got this info from a dealer.

89mm stroke with B16 Head = 9.7:1 CR
87mm stroke with B16 Head = approx. .5 pt lower.

what will a GSR head yield with these pistons on a GSR Short block with the 87mm
stroke?

 

I would need to know what model number piston you are talking about to give you an answer. It would also help to know how thick a head gasket you will be using. I can also give you dome volume numbers for any model. What dealer did you get your info from?

 

earl, spec sheet says shelf part # SC7018 and outside the box is 27566. piston is 84.5mm for gsr block. plan to use .043 cometic hg. got it from a local dealer that says it was supplied from race engineering.

 

9.40:1 with a GSR/ITR stroke of 87.2mm and a .043" Cometic gasket and GSR head approximately. The dome displacement should be approx -6.2cc

 

84.5 mm bore
87.2 mm stroke
41.6 cc chamber b18c head
.043" thick head gasket
-7.2 cc dome volume (SC7018)
.020" piston in the hole
9.44-1 compression ratio
How far down the hole the piston sits will affect this ratio.
to play with combinations, go here
http://www.c-speedracing.com/h...c.php

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostfed &raquo;</TD></TR><TR><TD CLASS="quote">9.40:1 with a GSR/ITR stroke of 87.2mm and a .043" Cometic gasket and GSR head approximately. The dome displacement should be approx -6.2cc</TD></TR></TABLE>Very good approximation...who needs a calculator

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by earl &raquo;</TD></TR><TR><TD CLASS="quote">84.5 mm bore
87.2 mm stroke
41.6 cc chamber b18c head
.043" thick head gasket
-7.2 cc dome volume (SC7018)
.020" piston in the hole
9.44-1 compression ratio
How far down the hole the piston sits will affect this ratio.
to play with combinations, go here
http://www.c-speedracing.com/h...c.php</TD></TR></TABLE>

The LS/GSR/ITR show as .030" piston to deck height. If it is -7.2cc then it will be 9.46:1 CR

 

Also if we do a .030" piston to deck height and -7.2cc dome displacement we will be at approx 9.26:1 CR

 

We can only really guess on the piston to deck height. Who knows if the block has been decked. The C5 CP Pistons come with a zero deck height as standard. On these kind of deals, you really don't know what to expect until you throw a piston in.

 

That little measurement can really make a change

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by earl &raquo;</TD></TR><TR><TD CLASS="quote">We can only really guess on the piston to deck height. Who knows if the block has been decked. The C5 CP Pistons come with a zero deck height as standard. On these kind of deals, you really don't know what to expect until you throw a piston in. </TD></TR></TABLE>
True only TRUE way to do it is cc the head and then the piston in the block.

 

thanks guys!

btw, ten thou was taken off the block.