VE Calculator For Cylinder Porting

I’ve used the forum’s calculator on half a dozen builds and each one’s shown big gains in accuracy and repeatabily. If it’s not smack on it’s definitely good enough for setting up well performing gear.

It gets my thump up. The Irish in me is too lazy to sit down and do the calcs manually so I use it a fair bit, especially with porting jobs. :+1:


Sorry I must not have explained properly. Ive seen comments referring to ratios worked out on the cylinder volume not taking into account the unused volume in the variables I mentioned, for which the difference in volume can be vast between the 2 calculations.

So given there’s obviously a lot of trial and error here and the fact you seem super confident, I’m very comfortable to port my current cylinder on your recommendation and see how it goes.

For clarity, are the ratios you cited above based on calculating cylinder volume as i mentioned in my first post or just simply or the full length of the cylinder from tip to tail?

Ahhhh I think you might have just answered my previous question then, you obviously do take those other variables I mentioned into account.

This means with a 7.3mm inner barrel at 330mm in length a 100% cylinder (piston stroke of 60mm) gives me a 1.88:1 VE ratio.

I might just lengthening the barrel to bring the ratio down, porting such a tiny amount might be a bit over the top!

Thanks Rattler :+1:t3::+1:t3::+1:t3:

No , you are trying to outsmart the calculator.
Here is your ratio on your numbers above

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Ah ok now I got it.

That calculator takes into account average (I assume they aren’t all identical, but maybe they are) depth of cylinder head (minus AOE of course).

I thought it would be far more scientific approach to measuring but makes sense now. Thank you!

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