Compression Ignition Addict
Join Date: Aug 2007
Location: Buffalo, NY
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In order to make a diesel engine EPA compliant, the EPA looks for harmful NOx (Nitrogen Oxide) output from diesel exhaust.
NOx is a byproduct of the main power component of diesel burning engines, Oxygen.
To reduce NOx to EPA acceptable levels, exhaust gas (EGR) is re-introduced in to the engine intake to cut back on oxygen levels entering the combustion chamber.
Less oxygen to burn means less power, less economy, systematic destruction of the internal engine, high temperature and shorter oil life, but less NOx is released making the engine compliant.
The 6.4L engine relied 100% totally on EGR to make emissions, and that is why they are so inefficient stock.
2011 introduced SCR (urea) which is injected in the exhaust stream after the engine. This mixture enters a catalyst, again in the pipe after the engine. This mixture of exhaust and urea exits the catalyst with dramatically lower NOx output. This allows the engine to reduce EGR intake by over 40%, and still remain compliant.
That is why the 6.7L runs so well stock. It is allowed to actually burn more oxygen than the 6.4L, while still being EPA compliant.
Once deleted from EGR, the 6.4L becomes the best performing diesel engine on the road today. Getting rid of ANY EGR will allow your diesel to burn oxygen again, and to perform to it's potential.
KEM 345 tuned.