Octane question

ptwob311 · 04-08-2009, 04:47 PM

Flame suit....on....
So i know i have no post but i've been lurking for a few months and have recently thought of a question that i have not been able to find the answer to. I've had my 07 335i E90 for about 3 months now.

I know on my bike (yamaha YZF-R1) i can run race gas/high octane and its fine.... even the leaded stuff. The bike comes alive, seeing as it is such a high compression engine and tuned for high performance. But i have also delt with many different cars in the past and i know to run the high octanes and race gas you need to adjust the timing or get detonation (once you get to high enough octanes).... my question is this.....
I see many people running 100+ octane... are they doing anything to the cars or does BMW have some sort of ECU capability to adjust the car's timing for higher octanes. If so what is the highest you can go (on a stock E90) before you get detonation and are the benefits of the higher octane worth the price?

Thanks to anyone who can clear this up for me.

Mike@N54Tuning.com · 04-08-2009, 04:57 PM

Most are running race gas with a tune, and a map specifically made for race gas.

Mike

E82tt6 · 04-08-2009, 05:20 PM

Our ignition system is also "smart", and will try to push spark advance as far as it can (with in reason) to ensure maximum efficiency. This engine has an extremely high effective CR, thanks to a static CR of 10.5:1, AND boost, so it does benefit from greater knock resistance specially at higher than stock boost.

ptwob311 · 04-08-2009, 07:25 PM

Cool, thanks for the info guys.

So what is the highest octane on stock E90? 100 octane? I usaully run 108 or 110 in the bike, but that is leaded and i know would not do well in the car.

E82tt6 · 04-08-2009, 08:17 PM

You won't see all that much power gained stock, but the sunnoco pump 100 is always a safe bet. Anything more would indubiably be overkill on stock boost, even 100 likely is.

SoCalTech · 04-08-2009, 11:28 PM

I think you misunderstand what octane is. The octane rating is the fuels ability to resist knock (pre-ignition or detonation). Going with a lower octane is what's going to cause knock. Going with too high of an octane will not cause knock.

04-08-2009, 04:47 PM	#1
ptwob311 Second Lieutenant 13 Rep 212 Posts Drives: 335i Sedan Join Date: Mar 2009 Location: Louisiana iTrader: (0)	Octane question Flame suit....on.... So i know i have no post but i've been lurking for a few months and have recently thought of a question that i have not been able to find the answer to. I've had my 07 335i E90 for about 3 months now. I know on my bike (yamaha YZF-R1) i can run race gas/high octane and its fine.... even the leaded stuff. The bike comes alive, seeing as it is such a high compression engine and tuned for high performance. But i have also delt with many different cars in the past and i know to run the high octanes and race gas you need to adjust the timing or get detonation (once you get to high enough octanes).... my question is this..... I see many people running 100+ octane... are they doing anything to the cars or does BMW have some sort of ECU capability to adjust the car's timing for higher octanes. If so what is the highest you can go (on a stock E90) before you get detonation and are the benefits of the higher octane worth the price? Thanks to anyone who can clear this up for me.
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04-08-2009, 04:57 PM	#2
Mike@N54Tuning.com Joint Chiefs of Staff 5037 Rep 116,174 Posts Drives: 2007 335i, 2015 M3 Join Date: Dec 2008 Location: N54tuning.com iTrader: (89)	Most are running race gas with a tune, and a map specifically made for race gas. Mike
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04-08-2009, 05:20 PM	#3
E82tt6 Colonel 109 Rep 2,626 Posts Drives: '08 Black Saphire Z4 MC Join Date: Oct 2007 Location: New Jersey iTrader: (0)	Our ignition system is also "smart", and will try to push spark advance as far as it can (with in reason) to ensure maximum efficiency. This engine has an extremely high effective CR, thanks to a static CR of 10.5:1, AND boost, so it does benefit from greater knock resistance specially at higher than stock boost. __________________ '08 Black Saphire/Black Z4 M Coupe RIP Gretta: Blue Water/Lemon 135i. Died to save me. -ChuckV
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04-08-2009, 07:25 PM	#4
ptwob311 Second Lieutenant 13 Rep 212 Posts Drives: 335i Sedan Join Date: Mar 2009 Location: Louisiana iTrader: (0)	Cool, thanks for the info guys. So what is the highest octane on stock E90? 100 octane? I usaully run 108 or 110 in the bike, but that is leaded and i know would not do well in the car.
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04-08-2009, 08:17 PM	#5
E82tt6 Colonel 109 Rep 2,626 Posts Drives: '08 Black Saphire Z4 MC Join Date: Oct 2007 Location: New Jersey iTrader: (0)	You won't see all that much power gained stock, but the sunnoco pump 100 is always a safe bet. Anything more would indubiably be overkill on stock boost, even 100 likely is. __________________ '08 Black Saphire/Black Z4 M Coupe RIP Gretta: Blue Water/Lemon 135i. Died to save me. -ChuckV
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04-08-2009, 11:28 PM	#6
SoCalTech Captain 24 Rep 648 Posts Drives: Not a BMW yet... Join Date: Oct 2008 Location: Redondo Beach, Ca iTrader: (0)	I think you misunderstand what octane is. The octane rating is the fuels ability to resist knock (pre-ignition or detonation). Going with a lower octane is what's going to cause knock. Going with too high of an octane will not cause knock.
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