Super V.E. for diesels

[oil pan 4]

Originally Posted by Diesel_Dave

Diesels typically aren't as optimized for reduced pumping losses (high VE) as you might think. In typical spark-ignited naturally aspirated gassers, high VE is pretty much the only way to get more torque at any given speed. So if you want to get more torque you pretty much have to increase the VE. On a diesel however, you can just add a little more fuel and/or a little more boost and you'll get the torque. Sure the FE will be sub-optimal, but it's just so much easier than redesigning heads and intakes.

It just goes to show you how well the efficiency concept of a combined cycle intercooled turbodiesel engine works.
They started off real efficient and cranked out amazing power levels with out much added complexity or engineering.
Fuel economy didn't matter much as diesels could beat their gas fuelled counterparts with ease in head to head tests and on top of that diesel fuel was quite a bit cheaper than gas until about 10 years ago.
But times are changing and with diesel fuel prices projected to soon rocket past $4/gal in the U.S., adaptations need to be made.

[oil pan 4]

I have read some large diesel engine papers that show loss of efficiency when intake air temperatures start to drop below 30'F to 40'F.

[ConnClark]

Diesel pr0n

tuned intake, exhaust header, turbo, monster intercooler, and a blower.

[ConnClark]

Originally Posted by oil pan 4

I have read some large diesel engine papers that show loss of efficiency when intake air temperatures start to drop below 30'F to 40'F.

I have read some that they are good down to -5F

[UFO]

Originally Posted by ConnClark

Diesel pr0n

tuned intake, exhaust header, turbo, monster intercooler, and a blower.

That's a whole lotta hardware just for a clanky old 617.952. I wonder if they got more than 200hp or 200 hours of life out of it....

[ConnClark]

Originally Posted by UFO

That's a whole lotta hardware just for a clanky old 617.952. I wonder if they got more than 200hp or 200 hours of life out of it....

They got a tad over 400 HP.

200 hours of life might be right. They made a couple of videos one of a drag race and one of it doing doughnuts. After which it disappeared only to reappear with a om603 engine.

[oil pan 4]

I was reading my cummins manual today and apperantly cummins recomends that when operating at +20'F or less to locate your intake inside the engine enclosure.
Also to use grill shutters below 32'F and a winter front below 0'F.

[Daox]

Doesn't this kind of go against the theory of super VE? Cold air is more dense so you get more air in the engine which is what super VE is about, right?

[UFO]

Diesels require heat for efficient combustion, and they already run with an excess amount of air. So colder air will not improve performance in the way it will for a gasser.

[Diesel_Dave]

The concern is that for super cold air you can start to extend to combustion delay and start getting bad combustion (white smoke, etc.). It's not as much of an issue on the newer common rail engines as it used to be on the older diesel with mechanical fuel injection and low fuel pressures.