Specifications

F-250/F-350/F-450
SD Pickups
17
esourcebook.dealerconnection.com
RE&T: 2012 Source Book
F-250/F-350/F-450
Super Duty Pickups
Performance/Handling
2012
June 2011
Diesel Engine Emissions cont’d
MAKE THE POINT: SCR Competitive Advantages
The Selective Catalytic Reduction (SCR) has strong advantages over the competitive lean NOx trap system,
similar to what a customer would find in a Ram Pickup truck.
Lean NOx Trap
• Dieselenginesnormallyoperatewithanexcess
ratioofair-to-fuel(alsoknownas“lean”operation)
• ALeanNOxTrap(alsoknownasaNOxAdsorber
Catalyst) chemically traps the NOx in the
exhaust on the surface of the catalyst during
lean engine operation
• Asthesurfaceofthetrapbecomesfull,the
system triggers the engine to run rich (increases
the fuel-to-air ratio) to clean the trap
SCR Advantages
• Designedforgreaterfuelefficiencycomparedto
Lean NOx Trap
• LeanNOxTrapsystemsconstantlycyclebetweena
lean and a rich fuel mix, which consumes more fuel
than an SCR system
• LeanNOxTrapsalsotrapthesulfurindieselfueland
can become clogged, requiring a higher temperature
regeneration to remove the sulfur from the trap
• It’sexpectedthatinthefutureallOEMswillrelyon
this technology
ENGINEERING INSIGHT
Absorber vs. Adsorber
What’s an Absorber?
We’re all familiar with something that absorbs: a sponge. A sponge soaks up (absorbs) a liquid from the
outside and stores the liquid internally until full. Once the sponge is full, it stops absorbing and can only take on
additionalliquidifdrained(squeezed).
What’s an Adsorber?
An adsorber, on the other hand, attracts and holds particles on an outer surface — similar to a pleated filter on a
vacuum cleaner, a furnace filter or charcoal granules in a vapor canister.