laughinxxx

What's the stock compression ratio in the H22A1? I'm trying to figure out how high of cr I can go with forged pistons before I have to use race gas when I spray nitrous.

JG Luder

After talking to Warren, he knows someone who did 11.5:1 and happy gas. I'd stick with 10:1 or 10.5:1 for safety sake... you don't have the luxury of $$$ to back you up when things go wrong.

laughinxxx

People on SHO have ran DP kits on on ITRs, so I know the 10.5:1 is safe. I really want to run 11:1 to gain some extra hp when I'm not spraying, but what is the stock cr?

Blownlude

The H23 motor is 9.8:1 I believe stock for the VTEC is less than that.

JG Luder

um... actually, the stock USDM H22A1 and A4 is 10:1.

laughinxxx

So 11:1 is up there a bit. That extra 15 hp would be nice though.

JG Luder

more along the lines of an extra 8-12... depending on what you have done. My +13:1 was crazy.

laughinxxx

Is 11:1 fine with 93 octane?

Greyout

I have the JDM motor, which runs around 10.6:1 . My ignition is advanced to 19 degrees (15, +/-2, is stock). On 93 octane I have no problems, although I think the knock sensor has tripped a few times, but before I could hear ping.

laughinxxx

Not bad. There may be hope for my 11:1 cr yet.

akkording

My block is in the machine shop getting .25 OB Type-S pistons (11:1 CR) I was planning on using a 80 shot direct port kit I have sitting in my garage. It can be done! Just get the timing and fuel right or else say good bye to happy times.