Need help with piston selection/ordering
Joined: Sep 2002
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From: You wish I was..., USA
Re: Need help with piston selection/ordering (NYb16)
That's very understandable unless you see it you don't believe it. I was the same way until I saw it on a very well designed Chevy 350SB. It ran 30lbs of boost with 11:1's on pump gas. It also had the best looking ECU configuration I've ever seen. Until mine comes out that is. 
I've heard of more compression on the same boost, but I haven't seen his car yet. It runs the same ECU from what I'm told. MAF sensor systems are much more accurate and reliable.
I've heard of more compression on the same boost, but I haven't seen his car yet. It runs the same ECU from what I'm told. MAF sensor systems are much more accurate and reliable.
Joined: Jul 2002
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From: Chandler, AZ
Re: Need help with piston selection/ordering (tzsir)
Its cool to see that some people actually back me up with going higher compression with turbo. Some people are so stuck in the old mindset of low compression for boost. I get so much crap for my choice of pistons, yet I put out more power than all the people who are talking. But then they point out that my car is not running right now. Oh well...
Joined: Dec 2001
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From: Louisiana
Re: Need help with piston selection/ordering (tzsir)
when i used the word 1.8 block I was using it as a naming reference (LS, GSR, TYPE R) and not a measurement of displacement.
bottom line is stroke & bore does affect compression. stroke has a big affect on it. for example take a b16b PCT pistons in a stock b16b the compression is about 10.8-11.0 to 1, put those same pistons in a b18c block with a 87.2 stroke same head and the compression jumps to about 12.0 to 1.
the same thing applies to your 83 mm piston. Its 9.0 in a b16 block with a b16 crank, and you use those pistons in a b18 block with a b18 crank the compression will go up.
the larger stroke (more displacement) is being compressed into the same space (combustion chamber) as the small stroke (less displacement), so why wouldn't the c/r go up? its simple.
compress more into the same space and its going to be more compressed
I don't know why tszir with his pending masters can't figure that out. I've never taken a engineering course in my life
[Modified by SEFI8LOxCivic, 5:44 PM 1/13/2003]
Ok dick. Do I need to get in an arguemant with your sorry *** too? By the way the B18c and B16b in Japan don't run the same combustion chambers. They are individualized to the stroke and flow characteristics of each block. I'm sure you can understand that correct? Stroke also effects flow with piston speed and that's taken into account at Honda that's why their engines flow so well for specific displacement. Please read on and let me school you. Besides haven't decided to go back to school yet. I was made an offer that is very tempting. Read on anyways.
Actually it's because the combustion chambers in the heads are different. It has nothing to do with the stroke in this situation, if it did the pistons would have to be checked so they didn't go out of the sleeves, but your supposed to clay them when using different pistons than the head was designed for. Trust me that's why there's a difference when you build an Ls vtec depending on which head you use.(that is if your using the same exact pistons with each set-up) Stroke and rod length effect the dimensions but that's only to increase or decrease the actual displacement of the entire set-up. In this situation it's the combustion chamber. Stick with the pistons designed to work with that head and check your clearances.
I think you're the one that needs to take some engineering courses and understand that it has nothing to do with this kind thing. This is design geometry from an engineers point of view, but it's also common old school hot-rod logic.
edit: Sorry my English sucks...
Go with high compression and lower boost levels. You wil have next to no lag. If you go BB turbo lag will no longer be in your vocabulary.
[Modified by tzsir, 1:47 PM 1/13/2003]
[Modified by tzsir, 2:02 PM 1/13/2003]
bottom line is stroke & bore does affect compression. stroke has a big affect on it. for example take a b16b PCT pistons in a stock b16b the compression is about 10.8-11.0 to 1, put those same pistons in a b18c block with a 87.2 stroke same head and the compression jumps to about 12.0 to 1.
the same thing applies to your 83 mm piston. Its 9.0 in a b16 block with a b16 crank, and you use those pistons in a b18 block with a b18 crank the compression will go up.
the larger stroke (more displacement) is being compressed into the same space (combustion chamber) as the small stroke (less displacement), so why wouldn't the c/r go up? its simple.
compress more into the same space and its going to be more compressed
I don't know why tszir with his pending masters can't figure that out. I've never taken a engineering course in my life
[Modified by SEFI8LOxCivic, 5:44 PM 1/13/2003]
Ok dick. Do I need to get in an arguemant with your sorry *** too? By the way the B18c and B16b in Japan don't run the same combustion chambers. They are individualized to the stroke and flow characteristics of each block. I'm sure you can understand that correct? Stroke also effects flow with piston speed and that's taken into account at Honda that's why their engines flow so well for specific displacement. Please read on and let me school you. Besides haven't decided to go back to school yet. I was made an offer that is very tempting. Read on anyways.
Actually it's because the combustion chambers in the heads are different. It has nothing to do with the stroke in this situation, if it did the pistons would have to be checked so they didn't go out of the sleeves, but your supposed to clay them when using different pistons than the head was designed for. Trust me that's why there's a difference when you build an Ls vtec depending on which head you use.(that is if your using the same exact pistons with each set-up) Stroke and rod length effect the dimensions but that's only to increase or decrease the actual displacement of the entire set-up. In this situation it's the combustion chamber. Stick with the pistons designed to work with that head and check your clearances.
I think you're the one that needs to take some engineering courses and understand that it has nothing to do with this kind thing. This is design geometry from an engineers point of view, but it's also common old school hot-rod logic.
edit: Sorry my English sucks...
Go with high compression and lower boost levels. You wil have next to no lag. If you go BB turbo lag will no longer be in your vocabulary.
[Modified by tzsir, 1:47 PM 1/13/2003]
[Modified by tzsir, 2:02 PM 1/13/2003]
I am no way an engineer, but i atleast passed basic physics. I here you talk about this and that mumbo jumbo with some fancy words. But to think that a given 83mm piston w/ 9.1:1 CR is going to be the same regardless of stroke is ridiculous.
The equation to calculate the compression ratio of a given motor in a nutshell is :
CR = (stroke volume + compressed volume)/compressed volume
All things being equal, the stroke volume is directly porportional to the compression ratio.
X = Y/Z >>>>>> Increase in Y yields and increase in X
So in other words, with all things being equal (bore, combustion chamber volume, deck height, headgasket thickness, etc.) an increase in stroke length will yield an increase in compression.
When choosing a piston, choose the correct application for your block and head. A 9.1:1 compression piston for a b16 head and block will yield about a 10.3:1 compression ratio in a gsr head and block. Choose a gsr block and b16 head, and the compression will drop about .2 to about ~10.1:1.
Joined: Sep 2002
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From: You wish I was..., USA
Re: Need help with piston selection/ordering (boostaholic)
Please read my post again. I said in this particular instance stroke doesn't matter. It's the combustion chamber cc's that are changing the total area that is being compressed. The pistons are the same between the B16 & B18 as far as height it's the dome shape and size that varies according to the head they were designed for. That has nothing to do with physics it's geometry. The B18 head has a smaller combustion space to allow better flow with a longer stroke. The B16 has a higher, larger combustion space to increase the anhle at and turbulance because the stroke is shorter and the piston speeds are slower. If I need to in depth to what I'm saying I will. The person that started the thread understands what I'm trying to explain so it doesn't matter if you understand how the combustion spaces work. We worked this out when people first started the whole Ls/VTEC thing back about 3 or 4 years ago. I thought it would be common knowledge by now. -Later *****-
P.S. Sure you know your physics? What good are they if you don't know when to apply them?
P.S. Sure you know your physics? What good are they if you don't know when to apply them?
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From: Louisiana
Re: Need help with piston selection/ordering (NYb16)
but my question still stands. will 9:0:1 be the same no matter what size bottom end i mate to the b16 head?
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From: GO LEAFS GO, NY, USA
Re: Need help with piston selection/ordering (boostaholic)
but my question still stands. will 9:0:1 be the same no matter what size bottom end i mate to the b16 head?
Here is his original question. And no the b16 and b18 pistons are not the same. A b16 piston designed for 9:1 CR in a b16 block/head will not yield the same CR in a gsr block even with the same b16 head.
I WILL Be ordering pistons this week. i have a B16 block sleeved to 83mm with Darton Sleeves. i have a stock crank, and a stock B16 head.
I want something in the 9:0:1 range. when i order, should i just tell JE this, or do i need to know anything else? i dont want to think iam ordering the correct piston, only to find out months later and $500 later that its the WRONG piston! somone take me under their wing! how do i get the CORRECT piston given my block/head
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From: Chandler, AZ
Re: Need help with piston selection/ordering (NYb16)
tell them you want 83 mm 9.0:1 cr pistons for a b16, they should ask you what head you are running, tell them b16 head. Id go with a flat top piston. thats about all theyll need to know. Oh, be ready to spend more than 500 for those too.
I am a bad person
Joined: Aug 2002
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From: South Florida
Re: Need help with piston selection/ordering (highbrid)
heres a link to a set if you decide you dont want to wait.
https://honda-tech.com/zerothread?id=384297
https://honda-tech.com/zerothread?id=384297
Joined: Jul 2002
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From: Chandler, AZ
Re: Need help with piston selection/ordering (Scott - 93HB Si)
because most people read super street or sport compact car and see that the pros go with real low compression so they assume they should go with low compression too.
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