Turbo diesel dilema!

[blueflame]

Short journey FE likes higher IAT. Quicker warm up times.

[JackMcCornack]

Originally Posted by nubbzcummins

JackMcCornack: Could you explain pumping losses that occur with my setup running in boost other than at idle and going down steep grades?

I'll give it my best.

Energy is required to turn the engine over. Some of that energy is used to pump air through the engine, whether or not that air is used in combustion. Your Cummins and my Kubota both ingest more air than they need for complete fuel combustion, except when they're operated at full power.

At idle, the combustion process produces exactly enough power to keep the engine running--enough to overcome the engine's friction losses and pumping losses. Hotter air (less dense) reduces pumping losses, and for a given idle RPM, less fuel is required with higher than ambient intake temperatures, and I'm thinking that holds true from slightly higher power than idle all the way up to somewhere close to full power.

Seems like maybe I should put some temp sensors in my turbo in/out airstreams and check. If it turns out I'm full of bleep, I'll sure let y'all know.

Originally Posted by nubbzcummins

Also how does warmer air make it more efficient vs cooler air which makes more power and requires less boost to achieve the same required power to overcome all drag/losses on the vehicle?

A lot of the advancements in power come from auto racing, which is normally defined by engine displacement, and the max horsepower per cc limit is almost always determined by how much air mass you can get into the engine. Cooler air = higher density = more mass = more potential horsepower. Maximum power comes when all the air is used in combustion, max economy comes when all the fuel is used in combustion.

In our engines, at most power settings, we have all the air we need. Your and my engines don't even throttle the air, ours vary the power output by adjusting how much fuel gets squirted in to the system. I don't think cool air makes more power until the engine starts running short of air. But I'm also thinking, maybe I should set up an air intake with a flap, sort of like the carb heat flap on ICE airplanes, so I can see if my boost goes up in cruise when I switch to warm air. If so I'll be surprised, but life is full of surprises and one more won't hurt me.

[ConnClark]

A diesel is an engine that gets more efficient with the more excess air it ingests. That is why they do not put throttles on them. Outside of decreasing warm up time, a warm air intake on a diesel does absolutely no good .

The more air ingested into the cylinder the higher the percentage of fuel energy that goes to heat it instead of the cylinder walls. Not only that but excess air also increases the specific heat ratio of the combustion gasses that further increase efficiency. Further more it promotes more complete combustion.

An intercooler improves the efficiency of a diesel by several mechanisms. It reduces the heat lost to the cooling system. It reduces the work needed to drive the turbo. Lastly it increases the specific heat ratio of the combustion gasses.

An intercooler that is prevented from doing its job is just dead weight and a restriction in the intake path.

[blueflame]

If the thermostat never opens due to excessive cooling from either winter or large radiators/cooling systems, couldnt warm/hot IAT increase FE?

Less fuel used to keep engine hot?

[ConnClark]

If the thermostat never opens the radiator never gets used. I have had a car over heat in below freezing weather due to a thermostat failing. It would have to be very very very cold for a correctly functioning thermostat not to open on a running engine.

[blueflame]

Yes. Thanks for pointing that out.

Extra engine warmth from intake air will only keep the thermostat open longer. And as summer begins, possibly LOWER FE if grill block needs to be made smaller(increasing drag) due to overheating, that would not have occurred if intake temp was lower....

I guess I'm done with modding fuel/air/iat on this van.

Twiddle thumbs

[ConnClark]

Originally Posted by blueflame

I guess I'm done with modding fuel/air/iat on this van.

Twiddle thumbs

Try modding a cold air intake. Diesels are more efficient with cold air. Also try and come up with a ram air intake. That will help a little too.

This paper below shows the correlation of intake temperatures and efficiency of a modern diesel engine. (see the graph at the bottom left of page 5)

http://www.buet.ac.bd/me/icme/icme20...ME05-TH-35.pdf

[Christ]

Originally Posted by blueflame

Yes. Thanks for pointing that out.

Extra engine warmth from intake air will only keep the thermostat open longer. And as summer begins, possibly LOWER FE if grill block needs to be made smaller(increasing drag) due to overheating, that would not have occurred if intake temp was lower....

I guess I'm done with modding fuel/air/iat on this van.

Twiddle thumbs

Why not try some aero modding further back on the vehicle?

Don't give up... giving up is why this country is going to ****.

[nubbzcummins]

ConnClark: Thanks for you input and the helpful link. I guess the grill block will be removed partially so the intercooler can get some air to cool off with to lower my fuel consumption. I wonder if the FE that I will gain with removing the grill block off will overcome the extra drag associated?

[ConnClark]

Originally Posted by nubbzcummins

ConnClark: Thanks for you input and the helpful link. I guess the grill block will be removed partially so the intercooler can get some air to cool off with to lower my fuel consumption. I wonder if the FE that I will gain with removing the grill block off will overcome the extra drag associated?

With as much drag as a pick up truck inherently has, I would expect a grill block to be a drop in the bucket. Of course this is a dodge pick up so the drop, like the grill, is a little bigger than most. I however expect that improvements in engine efficiency will dominate in this case.