Premium Gas - BMW Forum

donutchow · 07-25-2003, 12:29 PM

why do bmw's require premium gas? and how does the engine know the difference in octane, if you put in regular 87 does it not run as well, or could it actually cause harm to the engine?

MrM3 · 07-25-2003, 12:42 PM

bmw and many other perfromance built engines require premium gas becuase of their high compression. but u can run 87 octane in most bmw engines becuase they have knock/ping sensors that will automatically reduce the engines capabilities so the engine will run smooth and so the lower octane gas wont hurt the engine, but it still isnt a good idea becuase it will feel less powerful and it isnt the way the engine is meant to run

DesmoBob · 07-25-2003, 12:51 PM

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

knock = pre-detonation of the fuel before the spark can ignite it

2.link · 07-25-2003, 01:48 PM

I don't really mind paying for premium. There is a 76 station near me that has this high octane fuel at 115 its like $3.25 a gallon. I was thinking about filling up with that, what do you guys think?

DesmoBob · 07-25-2003, 01:54 PM

Quote:

Originally posted by Asio@Jul 25 2003, 10:28 AM
I don't really mind paying for premium. There is a 76 station near me that has this high octane fuel at 115 its like $3.25 a gallon. I was thinking about filling up with that, what do you guys think?

egad don't do it. unless you have radically advanced your ignition timing or are revving to 10,000 rpm.

there's one unocal station here too that sells ridiculously high octane stuff.

i think only the full-on dragstrip guys use it.

2.link · 07-25-2003, 01:55 PM

Quote:

Originally posted by DesmoBob+Jul 25 2003, 11:34 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (DesmoBob @ Jul 25 2003, 11:34 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-Asio@Jul 25 2003, 10:28 AM
I don't really mind paying for premium. There is a 76 station near me that has this high octane fuel at 115 its like $3.25 a gallon. I was thinking about filling up with that, what do you guys think?

egad don't do it. unless you have radically advanced your ignition timing or are revving to 10,000 rpm. [/b][/quote]
?

used

DesmoBob · 07-25-2003, 02:01 PM

i.e., you won't notice any benefit. high octane = retards detonation. 92 should be quite sufficient for street cars. when you advance your ignition (like a racing motor), you are predisposed to predetonation, thus needing higher octane (100+). also, if you are running really high compression (resulting in higher revs), predetonation can be even more catastrophic.

GreenDragon · 07-25-2003, 02:05 PM

Quote:

Originally posted by DesmoBob@Jul 25 2003, 05:41 PM
i.e., you won't notice any benefit. high octane = retards detonation. 92 should be quite sufficient for street cars. when you advance your ignition (like a racing motor), you are predisposed to predetonation, thus needing higher octane (100+). also, if you are running really high compression (resulting in higher revs), predetonation can be even more catastrophic.

I.E - Engine fall down go Boom.

ghead

2.link · 07-25-2003, 03:24 PM

Quote:

Originally posted by GreenDragon+Jul 25 2003, 11:45 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (GreenDragon @ Jul 25 2003, 11:45 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-DesmoBob@Jul 25 2003, 05:41 PM
i.e., you won't notice any benefit. high octane = retards detonation. 92 should be quite sufficient for street cars. when you advance your ignition (like a racing motor), you are predisposed to predetonation, thus needing higher octane (100+). also, if you are running really high compression (resulting in higher revs), predetonation can be even more catastrophic.

I.E - Engine fall down go Boom.

ghead

[/b][/quote]
ah ty for explaining it in english to me :P I did understand all the techinbabble that he said too...

fatty · 07-25-2003, 04:26 PM

in mine i only use shell optimax fuel.... (higher octain)

m42technic · 07-25-2003, 11:56 PM

Basically, buying gas with an octane rating higher than your car requires = flushing your money down the toilet.

fatty · 07-26-2003, 02:49 PM

Quote:

Originally posted by m42technic@Jul 26 2003, 07:36 AM
Basically, buying gas with an octane rating higher than your car requires = flushing your money down the toilet.

whys that.....

mine seems to be running a lot faster on the higher octain....

Spetsnaz Op · 07-26-2003, 03:14 PM

i'd run 89, then again i'm cheap

woobiee · 07-26-2003, 06:46 PM

i use 91-92octane and one time, right about to leave Ohio, i had half of a tank of normal 91octane fuel, i filled up the rest with 100 octane at a sunoco station. drove from Ohio to MD with ONLY half a tank! usually its a full tank of gas from Ohio to MD (about 380 miles) So 380miles with half a tank is incredible. The only explaination I have is the higher octane fuel i pumped in.

GreenDragon · 07-26-2003, 06:51 PM

Quote:

Originally posted by woobiee@Jul 26 2003, 10:26 PM
i use 91-92octane and one time, right about to leave Ohio, i had half of a tank of normal 91octane fuel, i filled up the rest with 100 octane at a sunoco station. drove from Ohio to MD with ONLY half a tank! usually its a full tank of gas from Ohio to MD (about 380 miles) So 380miles with half a tank is incredible. The only explaination I have is the higher octane fuel i pumped in.

Damn. It probably mixed to give you a high 90's octane fuel up in there. Sweet.