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      08-18-2008, 10:01 AM   #1
JuniorDee
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Racing Fuel?

Out of curiosity, has anyone put racing fuel in their M3 other than what I have read on this post:

http://www.m3post.com/forums/showthread.php?t=164325

any dangers with putting 110 octane in?
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      08-18-2008, 10:17 AM   #2
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higher octane should be fine so long as you make sure it's unleaded fuel. I mix it in at times when I can find it just to try to get a 93 octane mix since all we get here in LA is 91.
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      08-18-2008, 10:36 AM   #3
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Should have no problems at all!Here in the UK we have BP Ultimate 102 Ron at some pumps and that is excellent if not a tad expensive($8.00 a litre at todays exchange rate!)

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      08-18-2008, 12:23 PM   #4
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Will there be any significant benefit, given that the engine is naturally aspirated?
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      08-18-2008, 12:32 PM   #5
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I'm just guessing here. But I'd think there would be very little benefit if any at all. The engine was not tuned by BMW for 110 octane fuel so I would think it's not going to take advantage of the higher octane fuel. I am positive you will lose some HP with 87 octane and the computer will back of timing to not allow knocking. You might see a little gain with the race fuel as it will burn slower. You will not cause any damage to the car, just your wallet when you go to pay for the more expensive fuel.
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      08-18-2008, 12:53 PM   #6
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PencilGeek got +14hp with 100 octane vs. 91 octane. I guess the DME will adapt to the higher octane. How much remains to be seen. At some point, there is no gain...the DME cannot advance timing infinately, so there is a max benefit somewhere. Whether that be 93 octane, 95, 100, or somewhere else is the question.
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      08-18-2008, 01:19 PM   #7
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I asked this question based on pencilgeek's results. I was thinking of mixing 93 with 110 to get to around 100. I was just afraid that if I run much higher than 100 and the engine is running rich then I could possibly have the engine running too hot.
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      08-18-2008, 01:31 PM   #8
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Quote:
Originally Posted by GT3 Tim View Post
PencilGeek got +14hp with 100 octane vs. 91 octane. I guess the DME will adapt to the higher octane. How much remains to be seen. At some point, there is no gain...the DME cannot advance timing infinately, so there is a max benefit somewhere. Whether that be 93 octane, 95, 100, or somewhere else is the question.
+1 seen results that show an improvement. Also, since people can get more than 91 in Europe and in the US (just not Cali) the car is likely designed to use better than 91. Also, you get better mpg, though not nearly enough to justify the cost (101 octane near me costs $8.99/gallon)
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      08-18-2008, 03:40 PM   #9
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as long as you run UNLEADED race gas it will be fine....I tried some 100 octane & there is an improvement!
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      08-18-2008, 04:27 PM   #10
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Quote:
Originally Posted by icemang17 View Post
as long as you run UNLEADED race gas it will be fine....I tried some 100 octane & there is an improvement!
+1

Higher octane, even 110, etc. won't cause a problem as long as it is UNLEADED.
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      08-18-2008, 07:47 PM   #11
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I've heard that mixing methanol with the gas can give 100oct, In Guatemala gas is the worst, so someone told me he had done this to his Cupra R, it's just a tank of methanol and it mixes with the gas before combustion and it gives you 100oct or whaatever octane you want, do you guys think this is a safe mod??? The only doubt we had was if the car could recognized the higher octane, and since it does do you think there's any drawbacks? any info woul really help since I was tempted to do it but wanted expert opinion, and I see some of the board members are experts, thanks
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      08-19-2008, 10:11 AM   #12
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Quote:
Originally Posted by ChinoOrtega View Post
I've heard that mixing methanol with the gas can give 100oct, In Guatemala gas is the worst, so someone told me he had done this to his Cupra R, it's just a tank of methanol and it mixes with the gas before combustion and it gives you 100oct or whaatever octane you want, do you guys think this is a safe mod??? The only doubt we had was if the car could recognized the higher octane, and since it does do you think there's any drawbacks? any info woul really help since I was tempted to do it but wanted expert opinion, and I see some of the board members are experts, thanks
Not really sure. I think you would be fine, but I don't want to tell you to go for it and then you have an issue!

I have also heard of people using Acetone, Toluene, etc. I think the major issue is not with the additive per se (as most "octane boosters" are basically comprised of this stuff), but with the purity. The crap you buy from Home Depot, etc. is not "pure". If you could get some laboratory pure stuff, then maybe...but personally, I would not risk it. I am not a Chemist, so I don't think I would go down that road based on what some numbnuts said on the net!
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      08-19-2008, 11:19 AM   #13
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Quote:
Originally Posted by JuniorDee View Post
I asked this question based on pencilgeek's results. I was thinking of mixing 93 with 110 to get to around 100. I was just afraid that if I run much higher than 100 and the engine is running rich then I could possibly have the engine running too hot.
I don't see why your engine would run richer with higher octane fuel. The ECU should change ignition timing only, and not the air/fuel mixture.
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      08-19-2008, 12:14 PM   #14
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Quote:
Originally Posted by lucid View Post
I don't see why your engine would run richer with higher octane fuel. The ECU should change ignition timing only, and not the air/fuel mixture.
The ecu will adjust timing, but it does also adjust your A/F mixture...that is what the O2 sensors are for. However, as long as you don't contaminate the O2 sensors (with leaded fuel, etc.), they should function properly and keep you at ideal A/F ratios all the time...octane levels would not effect this.
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      08-19-2008, 12:18 PM   #15
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I have 101 in right now and definitely notice a difference.
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      08-19-2008, 12:25 PM   #16
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Quote:
Originally Posted by GT3 Tim View Post
The ecu will adjust timing, but it does also adjust your A/F mixture...that is what the O2 sensors are for. However, as long as you don't contaminate the O2 sensors (with leaded fuel, etc.), they should function properly and keep you at ideal A/F ratios all the time...octane levels would not effect this.
I know the ECU adjusts the A/F mixture, and many other variables as well, but that's not the question. The question is why would the ECU change the A/F mixture in the presence of higher octane fuel? What is the relationship between A/F mixture and octane?
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      08-19-2008, 12:35 PM   #17
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Quote:
Originally Posted by lucid View Post
I know the ECU adjusts the A/F mixture, and many other variables as well, but that's not the question. The question is why would the ECU change the A/F mixture in the presence of higher octane fuel? What is the relationship between A/F mixture and octane?
I don't think there is a relationship between A/F ratio and octane...I thought I said that in my last sentence...maybe not.
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      08-19-2008, 12:39 PM   #18
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Quote:
Originally Posted by ///MWorld View Post
I have 101 in right now and definitely notice a difference.
I can't imagine being able to notice the difference of 14hp gain as Pencilgeek got. Of course it can be measured, and if you are on the track. But driving on the street in a 414hp car compared to possibly a 428hp car can't really be that noticeable. Can it?
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      08-19-2008, 12:53 PM   #19
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Quote:
Originally Posted by GT3 Tim View Post
I don't think there is a relationship between A/F ratio and octane...I thought I said that in my last sentence...maybe not.
Now that I read your post again, it seems like you did, but the first part threw me off I guess.

Anyway, there actually may very well be an indirect relationship. Maybe a richer mixture will be more likely to knock, and in the presence of higher octane, mixture can be made richer for more power. However, there are many other relationships between mixture and efficiency and emissions, and I would assume those would dictate mixture more than anything else.
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      08-20-2008, 10:02 AM   #20
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Quote:
Originally Posted by J08M3 View Post
I can't imagine being able to notice the difference of 14hp gain as Pencilgeek got. Of course it can be measured, and if you are on the track. But driving on the street in a 414hp car compared to possibly a 428hp car can't really be that noticeable. Can it?
I agree. I wouldn't think you would notice a difference.....However, things like throttle response, etc. can be felt. That may enhance the feeling of more power...I dunno.
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      08-20-2008, 11:39 AM   #21
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Pencilgeek got a 14hp gain with 100 octane (same gas I buy)....but he also got a 17hp gain with the evosport pulley and Gruppe M intake....so in theory a M3 with the pulley, intake and 100 octane would be about 390whp....
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      08-20-2008, 04:31 PM   #22
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Quote:
Originally Posted by J08M3 View Post
I can't imagine being able to notice the difference of 14hp gain as Pencilgeek got. Of course it can be measured, and if you are on the track. But driving on the street in a 414hp car compared to possibly a 428hp car can't really be that noticeable. Can it?

The noticable difference would be the torque gain in the lower rpm range,right where you can use it.14 hp at the top end you would never notice in the a seat of the pants test.Torque is good
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