Trying to get together the last of the major parts to start my build. What I will have is a B18C1 block using a LS crank/rod combo, and B16 head with Skunk2 Pro2 cams. I'm trying to get the maximum CR possible with off the shelf pistons without smashing valves. Can anyone provide some guidance on what will work?

Thanks.

*edit* Forgot to add the car will be run on race gas and is race-only. Really looking for mechanically maximum CR.

 

With a PR3 piston you will be at 11.3, a P30 will be roughly 11.4 and a P73- 00 will give you an 11.41. I would be happy with that CR in a street/ daily driver car, but if your looking to something along the lines of Pro series cams I would say a 12:1+ CR would be more ideal. You can play with the headgasket and milling still.

 

Thanks, edited my first post to add this is not a street/pump gas car.

 

Anyone?

 

The best way to bump compression is not to necessarily buy the largest dome size pistons you can. Your better off going with a jdm integra type r piston (not pct civic type r) and milling the head along with decking the block to bump you to around 12.5:1 compression. You will be able to run a fairly large cam with out the worry of tapping valves.

If your going for maximum compression, hell buy a set of 14:1 forged pistons, mill the head to the limit, deck the block to the limit and see how close you get to 17:1 compression. Lol. It would probably sound like a lawn mower running over a bag of nails under the hood.

Regardless of what you do, I HIGHLY recommend that you have the motor clayed because you are going for high compression with big cams. Just my $.02

Good luck with your build.

 

Really the best way is to account for the slight difference in compression based upon the LS Crank in the GS-R Block; as one that has performed this build I can tell you that milling the head and decking the block to a higher level. You get one chance to do that correctly. I have found that the best way is to use a decently set compression piston, (Wiseco if aftermarket, USDM ITR or USDM B16 if staying OEM), and use the correct headgasket and headstuds to match. Using an LS crank in a GS-R is a little more delicate than the typical LS/VTEC, even though a similar result occurs. Don't go too aggressive with the piston w/ such an aggressive cam such as that, or you will regret it.

Claying would be best to do regardless of your decision. I'm in the process of doing a similar build right now for a friend of mine, (Project "SHE"), so let me know of questions, and we can exchange information.

 

Thanks guys I appreciate it. I think I'll look at a set of advertised 12.0 CR or so pistons and have the engine builder determine if it would be safe to raise it through either milling the head or decking the block.

 

12:1 is a good number. I didn't know if you were going forged or cast with pistons, so I just suggested a good oem piston. I didn't want to see you end up with pct civic type r pistons. Your compression would be around 13.2:1 ish. They are also extremely heavy pistons.

I'm just not a big fan of pistons with huge domes after previous and current experiences. Just kind of a personal thing. As I said previously, best of luck with your build.

And one other thing. It would not be a bad idea to take the bare minimum off the the head and block to ensure the mating surfaces are perfect; even if your aren't trying to raise the compression by doing so(keep in mind it does a bit).

Also keep in mind 12:1 pistons in a gsr motor will be about 12.3:1 in a gsr motor running an 89 mm setup as opposed to the stock 87.xx mm setup.

Just kind of wrote things down as they came to mind. Sorry if they seemed really random.

 

No thanks for all the info. The head has already been milled, the block still has to be decked. Now just gotta find the right deal.

 

i've gotten good deals from psi proformance in the past. so might want to check them out

 

im using manley pistons from slowbloy racing paid about 400 and supertechs are also priced similar...but manleys are good quality...didnt need balancing..

 

All of the last 6 posts i've seen you make are almost identical.