Trying to decide on 9.0:1or 9.8:1 CP Pistons. I finally blew a ring land so its time for a mild rebuild. I really loved how my stock GSR responded in and out of boost due to its high compression set-up. Would really like the same response so I'm leaning towards the 9:8 but it seems there is a preference for lower compression pistons in this forum. I looked at C-Speed's calculator but could not find CP's piston dome displacement to get an accurate result. Anyone know what the final compression ratio will be for a 81.5mm bore B18c1 with stock GSR head, OEM head gasket with 9.0:1 (SC7011) and 9.8:1 (SC7016) pistons? Block and head will be resurfaced. The builder has not yet given me any info on how much will be machined off but I do remember him saying that it would be the standard resurface (no warps or irregularities from the initial inspection) I'm aiming for 350-400 whp on E85 tuned with S300.



Modified by mrchris1979 at 12:52 PM 10/31/2007

 

With your power goal in mind, you could run the 9.8:1 with no problems...plus youre running on E85 which will help immensely. I cant wait for my E85 tune....hopefully next summer!

 

Sounds good. E85 is starting to become a popular fuel choice here. Anyone else using the CP 9:8 piston sets? Post up some dyno graphs or some numbers. I'm interested to see what set-ups other people are running on similar compression ratio numbers. I just got an E-mail back from Laskey Racing saying they will be taking off .003-.004 off the head. Not sure how much more that will be bringing the compression up.

 

I think I have one here from 9.8:1 CP pistons GS-R Darton MID sleeved 84mm bore/ 89mm stroke on a T3/T04E 60 trim turbocharger at 12.9psi. It used stock cams and stock 8200rpm redlline. Could have done more but it was only 30 degrees outside during the date of the tune. The powerband was very linear and a blast to drive on the street so much that a Quaife LSD was added later that week

 

It's 9.8:1 or 9.0:1, not 9:8 or 9:0. It's a ratio, how can you have a ratio of 9 to 0? And 9:8 would be 1.125:1, motor's not going to run with 1.125:1 compression. Get it right.

 

^

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tokesGTR &raquo;</TD></TR><TR><TD CLASS="quote">It's 9.8:1 or 9.0:1, not 9:8 or 9:0. It's a ratio, how can you have a ratio of 9 to 0? And 9:8 would be 1.125:1, motor's not going to run with 1.125:1 compression. Get it right.</TD></TR></TABLE>

Im pretty sure everyone new what he was talking about.

 

lol 9:0 compression would be 0 compression....i think we all figured it out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHCD16y8 &raquo;</TD></TR><TR><TD CLASS="quote">

Im pretty sure everyone new what he was talking about.</TD></TR></TABLE>

Yeah, I'm pretty sure everyone KNEW as well, but it's a pet peeve.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tokesGTR &raquo;</TD></TR><TR><TD CLASS="quote">It's 9.8:1 or 9.0:1, not 9:8 or 9:0. It's a ratio, how can you have a ratio of 9 to 0? And 9:8 would be 1.125:1, motor's not going to run with 1.125:1 compression. Get it right.</TD></TR></TABLE>

Someone's having a bad day haha. Have a

 

tokes has been an unhappy nissan driver as of late.

to the op: i run 9.8:1 CP's in my built gsr. No dyno #'s yet, but it drives beautifully so far. Make sure you dont buy an 'old' batch. They had issue with the valve reliefs being too thin on the edge of the pistons. I think the revision was from august of last year.

edit: found the thread discussing the valve relief issue
https://honda-tech.com/zerothread?id=1901519

 

I was running the 9.8:1 81.5mm wiseco. I made 392 at 15psi on pump (91) with a 60trim. I went with the same ratio again.

 

I'm just starting a build myself and trying to figure out what CR to use. I'm going to ask my tuner to see what he thinks. If you tuner isn't comfortable going to those power levels with the higher CR you might want to go with the lower CR.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tokesGTR &raquo;</TD></TR><TR><TD CLASS="quote">It's 9.8:1 or 9.0:1, not 9:8 or 9:0. It's a ratio, how can you have a ratio of 9 to 0? And 9:8 would be 1.125:1, motor's not going to run with 1.125:1 compression. Get it right.</TD></TR></TABLE>

Dang bro. Chill. I edited my post just for you. Hope that relieves your peeves a bit. Anyway, thank you for the dyno graph and also posting up some numbers. I was just told by Laskey Racing that they do a clean up cut on the head of about .003-.004". It appears that the head has been milled before too so I will have to account for this in addition to the block being decked. I looked at C-speeds calculator but just don't have all the needed numbers to get an accurate calculation of my motor's final compression ratio. I will be using only the OEM head gasket so once it's all said and done, can I assume that I will be at 10.1:1-10.2:1 CR? Since it will be on stock sleeves and plan for no more than 400whp, I think that that ratio should be just right for good boost response and make great power at a lower boost level. Using E85 will definitely give me a better advantage too. One of our tuners out here "servion" tuned a 11.5:1 CR B-series to 450whp uncorrected with an SC61 with zero issues. I'm hoping to get 400whp with my T3/T04e 57 trim.


Modified by mrchris1979 at 1:57 PM 10/31/2007

 

400whp on a 57 trim on 92-93 octane shouldnt be a problem...just be sure to get a good tune

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">400whp on a 57 trim on 92-93 octane shouldnt be a problem...just be sure to get a good tune </TD></TR></TABLE>

Is everyone completely incapable of reading?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrchris1979 &raquo;</TD></TR><TR><TD CLASS="quote">I'm aiming for 350-400 whp on E85 tuned with S300.</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrchris1979 &raquo;</TD></TR><TR><TD CLASS="quote">Using E85 will definitely give me a better advantage too.[/i]</TD></TR></TABLE>

He's running E85, not just pump gas.

Call up CP and give them the specs on your motor and they'll tell you basically exactly what the static CR will be. I don't know why they don't list the dish/dome volume on their website, but they will calc your compression ratio for you. I say run the 9.8:1 pistons for E85, a little bit extra compression certainly can't hurt. Considering someone just made 700 WHP on E85 with a B16, I don't think you'll have any troubles reaching 400 with a bigger motor.

 

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

Is everyone completely incapable of reading?
</TD></TR></TABLE>

apparently, but then again, it seems you're incapable of being anything short of a complete *******...i guess we're even

 

10.4:1 here love the high compression.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">apparently, but then again, it seems you're incapable of being anything short of a complete *******...i guess we're even</TD></TR></TABLE>

HAHAHA, and e85 coming from the same pumps as 87-93 would make it a PUMP gas.

i think u need vtec in ur life

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">

apparently, but then again, it seems you're incapable of being anything short of a complete *******...i guess we're even</TD></TR></TABLE>

Being an ******* who knows how to read will take you much further in life than being illiterate. I guess we're not even.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93supercoupe &raquo;</TD></TR><TR><TD CLASS="quote">

HAHAHA, and e85 coming from the same pumps as 87-93 would make it a PUMP gas.

i think u need vtec in ur life </TD></TR></TABLE>

And since you can't even read what the illiterate wrote:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">400whp on a 57 trim on <FONT SIZE="5">92-93 octane</FONT> shouldnt be a problem...just be sure to get a good tune </TD></TR></TABLE>

Wasn't talking about E85 there, champ.

 

I didnt care so much that i had accidentally written the wrong fuel down. I read threads and sometimes space on simple things like that...either way he can make that kind of power...he's better off on E85 as you know.

The part that gets me is that instead of just correcting me, you take it upon yourself to slam me. You did that earlier in this thread as well. People make little mistakes...you fall under that category as well. Im sure in life, you've made AT LEAST 1 mistake somewhere along the line. Next time, just simply say something rather than being a dick about it...all that does is **** people off...

 

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

Being an ******* who knows how to read will take you much further in life than being illiterate. I guess we're not even.

And since you can't even read what the illiterate wrote:

Wasn't talking about E85 there, champ.</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tokesGTR &raquo;</TD></TR><TR><TD CLASS="quote">

Is everyone completely incapable of reading?

He's running E85, not just pump gas.

Call up CP and give them the specs on your motor and they'll tell you basically exactly what the static CR will be. I don't know why they don't list the dish/dome volume on their website, but they will calc your compression ratio for you. I say run the 9.8:1 pistons for E85, a little bit extra compression certainly can't hurt. Considering someone just made 700 WHP on E85 with a B16, I don't think you'll have any troubles reaching 400 with a bigger motor.

</TD></TR></TABLE>

Pretty positive that is what he is referring to there, champ. Next time take the ***** out of your *** before posting. You sound like such a hateful bitch.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bamf3000 &raquo;</TD></TR><TR><TD CLASS="quote">

Pretty positive that is what he is referring to there, champ. Next time take the ***** out of your *** before posting. You sound like such a hateful bitch. </TD></TR></TABLE>

i love it, i really do.

Lets stop getting hung up on the grammar of this thread and help this dude w/ his legit question.

And i think its pretty well known that e85 is going to have a greater threshhold for detonation and will probably help to keep combustion temps down, so going from 9to1 to 10to1 is only gong to help.

But if u happen to have to run regualr fuel, among a different tune, ur going to have a harder time maintaining the same power level.

 

yeah tokes is an A-hole.
Honestly with the advancement of tuning to where it is now you should be fine. people turbo itr motors and have no problems so i dont see why a little lower compression along with forged pistons would be a probem.

 

My built motor has 9.8:1 CP pistons in. I'm looking at pushing 400 on pump gas. So you will be fine on e85.