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why would you need new Pistons?? did one Detonate? or are you PLANNING on detonating one lol. and whats with "PERFORMANCE" Pistons... theres no such thing.

theres OEM Pistons from Honda and then theres Forged pistons (built stronguer) so what exactly are you talking about.
 

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usually when people are asking for "'PERFORMANCE' Pistons", it means they are looking for a higher compression or stronger alloy metal piston, hmm sorry but some people are really odd, they whore every message they see only to make comments that no one really cares to hear, but oh well that's life, and there's always someone out there that wants to aggravate it
 

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actually no if he would have said Forged Pistons... i woulda said ok.. but "PERFORMANCE" pistons... Just cus u have Forged pistons wont give you 10hp... its just gonna make yur engine stronguer and more durable... how can a Piston increase Performance? Catch my drift??
 

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i guess he was talking about cast/forged pistons that raised compression...thats the only thing i can think of for "performance pistons" cause in that cause you would be gettin performance
 

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it will increas performance for the simple fact that you are purchasing it for the sole purpose of using it for a specific application, I mean come on no one goes to the store and says I think I will bake a cake and then decides he doesn't want to eggs for the recipe, now do you see my point, this is getting way off topic, the point is he was looking for an intelligent and usefull answer not some smart remark, dwn-shift at least gave the guy a link to go check out, whereas you only flexxed your lack of knowledge but huge mouth and probably caused the guy to say screw it and leave, but alas, you in your world will always be right Pimp
 

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its not the Fact that Im right or Wrong.. its Common Sense... its FACTS.

Forged Pistons are just stronguer... they dont raise compress just like that.and therefore dont change performance.. adding a turbo... Nitrous and other stuff is gonna add performance but the pisonts will do is allow that to go higher...

what im saying.. if you wanna take yur Cake.. its like saying Fat Free Eggs... well the eggs arent fat free... eggs are eggs... you might have Big eggs instead of small but still eggs.

the fact is "Performance Pistons" dont exist and I was simply asking him to clarify what he wanted. once he answered i could have given him a link to what he wanted.
 

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whoa settle down people... :)

Lude019, i don't think anyone make anything special for the b21a.
if you are looking for higher compression, try checking out gsr or type R pistons that are 2.5mm oversized. you WILL have to bore out your block a little bit... you will have to get your connecting rods modded for the pistons.

b21a bore is 83mm, too big for regular teg pistons 81mm... too small for h22pistons 85mm. we're the odd man out, unless you want to pay big bucks for a custom job.
 

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Discussion Starter #10
Thanks to the people that helped me out. Reason i was asking this question was, because I have 250,467 miles on the ride. I wanted to buy new engine parts. Oh and I wasnt asking for "HP" I just wanted some pistions that were better then the stock ones. Reyke thanks for the help and down-shift and sr126.
 

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Pimpstecy said:
actually no if he would have said Forged Pistons... i woulda said ok.. but "PERFORMANCE" pistons... Just cus u have Forged pistons wont give you 10hp... its just gonna make yur engine stronguer and more durable... how can a Piston increase Performance? Catch my drift??
Yes, forged piston won't give you anything if they are at the same compression level as stock... However, a forged "high compression" piston will make the squish area more dense and will generate significantly more power if the rest of the setup is dialed in and tuned properly... it's like the whole "anti-Gude" approach to a solid n/a setup... you can either mill the head, ie Gude, or you can go into the block and change pistons to raise the MEP.... we can go up to around 12 to 12.5:1 w/ the right tuning... and that will equal a "significant" power increase....
 

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oh my god dude... yur Dumb.. (Edit: Im over-reacting)

"High-Compression" Pistons dont ADD compression/preformance/hp...

its High Compression Pistons meaning it can TAKE a higher compression. (i.e. Turbo or any other forced induction system.)

now shaving a bit off yur Head would highten the Compression... but I dont recommend it.
 

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Pimpstecy said:
oh my god dude... yur Dumb.. (Edit: Im over-reacting)

"High-Compression" Pistons dont ADD compression/preformance/hp...

its High Compression Pistons meaning it can TAKE a higher compression. (i.e. Turbo or any other forced induction system.)

now shaving a bit off yur Head would highten the Compression... but I dont recommend it.
Wow Pimp, I thought you were more knowledgeable than this... First of all, compression is a function of several factors, on of which is volume... So, why do you think when you see "low compression" pistons they are usually dished or concaved? b/c they allow more volume in the squish zone and thus, less compression is induced given the same rate of flow (ie cam timing, etc) and stroke length... A "high compression" piston built for performance usually takes two avenues to increase compression: they are usually dome shaped and/or they utilize different wrist pin placements to get the piston further up the cylinder... Dude, it's basic geometry... if you have a cylinder w/ a given volume and you increase or reduce the surface area of one of the ends of the cylinder, the volume changes... so if you have a given stroke length you get a different volume as you shove that one end up into the other end... Please tell me you don't really think that higher compression pistons are called that b/c they can "take higher compression" :shock:

You have much to learn Grasshopper....
 

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thats what i was saying before.i raised my compression to 10.5 w/o forced induction. just a different piston and a little millin' of the head
 

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tomorrow I am going to the machine shop and having one of my heads to be milled all the way down till about a few tenths from the valves, it's kewl becuase I have 2 others in the backyard that I can put on if anything goes wrong, and yes you could go with b20b pistons, but if I recall correctly the limit to even think of overboring the b20 and b21 is 85, and the 84 is 1mm too close.

By the way stay away from factory Type R and GS-R or any other factory b series high compression pistons, becuase of the simple fact that the piston pin hole is too large on the b20 and b21 pistons and they would have to widen the bore on the piston pin holes to accept the b20 pin, and you can't press bushings into the connecting rod becuase the bush would be too difficult to cut and make and would sky-rocket your costs becuase they had to fabricate the bush for you, believe me I was a fool and ran out and payed 300 for overbore type R pistons (and they were the cheapest out of all of them) went to machine shop after machine shop and they all said one or two of the same things. the only way it would work is if you got a set of custom rods to connect the crank to the pistons with, I hear eagle rods are really economically priced and plus it would allow you to rev higher with the stronger pistons, making way for some cams that can make power well beyond factory redline
 

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forged pistons vs. OEM/aftermarket

ok. not sure which path to follow here because i read a lot of different ways to either not do it or to add compression. heres what i wanna do, and what im looking for is the best way (meaning the least chance of blowing up my motor) to make it stronger and put out more power without going all out and having that custom job done for the type r or gsr or whatever you guys were talkin bout up above. i have heard that if i were to ever want to run nitrous and/or a turbo i HAVE to have forged pistons. true or false? also, i read in diamond sleeper's very detailed rebuild post that if i dont use genuine honda pistons bored ONLY to maximum of about .025" over and same with rings, that it will start burnin oil at like 25k or less. eek. im scared to change any bore sizes or anything now. if someone could just give me a straightforward yes/no about what to do for this purpose of making a high-horsepower motor, without having to mill the head which would fuck with my timing (im already very nervous bout messing with timing to beginwith), i'd appreciate it. thanks

mike
 

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To run forged pistons in a B21 it must be sleeved.
You are better off buying a b20a5 block and putting forged bits in that.

The stock honda pistons and rods are good for at least 230-250whp with good to excellant tuning.
 

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To run forged pistons in a B21 it must be sleeved.
You are better off buying a b20a5 block and putting forged bits in that.

The stock honda pistons and rods are good for at least 230-250whp with good to excellant tuning.
ok... unfortunately im already strapped for cash, so as it is i have to rebuild this beast one piece at a time lol, paychecks every 2 weeks instead of every week sux ass. anways, my point being that i cant afford to get a b20 block, not to mention i cant afford to pay to have sleeves put in. also, while im talkin bout sleeves, i read something in someones post last night that the b21a1 blocks are sleeved already from the factory. i just tore mine apart today and i can definately say theres no sleeves there. just a normal block. ive seen the inside of a 1.5L crx motor and i can definately say those are sleeved stock. so mine looks nothing like that. anyway why would i want to sleeve it, wouldnt it make the bore a lot smaller? i may be way out of the loop but it just doesnt add up to me. so now with the understanding that i want to just use my existing stock b21 head and block, what pistons should i use? OEM oversized, or aftermarket, or forged? also keep in mind in addition to eventually later on turbo'ing it, at the time of rebuild i am going to try to get my hands on some stage 2 or 3 cams if such a thing is made for the b21. i hope to god i can find some.
 

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Bob said to get a B20 because the cylinder walls of the B21 are lined with Fiber reinforced material. Which will chew through rings quickly under boost. Im buying a B21 that has already been re-sleeved with iron sleeves and bored out to 84mm for my new pistons.
 
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