How do you eco-drive a diesel ?

[Piwoslaw]

A little google'ing, and I think I've found something on this device. Here's something very scientific, I'm not sure how relevant it is:
Analytical conditions for field ionization mass spectrometry of diesel fuel
Here is the abstract to the article I read, in it there is a link to the whole article:
Electrorheology Leads to Efficient Combustion
Here is a short commentary:
Simple device uses electrical field to boost internal combustion engine efficiency
and another, this one criticizes the company which holds the patent:
Electricity + gasoline = more mpg?

[roflwaffle]

Here's a good summary. They used it on an older IDI diesel, so it may only help w/ lower injection pressures and/or with vehicles that have a well worn FI system. Stuff like this has been around for decades IIRC, and was can be used to reduce the viscosity of crude and some of it's refined byproducts. That said there are some valid apprehensions regarding this device, and if it is a scam I think that the testers were smart to use a Benz instead of something w/ a rotary pump like a VW diesel where dynamic timing (as well as efficiency) depends on fuel viscosity.

[ConnClark]

So far the claims of this device are dubious at best. This scientist is funded by a company that makes fuel magnets. His work has only recently been published but no other independent experimental verification of his claims exists. There is some independently verifiable evidence that magnetic fields can lower the viscosity of crude oil however crude oil has a large number of chemical components and metals that are refined out when it is converted to fuel.

The following report has found no statistically significant improvements in mileage of this scientist's benefactor's device. This latest announcement from this scientist may just be an attempt to keep research money coming in by changing the magnetic field claims by this company to electric field claims.

http://wwwcgi.rand.org/pubs/technica...RAND_TR313.pdf

Until there is duplicated experiments and results by an independent party I will regard this research dubious. The key factor is if diesel fuel is indeed an electrorheological fluid. So far the only name that pops up in this area of research is this scientist. This is starting to smell a lot like the acetone scam in as far as the only evidence to back up the claims come from the person making them.

[Big Dave]

I put a free-flowing exhaust (you could drop a Cokr can through it) and a free-flowing warm air intake and it didn't help a bit.

One thing you can do. Put a pyrometer on it and drive to keep EGT under 600 degrees F.

[ConnClark]

Originally Posted by JQmile

When you drive, make sure not to be under boost at all. If the load is too high (say, accelerating up a hill) then the turbo will start to make boost, and the fueling curve will respond to the rise in boost pressure (add more fuel). This only applies on a turbodiesel of course.

Boost pressure does not increase fuel. It does allow the injection system to inject more fuel if you have the petal floored. A turbocharger does however get its power from the energy not recovered by the piston. You are correct in that trying to drive with a low amount of boost is an indication of the piston extracting as much power as it can. This does not mean that you should try to prevent your turbo from creating boost via modifications. Boost actually increases the efficiency of a diesel engine by promoting more complete combustion and more heat energy going into the working fluid and less heat energy being lost to the engine block.

Originally Posted by Big Dave

I put a free-flowing exhaust (you could drop a Cokr can through it) and a free-flowing warm air intake and it didn't help a bit.

One thing you can do. Put a pyrometer on it and drive to keep EGT under 600 degrees F.

Well as I stated before you shouldn't expect a lot. I also wouldn't expect a lot of improvement from anything on a big pickup truck

Also note that a warm air intake does not make a diesel more efficient. It actually lowers its fuel economy and increase NOx emissions.

[tasdrouille]

I use boost, and plenty of it. I'm always accelerating at 5 to 10 psi in my TDI. I usually shift at 1600 rpm and cruise at the lowest speed possible. If I need to go up a huge hill, I just stick it at peak torque and give it up to 95% load. That's how I did my 79.9 MPG tank.

Originally Posted by ConnClark

Also note that a warm air intake does not make a diesel more efficient. It actually lowers its fuel economy and increase NOx emissions.

I agree with the NOx statement, but I'd like to have a reference on your reduced fuel economy claim as it's not been my experience.

Originally Posted by ConnClark

A nice free flowing intake helps too. [...]
If you have a turbo engine adding an intercooler will help. It may shift your power band to a lower rpm to some degree but it improves both performance and mileage.

The intercooler definitely help pack more air in, but I don't see how it improves fuel economy by itself. In fact it's a significant restriction in the intake. In my TDI there's a 3 psi pressure drop from the IC. Could you please provide a reference?

[vtec-e]

I tried blocking up the intercooler a bit on the diesel cee'd but the fuel economy literally tanked. I drove it easy, hard, and both drank diesel like theres no tomorrow. Maybe different brands of tdi behave differently with blocked up/ removed intercoolers. I do agree though, that gentle driving will not have the turbo compressing much, therfore cooler intake air. I can't wait to get something with a 1.4tdi next year....and a scangauge!

ollie

[tasdrouille]

Ollie,

On my TDI, timing is pulled back with higher intake air temps for NOx reduction purposes. If I unplug the IAT sensor, the ECU assumes -15 F IAT (vs ~90 F) and I can see the timing being adjusted by 2 degrees as I connect and disconnect the IAT sensor. I too blocked airflow to the IC, but instructed the ECU IAT was cold, and my mileage did not go down.

Your KIA is probably a much newer car than my 99 and there might be other emissions systems affecting how it reacts to intake air temps. A couple degrees less advance should really not affect mileage all that much alone.

[Duffman]

I think more so than in a gas engine there is an optimum intake air temperature in a diesel. Cold air is more dense and therefore has more O2 which is definately good for FE but a diesel also requires heat to run so a charge that is to cold may not run well either.

[ConnClark]

some data on what happens when you add an intercooler with no fuel adjustment. The more air you have in the cylinder the less heat that gets transferred to the cylinder wall when the fuel burns. Also with more excess air in the cylinder you have a leaner burn and the specific heat ratio of the combustion gases increase which further improves FE.

The same effect happens to a lesser degree with a cold air intake.

If its -60 degrees out I might consider warming the intake air, however I would have far more pressing concerns to deal with keeping my fuel from gelling up.


(From the Diesel Engine Reference Book, Second edition) Get a copy!!!