At least I don't think they are n00b questions. you guys be the judge at that.

I'm freshening up my GSR (new rings/bearings,200,000 mile engine) and while I'm in there, I'd like to upgrade the pistons.

#1: By installing ITr pistons, whats that gonna do with the factory balancing? I know its gonna throw it iff, but would it be enough to worry with?

Also, pistons aren't perfect, and the pistons in the engine will have worn the cylinders a certain way.

#2: The cylinders will be honed, but by installing the ITR pistons, is it going to have much of a negative effect?

I'm looking at JDM ITR pistons.. The CR will be around 11.1-11.3 (from what I've seen). The head has to be milled so it sits flush, I think it's 1 thousandth?

#3: With that, should'nt my CR be around 11.3-11.5:1?

One more thing.
#4: I have ITR cams.. Any danger of the valves hitting?

Thanks for any help.
Terrance

 

#1 Factory balance off, most likely no. Make sure the shop balances your pistons.
Are you running new rods? Are the pistons stock bore or 0.25 over?

#2 You want the cylinders honed so the rings seal up. Break in is critical. No negative effect.

#3 ZealAutowerks - Honda Compression Calculator
gave me a number of 11.6:1

#4 If the cams are installed correctly then no. But just to be safe you can clay it and/or degree your cams.

fyi.. In my GSR I have USDM Pistons on ITR Rods with ITR cams, head milled 15 thousandth, all tuned on an S300 and runs great.

 

Thank you so much for an informative response.

The pistons will be stock bore.

11.6.:1 is high... Damnnn

And the cams will be clayed... The primaries is simple, but that brings up a question...

How exactly do I cay the Vtec lobe?

 

Yeah i was wondering the same, do you have to lock the rockers?

 

Yes, you have to lock the rocker arms.

 

11.6:1 is wrong....you'd only be looking at 11.3:1 max. If you wanted to know for sure, have your head cc'd. I would also go oversize on your new pistons to 81.25mm, have your block bored and honed. Do it right, do it once, and do it properly.

 

00Red_SiR
What calculator did you use? If there is a better one out there please share.
ZealAutowerks - Honda Compression Calculator always seemed to work really well.

 

i've been running jdm itr piston in my car , i haven't had no problems, 12k on the motor since the rebuild.

 

How do you lock the rockers?

Air pressure maybe? <no clue>

**Edit**
https://honda-tech.com/zerothread?id=1105704

Any other ways?

 

The way I recommend is to switch the pins.

 

I havn't disassembled the rockers.. But I've seen the pins your referencing (they had rusted in my head from the water, fromthe blown headgasket )

I thought there was only 1 pic per set of rockers?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OH_1fstgsr &raquo;</TD></TR><TR><TD CLASS="quote">00Red_SiR
What calculator did you use? If there is a better one out there please share.
ZealAutowerks - Honda Compression Calculator always seemed to work really well.
</TD></TR></TABLE>

The Zeal calculator is ok I guess but I find it tends to read a little high. C-speed is one I like personally but to answer your question I simply used my head. If you stick JDM ITR pistons into a b18c block, you're going to get JDM ITR compression which is 11.1:1. Add the GSR head and that'll give you about a .2 bump in compression for a total of 11.3:1. If you plane the head .010" (thou) that's usually good for about another .2 bump in compression but you really need to cc the head before you can make that assumption. If you go to oversize pistons that will also increase compression a little.