Guys, if each cylinder were 205psi in each cylinder in my A15, can you identify what compression ratio the engine has and if so what would it be?

No not really if all is totaly standard someone may be able to guess. The only real way is to take the head off an measure the cc's.

as far as i know compression gets measured in atomspheric preasure, but if i do the conversion i get 13.95 : 1. Can this be right

The only way ive heard is as freak has said, you measure the cc of the combustion chamber and take into account the head gasket and any piston dish (if any), even take into account the little bit down the sides of the piston and above the ring, then do some maths. or if your lazy, have a look at this, http://www.newcovenant.com/speedcraft ... tors/compressionratio.htm

13.95 Its almost a disel. Or it would require methanol. Low comp engines are 9.0.1 whilst the high comp head is 9.5.1 and when modding most people aim for around 10.1 so you can still run it safely on pump gas.

I don't know what compression ratio you have but you must be using good fuel. What do you use?

use caltex vortex 98

Freak, you reakon thats about the limit, 10:1 on pulp fuel? is that about when an a-series really start to detonate on pulp?

Yes. And the motor more than likely will have enough heat from compression to ignight itself therefore running after you trun the key off. Plus it will do some serious damage to the rest of the motor.

I know im not FREAK but i hope this fills you in.

Before you panic, how good is your compression gauge. Some are great but some are woeful. Even though 205 PSI is high, I had a mate with a 202ci Holden red motor running similar figures & it ran fine on super petrol. Is the head alloy on the A15. If so apparently they cope better with higher compression.