This is true - ethanol contains a considerably lower energy value (BTUs -
British thermal units). Ethanol also has a higher evaporative loss. Gasohol
is usually a mixture of 10% ethanol in gasoline.
In short, it would not be unreasonable to see a 5-10% reduction in gas
mileage (but 10% at the most) with gasohol. In the old days, I saw a
similar boost of a little more than 5% in gas mileage using higher octane
fuel. But that was when tetra-ethyl lead and a few other chemicals were
used to boost the octane. However, even a 10% boost in gas mileage did not
erase the fact that the higher octane fuel cost maybe 20% more, negating
any real savings of any kind.
David
67 BGT
71 BGT
At 04:19 PM 7/5/00 -0700, Max Heim wrote:
>I believe ethanol contains less energy (BTUs or calories) per gallon than
>gasoline, so you are correct in noting that adding ethanol to gasoline
>will reduce mileage. I don't think "gasohol" is allowed to be sold in
>this area, so I have no experience myself, and didn't consider it in my
>reply.
>
>Reynolds,John had this to say:
>
> >Max,
> >
> >That's what I thought (regarding the higher octane in a newer car with a
> >knock sensor); however, that doesn't apply when the octane is boosted with
> >Ethanol - I actually get lower gas mileage on my 92 Ford CV when using the
> >Ethanol.
> >
> >John Reynolds
> >1979 MGB (in restoration) - will run on 87, too!
> >
> > -----Original Message-----
> > From: Max Heim [mailto:mvheim@studiolimage.com]
> > Sent: Wednesday, July 05, 2000 4:01 PM
> > Cc: MG List
> > Subject: Re: Octane and altitude ratios???
> >
> > Your Explorer may get better mileage with premium fuel since
> >it has a
> > knock sensor, which automatically advances the timing
> >(within a limited
> > range) until it encounters knock, then retards until the
> >knock stops,
> > several times a second, thus maximizing efficiency based on
> >current fuel
> > and conditions. Your B is unable to do this (obviously) so
> >octane should
> > not affect gas mileage (unless you adjust the timing to
> >suit). The oil
> > companies spend a lot of money trying to insinuate that your
> >car will go
> > faster, get better mileage, and be more reliable using their
> >premium
> > grade fuels, but for the most part that is baloney. You can
> >advance the
> > timing on your B to take advantage of high octane fuel to
> >get some
> > benefit, but the "proprietary" additives advertised, such as
> >"Techroline"
> > or "Techron", are mainly detergents intended for cleaning
> >fuel injector
> > systems on late model vehicles, and do nothing for
> >carbureted engines.
> >
> > I have always suspected that the PO of my B's engine had
> >planed the head
> > (the donor car had headers and dual Weber DCOEs, which the
> >wrecker sold
> > separately), as it seems to require 92 octane fuel at the
> >stock timing
> > setting, to avoid knock and overrun. So YMMV. But in general
> >there is no
> > benefit to running higher octane than required to avoid
> >knock.
> >
> > Andrew B. Lundgren had this to say:
> >
> > >That damage to the pocket book is what I am trying to
> >avoid. I have a
> > >Ford Explorer as well as an MGB that gets 15-16mpg... The
> >owners manual
> > >says 87 or higher, but I think that is calcualted for
> >sea-level. When I
> > >buy the highest available octain I get better gas
> >mileage... This is just
> > >one of lives mysteries I wanted to understand better.
> > >
> > >
> > >On Wed, 5 Jul 2000 Gonaj@aol.com wrote:
> > >
> > >> Maybe I have misunderstood something in the past, but I
> >am under the
> > >> impression that your engine never needs a lower octant it
> >simply nosen't
> > need
> > >
> > >> the higher octane. In other words there is no loss or
> >damage due to higher
> > >> octane than necessary, other than to your wallet unlike
> >the damage wich
> > >> results from lower than necessary octane.
> > >>
> > >> If I am wrong here please explain.
> > >>
> > >> George
> > >>
> > >
> > >
> >
> >
> > --
> >
> > Max Heim
> > '66 MGB GHN3L76149
> > If you're near Mountain View, CA,
> > it's the red one with the silver bootlid.
> >
>
>
>--
>
>Max Heim
>'66 MGB GHN3L76149
>If you're near Mountain View, CA,
>it's the red one with the silver bootlid.
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