When is too much fuel

[six5turbofan]

Always heard the more fuel you throw at a diesel the more pwer it makes... When is it too much ? Once I see black smoke pouring out at wide open throttle on a hill isn't that unburnt fuel ? I notice on ours that at almost full throttle pulling a load it is just starting to put out a little black smoke, if I mash it all the way down smoke gets heavier but don't feel anymore pull. Is that just a waste ?

[njdevi11]

To answer your questions:

YES. YES. YES. YES...

Black smoke happens when there is not enough air in the cylinder and the fuel cannot burn anymore. So when your seeing black smoke basically your seeing unburnt fuel going right through your engine.

Combustion needs three things to work: Fuel, Heat, Oxygen. if you take away any of those the combustion will stop. So when you see the black smoke, the combustion burnt all the oxygen and it stops dead in its tracks.

Now this isn't recommended but if you want to get the more power from that more fuel, you turn the turbo up putting more fuel into the engine, or you can get an inter cooler. The inter cooler will make the air more dense stuffing more oxygen molecules into the cylinder with the same boost/displacement.

[sixnickel]

IF you have good boost, Good exhaust flow (4" and all that good stuff) EGTs below 1100 df pre turbo and some black smoke thats OK. More fuel, more smoke, more EGTs thats to much fuel. Basically it's the EGTs that control the WHATS TO MUCH FUEL