[M5M3911lover]

Check out the HP and Torque. Article in the new edition of Car and Driver.

[devondragon]

Originally Posted by M5M3911lover

Check out the HP and Torque. Article in the new edition of Car and Driver.

That's not as bad a difference as I expected! I'm stuck in 91 land these days

[SpeedyDad]

More torque with the lower octane fuel? Why would that be? This makes those of us who only get 91 feel a little better. This motor is seriously underrated by BMW. Likely around 660hp and 660lb/ft at the crank. Way more torque than advertised.

[limeypride]

Originally Posted by SpeedyDad

More torque with the lower octane fuel? Why would that be? This makes those of us who only get 91 feel a little better. This motor is seriously underrated by BMW. Likely around 660hp and 660lb/ft at the crank. Way more torque than advertised.

Agreed. I'm also confused why the torque would go down--I suspect it's just one of those random variations that we always see when dyno'ing our cars; could be slippage, heat soak...

And as for 2.7s, I've only managed 2.8s even with the tune. It might require a prep'd surface I suppose.

[bradleyjs]

So, what’s the deal with certain states not having 93 octane? Is it for some type of pollution control measure?

[Aronis]

I'd like to see a similar comparison with the Alcohol containing Gasoline vs Pure Gasoline. I like to get into discussions with people about simple numbers. With multiple cars I have tested MPG with and without the alcohol. In every vehicle tested (long drives) the alcohol containing fuel got about 10% less miles per gallon which means one burns MORE fuel to go the same distance with the alcohol added to the gasoline. (that is read - less environmentally sound).

So with the alcohol added what effect does it have on Hp? My experience was that with my RS6 and A8L (both turbo v8's, both over 450 hp), the cars were noticeably quicker on the Pure Gas. The kicker is you now pay MORE for the Pure gas per gallon when the first gas that came along with Alcohol was more expensive than the pure gasoline!

I have put pure gas in my M5 once, but noticed it was only 91 octane so I did not fill the tank. I would rather use the 93 octane from other gas stations, but I have not read much on alcohol addition and it's effect on octane, ie. it's real effect, not the hype.

I know ETOH engines can get crazy amounts of power, but from what I understand that is usually at higher RPMs than normal car engines.

Mike

[limeypride]

@those_of_you_that_are_not_Mike: anyone know how to unsubscribe?

[calpharo]

Originally Posted by Aronis

I'd like to see a similar comparison with the Alcohol containing Gasoline vs Pure Gasoline. I like to get into discussions with people about simple numbers. With multiple cars I have tested MPG with and without the alcohol. In every vehicle tested (long drives) the alcohol containing fuel got about 10% less miles per gallon which means one burns MORE fuel to go the same distance with the alcohol added to the gasoline. (that is read - less environmentally sound).

So with the alcohol added what effect does it have on Hp? My experience was that with my RS6 and A8L (both turbo v8's, both over 450 hp), the cars were noticeably quicker on the Pure Gas. The kicker is you now pay MORE for the Pure gas per gallon when the first gas that came along with Alcohol was more expensive than the pure gasoline!

I have put pure gas in my M5 once, but noticed it was only 91 octane so I did not fill the tank. I would rather use the 93 octane from other gas stations, but I have not read much on alcohol addition and it's effect on octane, ie. it's real effect, not the hype.

I know ETOH engines can get crazy amounts of power, but from what I understand that is usually at higher RPMs than normal car engines.

Mike

So I have been reading up on this quite a bit. It is my understanding the EtOH (ethanol) has a very high octane (for example E85 (85% ethanol) has an octane rating of 105). What I do know is that ethanol has a larger volume but contains less "energy". Hence why with EtOH containing fuels, they fill your tank but you don't get as many miles out of them.

From my conversations with guys who race/track their cars regularly, many of them add about 3 gallons of E85 fuel to their tanks to increase to octane rating (read, more horsepower) and have the added benefit of the cooling effect of ethanol on their engines. For our F90 on a full tank of 91 octane (E10) mixed with 3 gallons of E85 is makes the total ethanol concentration 21% and octane 93.1. This is basically a "poor man's way" of increasing octane without paying $10/gallon of 101 octane race fuel.

But I too would like to see the difference on a dyno as fuel as fuel economy for a stock car of:

regular gas vs.
higher ethanol gas (ie. E21) vs.
race fuel (101 octane mixed with regular fuel 50/50 mix)

[limeypride]

@those_of_you_that_are_not_Mike_or_calpharo: anyone know how to unsubscribe?

[Aronis]

Originally Posted by limeypride

@those_of_you_that_are_not_Mike_or_calpharo: anyone know how to unsubscribe?

Just turn off your computer.

Mike

[limeypride]

Originally Posted by Aronis

Just turn off your computer.

Mike

Ah, I thought it was rather funny... big fail on my part I guess.

Sorry, please carry on.

[Aronis]

Originally Posted by limeypride

Ah, I thought it was rather funny... big fail on my part I guess.

Sorry, please carry on.

I know you were joking. LOL.

Mike