My recently swapped motor appears to be in need of new piston rings.
Since this motor will stay NA for auto-xing, I was thinking it might be a good time to swap out the pistons for higher compression pistons. Is this a good idea? Would only adding higher CR pistons net any noticable gains and would they need the addition of any other parts to maximize performance. Currently, the motor has a DC 4-2-1 header, crappy intake, 7lbs flywheel, and Apex'i WS exhaust. Thanks.

 

Anyone?

 

higher Compression makes a world of difference. a good flowing head with bigger cams would work very well. i used CTR pistons and it ripped... and i mean ripped HARD! if u want more peace of mind... then i say get p30 pistons and dont worry about when your motor is ganna give out.

 

I have alot of customer (majority of them) whom buy brand new ITR blocks and auto-x it every other weekend. Alot of them tend to stick with OEM parts, but its up to you.

Also, alot of them just have simple boltons like yourself.

 

Correct me if I'm wrong...but can't you buy 81.0 mm CTR pistons that will simply slide right into his B18C1 Block and be good to go? or do they only make them in 81.25mm? I have a friend with a 96 GSR with bolton's and he was wondering the same thing... If not, whats the best piston to use that will just slide right in without touching the factory block bore specs?

My buddy is also going to upgrade the GSR head with Portflow valvesprings and re-tainers ($320) and do a CTR intake cam upgrade and he'll be set. Might be something you'll want to look into for AutoX....great mid range torque, yet a farely cheap upgrade.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erics99si &raquo;</TD></TR><TR><TD CLASS="quote">Correct me if I'm wrong...but can't you buy 81.0 mm CTR pistons that will simply slide right into his B18C1 Block and be good to go? or do they only make them in 81.25mm? I have a friend with a 96 GSR with bolton's and he was wondering the same thing... If not, whats the best piston to use that will just slide right in without touching the factory block bore specs?

My buddy is also going to upgrade the GSR head with Portflow valvesprings and re-tainers ($320) and do a CTR intake cam upgrade and he'll be set. Might be something you'll want to look into for AutoX....great mid range torque, yet a farely cheap upgrade.</TD></TR></TABLE>
well when you take any piston out of any block, honing it is highly recommended. so honing it out .25 isnt that hard.

for daily use p30 pistons will last much longer without wearing out your bearings, gaskets, and rings faster

 

yes, they make 81mm ctr pistons stock bore. i just bought some just clean your walls up a bit and pop em in

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92redgsr &raquo;</TD></TR><TR><TD CLASS="quote">yes, they make 81mm ctr pistons stock bore. i just bought some just clean your walls up a bit and pop em in</TD></TR></TABLE>

thanks for the clearification... What should my friend look to spend on some 81mm CTR pistons? Advice where to get them? Thanks

 

1. P30 pistons, what are they? (CTR?)
2. Is honing important when replacing pistons?
3. To what degree with adding CTR pistons decrease longevity and reliability?
4. What would honing of the cyliders set me back? (approx.)

Bear in mind that my goal is a streetable NA set-up with regular auto-x. I'm interested in power throughout the rpm range. I'm only looking at upgrading the pistons because the rings are going and I might as well save money on labor to upgrade now. In the future, I'd like to add ITR/CTR or stage 1 cams, intake mani, and larger TB. Any suggestions are highly appreciated!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saber1 &raquo;</TD></TR><TR><TD CLASS="quote">1. P30 pistons, what are they? (CTR?)
2. Is honing important when replacing pistons?
3. To what degree with adding CTR pistons decrease longevity and reliability?
4. What would honing of the cyliders set me back? (approx.)

Bear in mind that my goal is a streetable NA set-up with regular auto-x. I'm interested in power throughout the rpm range. I'm only looking at upgrading the pistons because the rings are going and I might as well save money on labor to upgrade now. In the future, I'd like to add ITR/CTR or stage 1 cams, intake mani, and larger TB. Any suggestions are highly appreciated! </TD></TR></TABLE>
1. p30 pistons are second gen b16. PCT is from a CTR.
2. honing is very important. you should do this every time you take out you pistons. they allow oil to stick to the cylinder walls allowing less friction between the rings and the walls.
3. it depends on which setup u have CTR pistons in. if they are in a b16, the compression isnt dangerously high. so nothing bad happens (that is if u know how to drive it and its tuned for the right amount of fuel and such). it they go into a gsr, the CR will be high as f**k and the motor will be detonating aften which wheres down the bearings faster than normal. head gaskets and rings also wear out after time fron high compression. the higher the CR, the sooner they go.
4. im not entirely sure how much honing costs. its a standard procedure, so it shouldnt be alot at all. no parts needed somaybe $20 for labor.

 

So, it sounds like the P30 (B16) pistons would be safe. Any idea what that would raise my compression to? Would I only need the p30 pistons and rings, then? How much tuning would be recommended. Still learning all this tech stuff, thanks for the info.

 

what motor do you have again???

 

My car's new heart is a JDM B18C (OBD1).

I just checked hondaautomotiveparts.com and they show two pistons for the 2000 Si. One is marked as std and the other is OS 0.25. I guessing one is "normal" and the other is "oversized" by 0.25. If that is the case, why have two pistons of differing diameter?

 

more displacement =more power. just a small way to make more power without resleaving it to a bigger bore.

and yes, std is standard size and OS is oversized.

well since your motor is a jdm b18c the CR is already a nice 10.6:1 so if your only ganna be using ITR/CTR cams, a thin head gasket should do the job. should be roughly 10.8:1-11:1 which is the same as a US or JDM ITR.
OEM specs are always the most reliable cuz honda spends millions of dollars building the perfects motor that it has. honda has made thier motors to put out the max power each setup is capable of, and still retaining its great reliability. there wont be any valve to piston clearance problems cuz the lift on those cams are pretty mild, compared to the other race cams.

i would go with the p30 if you got your heart set on changing the pistons cuz they will give you a healthy 11.5:1 give or take. the pr3(b16 first gen) and the Jdm ITR pistons are roughly the same, so for the price u wont get that much power. with those pistons your CR should be roughly 11:2.1, which is also very respectable and safe.

um... did i answer all your questions... i cant remember...

 

So, if I have this straight, honing the cylinders is highly suggested and if done to accomodate p30 pistons it will slightly increase displacement (i.e. more power) and up the CR by about one full point (i.e. more power)? Plus, the set up will still retain a large degree of the factory's intended drivability and reliability? The above set up will also work well with the later addition of CTR, ITR, or stage 1 (Skunk?) cams? One other thing, to maintain a robust bottom end, are there any special or additional things to do/add to the block for the above set up? Thanks again.

 

A little porting and polishing will help you too. Make sure whomever does it has a flowbench, porting by the seat of your pants is BS.

 

I remembered that I had 7 pr3 pistons and rods in my storage from my b16a2 back in the day (dunno how I ended up with 7 pistons...weird) anyhow I am giving those pistons to my friend with the 96 GSR and we've figured out that his compression will be bumped up to 11.3ish using them. What rods does he have to use?

Does he keep using his GSR rods he has now, or does he need to use the b16 rods? Obviously we'll need a new set of piston rings though we're curious about about the rod to use. It's cool that I have some old junk parts (that I'd never use...just sitting there for the past 3-4 years) that will workout for him.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erics99si &raquo;</TD></TR><TR><TD CLASS="quote">I remembered that I had 7 pr3 pistons and rods in my storage from my b16a2 back in the day (dunno how I ended up with 7 pistons...weird) anyhow I am giving those pistons to my friend with the 96 GSR and we've figured out that his compression will be bumped up to 11.3ish using them. What rods does he have to use?

Does he keep using his GSR rods he has now, or does he need to use the b16 rods? Obviously we'll need a new set of piston rings though we're curious about about the rod to use. It's cool that I have some old junk parts (that I'd never use...just sitting there for the past 3-4 years) that will workout for him. </TD></TR></TABLE>
use your GSR rods

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allmtr &raquo;</TD></TR><TR><TD CLASS="quote">
use your GSR rods </TD></TR></TABLE>

Thank you sir, will do

 

I just checked out c-speed's website and used their CR calculator. My jdm b18c head with matching block and 81.25 pr3 pistons will up displacement to 1808 cc's and CR to 11.4~ This may be the route I go. Will this be safe with 91 octane pee water and limited tuning?

 

11.4CR is safe to run on 91 pump gas yes...

 

my friend ran a thin head gasket on his b18c1 and had clearance problems , all he had change was the pistons to itr usdm spec . An also was running CTR cams .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saber1 &raquo;</TD></TR><TR><TD CLASS="quote">I just checked out c-speed's website and used their CR calculator. My jdm b18c head with matching block and 81.25 pr3 pistons will up displacement to 1808 cc's and CR to 11.4~ This may be the route I go. Will this be safe with 91 octane pee water and limited tuning?</TD></TR></TABLE>
yes it is. make sure you got all the right fuel management exponents and retard timing a little. fuel pump and pressure regulator are the main ones u need. also a vafc will help out alot too.

i think dyno tuninig it would help with any detonation problems u might have

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spoon1 &raquo;</TD></TR><TR><TD CLASS="quote">my friend ran a thin head gasket on his b18c1 and had clearance problems , all he had change was the pistons to itr usdm spec . An also was running CTR cams . </TD></TR></TABLE>
the cam gears must have been adjusted quite a bit, cuz my friend had a milled head and skunk stage 2 and had no problems


Modified by allmtr at 3:05 PM 9/25/2003

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allmtr &raquo;</TD></TR><TR><TD CLASS="quote">
1. p30 pistons are second gen b16. PCT is from a CTR.
2. honing is very important. you should do this every time you take out you pistons. they allow oil to stick to the cylinder walls allowing less friction between the rings and the walls.
3. it depends on which setup u have CTR pistons in. if they are in a b16, the compression isnt dangerously high. so nothing bad happens (that is if u know how to drive it and its tuned for the right amount of fuel and such). it they go into a gsr, the CR will be high as f**k and the motor will be detonating aften which wheres down the bearings faster than normal. head gaskets and rings also wear out after time fron high compression. the higher the CR, the sooner they go.
4. im not entirely sure how much honing costs. its a standard procedure, so it shouldnt be alot at all. no parts needed somaybe $20 for labor.

</TD></TR></TABLE> VerryWell put for someone that doesnt know much about honing ....whenever you pull pistons it is recommended that you hone the block....as far as pistons go we offer a itr style piston in a 20 over and 40 over....we put together a road race car with 40 over pistons our headwork, valvetrain , and cams the car put down 213 to the wheels with hondata