[A4] Need for Premium Gas in 1.8T quattro?

[thejimrose]

not nonsense.. there were a few very qualified opinions over on the ducati
forum that related this.

im NO engineer [was a philosophy major actually..] but this is how i've
'bottom lined' it in my head.  the higher the octane rating the LESS
combustible the mixture is. the reason is so the fuel is more predictable
under compression, and thus more resistant to unintentional combustion.
hence better for high perf, turbo, etc engines that run high comp, or under
lots of heat.

however, and i dont recall why chemically, the resistance to ignition can
make for less complete burning fuels, hence in certain applications [like a
ducati Ltwin] people had reported MUCH cleaner valves and pistons with low
octane fuel. i know that my pistons + plugs were always pretty carboned and
i always ran premium as per ducati's reccomendation.

who, like audi, are another group of engineers famous for getting some
things wonderfully right and other horridly wrong.

but, as always, ymmv..

On 9/21/06, Grant Lenahan <glenahan at vfemail.net> wrote:
>
> Nonsense. The main difference between low and high octane is:
>
> 1.) more resistance to knock
> 2.) sometimes, a better detergent package (since its more expensive)
>
> A turbo engine, by definition, operates at a high effective compression
> ratio.  So high octane is almost a requirement, mitigated only by an
> knock sensor which will retard timing and performance to protect the
> motor.
>
> More detergent will result in cleaner running.
>
> I have no idea what "more combustible" means in this context, so I wont
> comment.
>
> Grant
> On Sep 21, 2006, at 1:46 PM, thejimrose wrote:
>
> > i wonder about this too.. from experience with ducati's, the
> > reccomendation
> > is always run high octane, but lota of guys ran low octane as it's more
> > combustible and tended to build up much less carbon in the head +
> > valves.
> >
> > not sure how that might translate.. but i seem to get much better
> > mileage if
> > i run premium, which i think offsets the price of the gas..
> >
> > jim
> > _______________________________________________
> > quattro mailing list
> > quattro at audifans.com
> > http://www.audifans.com/mailman/listinfo/quattro
> > ---
> > Watch this space for ads :)
>
>


-- 
nobody ever listened to me until they didn't know who i was.
-banksy