I've got an H22A4 engine, and I want to bump up the CR to about 12.1:1. My question is how do I do this when I can only find forged pistons that are 11.5:1. I know I have to resleeve the block, but how can I get my CR this high? Does anyone have a formula for CR? Also does anyone know how much Bill Gude from Bullfrog heads mills off the cylinder head? He doesn't respond to my Emails.

 

Have the head decked.

Also, I would normally say not to buy anything from Bill Gude. However, he would be able to do a good job milling down the head. He has a lot of experience doing it. Stay away from his head packages, though.


[Modified by Mr. Furious, 7:43 PM 11/5/2002]

 

If you're sleevin the motor how much are you gonna overbore??? If you want you can go to 90mm then drop some Rollerwaves in it. Check them out. http://www.theoldone.com/components/pistons/

 

Too Late I already had the head package, but then I had to pull it off and have the valves redone, and get a multi angle port while it was off. That's why I wanted to know how much he took off the head, because my guy had to take off another 5 thousands to get the angle out. It looked like BIll used a belt sander on it. I want to overbore, but I can't find any overbore pistons for the H22A4. I want to keep it street, I can only get 94 octane. So do you think I could get a 12.5:1 CR without detonation?

 

get hondata and lots of tunning time and it would run ok, but be carefull on what you do cuz you would be close to the barrier of detonation, o! and look for the tuolene or something like that, it is an octane booster, there is a thread around here, do a search

 

Are you seriously wondering this? Thats rediculous. No.

 

On the stock head, without being seriously modified to run that compresison (and taking into account the cam profiles of an H22), yes 12.5:1 is too high for comfort. But 12.5:1 can be safely run on pump gas, you just need to design the chamber specifically for it.

 

What I'm probaly gonna do is go with the 90mm pistons from the old one, I think the CR range on them is like 11.6 to 12.1:1. This should be safe for 94 octane right? Hey I'm not asking to get flamed I'm just trying to get the right info before I get into this project! There was a guy in the Prelude forum who said he was running 12.5:1 with 45 psi of fuel pressure on pump gas with no detonation. That is why I asked. If anyone in this forum can put me in the right direction to gather this info it would be greatly appreciated. I want the most compression and the biggest pistons combined with the right rods for 93-94 octane, that's all I'm asking!

 

That will be fine.... You're gonna have to back down ur timing and richen it up a bit but you should be cool.. I haven't worked with H22's a lot so i don't know everything about them.. On my friends CRVTEC we run it with 12.5:1 compression and 92 octane, no detonation at 12 degrees. Have fun.

 

You can start bumping a lil' with H22A Type S pistons and cam shafts. Not sure how big of a difference though.