jovasi

I've just discovered the gas station down the street sells 110 octane racing fuel. Now my question is, how much would you recomend puting in per tank of gas? The reason I am asking is that I was going to purchase some octane boost because she's been sitting in the garage all winter with 3/4 of a tank. I was told just to put about a half gallon of 110 in to boost the octane. I'm figuring it wouldn't hurt to do this all the time. I'd like to hear your guys opinions.

all_bark

iTrader: (5)

waste of money.

I filled my tank with it when i was at the track and it did nothing for performance! i failed to realize that the ecu is set for 91 octane gas and anything better really does not help...

people, if i am wrong, please correct me, but i definitely did NOT feel any increase in performance.

jesseenglish

Unless you're worrying about detonation because you're running 10 PSI of boost it's a waste of money.

JST4FN

You do not need any more octane than your engine requires. Higher octane gases burn slower and can hamper performance. It is also probably leaded fuel which will mess up your convertors and O2 sensors over time.
Thanks Mike

jesseenglish

Leaded fuels were banned in the US almost 20 years ago.

PhoenixINX

Called out...

MIAPLAYA

iTrader: (3)

So from the above posts its being said that 110 would NOT increase any performance. Is there a specific reason. Does the ECU not adjust to the better fuel. I know that when I had my Spec I filled up my tank with 101 and I had to drive it down to half a tank before the ECU adjusted and actually showed a change. I would think that 110 would do SOMETHING for you.

jesseenglish

The ECU would have to know there was a higher octane fuel so it could advance the timing and adjust valve timing to take advantage of the slower burning fuel. ECU, just doesn't have any way of knowing that.

MIAPLAYA

iTrader: (3)

I'm new to the VQ game so don't think I'm being an @ss. Just trying to learn. That being said. Couldn't it tell from the A/F readings off of the O2s?

jesseenglish

Don't think you're being an @ss. Higher octane has no real effect on A/F ratios. Higher octane fuel describes the tendency of the fuel to avoid detonation. As compression ratio goes up, fuel burns faster. The higher the compression ratio engine you have, the higher octane fuel you'd need because it burns slower and more evenly.

MIAPLAYA

iTrader: (3)

ah I see. I know that I dropped about .1 on the 1/4 after that race gas but I never really knew if it was the gas or just the day. Now I know. This also explains how my friends GTP responds so well to it

Traffic

The Sunoco somewhat near me sells GT100 and GT Plus, and I believe they also sell Sunoco's Standard 110 octane, Supreme 112, and Maximal 116 leaded fuel.

jesseenglish

Interesting, I did some research on it and it is indeed leaded fuel. It also says it is for offroad use only, so it is illegal to use in a car driven normally.

There must be an exemption for race vehicles.

With that said, you'd only need to run an octane that high if you were running somewhere in the neighborhood of 17:1 compression ratio or 11 PSI of boost on the VQ35 with full timing.

all_bark

iTrader: (5)

leaded fuel is definitely available at tracks for off road use.

110 octaine i belive is leaded...

jovasi

What octane would you recomend running jesseenglish?

jesseenglish

If your worried about it because it's been sitting all winter, just drive nicely until you run the tank empty. Gas does break down after sitting for a long time if it doesn't have additives to stabilize the fuel. However most major gas stations fuel have stabilizers in them already when you buy them to prevent the fuel from breaking down when it's stored in their underground gas tanks.

I wouldn't worry about it. Get an octane booster if it makes you feel better, but whatever you do, don't put leaded fuel in your tank.

jovasi

So what I've been hearing, it sounds like the motor was meant to run on 91. Is this true?

fluidz

YES the VQ was designed to run 91 octane nothing more or nothing less, unless you are boosting.........then you could run as a safety margin.... octane boost or 3 gallons of high octane fuel to your 91 octane fuel to avoid any pre-ignition/detonation issues.............

phile

I've always used 93 octane.

Isn't it a funny concept that less volatile fuel is used as racing fuel? I guess it's strange to me because I don't know the underlying principles. Why don't we make engines strong enough to handle more explosive fuel? You'd think it would make more power. My guess is that it's harder to maintain consistent power with more volatile fuel?

jesseenglish

It's because you get more power when you raise the compression ratio. If you're running low octane fuel on a high compression motor the fuel will pre-ignite just from the pressures applied to it. You need fuel that won't burn prematurely to handle the higher pressure.