Re: [Fwd: 100 Ocatane fuel]

["Jeff Lloyd" <jslz3@xxxxxxxxxxx>]

I beg to differ, in a car with a modern injection system, the computer will 
lean out the mixture with a higher octane fuel when it detects the extra 
oxygen of the unburnt fuel..

My Z3 pings on anything less then 92 octane, 11:1 compression, but my Tow 
Vehicle, (1990 Caddy) with like 8.5:1 compression gets a siginficant 
increase in mileage with higher octane fuels. (about 2-3 MPG)  But this car 
with a 5.7 litre V8 and 5500 lbs (9000lbs towing) is a fuel hog and the 
increased mileage does not offset the increased cost of the super unleaded. 
but there must be more "bang per ounce" if the injection decides to lean out 
the mixture, and advance timing using the higher octane fuel.

also the Z3 produces 140hp and 140 ftlbs of torque from 1.9 litres, the 
Caddy produces about 180hp from 5.7 litres and about 300 Ftlbs of torque. 
Much of this is due to increased compression but per ounce of fuel consumed 
the Z3 requiring Super unleaded Creates much more work per gallon of fuel, 
moving a 2600 lb car at 40MPG vs. a 5500 LB car @ 13Mpg...

YMMV (really)
Jeff Lloyd

>From: "Doss Donaho" <ddonaho@domain.elided>
>Reply-To: "Doss Donaho" <ddonaho@domain.elided>
>To: <bmw-digest@domain.elided>
>Subject: Re: [Fwd: 100 Ocatane fuel]
>Date: Thu, 2 Dec 1999 17:14:43 -0600
>
>I don't think octane ratings have anything to do with a fuels ability to
>clean your engine.
>This 100 octane fuel probably has less cleaning agents due to the additives
>needed to obtain the high octane rating taking up volume that would
>otherwise be used for cleaning agents.
>I've read that lower octane fuels actually have more work producing ability
>and I think it is because less volume is wasted on octane increasing
>aditives.
>I think octane rating is a way to measure the resistance to pinging.
>It has nothing to do with cleaning or power.
>High performance engines need it because they have higher compression and
>will ping themselves to death on 89.
>
>Doss
>
>
>-----Original Message-----
>From: Morty Kessler <mkessler@domain.elided>
>To: bmw-digest@domain.elided <bmw-digest@domain.elided>
>Date: Thursday, December 02, 1999 9:11 AM
>Subject: [Fwd: 100 Ocatane fuel]
>
>
> >
> >
>
>

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