100% Octane Fuel Safe to Run?
 

Hey guys,

I tried filling up with Shell's new 100% octane fuel with 5% Ethanol tonight. I normally just run the 98% octane and to be honest I didn't really feel much of a difference although the 100% is abit more expensive.

I'm running a Series 7 so not too sure if there are any side effects to this? I noted my car still runs a 10-9-11 after I filled up.

Octane is resistance to burn - so unless you're taking advantage of it by changing the fuel delivery and ignition characteristics of the system - nothing will effectively change. You'll have more safeguard against uncontrolled detonation, but that's about it.

It's not %, LOL. Unless you are tracking the car and want the extra little bit of safety, there is no need to run 100 over the 98.

Or if you're tuned for it, with more ignition lead/ higher boost. It sounds like you aren't so i don't see the benefit.

If it's 100% octane, how can it be 5% ethanol? It'd have to be 95% octane. Duh.

If you aren't tuned for it, there isn't really any point.

Is it a jap import? (I believe it would be being a series 7) As the jap models are factory tuned to run on 100 octane, as thats the fuel that is used in japan.

I have ran many a import on 98 octane even though the jdm factory tune is for 100 never had an issue yet. If you were to get your car tuned for that fuel that would be a different story however.

- Neil

Yes its a stock JDM S7. Its not the Octane that I'm concern with its the Ethanol thats has been added to it, in this case 5%.

There's been quite some debate over here with some motorist refusing to use any type of fuel with ethanol as an additive because it could be harmful so just wanted to clarify this.

I would run 110%
because I always give 110% and I expect my car to give 110% as well



lol, you need to figure what octane is and how it works before you start worrying about how much to run in your car

It was a typo my bad...meant to be 100 RON or 100 Octane with 5% Ethanol.

No one has yet to answer what his REAL question is, that being is the 5% ethanol ok to run in an FD?

This is a good question. In the marine world, you do NOT run ANY ethanol....ever....in a boat. The hygroscopic properties of the alcohol, along with its corrosive properties, means you can't run it.

That I don't know. However with the current price of gas who even has the money to run their FD? :icon_tdow

Almost all the gas around here is 10% ethanol and has been for a while. Running only 5% should be fine.

ethanol is perfectly fine for your fd or for any car for that matter it also helps reduce knock much like lead used to do in the old days.

Wrong.

Ethanol in the same volume is about 30% leaner than gasoline. In other words it takes 30% more ethanol to get to optimal air fuel ratio. So with 5% of that crap in your gas your car will run about .2 lambda LEANER on ethanol while in open loop operation. If you have a newer car that is closed loop all the time or at cruise in the FD this doesn't apply because the A/F sensor still reads the same, 14.7 is still optimal for ethanol so the ECU just pumps more in as long as your fuel system can supply it you could run even more ethanol.

Needless to say, I will be tuning my car on E10 93 octane here in the States. That way if I run regular gas the car will be richer, not leaner :) But I will probably run the regular stuff day to day if I can find it, that way the fuel in the tank isn't hygroscopic (ethanol has a nasty habit of absorbing water causing fuel system corrosion).

Yes the hygroscopic property is bad, but the real reason you don't want to run it in boats is because it softens fiberglass gas tanks and turns the resin back to gel, and that just isn't any fun

I believe Chuck (cewrx7r1) has documented on his car that it runs 0.2 to 0.3 points leaner on 10% ethanol. Anyone who knows Chuck knows that this is an accurate number.

yea, damn ethanol adheres to water. stupid polarity.

Its not actually 100 octane, they use a different rating. I think its equivilant to like 98 or 99.

Damn.

I actually did the math. Should have just looked up "ethanol" and "cewrx71" for user name and I would have saved some brain pain