As some of you might remember, Im planning on swapping a b18c1 short-block under my b16a head. I will hopefully be reusing my JDM b16a sirII pistons. I am trying to figure out my CR but Im having trouble on the C-speedracing comp calculator. I dont know what to put down for the piston-to-deck height. I think I am supposed to select the b18 p2d height which would give me a CR of 11.3 but that seems awfully high to me considering the USDM b18c5's CR is 10.5. Is this CR right and if so, will I have to build up my block to handle something this high? Will my stock jdm b16a sirII int and exh cams work alright? TIA.

 

http://www.c-speedracing.com

How-to section has a compression ratio calculator.

 

Spade, that was the point of his post I think. He tried to use the C-speed comp calc but didnt know what to dial in.

 

i think that it will be thhat high if you are using b16 pistons, the b18c5 is almost 12:1 when ctr pistons are put in the block.... i could be wrong, but 11 sounds about right for your application.

 

Thanks for the replies. Can someone confirm the 11.3 CR I got from C-Speed? And if anyone knows about the other two questions, I'd appreciate the help there still. Thanks again.

 

11.3:1 CR is correct, you'll be fine with those cams.

 

Ok, thanks. Would I be able to run that high a CR w/o doing anything else to the b18c block? Here is my projected setup:

-Jdm b16a sirII Head
-B18c1/5 Shortblock
-Jdm b16a Pistons
-GSR Timing Belt
-GSR Head Bolts/Studs

w/ an AEM CAI, DC Sports 4-2-1 Header, Skunk2 Int Mani, 2.5" Custom Exh

I know u hate this kinda question but any idea what this might put down after its properly tuned. TIA.

 

yeah, would the b18 rods hold up to that high of compression, couple with a form of force induction?

 

if you are running 45psi, then you should build up the bock alittle

 

What do you suggest? Would a Golden Eagle BlockGuard be enough?

 

You don't to do anything to the bottom end. Get your rods shotpeened for cheap insurance. With that setup and stock cams you should dish out about 155-170whp.

 

I think thats a pretty low estimate.. my jdm b16 made 151hp with just bolt ons..

I'd say you would be closer to 165-180whp with that setup.

 

Bump for opinions.

 

Bump Again!