I know this has been talked about but I couldn't find it when I searched. I'm actually interested in the jdm h22 pistons. What is the compression highth of these and what would they raise the compression by in an h23? I've also heard that you can't use the h22 rods in an h23. Why? I wouldn't think that the .2 or so diff in rod lenght would make a big difference.

Also, if someone could post the measurments needed to calculate cr that'd help allot. I think my numbers are wrong and would like to confirm them.

Thanks

 

you cant put H22 pistons into an H23 block without changing the rods and crank for the H22 parts.

the wrist pin location on H22 pistons is 1mm higher than on H23 pistons. if you swap pistons only, the pistons will extend 1mm above the deck, and the shoulder of the piston will crash into the head.

plus, with an H23 head, it features a much smaller combustion chamber volume... 50cc compared to 53.8cc of the H22 head. the H23 head also has a different valve angle, which can cause interference with an H22 pistons' dome and valve reliefs.

you can get custom rods that are 1mm shorter to accomodate the H22 piston, but it will still cause valve interference due to the H22 pistons' dome design combined with the shallow combustion chamber on the H23 head.

H23 uses dished pistons in combination with the shallow roof to create a 9.8:1 compression ratio. the H22 uses domed pistons with a deeper roof to create a 10:1 compression ratio.

hopefully this is all enough description for you to realise that you're idea is not possible for simplicity's sake.

 

^^^^

Very good info.

Thanks for taking the time to write that out man.

 

this might be a little off the subject, but what give you the extra .6:1 on a jdm H22 vs a usdm H22 I thought it was the pistons.

 

Correct me if I'm wrong, but I thought people have moded their h23 rods to accept the h22 wrist pins.

According to my info, both deck heighths are 8.655mm, the h22 rods are 14.3cm long compared to the h23s 14.15, and the h22s compression heighth is 3.10388cm compared to the h23s 3.05562cm. Both are usdm models. If this info is correct and I'm not missing anything, the h22 pistons will come up .198mm higher. Am I completely missing something here???