87 Octane

Thik · 04-08-2013, 04:46 PM

Curious: What would you rather? 91 octane 100% gas or 93 octane with 10% ethanol?

thedge9 · 04-08-2013, 06:37 PM

First, Octane rating has nothing to do with the potential energy in the fuel period. Sorry, just a clarification I though some might need given their posts.

“Higher octane ratings correlate to higher activation energies: This being the amount of applied energy required to initiate combustion. Since higher octane fuels have higher activation energy requirements, it is less likely that a given compression will cause uncontrolled ignition, otherwise known as autoignition or detonation.”

And therefore…

“A fuel with a higher octane rating is less prone to auto-ignition and can withstand a greater rise in temperature during the compression stroke of an internal combustion engine without auto-igniting, thus allowing more power to be extracted from the Otto-Cycle.”

So…

Octane rating only has bearing on the compression ratio of the engine and how well it can use the energy of the fuel. It’s the engine that cares what the octane rating is, and nothing else. If you do not use proper octane rated fuel in a highly compressed engine you can cause damage from premature detonation period. All it requires is the right loading and ECU not being able to keep the engine from knocking.

If you want to discuss premium petrol and their ability to provide more efficient power extraction; Shell has consistently beaten other manufacturers. I have no idea why.

track_warrior · 04-09-2013, 02:01 PM

I put 87 in my truck but i have a 87 oct diablo tune that makes fuel efficiency a priority and tunes the ecu to handle 87 oct fuel. From 12 combined i now get 13 lol, but it makes sure the truck will run properly on 87. Even though the ECU will detect and adjust timing i would still not run 87 oct on a car that was not designed or properly tuned to do so. Shell 93 is the only thing that goes into my M3.

Chriskm3 · 04-09-2013, 04:02 PM

Quote:

Originally Posted by radiantm3

He should fish them out and make LED angel eyes. That's savings right there.

Haha

MDIVISION · 04-09-2013, 04:48 PM

Just another mooch driving an M3..

04-08-2013, 04:46 PM	#67
Thik First Lieutenant 141 Rep 371 Posts Drives: 2010 Space Grey E92 M3 6spd Join Date: Jan 2013 Location: Toronto iTrader: (0)	Curious: What would you rather? 91 octane 100% gas or 93 octane with 10% ethanol?
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04-08-2013, 06:37 PM	#68
thedge9 Private 15 Rep 81 Posts Drives: 2013 E92 M3 MT Join Date: Feb 2012 Location: Fountian Hills, AZ iTrader: (0) Garage List 2013 E92 M3 [0.00]	First, Octane rating has nothing to do with the potential energy in the fuel period. Sorry, just a clarification I though some might need given their posts. “Higher octane ratings correlate to higher activation energies: This being the amount of applied energy required to initiate combustion. Since higher octane fuels have higher activation energy requirements, it is less likely that a given compression will cause uncontrolled ignition, otherwise known as autoignition or detonation.” And therefore… “A fuel with a higher octane rating is less prone to auto-ignition and can withstand a greater rise in temperature during the compression stroke of an internal combustion engine without auto-igniting, thus allowing more power to be extracted from the Otto-Cycle.” So… Octane rating only has bearing on the compression ratio of the engine and how well it can use the energy of the fuel. It’s the engine that cares what the octane rating is, and nothing else. If you do not use proper octane rated fuel in a highly compressed engine you can cause damage from premature detonation period. All it requires is the right loading and ECU not being able to keep the engine from knocking. If you want to discuss premium petrol and their ability to provide more efficient power extraction; Shell has consistently beaten other manufacturers. I have no idea why. __________________
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04-09-2013, 02:01 PM	#69
track_warrior Captain 98 Rep 728 Posts Drives: F80 M3 Join Date: Oct 2010 Location: Merida, Yucatan iTrader: (1)	I put 87 in my truck but i have a 87 oct diablo tune that makes fuel efficiency a priority and tunes the ecu to handle 87 oct fuel. From 12 combined i now get 13 lol, but it makes sure the truck will run properly on 87. Even though the ECU will detect and adjust timing i would still not run 87 oct on a car that was not designed or properly tuned to do so. Shell 93 is the only thing that goes into my M3. __________________ Compensating a heavy car with horsepower is like giving an alcoholic cocaine to sober him up...
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04-09-2013, 04:48 PM	#71
MDIVISION Major 272 Rep 1,178 Posts Drives: 2015 M3 Join Date: Feb 2013 Location: Silicon Valley iTrader: (1)	Just another mooch driving an M3.. __________________ 2002 E46 M3 Coupe.. SOLD 2011 BMW 1M Coupe SOLD 2013 BMW M3 Coupe SOLD 2014 BMW 335i MPPK SOLD 2015 M3 SOLD
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