[nikwho]

so, i have my impreza WRX that has quite a few performance mods.. including suspension, blow-off valve, exhaust, intake, a fuel management system.....etc, etc.. the guy i bought it from was a mechanic that just had fun tweaking on this thing.. so, heres my question.... they say that the need to run premium fuel only..... and i would assume that because of performance mods, this would be more important with my particular vehicle... so, i loaned it to my nieghbor just to run into town really quick and pick up a part for his truck thats torn apart.. i should have just driven him, i suppose.. but he is a very trustable guy. so, he was trying to be nice and he filled up the tank for me. well, it was pretty much completely empty and he filled it up all the way with 87.. so, i have driven it into town twice now and feel mild performance diferance but no pinging or detenation that i can hear. What is the pos. neg reprocussions from running 87? will it hurt anything or will performance just suffer a tad.. Its down to a little more than 3/4 tank now. i guess ill just keep topping it off every day with premium....?

 

[manimal]

it may cause your flux capacitor to stop fluxing for a bit but a big jolt of electricity should fix that

i now have a 94 impreza wagon...am i supposed to run premium in it? best handling car i've ever had, btw.

 

[laura]

I have a subie (outback 03', 6 cylinder, factory). I had major troubles with it when I first got it and they told me it was because I wasn't running premium fuel in it. So I started running premium. In Memphis we get 93 octane. When we took it on a 5500 mile road trip I could only find 91 or 90 so I used it with no problems. Are 2nd highest quality gas is 89 octane and tomorrow when I fill up, I am using that to see if it gives me any problems. After a small suit against our subaru dealer my issue was fixed (a supposed computer problem) and I have just been running premium to be on the safe side, but premium is breaking my budget really.

 

[stevew]

The funniest sound you will ever hear is a lawnmower running on C16(116 octane).

Buy some of the fuel additive stuff at the auto parts store.

 

[Ian F]

For the most part, it won't hurt anything. The difference is you probably won't get the most out of the engine on lower octane.

Most modern cars have knock sensors which detect knocking/pre-ignition. When pre-ignition is detected, the ECU makes adjustments to eliminate it. However, it happens so quickly you will probably never notice it working.

When just puttering around in day to day driving, you probably won't notice any difference in power. But if you do track sessions, make regular runs through the twisties or put the car on a dyno, you'll see a difference. It can also affect emissions in modded engine, so prior to getting a car sniff-tested (if required), run a couple of tanks of premium through it.

 

[BillT]

Your car is fine...the only issue is that it may not be running at full strength (due to the ECU detecting knock/detonation and pulling timing)...either drive it conservatively until you fill it up again with premium or go get some octane booster at the local Pep Boys.

 

[erastusboy]

you could maybe throw some octane boost in if your worried about it?

just a suggestion never actually used it.

 

[HaveFaith]

First of all, the question was definitely answered BillT.

Secondly, and more importantly, take off the blow-off valve. All that does is hurt performance and cause the car to run worse than it would.

 

[erastusboy]

but it sounds so cool.


pssssssshhhh

 

[Jimmy_Pop]

the 87 gas will not hurt your car, or mess with your sensors or anything. you will not get worse mileage either. if anything, you will get better mileage - IF - you keep your engine out of boost (or very low boost, never WOT)

Just keep out of the boost until you have cycled all the 87 out of your system.

Being a turbocharged motor, your static compression ratio is anywhere from 8.7:1 or 9:1. But under boost, it might be as high as 15:1 or higher. that high compression ratio demands high octane gasoline and retarded timing to keep from blowing a headgasket or breaking a piston. By adding 87 octane, if you race your motor, the 87 gas is actually "more flamable" and will combust while the piston is still on its upstroke and your engine will die a nasty death.

Just be careful, keep your foot out of the gas and kick your friend in the nuts.

joel
-1995 Z28 720 rwhp @ 22psi 9:89@152 street "legal"


Damn, i miss cars but DH is soo much cheaper.