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I think you mean the Diesel Particulate Filter delete. http://news.pickuptrucks.com/2013/01/epa-says-dont-touch-paticulate-filter.html http://news.pickuptrucks.

• abakker 11y ago
  That is certainly one part of it, though many people go significantly further. frequently, this involves simply sawing off the whole exhaust system and having a local muffler shop fab a new set of pipes and mufflers for you. The truck that my friend has is a ram 2500, with a chip/tune and the exhaust removed, it dynos at about 490HP/1100 ft-lbs of torque, and still achieves ~25mpg highway. The downside is that there is an unknown emissions toll for doing that modification. Again, I have to wonder though, at almost 10mpg better, is the reduced emissions actually logical? i.e. do the emissions reduction systems really make up for needing to burn additional fuel to do the same work?
  • hapless 11y ago
    Whether it's "logical" depends on your goals. If you value public health more than fuel efficiency, then yes, emissions controls are a logical choice.
    • vonmoltke 11y ago
      abakker was questioning how much the increased emissions per unit fuel was offset by the reduction in fuel required for a given distance. When calculating vehicle emissions per distance traveled, those counteract each other.
    • abakker 11y ago
      well, thats what I'm getting at. By getting 10mpg better, do you produce fewer total emissions than if you had the emissions controls in place, but burned more fuel? I imagine than there are many possible solutions where it makes sense to use strict emissions controls at the cost of fuel consumption, but there are also others where the increase in mileage would reduce total emissions further than the emissions controls would. rough estimate. on a 25 gallon tank of diesel, with emissions controls in place, the truck goes 350 miles. on that same tank, the truck goes 625 miles with the emissions removed. so, to go 625 miles with the exhaust controls in place would use ~44 gallons of fuel vs 25. Is that actually a net environmental benefit? My gut tells me that the environmental costs of refining, transporting and burning the extra fuel are higher than the marginally higher emissions in the unrestricted truck. I don't expect those numbers would work out the same in all vehicles or cases though. I think public health and fuel economy go hand in hand. the total environmental costs of petroleum are much higher than the emissions that come out of cars. reducing demand through greater fuel economy should be factored in to the overall emissions equations.
      • hapless 11y ago
        EPA emissions limits are based on grams of pollutant per horsepower-hour. In order to reach compliance, your emissions control equipment needs to reduce pollution much faster than it reduces efficiency. It's not uncommon for illegally chipped/straight-piped trucks to see 50% improvements in fuel efficiency, but they're belching out tens or hundreds of times the volume of common pollutants (depending on the pollutant)
        • abakker 11y ago
          Thanks for that info. Out of curiosity, is there any accounting for the other emissions involved in making the fuel, though? Full transport and refining is energy intensive. on-vehicle emissions controls are also costly, and also use energy to make. Finally, petroleum is a finite resource. I am all for emissions controls on vehicles if they genuinely reduce net emissions. If the reduced fuel economy doesn't equal out though, then at best, we're simply moving the emissions out of cars and into refineries/shipping/factories instead.
          • hapless 11y ago
            I have a hard time believing that we're moving the emissions. 1. The efficiency/emissions tradeoff is almost entirely a diesel problem. For intrinsic reasons, gasoline engines suffer much less from emissions controls. The relevant systems are both much less complicated and much less intrusive. There is very little efficiency gain available by e.g. removing your catalytic converter. (The vapor reclamation requirements can be very complicated, but those parts do not intrude on the function of the engine, so they are not making the system less efficient) 2. The math doesn't work out on the back of a napkin. Emissions controls can reduce total tailpipe pollutants by as much as 99%. Even if it caused 2x the fuel consumption, how on earth would that result in a 100-fold increase in emissions in the distribution chain?