Increasing EGR flow for better mileage

[Piwoslaw]

I read about how PSA is improving its 1.6 HDi turbodiesel by increasing the bore and shortening the stroke. This keeps the displacement, but reduces the surface area through which heat can be lost. The larger bore also allows slightly larger valves, which reduces pumping losses. I have no idea how much this helps FE, my guess is barely.
Cooled EGR and an intake restriction to help suck more EGR have been standard for years.

[Daox]

I haven't seen cooled EGR on any gasoline engine with the exception of the 2010 Prius. Are there others using it?

[Bill in Houston]

Originally Posted by ConnClark

The real gain is going with the direct injection.

I know I should know this already, but what is the advantage of direct injection?

[ConnClark]

Originally Posted by Bill in Houston

I know I should know this already, but what is the advantage of direct injection?

More precise control of when and where the combustion takes place in the cylinder (keeping the majority of combustion away from the walls of the cylinder).

[ConnClark]

cooled egr on a gas engine
http://www.swri.org/3pubs/ttoday/Sum...n-and-Cool.pdf

Just keep in mind that the results these guys achieved was done through adjusting mixture as well as the EGR percentage (and other factors too) and not just simply cooling the EGR.

[Bill in Houston]

Originally Posted by ConnClark

More precise control of when and where the combustion takes place in the cylinder (keeping the majority of combustion away from the walls of the cylinder).

Interesting. Thank you.

[Piwoslaw]

I recently came across a research paper which may be of interest. Tests proved that increasing EGR in a diesel lowers exhaust gas temperatures, which lowers NOx emissions, but too much EGR will increase PM and won't help milage.

[arcosine]

Originally Posted by Piwoslaw

I read about how PSA is improving its 1.6 HDi turbodiesel by increasing the bore and shortening the stroke. This keeps the displacement, but reduces the surface area through which heat can be lost. The larger bore also allows slightly larger valves, which reduces pumping losses. I have no idea how much this helps FE, my guess is barely.
Cooled EGR and an intake restriction to help suck more EGR have been standard for years.

This is in fact opposite, larger bores and shorter strokes have more surface to volume ratio in the combustion chamber.

[Daox]

I was just reading an article in Automotive Engineering magazine and they were talking about Mazda's Skyactiv engines. Guess who is using cooled EGR on their 14.0:1 direct injection engines now? Yep, and 'large amounts' of it at times too.

[Olympiadis]

Daox, I was curious to see the test results from your EGR experiments. Did you abandon the project?