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Old 12-29-2013, 08:40 PM   #85 (permalink)
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Originally Posted by cRiPpLe_rOoStEr View Post
Altough CNG has to rely either on a spark plug or a secondary fuel to provide compression-ignition, it actually ends up even improving the combustion of regular Diesel fuel since it ends up increasing the flame propagation inside the combustion chambers.

It makes sense because you gain extra power without adding extra air. Also your exhaust is much cleaner.

If you add more diesel fuel you will gain extra power but you also "gain" much more smoke.

Just to remind others how diesel engine works: high pressure pump is the device that controls amount of diesel injected. The main parameter is used by pump is engine RPM. Pump is always hunting to keep right engine RPM.

When CNG is delivered into combustion chamber regular amount of diesel is injected. Because CNG gives extra power (stock 5.9 Cummings can get extra 100HP) your engine RPM will start climbing. As soon as this happens high pressure pump will start to cut down amount of diesel fuel injected until engine RPM is lower than we set it up with our gas pedal. This will happen very quick just few engine revolutions. This is actually normal pump operation cycle.
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