Been asked by a mate for a bit of help.....

He has an RS2000........ not a proper one, its a Mk5 Escort

Anyhoo, he is putting the 2.3 Galaxy bottom end on it and apparently the 2000 head and 2.3 bottom end together gives a CR of 11.8:1.
According to him he has looked in to it a little and the standard 2000 and the 2.3 both have a CR of 10.5:1 and he would like to drop the CR of the engine he's putting together to around the standard figure or something slightly higher than standard as he has heard stories of the 11.8:1 engines not lasting long.

Is there some sort of calculation/formula or whatever that can be done to work out how much extra volume in the chamber is needed to reduce the CR to his target figures???

Thankyou Please