Iwanna928

I have read many times about the CR of a hybrid being 10:1 using a 85/86 block with euro heads.

Does anyone know what the same block would be using US heads?

IcemanG17

the stock 5.0 32V pistons have a CC of about 6.5...but will add a touch more with the two valve cutouts...the USA head vs the Euro 16V is 3.5cc more so it will be a touch less compression....

Iwanna928

Thanks!

Fabio421

If Brians correct, adding 3.5 cc's to the combustion chamber will yield a comp. ratio of 9.35:1 by my calcs. I wish I had seen this thread sooner. I just dropped a pair of US 4.5L heads and a set of Euro S heads off at the machinist this afternoon. I can cc them when I get them back.

#'s used were:

Head Gasket @ 1.5mm thick X 100mm diameter
Piston: -6.5 cc's ( this number will increase in your application due to the necesity of larger valve reliefs.
Chamber: 56 cc ( I arrived at this # by adding 3.5 cc's to the known Euro S #'s of 52.5 cc's )

mark kibort

yeah, the 85 pistons with notches are about 8ccs. euro heads vs US heads was 47cc vs 53cc if I remember correctly.

Ian928

I know we have argued about this before Mark, but I am sure there is difference between Euro S and "S2" (84-). I have two sets of Euro S heads(from 1980), all 4 measures 52,5ccm. I am pretty sure the 47ccm heads came in 1984.

LT Texan

I measured 48cc's on my '86 Euro S heads. Just measured on 1 chamber, and the measurement was a little bit rough.