Turbo engine build specs

My friend and I are building charged micra builds - one will be a roots e45 and the other a gt17 turbo. Both will have around 7psi boost as the aim. The turbo might be turned up a bit for track days etc.

In terms of build what would be the best base a cga or cge?
I feel a cr of 9-1 would be a good compromise
I understand Corsa pistons give a cr of 8-1 but I’m a bit concerned re squish as they stop short of the deck - what deck reduction is required to get up to 9-1? I presume that cr is on a cga block with a cge crank in?

do the cga blocks have thicker liners than the cge as already 72mm and need to be 72.5 for the corsa pistons? Concerned about taking the liners too thin

seems a bit overkill but would custom forged pistons be the “right” way to set the engine up?


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The CGa autos (or at least the block I have) is fully-open deck, so think it's just teh cg10 and cg13 that are semi closed.