like the title says. could someone give me an estimated CR for these pistons in a stock b18c1 motor? estimated hp gains? right now all i have for power mods is the apexi world sport catback and an AEM cai.

 

note: i didn't have much luck in the search department

 

a little bit higher than a stock us itr. b18c head causes the compression to go up a tad around 10.8:1 or so. go to http://www.c-speedracing.com it has a compression calculator on their site.

 

wow, a CR calculator! cool. thanks for the tip.

Slain, you're right on target. 10.836222blah blah blah to be exact. i wonder how accurate that is. thanks dude. do you have any idea how much gain i could see from this? oh, and how about price for installation? i don't know how or have the tools to do it myself.

 

I've heard its about 10 hp for every 1 point you move ex.( so going from 10.0:1 to 11.0:1 will roughly net you 10 hp) in conjunction with other parts you are capable of gaing much more ex( camshafts)....

you will have to take in consideration the condition of your cylinders. will they need to be rehoned, or a slight bore. use standard pistons or .25 oversized.... the price will vary from place to place. do alot of homework on the place that does your work. last thing you need is to **** away your hard earned money.

 

how would i be able to tell if my cylinder walls should be rehoned? crap, i know i don't have the money for that. i would be getting these pistons in trade. this might sound stupid, but why would the walls need to be honed? do they get rough or something? the pistons are a standard bore, so boring isn't necessary i assume.

 

I have .25mm over pistons if you're interested.

I would go overbore just to be on the safe side. I would personally feel safer knowing that the rings had a freshly honed surface to seat in on and that any larger imperfections in the cylinders were bored away. Without rehoning, you will not be guranteed a good ring seal, which means loss of power, which means a waste of money.

Honing is when a fine stone honing tool is run through the cylinder to add some texture to the walls. This texture will allow the piston rings to abrade themselves ever so slightly, creating a leak free seal and eventually mirror like cylinder walls.

This work requires almost a full rebuild, and could run up to $1500 if you just sent it somewhere to have everything done including assembly. If you did most of it yourself, it could run you less than $500.

 

oh. def don't have the money for that.

 

I paid 800 dollars in labor for a motor rebuild. It was 300 for the balancing of the crank assembly and the hone job to the block. I put standard size p73 pistons in it. Although my engine runs good, It burns oil and I believe its the rings. I regret not boreing it out, and wouldn't ever put used pistons in a motor I was paying so much to have rebuilt.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMDA9 &raquo;</TD></TR><TR><TD CLASS="quote">I have .25mm over pistons if you're interested.

I would go overbore just to be on the safe side. I would personally feel safer knowing that the rings had a freshly honed surface to seat in on and that any larger imperfections in the cylinders were bored away. Without rehoning, you will not be guranteed a good ring seal, which means loss of power, which means a waste of money.

Honing is when a fine stone honing tool is run through the cylinder to add some texture to the walls. This texture will allow the piston rings to abrade themselves ever so slightly, creating a leak free seal and eventually mirror like cylinder walls.

This work requires almost a full rebuild, and could run up to $1500 if you just sent it somewhere to have everything done including assembly. If you did most of it yourself, it could run you less than $500.</TD></TR></TABLE>

couldnt of said it any better

 

if i were to overbore, say by .25mm, wouldn't it be just as easy to just go ahead and bore out to 84mm? i mean, if you're gonna bore, why not go ahead and bore well over the stock 81mm bore? i would think the price would be relatively the same, if not, just a little more. i just don't see why boring .25mm over should cost any more than 3mm over. is this correct? or close?

btw, thanks for telling me all this. i'm learning a lot.

 

I don't think it would cost anymore, but then you have two other issues to deal with.

First, the sleeves are going to be thinner. A B20 has 84mm bores, but I'm not sure if a B20 uses bored 81mm sleeves or genuine 84mm sleeves. Reliability could suffer as a result.

Then, if you want high compression 84mm pistons, you will be forced to use aftermarket forged pistons. Thats a whole other sack of **** to contend with.

I'd stick with OEM stuff unless you are planning on really maxxing you engine out.

 

Im building a gsr w/ type R pistons, balanced crank, ARP rod bolts, R cams, R header, R exhaust, hondata s200, skunk2 cam gears, skunk2 IM, and RC 64mm TB.
Ill let you know how it turns out in a few weeks..stay tuned...
Im shooting for 190hp...*keeps fingers crossed*

 

JDMDA9 - yeah, i realize that i would need aftermarket pistons for an 84mm setup. i know they cost a lot more. good point.

also, i think the B20 uses bored 81mm sleeves, cause you can't bore a B20 anymore than 84.5mm. if it used 84mm sleeves, i would think it would be possible to bore that out 3mm, to 87mm.

Sa21199 - yeah, def keep me informed. i'd like to know how all that turns out. sounds like a sweet setup. should pull pretty good. what chassis is that going in?