BMW M21
Template:Use dmy dates Template:Infobox automobile engine The BMW M21 is a straight-six diesel engine developed by the German engine manufacturer BMW. It has swirl chamber injection and is based on the M20 petrol engine<ref name="Bimmer" /> and was produced for BMW by the Upper Austrian Steyr engine plant from 1983 to 1991. It was succeeded by the M51.<ref name="Ran When Parked" />
Background
In the 1970s BMW decided to develop an engine, which would both be powerful and have a good fuel economy. This was caused by the oil crisis in 1973. In 1975 a group of BMW engineers started working on the M78/M105 diesel engine project, using the M20 petrol engine as the basis. By the time the engine entered production, the code name was changed to M21. The Steyr engine plant was planned from the beginning to be the sole manufacturer of the new diesel engine. It started as a joint venture with Steyr-Daimler Puch in 1978, but in February 1982 BMW took over the reins.<ref name=AC4459>Template:Cite magazine</ref> The first engines built there (in early 1982) were six-cylinder petrol units. Beginning in 1983, Ford was planning to buy 190,000 BMW turbodiesels over a period of several years.<ref name=AC4459/> With the American diesel market imploding in the early 1980s, Ford only built a small number of Lincolns thus equipped and only for two model years.
In 1983 at the IAA, the first passenger car was shown to the public which made use of the Template:Cvt M21.<ref name="AMS" /> It was the E28 524td, which has a top speed of Template:Convert and reaches Template:Convert in 12.9 s. This 5-series BMW was the fastest series production diesel car in the world in 1983. It has a fuel economy of Template:Convert.<ref name="Ran When Parked" />
Technical description
As per the M20, the M21 is water-cooled,<ref name="meyer" /> has a cast iron block and a SOHC valvetrain. The camshaft is driven by a belt,<ref name="Ran When Parked" /> each cylinder has one inlet and one outlet valve.<ref name="Bimmer" /> Compared to the M20, the M21 has reinforced connecting rods, cylinder heads, pistons, valves<ref name="Ran When Parked" /> and a reinforced crankshaft<ref name="Bimmer" /> with seven<ref name="meyer" /> bearings.
For faster engine startup the M21 has a glowplug system called instant start, which reduces the time to reach starting temperature compared to similar diesel engines.<ref name="Ran When Parked" /> The fuel is injected into swirl chambers.<ref name="Bimmer" />
A Garrett turbocharger<ref name="AMS" /> is used (without an intercooler). Initially, the M21 was only available as a turbocharged engine. In 1985, BMW introduced a naturally aspirated version of the M21, which was popular in countries with a high motor vehicle tax.<ref name="Ran When Parked" />
Initially, the fuel pump was controlled mechanically. From 1987 Bosch's electronically controlled fuel pump was used (EDC, called DDE, Digital Diesel Electronics by BMW),<ref name="Unixnerd" /><ref name="E30zone" /> which increased the torque output by Template:Convert. The updated engine has a smaller turbocharger, which improves response.<ref name="Bimmer" /> This also marked the introduction of the turbodiesel to the smaller 3-series (E30).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The naturally aspirated engine was fitted with ESC from 1989.
Models
| Engine | Aspiration | Power | Torque | Redline | Dates built |
|---|---|---|---|---|---|
| M21D24<ref>{{#invoke:citation/CS1|citation | CitationClass=web
}}</ref><ref name="meyer" /> ||rowspan="2"|Turbo-diesel || rowspan="2"| Template:Cvt | ||||
| Template:Convert at 2400 rpm |
1987–1992 (DDE) | ||||
| Natural | Template:Cvt at 4600 rpm |
Template:Convert at 2500 rpm |
5150 rpm | 1985.09–1989 1989–1992 (DDE) |
Applications:
- 1983 - 1988 E28 524td
- 1986 - 1988 E28 524d (naturally aspirated)
- 1985 - 1993 E30 324d (naturally aspirated)
- 1987 - 1993 E30 324td
- 1988 - 1991 E34 524td
- 1984 - 1985 Continental Mark VII<ref name="carscoops" />
- 1984 - 1985 Lincoln Continental<ref name="carscoops" />
- 1986 - 1987 Vixen 21 TD and Vixen 21 XC<ref name="autoevolution" />
- 1989 - 1991 Bertone Freeclimber
- 1992 UMM Alter II (four examples built)
See also
Bibliography
References
<references> <ref name="Bimmer">Andreas in Bimmer: Die BMW-Sportdiesel: Von 524td E28 über 530d E39 bis BMW M550d F10, published at 21 January 2012, retrieved at 9 April 2015. (german)</ref> <ref name="Ran When Parked">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> <ref name="AMS">Template:Cite magazine</ref> <ref name="meyer">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> <ref name="Unixnerd">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> <ref name="carscoops">Turbo Diesel Lincoln Continental M21 Template:Webarchive. Retrieved at 3 January 2017.</ref> <ref name="autoevolution">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> <ref name="E30zone">E30 Zone- M21 Template:Webarchive. Retrieved at 3 January 2017.</ref> </references> Template:BMW automotive diesel engines: 1980s to 2000s