surely the increase in boost pressure that he's lookin to gain from doing this will over compensate the loss of compression!

but the ET is already a low compression engine, at 8:1 it's lower than a lot of turbo engines of the same era, newer turbo engines seem to be running a lot higher CR. the Audi/VW 1.8T is 9.5:1 for instance. IMO you don't need to go lower than 8:1.

The engine I'm building will have re-worked combustion chambers but I will skim the head to compensate

i thought the ET was 8.5:1:confused:

Nope its defo 8:1.

no, the DET it 8.5:1 the difference is almost entirely down to the larger chamber volume of the head, the pistons aren't dimensionally much different really

I skimmed 40thou of my head when I rebuilt so i reckon my CR is 8:5 - 9.0:1. No problems with detonation so far, i plan on using water injection if I hear any when I up the boost further.

I make that about 8.7:1

Yeah I make it 8.65:1 with 83mm pistons, and with 84mm pistons 8.85:1

do you know the exact chamber size? I had to reverse engineer the calculation to work that out.

I used reverse technology as well to provide a combustion size of 64.61cc.