View Poll Results: What octane do you put in your 328i? | |||
87 octane | 2 | 2.25% | |
89 octane | 15 | 16.85% | |
91 octane | 72 | 80.90% | |
Voters: 89. You may not vote on this poll |
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08-14-2012, 01:08 PM | #1 |
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What octane do you put in your 328i?
The gas cap says 89, but out of habit I've been putting 91 in my car.
What octane do you guys put in your 328i? What's your thinking one way or another? |
08-14-2012, 04:25 PM | #3 |
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08-15-2012, 04:48 PM | #5 |
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In the UK BMW use 98 RON fuel when they quote the power output of the car. Therefore that's what we need to use for best performance / economy. I presume it's the same elsewhere.
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08-15-2012, 04:53 PM | #6 |
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Drives: F30 M-Sport 328i Estoril Blue
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98 RON here in Australia as well. Been putting it in my E90 since day 1 and will continue with F30 when it arrives. Like in the UK, performance figures here are based on 98RON fuel, but BMW's recommendation is for 95RON even though the car will adapt to fuel between 91RON and 98RON.
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08-16-2012, 07:30 PM | #9 |
I plead the 5th.
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Higher octane is generally more important for forced induction motors, such as the F30. Seems factory tune is to 89 and it probably would not make much of a difference, but I will stick with 91
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08-16-2012, 09:08 PM | #10 |
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American fuel for as bad as you think the quality may be, is actually decent enough. The manufacturers design the cars to be driven with near sludge for fuel so they have knock sensors that help all types of climates (hot mostly) to ensure that the cars can still "run" but they will not be at their best because the knock sensor primarily removes timing from the car.
That being said, I run 91 because I would like all 240hp available to me if the need comes up. I would put 85 in the car and feel fine if that was all the gas station had though. |
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08-28-2012, 12:48 PM | #12 |
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My Saturn SKY recommends 87, but the Turbo model recommends 91. Since I have forced induction on a 10.4:1 compression ratio engine I run Tier 1 91. I also run 91 in the 328i for basically the same reasons.
While not every computer is the same, the general principal of one Bosch ECU vs another is going to generally be the same. In the case of the ECU used in the Turbo Sky (and my SKY for that matter) there are 2 ignition timing tables among other tables that all have a multiplier for octane rating. Based on knock under specific conditions the engine will modify that octane rating and effectively change the 'tune' of the engine. If it's really bad you will eventually fall all on the low octane timing map and even when you do put better fuel in it may take a bit for it to adjust back to the higher octane. Without having extensive access to many details of the BMW ECU (Like I do with the SKY) it is all but impossible to know exactly how the engine is responding to the fuel being delivered, but for the most part just monitoring knock counts can help establish what works best for a given engine. The difference on the extents are so small that it would be almost impossible for a butt dyno to tell the difference and only with some telemetry could you really tell.
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08-29-2012, 07:31 PM | #14 |
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08-29-2012, 08:00 PM | #15 |
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08-29-2012, 11:18 PM | #16 | |
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The only consolation is that there is a station about 10 minutes from my house that sells 91 octane (regular price), 95 octane ($6.99/gallon), and 100 octane ($8.99/gallon). So if I ever get a UGR Gallardo I'll be able to fill it up... For about $200 |
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08-30-2012, 07:29 AM | #17 | |
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If you have a UGR Gallardo, $200 will be less than the bottle of wine you'd drink with your Kobe Beef Ribeye every night of the week Oh man, now I am making myself hungry. |
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08-30-2012, 12:18 PM | #18 | |
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Then again, spending $140k on your second car must mean you're pretty well off. |
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08-31-2012, 08:40 AM | #19 |
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For n/a motors i use 87. However for forced induction motors i use a good 91 octane. 76 and chevron are my preferences. Sunoco if i can find it. Learned it from my evo before where i experienced knocking on cheap gas. How much more if RON was lower. The f30 is a very quiet car so i wont probably even hear anything. I have yet to even hear the turbo
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08-31-2012, 05:47 PM | #20 | |
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09-01-2012, 07:33 AM | #21 |
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Run 91 Octane
On the four cylinder the manual said you could use 89, but when you do, it may throws a code to the computer that the turbo is running lean. It doesn't hurt the engine. But you may have problems down the line. For a few cents more a gallon run 91.
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09-01-2012, 12:34 PM | #22 | |
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Full tank of 89 gone and it drives exactly the same as 91 octane. I think people are just experiencing the placebo effect. Every body that's been in my car hasn't noticed or commented on any difference. Even after I tell him it's on 89, they say it feels just as fast. |
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