could a short block be built to run both high compression (11.5 or 12 to 1) & low compression (8.5 or 9 to 1) by simply changing the heads & head gaskets? if so, you could have a cam & heads for boost and a separate setup for higher compression. that would be cool!

 

I remember reading somewhere that either Saab or Volvo are working on a variable compression 5 cylinder motor. Basically, the head is hinged on one side, and has solenoids/actuators/something that can vary the height on the other side, and flexible gaskets all around. Said they could get a decent range of compressions, from 8:1 to 10:1 or something, all controlled by the ECU based on load/boost/throttle etc.

Also said it looked like a beating heart sitting there running, with the head rocking back and forth. Interesting concept; sorry I don't know deck height and such that would be useful answering your question.

 

TTT

 

Ah yes and yes..Simply have two different sizes of chambers..My 18* engine has smallish 36CC chambers and aproximately 16-1 compression.Currently im looking into buy some other 18* heads with 48cc chambers and running a .050" head gasket to run the engine on race gas..

Standard SBC heads are usually offered in a 76,72,64,52 cc chamber size..CNC machine work with concave headed valves can help bring up the compression..But unless its a race setup running in two different classes in two different seasons i wouldnt see why one would do such a thing..