JDogg

I'm gathering the parts to rebuild my motor due to a toast rod bearing.

I was doing some looking and ap2 rings are a different part number than ap1 rings. They seem to be the same thickness and are interchangeable.

does anyone know the difference between the 2 rings?

FWIW im rebuilding the motor using an ap2 crank and rods with my old ap1 pistons.

danthemang3

ap1 has frm cylinder liners and needs the correct rings to seal properly. get the ones for your year S2000.

JDogg

um.. dont they all have frm cylinder liners?

HondaKyle

Yes, F, H and C motors have FRM.

danthemang3

according to honda tuning which of course isn't always right does have in there only the ap1's have frm cylinders. maybe they aren't right but that's what i was going by.

HondaKyle

What? I can hardly understand that. All S2000 (F20/22) motors have FRM.

danthemang3

you must be trying pretty hard to be mr. cool. because i'm not sure what is hard to understand about that. sorry it's not typed to your exact specifications.

HondaKyle

Sorry, I'm not use to poor grammar on the S2000 forum.

danthemang3

haha because i failed to put a few comma's in there. i didn't realize we were in english class, and everybody in the S2000 forum is of the highest of class. i guess i should sell my ap2 cause i didn't put comma's in the right place on a honda forum. i could keep going on but i will let this forum pertain to cars instead of commenting on people's grammar.

JDogg

alright ladies.. get your panties out of a wad

All f2xC blocks are frm blocks...

now whats the difference between ap1 and ap2 rings.

HondaKyle

I've heard that the F22 rings seal better.

ricepicker

According to the changes on this page http://www.hondatuningmagazine.com/f...ges/index.html The bore increased from 3.42 in (86.86 mm) in the AP1 to 3.43 in (87.12 mm) in the AP2, if they were file fit rings, then it wouldn't be a problem, because most file fit rings give you plenty extra. But I imagine the rings are specifically cut with an exact ring end gap for the engine which it is supposed to go in under OEM specifications. SO, if that is the case, if you used F20 rings in a F22 block, you could lose ring seal, and if you used F22 rings in a F20 you could run the risk of butting together the ring ends. But then again, I'm not sure .3 MM would make that big of a difference.

JDogg

hmm.. i do have a set of ap2 pistons.. once i get my mess apart ill measure each and see if that is the case.

the only differnce in the part numbers for the blocks is the last 3 digits, ap1 is 000, ap2 010

JDogg

i got everything apart today.

the oil control rings are identical, but the spacer is way different. its more "dense" on the ap2

the ap2 2nd ring is the same thickness but has a step on the edge, much like rings i see on aftermarket pistons.

the top rings look 100% the same.

high_revs

hmm intresting information here, i always "assumed" the rings would have been identical..