · Oct 24, 2023

I always fancied a supercharger setup. Although if doing lots of work, it might be worth exploring getting a 4.6, the extra displacement is only a benefit if you are after more power and torque.

norseman · Nov 14, 2023

Henry_b said:
Composite gaskets will drop the comp ratio by about 0.3 - 0.6 on a 9.35:1 engine power loss is near enough unperceavable.

Late to the party I know, but I have done this to a 3.5efi & agree with Henry .. no perceivable effect on performance & I found that a slight increase in ignition advance was possible when using 95 octane fuel when the 'book' says 97.

Chalky. · Nov 23, 2023

Another question on compression (sorry for the slight thread hijack), are the dished tops of the sd1 pistons the biggest contributing factor for the higher compression on that engine over the rrc one? I presume sd1 pistons can be fitted to a Rangie engine?

Henry_b · Nov 23, 2023

yes all rv8 3.5 pistons are interchangeable.

Compression ratio change 3.5 v8

mcmental

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Henry_b

Think outside, no box required.

300bhp/ton

Well-Known Member

norseman

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Chalky.

Well-Known Member

Henry_b

Think outside, no box required.

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