The BMW M56 is a 2.5 liter 184 PS (135 kW; 181 bhp)
straight-six engine
The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine bala ...
. It is a re-engineered version of the
BMW M54B25 engine, manufactured in order to meet
SULEV
Super ultra-low emissions vehicle (SULEV) is a U.S. classification for passenger vehicle emissions. The classification is based on producing 90% fewer emissions than the average gasoline-powered vehicle. The SULEV standard is stricter than the stan ...
regulations in 4 US states.
Background
The updated 2.5 liter engine designated M56B25,
was produced between 2002 and 2006. It was the first BMW
Super Ultra Low Emission Vehicles (SULEV).
The M56B25 power output and vehicle performance was the same as the comparable model equipped with the M54B25 engine (US only). M56 SULEV models listed above were sold in California, New York and Massachusetts as 2003 models and in Vermont starting in 2004 model year.
In addition, these vehicles were certified as
partial zero-emissions vehicle A partial zero-emission vehicle, in the United States, is an automobile that has zero evaporative emissions from its fuel system, has a 15-year (or at least 150,000-mile) warranty on its emission-control components, and meets SULEV tailpipe-emission ...
s (PZEV): The vehicles meet the SULEV tailpipe emission standard, which is approximately 1/5 of the
ULEV standard. The vehicles conform to the Zero Evaporative Emissions requirements.
Models
From 2003 to 2006 - 325iA (E46) sedan, coupe and sport wagon with automatic or a manual transmission.
Market
Sales of this model started in 2003. The E46 SULEV has only been sold in 4 states in the US: California, New York, Massachusetts and later in 2004 in Vermont.
Specifications
* HC block in the air intake system:
Hydrocarbon escape via the intake system is prevented due to the use of an additional carbon filter incorporated in the air filter housing and a "closed" throttle valve actuator.
* Fuel system components:
All metal fuel system components (fuel rail, injectors, tank ventilation valve, etc.) are made of stainless steel and are fastened together using coupling type connectors.
* Fuel tank and tank ventilation system:
The fuel tank, tank filler neck and evaporative canister are made of stainless steel. Both the fuel pump and fuel filter are completely sealed inside the gas tank and require a complete replacement of the gas tank if either the fuel pump or filter fail.
*
Crankcase
In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block.
Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/a ...
ventilation system:
The crankcase ventilation valve is incorporated in the aluminum cylinder head cover.
* System components used to achieve SULEV tailpipe emission requirements:
# Dual down stream
catalytic converter
A catalytic converter is an exhaust emission control device that converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction. Catalytic converters are usually ...
s
# "Warm up" catalytic converters – high cell density technology
# Upstream oxygen sensors – wide band technology
# Pistons – only 3mm fire land
#
VANOS
VANOS is a variable valve timing system used by BMW on various automotive petrol engines since 1992. The name is an abbreviation of the German words for ''variable camshaft timing'' (german: variable Nockenwellensteuerung).
The initial version ...
– set to fixed position during start up for improved engine start
# New style fuel injectors–4 hole design (5 bar fuel pressure)
Secondary air system with secondary air mass flow sensor used for improved monitoring of secondary air flow.
In addition SULEV models also incorporate a "Direct Ozone Reduction System". The external heat exchange surfaces of the radiator are coated with a catalyst which reduces the ozone in the ambient air drawn through the radiator.
BMW M56 SULEV Gallery
File:BMW_M56_SULEV2.JPG, Engine bay of a 2004 325i SULEV
File:BMW_M56_SULEV3.JPG, A rare 325i SULEV with M56 engine imported in Ireland by an individual
File:BMW 325i SULEV.JPG, A rare 325i SULEV with M56 engine imported in Ireland by an individual
File:BMWM56Label.jpg, Information label on the underside of the hood of an E46 SULEV
File:BMW_M56_SULEV1.JPG, Information label about the SULEV radiator, located on the frontmost part of the air intake.
References
External links
BMW-Planet.com - M56 engine specifications
{{BMW automotive petrol engines: 1980s to 2000s
M56
Straight-six engines