Ok, like the title says I am looking for any information on compression ratios for LS pistons in a B16. The head that I will be using has been milled .020 from an all motor project.

What would I be looking at as far as compression. I would think that it would be lower, but I am not sure. Any information on this would be greatly appreciated. I am not dead set on going this route to build the motor but I am just interested in the possibility.

Thanks.

 

yes you can use B18A/B pr4 pistons in a b16 block.

but in your case you have bored it over .020 so the pistons wont fit unless you re-sleve your block stock.
Specifications:

b16a/b stock bore 81.00mm
b18a/b stock bore 81.00mm

normal dome for b16 pistons (not JDM) 6.01cc per piston
normal dish for b18 pistons -3.20cc per piston.

so the normal compression ratio for a b16 with OEM 3layer gasget is: 10.2.1
and the compression ratio for a 16 with ls pistons, OEM 3layer gasket is :8.6.1
ls pistons with 2layer gasket :8.7.1
ls pistons with 1layer gasket :8.9.1

hope that clears some htings for ya.

Nick

 

oh sorry i have ls pistons, rods and crank for sale CHEAP.

E-MAIL ME IF YOUR INTERESTED: Importordomestic@yahoo.com

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Importordomestic &raquo;</TD></TR><TR><TD CLASS="quote">yes you can use B18A/B pr4 pistons in a b16 block.

but in your case you have bored it over .020 so the pistons wont fit unless you re-sleve your block stock.
Specifications:

b16a/b stock bore 81.00mm
b18a/b stock bore 81.00mm

normal dome for b16 pistons (not JDM) 6.01cc per piston
normal dish for b18 pistons -3.20cc per piston.

so the normal compression ratio for a b16 with OEM 3layer gasget is: 10.2.1
and the compression ratio for a 16 with ls pistons, OEM 3layer gasket is :8.6.1
ls pistons with 2layer gasket :8.7.1
ls pistons with 1layer gasket :8.9.1

hope that clears some htings for ya.

Nick</TD></TR></TABLE>

Yes it does clear up alot. Thanks. What about with the head milled .020? Right now I am at about 10.5 with a stock head gasket and PR3 pistons.

So I guess that I would be looking at around 8.8:1 or 8.9:1 with a 3 layer factory head gasket.

What is the liklihood that I would blow a 2 layer head gasket? I would like to have around 9.1:1 or a little higher. Would the 2 layer bump me up too high? I think it would put me right at about 9.0:1 or some were around there. Right?

PM'd

 

your correct. if you milled .020 off the head then all the compression will jump a point.

3lyr - 8.8.1
2lyr - 8.9.1
1lyr - 9.0.1

you could also perform a step deck on your b16 block from stock : .020 to .010
that would raise your compression to

3lyr - 8.9.1
2lyr - 9.0.1
1lyr - 9.1.1

i wouldnt go anything thinner that a 2layer. and it should hold out as long as a OEm should. especially with good machine work and tuneing.

keep in mind these are jus math measurements. you would actually need you engine builder or a engine shop to calculate it for 100% exact, this is only 85%

im building a ls vtec for high boost and im going to go with 9.0 compresion ratio. i believe that it will be a good balance between street use (out of boost) and race.

also that's why i have ls parts for sale. i have raplced everything in my motor so i have ls parts out the wazoo. and cheap only 50K miles on all of them.

 

Great thanks.