I'm trying to get more info for my friend's JDM B18C5. Did a search but found not the answers i want.

His current OEM JDM B18C5 should be 11:1 compression. He need a new build with 82mm cast pistons so helped him search and found brands like RS, NPR etc.. Then after numerous emails/PMs, i then found out that these 82mm cast pistons are USDM design and not JDM models so need to find the effects compression of their different piston compression height and cc.

i did a search at http://www.zealautowerks.com and found the following on B18C5 engines:-

Piston type / diameter / dome cc / compression height / zeal calculated compression

JDM P73-00 piston / 81mm / 5.96cc / 30.23mm / 11.32:1 compression (i thought OEM from Honda Factory list 11:1)

USDM P73-A0 piston / 82mm / 3.64cc / 30.23mm / 11.0:1 compression

USDM PR3 piston / 82mm / 6.01cc / 30mm / 11.23:1 compression


From the zeal calculator, it does work out that on B18C5 engine, the USDM PR3 pistons does yeal a higher compression than a USDM P73-A0 pistons. But even with a 1mm overbore PR3 pistons the compression is still less than a stock 81mm JDM P73 pistons!!

Can anyone please tell me if this findings are accurate and TRUE?? Don't want give the wrong info to my friends over here!!

Thanks.

Chris

 

yup.. forgot to ask... Anyone know or used any JDM specs ITR pistons in 82mm??

Needed something with more compression in 82mm than the USDM PR3 and P73 pistons i find.

 

only choice you have is 82mm CTR replicas or deck the block. problem solved.

 

CTR replicas out of the question. Compression too high for mild setup daily used. Trying to keep compression below 11.8:1

Thanks

 

i got my pistons today as a matter of fact. i went with the PR3s 82mm. the way im gaining compression is through LS crank in GSR block. my motor should be around 11.5:1 or so. havent measured the chambers yet to be sure.
i agree though i dont condone using CTRs period.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1 2 NV &raquo;</TD></TR><TR><TD CLASS="quote">i got my pistons today as a matter of fact. i went with the PR3s 82mm. the way im gaining compression is through LS crank in GSR block. my motor should be around 11.5:1 or so. havent measured the chambers yet to be sure.
i agree though i dont condone using CTRs period.</TD></TR></TABLE>

Can you please post some pictures of the PR3 pistons. Side view to see tho DOME, top view to see how deep the valve relieve and the bottom view to see the constrution and any oilers at the pin like ITR.

Which brand is this??

 

we are having problems with the batteries in our camera, i think we need new ones, they dont charge for ****. i bought them through RS but they are made by safety pistons from the sources ive gotten. safetyautoparts.com i think is the website, but they dont have **** on the site.

 

Ok, let me help.

Does the RS PR3 pistons looked like this with the PR3 stamped on it?


Does it have domes as high as this with a PR3 stamp near the pin?


Does it have wrist pin oil hole shown below like the ITR pistons? This is important for me.

 

your in luck, camera seems to work.

 

Thanks alot.

How's the actually quality on them?

What about the rings build? Are they pre-gapped like OEM or you got to gap it yourself?

No wrist pin oilers on them

 

i havent had time to look them over, i just pulled them out of the box, looked and threw them back in. then i pulled them out for the pics. your the exclusive first looker.
i looked in the box at the rings but thats about as far as it went. you always check ring gap once the motor is bored/honed. on my aftermarket piston sets the ring gaps were always ****.
if you dont like the fact it doesnt have wrist pin oilers drill some.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1 2 NV &raquo;</TD></TR><TR><TD CLASS="quote">i havent had time to look them over, i just pulled them out of the box, looked and threw them back in. then i pulled them out for the pics. your the exclusive first looker.
i looked in the box at the rings but thats about as far as it went. you always check ring gap once the motor is bored/honed. on my aftermarket piston sets the ring gaps were always ****.
if you dont like the fact it doesnt have wrist pin oilers drill some.</TD></TR></TABLE>

Hehe.. Honoured to be the 1st looker..

Can we just get the machine shop to drill some wrist pin oilers to make them look like ITR??

 

as far as i know, its not a problem. ive heard of it being done before.

 

anyone else with more info?

Can anyone else confirm if the USDM PR3 pistons will yield more compression than USDM P73 pistons in a B18C block?

 

with P73 (compression height: 1.190", dome: 3.64cc): 10.8:1 cr
with PR3 (compression height: 1.180", dome: 6.01cc): 11.0:1 cr