Mike, … if a fixed quantity of air is served by a fuel injector calibrated maximally for that full air-charge….. but the air charge is reduced due to obstructed induction system…the mixture will be Richer than that programmed. At some point (it might be extreme) that too-rich mixture will have incomplete combustion…resulting in lower temp.
In another analogy, …there is a deliberate reduction in gasoline engines by use of a throttle-plate. Whatever air passes by the throttle plate is ideally mixed due to a carb venturi….or by a programmed injection system. Those engines which use a carb (throttle plate) for engine-speed ..automatically are leaned by the venturi mass air flow. If one were to continue delivery of higher fuel rates…with reduced throttle plate….the mixture would be excessively rich…and burn cooler.
Although diesels do not use that method…. use of a fixed-volume of air-charge and the injection system adds fuel to increase combustion which increases engine-speed.
But if you threw-in a throttle plate …or dirty filter or some other reduction in air intake…for a short period of rpm increase the tempt would rise as you mention…but continued addition of fuel in a severely restricted/choked induction system would eventually become excessively rich….and result in a decrease in temp. (and the excess fuel would eventually result in incomplete combustion…..“slobber” and contribute to a decrease in temp.)
Teach me how that is wrong, please.
Out of complete curiosity, were you opposed to reading the link provided to you above from banks power? It explains the effects of air and fuel delivery on a diesel engine very well.
Trust me, there was a time when I had the same opinion as yourself. However, I have personally experimented and tested this theory extensively with the Turbo development on my L2501 tractor....Combustion temperatures will rise with restricted air flow and the same fuel amount and stock air flow with additional fuel. The only way to cool combustion temperatures in a diesel engine (assuming the same fuel amount) is to add additional air flow (Turbocharger or unrestricted intake) and the cooling affect will depend on the fuel flow and extent of the additional air flow.
As an example, an L2501 tractor operating at 9,000 feet elevation will produce EGT temperatures in excess of 1,100 degrees completely stock. When at sea level, the same tractor produces a maximum EGT temperature of 800 degrees. Why? There is less air at 9,000 feet. So, with limited air flow capacity and the same fuel amount, the combustion temperatures and EGT temperatures increase.
Mike
