Larry,

In order to produce power, a diesel needs fuel and it needs oxygen.

If it is starved of oxygen, power is reduced.

Most normally aspirated diesels will run at high efficiency with 80F air. If
the air is hotter, it also has lower density. Therefore at higher
temperatures, less air (and therefore oxygen) is sucked in because the
engine sucks a fixed volume.

By the way, I am definitely not an expert! My total knowledge of diesels
stems from owning an old diesel car and having had 3 or 4 diesel sailboats.
But, check the above out on Google - I am sure it will come up with a few
pages explaining this. If not, maybe I will learn something

GBM

"Larry" wrote
Huh?? That might be true for gas engines, but diesel engines RUN on air
temperature. That's what the 22:1 compression ratio is for! You have to
raise the temperature of the incoming air up high enough to make the fuel
spray explode when it's injected....knock, knock, knock, knock.

The higher the intake air temperature, the better. The hotter the engine,
the better! Another great idea that got buried, probably by big oil, was
a
ceramic diesel engine invented by Mitsubishi, I think. The engine had NO
LUBRICATION and NO COOLING SYSTEM to increase the temperature of the
engine
into the glowing zone. The engine was even wrapped in an insulating
blanket to make it even hotter. Efficiency was amazing, hence my
suspicion
of another oil burial of the technology. Thermal efficiency was near 50%!

Funding was mysteriously pulled, like anything that is efficient, and
"reliability of ceramic parts" was the excuse to stop it, the cover story.

It has a 40:1 compression ratio, by the way....

80-150F mean nothing.