Differences between automotive & airplane engines

In article k.net,
Richard Lamb wrote:

I'm rather curious, considering the current fuel situation,

What would a healthy dose of alcohol do the the BSFC and power
output?

I'm a little familiar with some of the handling and corrosion
issues from a friend that races quarter midgets.

Richard

Alcohol contains only some 79% of the energy of gasoline.

"Orval Fairbairn" wrote in message
news
In article k.net,
Richard Lamb wrote:

I'm rather curious, considering the current fuel situation,

What would a healthy dose of alcohol do the the BSFC and power
output?

I'm a little familiar with some of the handling and corrosion
issues from a friend that races quarter midgets.

Richard

Alcohol contains only some 79% of the energy of gasoline.

Racers use alcohol for a lot of reasons, but mainly that water can put out
the fires when they happen. The corrosion issues for race cars are easier
to deal with because the life of a race car is short. A 3 or 4 year old
race car is seldom still run at most of the higher levels. Lower levels
they tend to last longer, but you won't see many 50 year old race cars
running (though with vintage racing thats changing too) An airplane has to
be designed to last.

On Tue, 14 Feb 2006 16:10:15 GMT, "mark"
wrote:


"Orval Fairbairn" wrote in message
news
In article k.net,
Richard Lamb wrote:

I'm rather curious, considering the current fuel situation,

What would a healthy dose of alcohol do the the BSFC and power
output?

I'm a little familiar with some of the handling and corrosion
issues from a friend that races quarter midgets.

Richard

Alcohol contains only some 79% of the energy of gasoline.

But alky also has a significantly higher octane rating.

Racers use alcohol for a lot of reasons, but mainly that water can put out
the fires when they happen. The corrosion issues for race cars are easier
to deal with because the life of a race car is short. A 3 or 4 year old
race car is seldom still run at most of the higher levels. Lower levels
they tend to last longer, but you won't see many 50 year old race cars
running (though with vintage racing thats changing too) An airplane has to
be designed to last.


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clare at snyder.on.ca wrote in message
...
On Tue, 14 Feb 2006 16:10:15 GMT, "mark"
wrote:

snip-------
Alcohol contains only some 79% of the energy of gasoline.

But alky also has a significantly higher octane rating.

The higher octane rating (~115 - 130) allows a higher compression ratio
and/or higher boost pressure. If the alky is allowed to fully evaporate in
the intake (as opposed to direct injection) you get a cooler, denser intake
charge. To get the most out of ethanol, the engine has to be designed for
it from the beginning. If this is done, my understanding is that the BSFC
is about the same as with gasoline.

Bush II is hot for cellulose (Sawgrass) to ethanol as a fuel source. Why
stop there? If you are bioengineering the bugs to do that, why not
bioengineer them to produce Iso Octane instead? Iso Octane is a perfect
motor fuel if made available in commercial quantities - no engine mods
needed

Bill Daniels

In article ,
"Bill Daniels" bildan@comcast-dot-net wrote:

clare at snyder.on.ca wrote in message
...
On Tue, 14 Feb 2006 16:10:15 GMT, "mark"
wrote:

snip-------
Alcohol contains only some 79% of the energy of gasoline.

But alky also has a significantly higher octane rating.

The higher octane rating (~115 - 130) allows a higher compression ratio
and/or higher boost pressure. If the alky is allowed to fully evaporate in
the intake (as opposed to direct injection) you get a cooler, denser intake
charge. To get the most out of ethanol, the engine has to be designed for
it from the beginning. If this is done, my understanding is that the BSFC
is about the same as with gasoline.

Bush II is hot for cellulose (Sawgrass) to ethanol as a fuel source. Why
stop there? If you are bioengineering the bugs to do that, why not
bioengineer them to produce Iso Octane instead? Iso Octane is a perfect
motor fuel if made available in commercial quantities - no engine mods
needed

Bill Daniels


Damn good point! I'm sure that somewhere, a smart bioscientist will see
the obvious!

"Orval Fairbairn" wrote in message
news
In article ,
"Bill Daniels" bildan@comcast-dot-net wrote:

clare at snyder.on.ca wrote in message
...
On Tue, 14 Feb 2006 16:10:15 GMT, "mark"
wrote:

snip-------
Alcohol contains only some 79% of the energy of gasoline.

But alky also has a significantly higher octane rating.

The higher octane rating (~115 - 130) allows a higher compression ratio
and/or higher boost pressure. If the alky is allowed to fully evaporate
in
the intake (as opposed to direct injection) you get a cooler, denser
intake
charge. To get the most out of ethanol, the engine has to be designed
for
it from the beginning. If this is done, my understanding is that the
BSFC
is about the same as with gasoline.

Bush II is hot for cellulose (Sawgrass) to ethanol as a fuel source.
Why
stop there? If you are bioengineering the bugs to do that, why not
bioengineer them to produce Iso Octane instead? Iso Octane is a perfect
motor fuel if made available in commercial quantities - no engine mods
needed

Bill Daniels


Damn good point! I'm sure that somewhere, a smart bioscientist will see
the obvious!

I certainly hope that you're right. One of the especially good things about
purely petroleum based products is that they are not especially
hydroscopic--and that they are easily separated from water with nothing more
than a very fine mesh strainer. I don't know of any easy way to accomplish
that with any of the flammable alcohols. And any re-refining of ethanol,
whether by distillation or fractional freezing, undoubtedly requires a
special license--at least in the U.S.

wrote:

When properly leaned for best economy, aircraft engines will turn in a
BSFC of under .40. Auto engines normally run in the range of .50,
even during cruise.


Those caveats are the killer, aren't they? You CAN'T 'properly lean'
the average aircraft engine, because they have horribly designed intake
manifolds. The mixture isn't distributed evenly. So to get two of them
properly leaned, you have to send the other two down into detonation
territory. Not knowing who's on first, the best bet is to **** your
money away in wasted fuel out the exhaust pipe.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

Bill,

Having built and tuned alcohol drag boat engines that WERE designed and
built to run alcohol, I've never seen this. Our alcohol fuel lines and pump
volumes were typically twice the area. That is, if a 3/8 line would
normally be used, we'd go to 1/2" line.

Alcohol (at least Methanol, which is what we ran) is actually a little bit
heavier than gasoline by about 10% at around 6.75#, and the specific gravity
of pure methanol is .81 while normal regular gasoline is .72. (Yes, we
jetted the pill in the Hilborns by chart initially based on density altitude
and specific gravity of the alcohol. I can probably find the conversion
charts somewhere if I looked hard enough.)

Anyway, higher volume and higher density does not equal the same or lower
BSFC. While Alcohol has a higher octane, it has a significantly lower BTU
content and that's what makes the heat that makes the engine run.

John Stricker

"Bill Daniels" bildan@comcast-dot-net wrote in message
...

To get the most out of ethanol, the engine has to be designed for it from
the beginning. If this is done, my understanding is that the BSFC is
about the same as with gasoline.

Bill Daniels

JStricker wrote:

Anyway, higher volume and higher density does not equal the same or lower
BSFC. While Alcohol has a higher octane, it has a significantly lower BTU
content and that's what makes the heat that makes the engine run.

-----------------------------------------------------------------------------------

Roger that.

-R.S.Hoover

Ok, I've been scolded for using the word "automotive" and then I was scolded for using "automobile". It would seem to me that in this context, "automobile" would be correct, but can someone give me a final ruling?

BTW, this has been a very informative thread. This is exactly what I read message boards for.