high compression

stlsupra · Post by **stlsupra** » Tue Jul 17, 2007 12:49 pm

anyone in stl build a high compression sohc vtec car?

i'm about to buy some d16a1 pistons but i'm concerned about how much is too much compression for the street? according to the comp calcs my build should be in the 12.14:1 area.

been reading alot on other boards but figured i'd ask around local first.

thsmrtone1 · Post by **thsmrtone1** » Tue Jul 17, 2007 2:30 pm

12.14=DAMN! what engine are they going in?

N2HIFI · Post by **N2HIFI** » Tue Jul 17, 2007 3:50 pm

i had 10.5:1 srp's in my z6/y8 motor and with the head and the block both milled and the big cam i had the compression was around there or even a bit more. Daily drove it on pump gas.

chris

SweetEBPSi · Post by **SweetEBPSi** » Tue Jul 17, 2007 4:10 pm

N2HIFI;55526 wrote:i had 10.5:1 srp's in my z6/y8 motor and with the head and the block both milled and the big cam i had the compression was around there or even a bit more. Daily drove it on pump gas.

chris

10.5:1 Isn't that bad. Mine has 10.1:1 stock, GSR has 10.5:1 (I think),and the ITRs have a 11.1:1. I think you could pull off the 12.14 but tune it really well. I'm not sure but if not tuned well and the high compression, I think your more prone to detonation. Not sure about that. Someone correct me if I'm wrong.

sharpie · Post by **sharpie** » Tue Jul 17, 2007 5:11 pm

my car is 11.6:1 and i daily drove it while i had it (in the body shop) didnt have any problems but since your that hight you might have trouble finding gas for it probally have to run nothing less than 93 octane which i can only find at some bp and like 2 qt's

ImAJandILikeToSuckMenOffForMoney · Tue Jul 17, 2007 5:13 pm

sharpie;55534 wrote:my car is 11.6:1 and i daily drove it while i had it (in the body shop) didnt have any problems but since your that hight you might have trouble finding gas for it probally have to run nothing less than 93 octane which i can only find at some bp and like 2 qt's

Ummm QT only has 91, BP, Shell, Phillips66, Conoco, and most others have 93. SO its not hard tp find just gotta pay the extra for it.

twkdcd595 · Post by **twkdcd595** » Tue Jul 17, 2007 5:13 pm

e85 is pump gas and would handle 12:1 without a problem... would make some great power too.

ImAJandILikeToSuckMenOffForMoney · Tue Jul 17, 2007 5:15 pm

twkdcd595;55536 wrote:e85 is pump gas and would handle 12:1 without a problem... would make some great power too.

Is this the corn fuel or something like that? I think a gas station in alton has it IIRC.

twkdcd595 · Post by **twkdcd595** » Tue Jul 17, 2007 5:40 pm

soundqjr;55537 wrote:Is this the corn fuel or something like that? I think a gas station in alton has it IIRC.

correct this would be a corn based ethanol (grain alcohol) fuel mixed with standard gas. 85% ethanol to 15% gas in the summer is standard, in winter some places bump it to 70-30 mix to keep the engine temps up in normal operating range (alcohol runs dramatically cooler, in cold weather this can cause some issues with getting to operating temps.).

in MO and IL... there is a TON of stations that have e85. oh and to add it has an octane rating of 105. for some interesting information check out the wiki on it. http://en.wikipedia.org/wiki/E85

JustRob · Post by **JustRob** » Tue Jul 17, 2007 6:06 pm

N2HIFI;55526 wrote:i had 10.5:1 srp's in my z6/y8 motor and with the head and the block both milled and the big cam i had the compression was around there or even a bit more. Daily drove it on pump gas.

chris

I'm basically reassembling this motor with a bigger cam LOL. The compression ratio of it was 12.3:1. I'll be bumping it down to 12.1:1 due to the different head design. I'll have to run 93 at all times and it will not be able to be driven without very good tuning.