1380 Turbo Compression ratio
Turbo Mini Forums

hi,

i have extensively looked into this topic! i a, struggling to work out what extra cc i need to suitable lower the CR i have a 1380 with 11cc dished pistons i have a couple of turbo heads and currently runing a skimmed 12g940 i know i will have to increase the heads cc to low CR but by how much to attain 8.0-1 - 8.5-1

Cheers

Total chamber volume = cylinder volume / CR - 1

So (1380/4)/(8.5-1) = 46cc

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

thanks for the reply!!

thats unattainable from the head.. would need to change the pistons??

You already have 11cc in the pistons, so allowing about 5cc for deck and gasket you need 30cc in the head which is just about possible I believe.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

That volume includes piston dish, ring lands, head gasket etc etc

EDIT: PM me your email address and I'll send you a handy spreadsheet that does all the work for you.

Edited by apbellamy on 13th Mar, 2012.

thanks for your replies, thats a little clearer now!!

thats a reasonable amount to take out

I achieved this with omega 11cc pistons and a med fis head.

User a cimetic head gasket. With standard chambers the 40 thou one should see you near with what you have.

Own the day