LDV Lorry Engines: Truck, Convoy engine, Pilot, Maxus
LDV Convoy also called DAF 400 Series and offered air suspension and a
2.5-litre Peugeot-sourced diesel engine. The LDV Pilot it's power came from a 1.9 litre Peugeot Diesel car engine.
The LDV Cub production was from
1996 – 2001. The LDV Maxus 120PS
2499cc diesel engine. At Engines and Gear Boxes they are offered as used, reconditioned
The diesel engine
is an internal combustion engine that uses compression ignition, in which fuel ignites
as it is injected into air in the combustion chamber that has been copressed to
temperatures high enough to cause ignition.
Compressing a gas raises its temperature, the method by which fuel is ignited in
diesel engines. Air is drawn into the cylinders and is compressed by pistons at
compression ratios as high as 25:1, higher than used for a spark-ignition engines.
At the end of the compression stroke, at the start of the power stroke, diesel fuel
is injected continuously into the combustion chamber through an atomizer, igniting
from contact the compressed air whose temperature is initially about 700–900 °C
(1300–1650 °F). Combustion further heats the air in the chamber, increasing its
pressure to move the piston downward. A connecting rod transmits this motion to
a crankshaft to convert linear to rotary motion and delivers power to an output
shaft. Scavenging (pushing products of combustion from the cylinder and drawing
in a fresh air) the engine is done either by ports or valves. To increase power,
a diesel engine may by mechanical supercharger or by an exhaust turbine, have a
turbocharger to to increase intake air volume. Use of an aftercooler/intercooler
to cool intake air after compression by a supercharger improves efficiency.
In cold weather, diesel engines
can be difficult to start because the cold metal of the cylinder block and head
draw out the heat created in the cylinder during the compression stroke, thus preventing
ignition. Most Diesel engines use small electric heaters called glow plugs inside
the cylinder help ignite fuel when starting. Some even use resistive grid heaters
in the intake manifold to warm the inlet air until the engine reaches operating
temperature. Engine block heaters (electric resistive heaters in the engine block)
connected to the utility grid are often used when an engine is turned off for extended
periods (more than an hour) in cold weather to reduce startup time and engine wear.
Diesel fuel is also prone to 'waxing' in cold weather, a term for the solidification
of diesel oil into a crystalline state. The crystals build up in the fuel (especially
in fuel filters), eventually starving the engine of fuel. Low-output electric heaters
in fuel tanks and around fuel lines are used to solve this problem. Also, most engines
have a 'spill return' system, by which any excess fuel from the injector pump and
injectors is returned to the fuel tank. Once the engine has warmed, returning warm
fuel prevents waxing in the tank. Fuel technology has improved recently so that
with special additives waxing no longer occurs in all but the coldest climates.
A vital component of
older diesel engine systems is the governor, which limits the speed of
the engine by controlling the rate of fuel delivery. Unlike in petrol (gasoline)
engines, incoming air is not throttled and an engine without a governor can overspeed.
Older injection systems were driven by a gear system from the engine and thus supplied
fuel in proportion with engine speed. Modern, electronically controlled engines
apply controls similar to those of petrol engines and limit the maximum RPM through
an electronic control module (ECM) or electronic control unit (ECU)—the engine-mounted
computer. The ECM/ECU receives an engine speed signal from a sensor and controls
the amount of fuel and (start of injection) timing through electric or hydraulic
Controlling the timing
of the start of injection of fuel into the cylinder is a key to minimizing emissions,
and maximizing fuel economy (efficiency), of the engine. The timing is usually measured
in units of crank angle of the piston before Top Dead Center (TDC). For example,
if the ECM/ECU initiates fuel injection when the piston is 10 degrees before TDC,
the start of injection, or timing, is said to be 10 deg BTDC. Optimal timing will
depend on the engine design as well as its speed and load.
Advancing the start of
injection (injecting before the piston reaches TDC) results in higher in-cylinder
pressure and temperature, and higher efficiency, but also results in higher emissions
of oxides of nitrogen (NOx) through higher temperatures. At the other extreme, delayed
start of injection causes incomplete combustion and emits visible smoke made of
particulate matter (PM) and
Modern diesel facts
fuel passes through the injector jets at speeds of nearly 1500 miles per hour (2400
km/h). Fuel is injected into the combustion chamber in less than 1.5 ms – about
as long as a camera flashes. The smallest quantity of fuel injected is one cubic
millimetre – about the same volume as the head of a pin. The largest injection quantity
at the moment for automobile diesel engines is around 70 cubic millimetres. If the
crankshaft of a six-cylinder engine is turning at 4500 rpm, the injection system
has to control and deliver 225 injection cycles per second.