What fuel do you guys use in your 135i?

[jeremyc74]

Originally Posted by maxnix

That's not necessarily true, especially if you are south of the Mason-Dixon line in the summer and you have DCI installed sucking from that preheated under hood air! It will help delay preignition under those circumstances.

Nope. The ECU maps are watching IAT and retarding timing based on that, no matter what the fuel is doing. You won't see any power gains at all running 100octane fuel on a stock car, even in 100 degree weather. The ECU simply won't take advantage of it.

[NYF32DRIVER]

Originally Posted by jeremyc74

Nope. The ECU maps are watching IAT and retarding timing based on that, no matter what the fuel is doing. You won't see any power gains at all running 100octane fuel on a stock car, even in 100 degree weather. The ECU simply won't take advantage of it.

Yes, But: ZERO ETHANOL !!!

[fwmcb]

The highest octane that we can get around here is 91, I'd like to try out some higher octane at some point.

[jeremyc74]

Originally Posted by maxnix

Not true either! If the fuel mixture is preigniting because the intake charge is not sufficiently cool, then the ECU will retard timing and performance will decrease. Higher motor octane fuel will raise this limit where preignition will occur.

There isn't going to be any preignition on 93 octane unless you're running a tune. The factory timing is too conservative for that. You aren't getting a damn thing from running higher octane fuel on a stock tune.

[tgxmike]

Originally Posted by aksundog

Best available in Alaska us 90. Sucks, but never heard of a octane related problem.

With all the oil we produce here you'd think we'd have better choices...

Certain places in the Continental US has lower octane also (85/87 only), I have only ever seen these is very high altitude areas. I believe the high altitude requires less octane because of the air density, but I'm not an expert on that.

[Tom K.]

Originally Posted by fwmcb

The highest octane that we can get around here is 91, I'd like to try out some higher octane at some point.

Over the past 12 years, I've run both 93 (available at home) and 91 (when travelling) in 5 different BMWs. There has been no noticeable difference, either in power or gas mileage.

Unless you have a different tune, save your money!

Tom

[RPM90]

Originally Posted by maxnix

That's not necessarily true, especially if you are south of the Mason-Dixon line in the summer and you have DCI installed sucking from that preheated under hood air! It will help delay preignition under those circumstances.

You're confusing "pre-ignition" with "detonation".

Pre-ignition is when the a/f mix ignites before the spark fires.
This can caused by hot spots in the combustion chamber from things like a hot carbon spot the plug itself.
The mix can "pre" ignite, but it's not the same as "detonation".
Pre-ignition happens before the plug fires. It can occur during the compression stroke, and that makes it a dangerous condition. The a/f mix ignites as the piston is rising to compress the mix, while pre-ignited mix has already started and is pushing against the pistons upward movement. It can be very bad.
Detonation is an explosion that doesn't have a single ignition point. It has multiple flame fronts colliding creating very high combustion chamber pressure and heat.

Now, what do you mean by "delaying" pre-ignition?
Perhaps you mean to say it will help prevent pre-ignition?

Yes, hot air can add to conditions that can cause detonation, especially in a force air engine.
High octane fuel is rated according to it's resistance to auto ignition.
The engine is tuned to perform it's best when certain conditions are met.
Timing advance helps achieve best performance, but at the potential for a/f mix detonation. To get the best performance a certain type of fuel should be used. In high po engines that means running the octane rating the manufacturer recommends.
The engine is tuned for that fuel.

If you're running in high load and high heat conditions, using a higher than needed octane fuel might help keep detonation away perhaps to a greater level, but as Jeremy points out, you won't gain any more power.
But, technically you might gain more protection against detonation, technically, maybe.

[fwmcb]

Originally Posted by Tom K.

Over the past 12 years, I've run both 93 (available at home) and 91 (when travelling) in 5 different BMWs. There has been no noticeable difference, either in power or gas mileage.

Unless you have a different tune, save your money!

Tom

Thanks, I'm glad to hear that I'm not missing out on anything. Living in Eastern Canada means that certain things aren't available. I'd just like to give it a shot at some point when I take a long trip!

[Tom K.]

Originally Posted by fwmcb

Thanks, I'm glad to hear that I'm not missing out on anything. Living in Eastern Canada means that certain things aren't available. I'd just like to give it a shot at some point when I take a long trip!

Living in the US and driving through the maritimes last summer, the main differences I noticed were that your gas was about 25% more expensive, your roads are much less congested, and I put on entirely too much weight when touring Gaspe. And for driving the Cabot trail, a 1er 'vert is second only to a BMW motorcycle.

Tom

[crzy4135i]

Originally Posted by BMW86

In the US I believe they use AKI and for the rest of the world we use RON.

I believe our Premium 98RON is the equivalent of 93AKI in the States.

Shell 93 AKI. fuel pump still good at 16k miles.

[babyboss]

we only get 95 ron( $1.15/litre) @ stations in south africa >>
woulda luv 2 use 98 .. ( avail @ tracks but xxx expensive $2.55/litre )

[romak47]

is it safe to run 110 octane? theres some here in Germany. thought id try it when i dyno my car again next time..

just wondering what map and timing i should have etc..

[The1]

Originally Posted by Tom K.

Living in the US and driving through the maritimes last summer, the main differences I noticed were that your gas was about 25% more expensive, your roads are much less congested, and I put on entirely too much weight when touring Gaspe. And for driving the Cabot trail, a 1er 'vert is second only to a BMW motorcycle.

Tom

Canada is pretty congestion free untill you hit the area between London and Toronto, and that's some of the worst driving you will see. I did 9,300 miles through Canada and the states back in April, and the worst part about returning home was the traffic here. Such a nightmare, and one of the most boring parts of the drive in my opinion, but that may be bassed on the fact that i've driven that part about a million times.

I've even heard my dad saying he would rather drive around New York City then around Toronto. I think he was exagerating. That being said, I haven't driven in NYC

The highest Octane we get in Canada is 94 unless you go to the race track. It's kind of sad I was thinking about buying a Lucas Octane booster and throwing it in to see what it would do with my tune, but i'm not really sure if there's any value. So much bad reviews on all the boosters except the lucas one, i can only assume it's just useless as well.