Avictar

Fellow hybrids...

To change the b18c1 head to ITR plus the TB and Intake manifold which will also include CTR cams...question...

1. What CR would i get with this set-up?
2. Do i really need to change the piston to prop up the CR?
3. If not opting for 2, what is the most cost effective way?

Cheers

PS: I know some will dispute me as to why i'd want to spend on a ITR head but for argument sake lets start can we stick to the question above..thanks...

Bumnah

I believe with an ITR head and CTR pistons in your b18c1 you'll be looking at 11.1:1 compression.

Putting in new domed pistons is a good way to increase compression. Spoon and mugen do sell thinner head gaskets that will up the compression just a tad bit over stock. If you are willing to put a new head on, I say put in the pistons/rings while you are at it.

Milling the head a little bit will help bump up compression a little bit more, but not a very good way of doing so.

I would recommend the Stage 1 Skunk2 cams over the CTR, pretty similar except the Skunk2's are more aggressive, and some valve train upgrade even more potential.

shivers

Is the ITR head going on a GSR bottom end?

If so, you will actually lose about .2 points of compression since the combustion chambers are designed differently.

Another option to consider is using an ITR TB and a Skunk2 IM designed for the GSR head. You will retain the compression, but you will get more air flow and top-end power ... if that's what you're going for overall.

Andy

The B18C1 head actually has a smaller combustion chamber, so if you put the B16A/ITR head on it, it will loose compression. The best way to get that back is new pistons. A thinner head gasket will work, but you may loose some of the reliablity. Personally, I agree with Bumnah and Shivers. For the same money as the ITR setup, you could go with Skunk2's stage 1's, valvetrain upgrade and their ITR copy IM and probably stomp the ITR setup into the ground (higher compression and more aggressive cams).

Bumnah

for some odd reason i thought he was putting in CTR pistons also.

I guess the CTR cams threw me off track

But yes they are correct B16/ITR head have bigger combustion chambers.

The skunk2 manifold is better choice than the ITR counterpart, it has a bigger inlet. 64 vs 62 on the ITR.

Avictar

Bottom end is B20B...cheers...