87 Octane

[eMvy]

Here in Delaware I use 94 octane from Sunoco.

[PINHEAD]

I put jet fuel in my car

[Krozi]

I use leaded 500 octane with mercury injection.

[ThunderMoose]

I hate Mr. I-use-87-octane-because-I-can't-tell-the-difference guy.

[AlpWtE92]

Originally Posted by Doctor J

Octane rating does not relate to the energy content of the fuel. It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced.

87 octane has more energy in it than 91.

As long as his engine is not pinging -- no harm done really.

and to the person that mentioned "LED" (sic) --- there hasn't been any lead in pump gas for years and years

Technically, I believe octane is a measure of how resistant the fuel is to knocking (caused by premature detonation of the fuel). You don't want knocking because it reduces engine preformance and will eventually damage your engine.

However, I agree that putting 87 octane gas will not damage the engine. Most cars today, including ours, have very sophisticated engine management systems that allow them to run on fuels of different octanes. The car's computers will make adjustments to avoid engine knocks caused by variations in fuel octane. However, the manufacturer designed and tuned the engine to run at its highest potential with a certain octane fuel, and if you do not use that octane fuel, the engine will not run at its highest potential. This is why those of us here in CA will never get to enjoy the full performance potential of our cars because we only get 91 octane gas (unless we find special stations that carry higher octane gasoline) and I have read that our engines were designed to run with 93 octane gas.

Thus, while I agree that it's cheap and stupid to save a few bucks and put 87 octane gas into an M3, he was not going to harm the engine. At least the guy was putting tier 1 gasoline into the car. Bad additive packages from cheap or no-name gas stations will hurt your engine more than 87 octane gas ever will.

[duk]

no long term damange as ECU will pull timing if you need to emergency pump on 87

using 87 all the time, i can't help but feel sorry for his engine

i wished i can get 93 on a regular basis, i dont mind paying pennies more

[Asiarush]

Originally Posted by dibxna

Glad someone else is a smart ass when it comes to spelling and grammar, ha!

was using my Iphone !! sorry for misspelling lead !

[klammer]

Use 93 all the time, as an aside, if I use 100, will I notice a difference up top? Also have 110 to choose from (both at the track, not around the corner), will that make a difference? Or is it just overkill and unusable at that point? Insights would be appreciated

[VegasEgg]

Roughly how much would a octane booster additive add to the octane rating?

[1MOREMOD]

Is a tuned car less able to deal with lower octane gas or does it still retard the timing in a similar way so no damage occurs. Conversely would using a higher octane than you are tuned for be a waste or can the tuned ecu manage to adapt and make more power?

[sensi09]

Originally Posted by klammer

Use 93 all the time, as an aside, if I use 100, will I notice a difference up top? Also have 110 to choose from (both at the track, not around the corner), will that make a difference? Or is it just overkill and unusable at that point? Insights would be appreciated

Waste of money IMO. It may be slightly faster in a head to head race, but nothing you will feel or notice.

[AlpWtE92]

Originally Posted by klammer

Use 93 all the time, as an aside, if I use 100, will I notice a difference up top? Also have 110 to choose from (both at the track, not around the corner), will that make a difference? Or is it just overkill and unusable at that point? Insights would be appreciated

This thread is a good read regaring use of high octane gas: http://www.m3post.com/forums/showthread.php?t=280965

In short, you may get more HP if you use 100 octane gas, but it's not as much of a difference than you would think. The problem is that BMW did not program and tune the engine for 100+ octane fuel. From what I've read, it seems that you may get more horsepower up to 100 octane, but you won't feel much of a difference than if you used 93 octane, which is what the car was really designed to use. More than 100 octane, and you might actually get less HP than using 93 octane.

[GewoW]

im driving an extra 80km to fill up with 94 instead of the 91 here...so yeah

[Swedish M3ffia]

Originally Posted by Wall$treet

While I agree it is not financially a savings to really put 87 instead of 91/93 to save 3 dollars a tank, especially given you bought the car for performance and to get the max horsepower peak you need the highest octane.

However add this to the misconceptions of the internet world and you have to realize if you never redline the car to peak power than 87 will feel absolutely no different than 93 as it won't be knocking or pre-detonating under mild-moderate load conditions.

Now if it is hot out and you rev it past 8k than you will definetly feel a difference. Maybe this guy just does not get on the gas and in that case he is absolutely right that literally there is no difference in power.

You always post such stupid comments and this time i had to step in. You have no idea what you are
Rakning about. Saying that you wont notice Ã* difference between 93 and 87 if you dont go to peak power is hilarious. I clearly notice Ã* difference between 91 and 93. You dont need an m3 and have no feel for power

[AbuArije5]

Originally Posted by Seattle S65B40

BTW, how does somebody look rich? You can never really tell. Those are often the people who are broke because they spend all of their money on trying to look "rich," with nothing left to back it up. No baller is going to be pinching pennies at the pump... (PP@P)

If you look rich and drive an m3 you are rich just face it

[Edjay]

Food for thought.
You may not do damage by using lower octane fuel. But most likelly you will spend more in the end. With lower octane, the engine is more likely to pre detonate. The knock sensor will pick that up and compensate for it. It does this in 2 ways. 1 would be to retard ignition timing, the other would be to richen the fuel mixture some. It does this in trying to lower combustion temp down. So imo the end by produuct if this would be less engine power but more fuel used. With less engine power, equals less mpg equals more money spent.

[Brucewonder]

Maybe it's a lease n he doesn't care

[Lay-Z M3]

Ahh just adds to the danger of a used car purchase or off lease buy.......just like a new girlfriend, you'll never really know how badly she was treated or abused previously!!!

[Chris345]

High compression engines need high octane gas so they don't knock/ping. Sure, it won't cause damage with today's sophisticated engine management computers, but like has been said earlier it will reduce your power by retarding the engine timing so it doesn't damage anything. Of course, computers can fail, or not go fast enough to prevent the knock.

I used to drive a '65 turbocharged Chevrolet Corvair. Without 91, that thing would ping like no other. Even with 91 when it got too hot and I was pulling hard up a hill...ping ping ping.

And, here on the west coast we can't get anything higher than 91 anyways.

[BobsM3Coupe]

Originally Posted by Doctor J

Octane rating does not relate to the energy content of the fuel. It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced.

87 octane has more energy in it than 91.

As long as his engine is not pinging -- no harm done really.

and to the person that mentioned "LED" (sic) --- there hasn't been any lead in pump gas for years and years

I believe leaded gas for on road vehicles was banned in the US in the mid 90's.

[sameh]

My car only gets SHELL 93. The one time I put gas from a HESS on why (just 5 gallons to get me to a shell) I still put 93 but I ended up with 8 cylinder misfire and reduced power on why. Don't play with gas, it'll burn you.

[serranot]

Yes the engine can run on 87 given the knock sensors, but it wasn't designed to run with the timing retarded, which is what the EMS does when it detects knock. Is one tankful going to hurt the car? I doubt it. If you run 87 all the time, now you're a test pilot. I get why it might happen infrequently. I don't get why one would choose to purposefully run 87 as a matter of practice. Sell the car and buy a Camry if you're going to do that.