I always use 94 but for emissions I've been told that it helps to run lower octanes. I was wonderin if i put in like 5 bucks 87 octane and 3 bottles of alcohol just for the drive to emissions testing... then when i finish i'll immediately fill up with 94 octane... will my car be alrite? Also what kind of alcohol do you put in? vodka :P jk

matt
thanks

 

I wouldn't even try 87. 91 MAYBE. If you stay out of boost...as in NEVER getting into boost? Then yes...but its a VERY good possibility of blowing an engine if you go full boost...even just once.

 

hhhmmmm...... i heard that rotarys were designed for 87 and putting anything more was a waste of money! (stock cars, not wildly modded).... right?

or is that just n/a's............ ooops!

 

I heard 87 is fine and recommended in the owners manual for the S4 TII's. I have no idea about the S5 TII's. Perfectly fine on a stock car. I ran 91 octane on my modded TII though.

 

Nope, Rx7's that are turbo charged (or for that matter any car that is turbo charged) needs to use a minimum of 91 octane due to there high compression ratio. The higher the octane rating the higher it can withstand pinging.
Although if you plan to use a lower octane for a very temporary purpose and dont go into boost AT ALL youll be fine.

 

I've never been to aircare before so dont laugh at me but... during their testing **** do they ever go into boost?

 

lol..... everyone says ...."you might be alright"..... ive been driving my car for almost a year @ 10 lbs. of boost.... WITH 87 OCTANE , sometimes 89...... but rarily! and she still drives great.... no problems at all w/ drivability ! still pulls like a son-of-a-bitch.... so, i dont believe it hurts anything!!

 

alright....someone with an owner's manual, what's it recommend?

 

to me it doesnt matter wat they recommend im always gonna use 94... just for air care im gonna use a lower octane.

 

shoot, in cali we dont even have 94.... if you want over 91, you havbe to get race gas.

 

S5 gas recomendations according to the owner's manual (have it here in my hand) are:
Non-Turbo: 87
Turbo: 91

 

Some scans from my 88 T2 manual

 

Odd... on the back of my '91 manual it says otherwise.

 

Maybe it's different for S4 and S5 cars? I don't know...

 

I ran 91 in my 87 n/a the first year I bought it and it always hesitated between 3 and 4 thousand rpms . I saw a thread in the history saying to use 87 I tried it and it hasn't hesitated since then .

 

s5 run higher octane for some reason... my 89 n/a says to run 91. s4 were designed for 87 turbo or n/a

 

Is the higher octane to reduce emisions or increase performance on the newer FCs ?

 

I have read some pretty good arguments in the history that in rotory engines no matter what it was 87 was the better grade because the easier detonation of 87 causes you to get more hp because 91 went off so far on the end of the rotation that you lost alot of push .

 

Higher octane is to aid with boost. It's a performance thing. It's the equivelant of dumping more fuel in....but with less fuel...ummm...yeah....

What model N/A do you have nfs05? Mine said to use 87 (GTU)...

 

Uhm.. it was probably telling you not to use 91 because it builds up more carbon and you have a higher chance of carbon locking your engine. I only use 87 in my '91.

 

yea but the octane grade only means at what point of compression it will detonate 91 is to prevent predetonation in high compression piston engines

 

in high compression engines if you run 87 on the compression stroke it will explode or detonate before the spark throwing the engine out of time so to speak also known as dieseling

 

91 lets the gas air mixture get to the maximum compression before the spark plug sparks

 

The Series 5 N/A has a much higher compression ratio than it's turbo counterpart and it's strongly advised to use only 87 octane in a N/A engine. As far as turbos go, I've only heard of/seen people use 91 in them.

 

Confirmed...according to a manual (of course this is AIM acquired "hear-say") the S4 TII recommends 87.