Fuel Economy

[Keith Browning]

Cetane, do you get to drive any 6.2 Super Duties? Any idea what kind of mileage they get???

I am gonna guess horrible because the truck I drove I couldn't keep my foot off the floorboard. Seriously, that is a nice engine.

[Cetane]

My department is diesel only, I dont know much about the current gas engines. I drove a 6.2 Raptor last fall but I wasnt concerned about FE. I would be surprised if it was alot better than the P356 offerings, the truck didnt get lighter. Maybe the 6R will help a little.

[Bruce Amacker]

Thats with a production cal with regen off so it wouldn't screw up my mileage.

Production cal with regen off? I'm confused here. I'd think it might be a non-production cal with regen off?

 

Could you explain? I thought all production cals would have regen enabled...

 

Thanks!

 

[joshbuys]

There is an option with the IDS hooked up to turn regeneration off for testing purposes. That is what I figured he was referring to.

[Cetane]

I meant it is the same calibration the trucks are shipping from the factory with except I shut off regen. I just wanted to point out it wasnt a special calibration that I created just to maximize fuel economy.

[Bruce Amacker]

So if regen is disabled, what happens if/when the DPF restricts? I understand disabling regen, but it seems like this would be a brick wall shortly when restriction occurred.

 

I am baffled by a fleet of school buses in one of my training fleets. The Cleveland School Board has 300+ T444E buses, 1999-2004 model years, all retrofitted with DPF's at the EPAs expense, that have no regen programmed into the ECMs, never restrict, and generate only a teaspoon of ash per year when serviced in a cleaning machine.

 

Most production trucks with DPFs don't have "issues" but some go into excessive amounts of regen or plug the DPFs in situations when they shouldn't, like a long haul tractor.

 

Then you have this fleet of school buses that in theory should be plugging DPFs on a weekly basis and never plug them. I'm just exploring the strategy behind when the processor decides it's time to regen and what happens if this is disabled/neglected.

 

Thanks!

 

[rlchv70]

They are relying on passive regeneration. To passively regenerate, you need high exhaust temps and NOx.

 

With the 6.7L, since it has SCR, the engine out NOx is likely higher than on the 6.4L. Therefore, it will passively regenerate more easily.

 

With the retrofits, pre-2007 engines also have higher NOx outputs. This allows them to passively regenerate more easily. Some of the systems require a certain duty cycle to ensure that they passively regenerate. Also, some of the retrofit kits allow some of the soot to pass through, unlike the 2007+ OEM equipment.

 

Here's more info on the equipment available for retrofit. As you can see, some of them actually include systems for active regeneration:

 

http://www.epa.gov/otaq/retrofit/verif-list.htm

 

http://www.epa.gov/otaq/schoolbus/retrofit.htm

[Cetane]

I only turned the regen off for the drive home. I knew it was going to regen at some point during the trip. Rather than have it screw up my mileage test, I turned it off. I reenabled regen this morning and let it run its course.