Compression Test - more than just checking for wear.

[XPC66]

how did you get this i understand the rest just not this
12.1 -1 =11.1

Well if you read the original post carefully you'll see CR-1.

It's simple algebra:

compression ratio = (Clearance Volume + Swept Volume)/Clearance Volume.

That's the same as saying Clearance Volume/Clearance Volume + Swept Volume /Clearance Volume.

When you have the same denominator as numerator it always equals 1, so yu can just write it as: Swept Volume/Clearance Volume +1.

All we are doing is reversing that for the exercise, because we want to isolate the swept volume portion.

 

[lyonsy]

i certainly hope iam not like any of the calls esp the last although i think its possible for my brother lol.

ok so like this
12.1 = 11.1
10.98 = 9.98
10.21 = 9.21
9.74 = 8.74
is this correct?

thanks for all your help xecute and xpc very much appreciated and thanks for hanging in there with me.

also what do you think a safe cyl pressure is to run aus 98ron pump fuel in a 2v head?
and in a xflow head?
thanks again

 

[xctasy]

Blow its freekin head of Lyonsy!




In my experience, the stock 165 psi (1130 kPa) should be enough to stop the big bang if you've got headers and good cooling. Your going to loose a lot of power compared to 1300 kPa, but if it detonates, you won't have any!

Avoid the later XF head, and use the earlier head with XF Valves and some proper XC pushrods.

I'd say anytime you add a cam, you could go up on compression to this 1130 kPa number.

 

[lyonsy]

just thinking what effect does having methnol/water injection on comp and cyl pressures or does it do nothing but cool the intake charge and cyl head to help prevent det.