Mercedes-Benz MB503 engine

{{Infobox automobile engine

|name=Mercedes-Benz MB503

|manufacturer= Mercedes-Benz

|production=1937-1939

|configuration=60° V12

|bore={{convert|6.22-6.38|in|mm|1|lk=on|abbr=on}}

|stroke={{convert|7.09|in|mm|1|lk=on|abbr=on}}

|displacement={{convert|42.35-44.5|L|cuin|0|lk=on|abbr=on}}

|valvetrain=24-valve, SOHC, two-valves per cylinder

|supercharger=Roots-type supercharger

|power={{convert|580-1200|hp|kW|0|lk=on|abbr=on}}

|torque= {{convert|1646-2521|lbft|Nm|0|lk=on|abbr=on}}

|fuelsystem=Fuel injection

|fueltype=Gasoline

|coolingsystem=Water-cooled

|compression=

|oilsystem=Dry sump

|weight={{convert|790-920|kg|lb|0|lk=on|abbr=on}}

}}

The Mercedes-Benz MB 503 was a German prototype four-stroke V-12 gasoline marine and aircraft engine, designed and concepted before World War II. The MB 503 was based on and derived from the Daimler-Benz DB 603 inverted V-12 aircraft engine. It was a liquid-cooled 12-cylinder inverted V12 enlargement of the DB 601, which was in itself a development of the DB 600.{{Cite web|url=http://ftr.wot-news.com/2014/11/25/maus-engine-by-captiannemo/|title = Maus Engine by CaptianNemo | for the Record| date=25 November 2014 }}{{Cite web|url=https://warspot.net/343-how-the-wehrmacht-s-diesel-stalled|archive-url=https://web.archive.org/web/20210512112628/https://warspot.net/343-how-the-wehrmacht-s-diesel-stalled|url-status=usurped|archive-date=May 12, 2021|title = How the Wehrmacht's Diesel Stalled}}{{Cite web|url=https://oldmachinepress.com/2017/03/05/mercedes-benz-500-series-diesel-marine-engines/|title = Mercedes-Benz 500 Series Diesel Marine Engines|date = 5 March 2017}}{{Cite web|url=http://www.tankarchives.ca/2021/06/germany-and-t-34.html|title = Germany and the T-34}} The eventual powerplants chosen to be used in the Panzer VIII Maus super-heavy tank were the MB 509 V-12 gasoline engine, derived from the Daimler-Benz DB 603; and also the MB 517 V-12 diesel engine.