measured cylinder pressure in my friend's maxima, came out to be 195 PSI. maxima has a 10.0:1 compression. measured pressure on my mini-me setup, came out to be 210 PSI. so if my motor is good, which it seems to be, my compression it at least 10.5:1. so i was wondering what gasoline should i use? and is there any harm in using a slightly higher octane fuel? like lets say i need to fill up w/ 92, but i use 93 or even 94?

 

No, no harm will be done. But, you will be flat out wasting your money. You won't gain any hp from higher octane gas than you need. If your worried, you can buy a bottle of octane booster for about $2 at pepboys or autozone.

 

ok for a while now im still trying to figure out what the hell is your avatar. is it some person spreading their legs and revealing their ******* or what?

 

actually i would run the higher octaine fuel if i were you , detination? with higher compression ratios , the higher the risk of it , and all the octaine booster is , is a combination of either alcohol and lubricants , i have seen a web site that tells you the formula to make them your self , and its way cheeper.

 

it's some part of a cooked chicken, i think it's the ***. i took the picture at work while testing the digital camera. then i thought it is the stupidest looking picture to use for your icon, so i put it in my avatar

 

yea, i know about the detonation problem when using lower octane fuel. that's exactly what i wanted to know though: what's the right octane for 10.5 CR? if there is a way to calculate those things from CR please post. and btw i've been filling up w/ 93 since the swap was complete. and i can get 94 at Sunco gas stations.

 

You sure you are at 10.5:1 compression? I doubt it.

I compression tested my ZC motor and got 200-210 psi in all cylinders. It has 9.6:1 compression.

Dustin

 

Compression testing gives you a reading in PSI which is not related to compression ratio. I have 210 psi ratings in each cylinder on my Celica and the stock compression ratio is 9.5:1 or lower, I believe. As for using higher octane fuel, don't even waste your money unless you motor is knocking, pinging ...... Higher octane fuel is harder to burn for a complete story on Octane check out the link below

http://www.sdstreetracing.com/articl...view.asp?id=25


[Modified by EVOCELICA, 10:47 PM 8/15/2001]

 

well first of all when manufacturers state the compresion ration its directly teh stroke and the bore they do no consider the dome of teh head, and teh valves and all that crap, so compression ratio alone will not give u what gasoline to use, what u have to chek is psi in teh cylinder, so if the maxima checks out at 195 with 10:1 and zc checks out to be 210 with 9.6:1 thats all good, cause they both have diffrent pistons chapes and domes, therefore in the maxima manual says use 91 octane (i know cause i have one) and if tis 195 then 210 is nto that far from it, u can safely run 91 otane in yours, u can do 93 just to be safe. As far as teh ZC motor goes that came from japan, and japan has higher octane then we do here so ts nothing special that it checks out at 195 psi with 9.6:! compression ratio.

 

exactly, and zc is a whole diff discussion. dont get me started on that...

 

You took a picture of my chickens a$$hole, and you think you can use it publically without my permission?!? Sheet boy, don't make me tell Lisa, she'll get on your a$$ )

hehe... but seriously... that's a picture of my chicken.... my lunch.. mmmmm