17.1 FACTORS THAT AFFECT WHEEL HORSEPOWER (Rev. 2007) All information subject to change without notice. 17-4 From Bulletin 1–MBE 4000–07 6SE412 0702 Copyright © 2007 DETROIT DIESEL CORPORATION Factors Considerations Temperature Controlled Fan A faulty thermo control will cause the fan to be locked on and drain power on a continuous basis. Air System Leaks (gaskets and seals) Air system leaks will result in insufficient air for optimum combustion. Biodiesel Should not be higher than 5%. Refer to Engine Requirements – Lubricating Oil, Fuel and Filters, (7SE270), available from authorized Detroit Diesel distributors.
Charge Air Cooler Leak Air system leaks will result in insufficient air for optimum combustion. Climate (fresh air temp) The maximum allowable temperature rise from ambient air to engine inlet is 15°F. Undersized or dirty air cleaner element, as well as damaged or obstructed air inlet piping can cause low power. Make sure under-hood hot air is not being taken in. Pressure drop across the air to air charge cooler should be checked (3.0 in. Hg maximum from turbo discharge to intake manifold). Check turbocharger boost pressure and compare to specification. Altitude Performance Site altitude has an effect on engine horsepower.
Expect approximately 2% loss in power when operating at an altitude of 1 mile, relative to sea level. PLD/VCU Settings Make sure vehicle settings such as: axle ratio, tire size, top gear ratio, etc. are set correctly to avoid a false sense of engine performance. EGR Valve A misadjusted or malfunctioning EGR valve will alter the amount of oxygen available for combustion as well as introduce inert gas that does not promote combustion. Exhaust Restriction A damaged, undersized, or otherwise restricted muffler or exhaust system can result in high exhaust back pressure. Refer to the engine specification sheets for maximum allowable pressure.
Barometric Pressure Sensor The engine will transition between EGR and boost mode at an altitude of 13,120 ft. Altitude is determined by the Barometric Pressure Sensor located in the PLD. A faulty Barometric Pressure Sensor will compromise the availability of boost pressure. EPV and Supply Lines Variable pressure output devices control the variable geometry turbo vanes and EGR valve position. Improper turbo vane or EGR valve positions will alter the air flow system balance and subsequently the combustion process. Air Compressor Leak An air compressor leak will cause the air compressor to work more and increase the parasitic load on the engine.
Air Conditioner Leak An air conditioner leak will cause the air conditioner to work more and increase the parasitic load on the engine. Excessive Play in Power Steering System Continuous movement of the steering wheel will call for continuous work by the power steering unit. This will increase the parasitic load on the engine. Alternator Load Excessive use of vehicle electrical power will cause increased use of the alternator. This will increase the parasitic load on the engine. Tire Pressure Under inflated tires will significantly increase driveline resistance to rotation.
Trailer Aerodynamics/Alignment A trailer that has poor aerodynamics or has misaligned axles (causing dog tailing) will significantly increase vehicle inertia and resistance to forward motion. Vehicle Payload As vehicle loading increases, vehicle inertia and resistance to forward motion increases.