I got my pistons in and the car runs great. However, I am using Pistons for use with a B16 VTEC Head which gives the motor a 9.0:1 Compression with that head. But since I am using the LS Head temporarily for now, what will the compression be at? 8.6:1?

 

So you have B16 pistons in your B20 block with a B18b head, right? If so, your compression is 11.4:1.

Well here's a link for you to figure it out yourself:
http://www.c-speedracing.com/howto/c.../compcalc.html


[Modified by Vu, 9:44 AM 8/9/2002]

 

I think the ls combustion chamber is actually smaller than the b16 head, so the CR should go up a little.. Not by more than a few points. I'm not 100% sure though.

-Mike

 

i think it will be like 9.2:1-9.5:1

 

You can measure it if you happen to have your head removed.

All you have to do is to stick a plexiglass with a tiny hole in it over the cylinder extremity (put the piston at TDC) and you measure the quantity of water needed to fill completely this volume with water.
You do the same thing on your head (before, make sure that the valves are tight and install a spark plug). These two volumes are the only ones that you need to measure. All the other volumes can be calculated. They are cylinders with known dimensions.

CR= (stroke vol + chamber vol) : chamber vol.

chamber vol= (vol. measured from cyllinder edge + gasket volume + Vol. measured on head)

See a picture of the technique on my personal site:

http://www.geocities.com/blaast97sh/bottomendpicts.html



[Modified by Blaast, 3:12 AM 8/10/2002]