Tryin2Rip

alright some may flame me for a while but i don't care say what you must hopefully its relevant....i recently bought a motor from someone and he told me that the pistons were cp 14:1's but insisted it could be run on 93, my question is there any way to identify what cr the pistons are, the dome on the piston doesnt look rediculously high but again i don't know... ive been searching but cant find pictures of what a 14:1 and 12:5 look like so if anyone could help me out it would be appreciated ill try and get a good picture of the block up soon

HondamanXxX

Don't really know why people would flame on you bro. I'll do a quick look search.

philosofy1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tryin2Rip &raquo;</TD></TR><TR><TD CLASS="quote">alright some may flame me for a while but i don't care say what you must hopefully its relevant....i recently bought a motor from someone and he told me that the pistons were cp 14:1's but insisted it could be run on 93, my question is there any way to identify what cr the pistons are, the dome on the piston doesnt look rediculously high but again i don't know... ive been searching but cant find pictures of what a 14:1 and 12:5 look like so if anyone could help me out it would be appreciated ill try and get a good picture of the block up soon </TD></TR></TABLE>

you bought a motor or a block? there is a difference. if you have a motor, you can just do a compression test, this will be able to tell you if the ratio is 14:1. i still recommend you to use 93 octane on any dohc vtec motor, stock or not.

Tryin2Rip

block....i want to run 93 because usually with a cr that high you have to worry bout detanation and all that bs on top of that i don't wanna run 100+ octane

doood

iTrader: (1)

see if you can see a part number on the dome of the piston and cross reference it with cp's parts catalog. although, i'd think a piston that made that kind of compression would be custom.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by philosofy1 &raquo;</TD></TR><TR><TD CLASS="quote">you bought a motor or a block? there is a difference. if you have a motor, you can just do a compression test, this will be able to tell you if the ratio is 14:1. i still recommend you to use 93 octane on any dohc vtec motor, stock or not.</TD></TR></TABLE>

how do you propose he find his compression ratio by doing a compression test?

Tryin2Rip

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doood &raquo;</TD></TR><TR><TD CLASS="quote">see if you can see a part number on the dome of the piston and cross reference it with cp's parts catalog. although, i'd think a piston that made that kind of compression would be custom.

how do you propose he find his compression ratio by doing a compression test?</TD></TR></TABLE>

haha i didnt wanna even get started on that one....i'm hopin the guy was just lyin to me but ill try and get a pic up this weekend the motors stored somewhere else ill get a pic up

jdm91CrxSi

110 octane at shell in lexington (at the PUMP) it's smells soo good

Tryin2Rip

posHonda

14:1 on pump gas is ridiculous

fatpride111

14:1 compression ratio???! what are you runnin', Jet Fuel???

hall97civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdm91CrxSi &raquo;</TD></TR><TR><TD CLASS="quote">110 octane at shell in lexington (at the PUMP) it's smells soo good</TD></TR></TABLE>

lmfao

its called sex panther, it works 100% of the time 50% of the time.
lol

hondamark35

yeah, sounds like an atom bomb there.. 14:1. if there's no head, there's no compression ratio...

if you're good at math you can figure it out. put one of the pistons at TDC and make a mold (something that will hold water, maybe modeling clay.. idunno) so that the dome is completely covered to the deck. do your best to fill this with water and measure the amount of water. this will be subtracted from your chamber volume.

then you need to know the stroke. TDC to BDC measurement. you may need to buy some measurement tools.

once you decide on the head and headgasket thickness you can put it all together to figure the theorectical, rough CR.

i know this sounds like baloney and a waste of time but you'll have an answer.

DCSportEJ1Civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">how do you propose he find his compression ratio by doing a compression test?</TD></TR></TABLE>

mathematics my freind. you get the compression in psi. pounds per square inch. you know the cubic inches of your motor, so the ratio is how much compression per square inch compared to the volume of the cylinder. i dont know the exact formula and i may be a little bit off here but its not that hard to look up and figure out. and 14:1 is rediculous. ive never heard of a piston that will make it that high. but maybe ive just never heard of it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdm91CrxSi &raquo;</TD></TR><TR><TD CLASS="quote">110 octane at shell in lexington (at the PUMP) it's smells soo good</TD></TR></TABLE>

and is probably $90 a gallon lol

Murk 'EM

no way its 14:1 thats wayy to high that will blow headgaskets and rings all day long, i dont care what you say 14:1 is very high... the only cars iv seen run 13:1+ is full drag cars.... muscle drag cars, logan motorsports over in elgin has a nova with 13.5:1 with (forgot the size) v8 it runs 10ish (he doesnt run it to what it can produce tho, he doesnt want to break **** so he turns the hp back) ... hes an all motor nothing but compression guy and HE was saying 13:1 is more then enough for a full drag car.. so unless your putting those "14:1" pistions in a big block you dont have 14:1 who ever sold you that is either a complete expletive or hes laughing at you right now for thinking you got a block with 14:1 CR pistons... 11.5-12:1 maybe but not 14... and at 12 you need to run 100+........... someone prove me wrong

Tryin2Rip

I know 14 is rediculously high thats why i think they aren't, i hope they arent id rather them be 12.5's but heres a picture maybe if anyone has had cp pistons they would know if this looks like a 12.5 or not....yea i know the mathmatical method your talkin bout i might give it a try....and yes you can run 93 on 12.5's all in the tuning

Syndacate

I've seen 14:1 before...never on a daily driven street Honda though...

Either way, you can't run 14's on pump 93 octane anyways.

The guy was just jerking your meat.

Tryin2Rip

ke98248

iTrader: (1)

What's the price on that stuff per gallon? $4.00?

trrbl1bmx

14:1 static compression ratio is not going to happen on 93octane. Octane is the fuel ability to resist detonation, I don't know the highest CR you can run, it really varies on the temp, humidity. But I would guess 12:1 would be close give or take a few tenths. Like previously mentioned to figure out your CR you have to have a cylinder head, headgasket, assembled block. Then do a block pour, cylinder head pour, and known headgasket volume.

trrbl1bmx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">I've seen 14:1 before...never on a daily driven street Honda though...

Either way, you can't run 14's on pump 93 octane anyways.

The guy was just jerking your meat.</TD></TR></TABLE>

You see them all the time... they're just not n/a just about any FI car is going to top 14:1CR.
I agree this guy is jerkin your meat.

posHonda

Ive seen 15:1 and it was a full drag car. If I were going n/a daily driven id stay below 12:1 even though it would put a limit to the setup.

Tryin2Rip

so has anyone purchased cp 12.5's that look similar to the piston i posted...???

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by p00n &raquo;</TD></TR><TR><TD CLASS="quote">

You see them all the time... they're just not n/a just about any FI car is going to top 14:1CR.
I agree this guy is jerkin your meat.</TD></TR></TABLE>

Yeah but a boosted CR is different from a naturally aspirated one.

A boosted one will only occur at peak boost - and that's only on a heavy boost app. Your typical evo or sti doesn't hit 14 - at least I don't think it does.

Though naturally aspirated is a completely different ball game - that means ur running 14 at 800 RPM.

Tryin2Rip

aright so we all kno 14:1 is way to much for a street setup i really just want to know if anyone can identify the piston that i posted because something like 14:1 would be a custom setup and this looks really similar to cp's online but im am not sure....anyone who has had cp 12.5's is that what they look like??

b16b18

Can you rotate the crank to TDC so that the piston is exposed and take another pic from the side angle. A piston in the 14:1+ range should come to more of a point. Anything higher and you start running into clearance problems like the tip of the piston hitting the spark plug.