Quote:
Originally Posted by euromodder
From what I've been seeing / reading , the CNG is fed into the air intake of a diesel @ low pressure.
(Getting it in along with the diesel would require very high pressures on CR or DP set-ups.)
The amount they feed in, is regulated by the TPS (throttle), and diesel injection is reduced because you need less throttle to keep a given speed or engine load.
(it may be necessary to dampen / reduce throttle input from the pedal to the ECU to keep the car drivable as you're feeding in more fuel than normal - yet not too much as you still want to be able to drive it on diesel alone if you're out of CNG.)
Without throttle input, you can let it run on diesel and the regular idle regulator in the car.
|
The problem with a fumigation CNG setup is that it displaces Oxygen while depressurizing, so it goes like choking the intake. That's why I'm more favorable to a direct-injection setup such as the one used in those Westport GX engines.
The video is more focused on the Westport HD system and the safety operation with an LNG fuel system, but you might get the idea. BTW there are some all-mechanical mixers that can be used to combine an amount of CNG with Diesel fuel, usually at fixed ratios such as 70% CNG-30% Diesel which at least is still effective to take benefit from the direct injection with CNG.