"Dale Scroggins" wrote in message
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"Blueskies" wrote in message
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"Morgans" wrote in message
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"Philippe Vessaire" wrote in message
news:19459447.yEvPs9oxTh@GastonCoute...
Hello

Torque curve page 6

http://www.subaru.fr/special/pdf/doc...esel_lo_08.pdf


Holy crap! That thing has the peak torque, and it is almost a level
line, from about 1600 rpm to about 2400 rpm!

That sucker should really pull a big prop, and well!
--
Jim in NC


Is the price of diesel fuel 25% above gasoline prices everywhere?
Jet A costs the same as 100LL now also, so what is the benefit?



1. Most diesels wear more slowly than gas engines. The fuel is a better
lubricant than gasoline is, and the combustion products are a bit more
benign.
2. No ignition system needed.
3. Turbocharging a diesel is a win-win proposition. EGT is lower, so
turbo system parts last as long as the engine, usually. Turbocharging
improves both performance and fuel efficiency (not always true for
gassers).
4. Full power available up to about 15K feet for most auto-type
turbodiesels.
5. Automatic mixture control.
6. No carb icing or vapor lock.
7. Lower fire risks.
8. I can make biodiesel for 67 cents a gallon. You or I can buy off-road
diesel or heating oil for much less than either auto gas, avgas or jet A.
9. For a given trip, less fuel is needed, both in volume and weight. 25%
to 35%, depending on the trip profile. If the diesel is turbocharged and
gasser is not, the diesel's ability to cruise significantly higher may
result in a bigger efficiency spread.
10. Props are more efficient at lower RPMs, usually. Diesels have torque
to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving
maybe another 5% efficiency gain, and a quieter cabin to boot.

Given time, I can think of more. Please note that gas engines were
abandoned decades, nay, scores of years ago in other transportation
sectors. It will be the same in aviation if the weight difference shrinks
enough.

DS

Of course there are all kinds of diesels just like there are all kinds of
spark ignition engines. Generalizations need to be made carefully. Over
the road diesels are heavy to absorb the heavy bottom end loads with less
expensive cast iron blocks. Automobile diesels tend to be heavy since there
is no compelling reason to make them light.

The one absolute is that diesel fuel will be around for a long time in one
form or another. The 'gotcha' is that the rest of the world runs on diesel
and when developing economies like India and China demand more fuel it will
be diesel they are after so the price is likely to remain high. Hopefully,
biodiesel will be cheap.

Aircraft diesels are very special since they need to be both powerful and
light demanding high tech metalurgy like titanium rods. To keep the weight
down, 2-stroke diesels look good. Opposed piston 2-stroke diesels look even
better since the bottom end loads are spread across two crankshafts.

The Subaru oil burner looks good but then so does the DeltaHawk and the
little opposed piston aircraft diesels from the UK.

Bill D