FI pistons have higher c/r????

[OldSkoolA20accord]

Do a20a3 pistons have a higher comp ratio then a20a1? would it make any difference?

[evil88accordLX]

the FI does have a higher compression ratio. dont know if its the pistons or the head itself. but sure, higher compression would give more power. i doubt that its very much though.

[OldSkoolA20accord]

eh well im just going to replace the rod and put a weber on it then save for the b-swap now that towloud is actually going to get mounts made

[greentee76]

It is the FI head that gives the FI engines higher compression.

[lostforawhile]

hmmm when i get a head rebuilt i might put on an FI head then

[Vanilla Sky]

The heads are the same, it's the pistons that are different.

[thegreatdane]

^^Yep it's the pistons. The A20A4 engine has the highest C/R pistons of the A20 engines.

[snoopyloopy]

what about in b20? just saying, you know...

[2drSE-i]

Yea its definately the pistons. The only difference between the heads is the intake manifolds.

[greentee76]

Hmmmm... I was told when I put a a20a3 head on my old a20a1 that I would get a raise in compression ratio? Also, I didn't see any real difference in the pistons between a20a3 and a20a1. But then again I don't think I compared them side to side.

[2drSE-i]

i think your thinking of the A18 head.

[greentee76]

My mistake.....
I went back and looked and we were actually talking about the difference in cam profiles.
Sorry for the misinformation.

[russiankid]

Yea its definately the pistons. The only difference between the heads is the intake manifolds.

I heard something about cams being different?:dunno:

[2drSE-i]

ok the cams are different as well. i was talking more like the actual head.

[evil88accordLX]

while i cant find the thread, and ill happily eat my words if wrong, now that i think about it im almost positive that the brochure that was scanned for the 89 accord said the FI model has a higher compression head. i think the thread was titled something like "look what i found".

[OldSkoolA20accord]

where do i get a20a4 pistons? same as a3? i know th a4 is the jdm versio n

[2drSE-i]

While im not 100%, i believe the A4 pistons should be the same as the A3. The difference between those motors is emissions shit, so i dont see why the pistons would be different.

[OldSkoolA20accord]

true. i just want it to be fast until my mounts come in. i pick up a b16 for $75 the other day. :rockon: just needs to be bored and new pistons. might sleevee it idk yet.

[thegreatdane]

While im not 100%, i believe the A4 pistons should be the same as the A3. The difference between those motors is emissions shit, so i dont see why the pistons would be different.


A3 is 8.8:1
A4 (without cat) is 9.4:1

The pistons are different.

[2drSE-i]

Wow really? My Engine book lists the A3 at 9.3:1 C/R.

[evil88accordLX]

http://www.3geez.com/forum/showthread.php?t=66662

found the thread. its 9.1:1 and 9.3:1 according to the brochure

[2drSE-i]

i knew i wasnt crazy.

[MessyHonda]

just get custom ones if you want more hp

[markmdz89hatch]

to throw in a bit more. I'm pretty sure the 86-87 A20A3's have lower compression pistons than the 88-89's. I know the pistons are different, but even Honda doesn't have the 9.3 (or 9.4) anymore. All oem replacements are also the lower compression.

Unless you are given an 88-89 A3 motor, or at least the pistons, I wouldn't waste the time going to chase them down and installing them with the hope to get more power. That little bit alone won't make much of a difference at all.