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Old 02-18-2016, 10:40 PM   #16 (permalink)
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I didn't say DPFs do not hurt economy.

Originally Posted by oil pan 4 View Post
When the dpf is deleted people are typically claiming a +5MPG improvement on ford 6.4L and 6.7L Cummins guys are claiming a 2 to 4 mpg improvement. Even ford claims that a dpf regeneration cycle can use up to 17 liters of fuel.Q
Nothing I have found any where supports the claim that the dpf system does not hurt fuel economy.
The dpf system on a diesel is nothing like the catalyst system on a gasoline engine. I believe that the converter on a gas engine has little to no effect on fuel economy.

If you dont live some where smog is a problem then getting over all lower fuel economy and burning up to 17l of fuel to reduce NOx, make your diesel particulate smaller and more harmful is irresponsible.
You made that leap of logic. I am simply saying the systems in place at this point are 1st generation solutions to the problem. Much the same way the catalytic systems in gasoline powered cars back in the early 70s were 1st generation solutions. Those systems were horrible and difficult to keep working and they did harm economy. Note that I say systems. The same way early catalytic converters in gas cars were blamed for all problems, so it is with DPFs.

DPFs will improve just as Catalytic Converters did. But, along with that will be an improvement in the SYSTEM.

You gave the OP the impression that all diesel emissions systems are useless and harm economy greatly. These are simple first gen systems with much room for improvement. Yes, it is simple to throw them out when they fail, but that doesn't help the environment and that isn't much of a challenge. By design, a good DPF should only cause around 1 psi of back pressure. This in itself is not going to reduce your mileage by 4 - 6 MPG. However, as they load up with soot, the back pressure increase does start to effect economy. This isn't the whole story of lost mileage as you have pointed out, the fuel wasted to burn off this soot is a big part of the lost fuel efficiency. Also, another big gain is the result of removing the exhaust gas re-circulation (EGR) component. This is not directly related to the DPF but many attribute the greater power and economy to the removal of the DPF alone and not to the EGR delete.

This is a complex subject that is gaining technological momentum and with a little knowledge and thought someone determined could put together a retrofit system on their diesel vehicle that would outperform the 1st gen designs.
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