M20 compression ratios for 2.8 stroker on E85

[Maximumtune30]

I'm gonna buy custom JE pistons. I'm still confused about the compression ratios for E85 fuel (104RON), I have spent about 20+hours reading about compression ratios for e85, some say 12:1 is the highest you can go, some say don't go under 13:1... I have a schrick 284/272 btw. In the winter time i will be mixing it with gas to about E70, so that will lower the octane rating also.

[digger]

I’d go around 12.5.
12 is upper max on pump gas with a decent cam
13.5 Would be better on a bigger cam e85

[clarkson]

E85 you can go pretty big on compression but depends on cam, intake and exhaust. If you are running a small cam like that I would go with what Digger said. There is a E85 beast of a thing in Aus that runs silly compression with 45mm webers and cleans up at the track, I think it was 250kw at the wheels

[Maximumtune30]

Thank you guys for the answers. I have the stock 2.5 intake manifold atm, maybe upgrading to RHD 40mm itbs later on + i will use stainless headers and 2,5" single pipe with no cats and a freeflow muffler. If i would use ditch the 284 and buy 288, should i use 13:1 comp. Is there any significant performance difference between 12.5 and 13:1 ?

[digger]

if you are going to use RHD ITB i'd get a 288 as a minimum. 13:1 over 12.5:1 is like a couple to a few hp at best as you are well into the diminishing returns area

[Maximumtune30]

What is the maximum lift the schrick dual springs can handle, will they handle 11,55mm lift + the hd rockers increase lift (idk how much).

[digger]

What is the maximum lift the schrick dual springs can handle, will they handle 11,55mm lift + the hd rockers increase lift (idk how much).

you'll probably have to contact them or mock it up.
Metric mechanic sell an outer valve spring to match the stock inner ones so id think they would work given the MM cam is slightly more lift that schrick