M5 Product Guide.
10-19-2005, 03:30 PM
#31
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My Ride: 545iSMGSilver GrayAuburn Dakota LeatherLogic 7 Premium SoundSports Package
Oh man... very :thumbsdown: :thumbsdown: :thumbsdown: Now I'll have to think twice before justifying a M5. 
10-19-2005, 04:05 PM
#32
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Originally Posted by robg' date='Oct 19 2005, 07:40 AM
[quote name='Centurion' date='Oct 19 2005, 01:00 AM']So, considering all that has been mentioned so far, does BMW have to retard the ignition for all the M5's sold in California (and other states) where the highest widely available octane is 91?? If so, doesn't this mean less than optimal engine performance (i.e. <500HP)? 
The reason I ask is because of this quote:
[quote name='cidair' date='Oct 17 2005, 11:05 PM']According to a engineer at BMW M, you will loose 10 - 12 hp if you run the M5 on 95 octane instead of 98 octane ( 98 is the recommended ).
The reason I ask is because of this quote:
[quote name='cidair' date='Oct 17 2005, 11:05 PM']According to a engineer at BMW M, you will loose 10 - 12 hp if you run the M5 on 95 octane instead of 98 octane ( 98 is the recommended ).
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[/quote]To the best of my knowledge, BMW does not adjust the timing based o the region. New engines will automatically adjust to prevent knock and damage, and there will be less than optimal performance.
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[/quote]Correct, the timing will be retarded until the 'knock threshold' is achieved. BMW has an 'ionic current sensor' that they use to detect the onset of knock. The car will automatically adjust each individual cylinder's spark timing such that the timing is advanced to the maximum level that does not result in knock. With 91 octane gas, there will be some adjustment of the spark timing, and the resultant loss of power. A 10-12 HP loss certainly sounds reasonable, and if it's cold out you may not see any loss at all. Remember, this drop in HP is not going to be perceptable to the average person. 10-12 HP equates to about 100 lbs of weight. That's the difference in performance between a car with a full and a quarter full tank of gas.
If you're really concerned, you could use some of the high quality additives to increase the octane.
10-20-2005, 05:15 AM
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Got it.
Thanks, and by the way, your car will be in your hands in a few days now...is there a pump near you that sells octane >91 or do you intend on supplementing the fuel with an octane boost?
Thanks, and by the way, your car will be in your hands in a few days now...is there a pump near you that sells octane >91 or do you intend on supplementing the fuel with an octane boost?
10-20-2005, 05:49 AM
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Originally Posted by Centurion' date='Oct 20 2005, 07:15 AM
Got it.
Thanks, and by the way, your car will be in your hands in a few days now...is there a pump near you that sells octane >91 or do you intend on supplementing the fuel with an octane boost?
Thanks, and by the way, your car will be in your hands in a few days now...is there a pump near you that sells octane >91 or do you intend on supplementing the fuel with an octane boost?
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10-20-2005, 05:52 AM
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Originally Posted by wolverine' date='Oct 20 2005, 06:49 AM
[quote name='Centurion' date='Oct 20 2005, 07:15 AM']Got it.
Thanks, and by the way, your car will be in your hands in a few days now...is there a pump near you that sells octane >91 or do you intend on supplementing the fuel with an octane boost?
Thanks, and by the way, your car will be in your hands in a few days now...is there a pump near you that sells octane >91 or do you intend on supplementing the fuel with an octane boost?
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[/quote]You lucky bastard.
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