Big bang firing order

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In engine construction, the big bang firing sequence is a structurally defined time sequence of the working cycles in multi-cylinder reciprocating engines . It is mainly used on racing or sports motorcycles .

background

In principle, an attempt is made to achieve an even interval between the work cycles (ignitions) in relation to the crankshaft rotation in multi-cylinder engines for reasons of smoothness and uniform power output . In the case of an in-line four-cylinder engine - four-stroke engine, this generally results in one working cycle every 180 ° crankshaft rotation (four working cycles with a total of 720 ° crankshaft rotation). Since, for technical reasons in motor sport (for example MotoGP ), a targeted, non-uniform power output is sometimes desired in order to achieve a certain slip behavior of the rear tire in the limit area, constructive measures are taken to deliberately design the sequence of work cycles so that in the drive train Pronounced load peaks arise from working cycles in close succession, followed by load breaks. The practical influence on drivability and lap times is controversial and is occasionally questioned.

The name Big Bang is based on the onomatopoeic description that several work cycles with the explosive combustion of the fuel-air mixture take place in very short succession and acoustically merge into a "big bang".

The variations in the ignition intervals basically have little or no influence on the absolute power values ​​of the engine ( power , torque , liter output , efficiency ), but only on the torque curve at the output observed during a few revolutions. Under certain circumstances, due to the force peaks, parts of the drive train ( primary drive , clutch , gearbox ) must be dimensioned larger.

Four cylinder engines

For example, in the inline four-cylinder of the current MotoGP machine Yamaha YZR-M1, instead of the usual four-cylinder crankshaft with a crank offset of 0 ° -180 ° -180 ° -0 °, a crossplane crankshaft with 0 ° -90 ° -270 ° -180 ° Offset used, which results in an irregular ignition interval of 270 ° -180 ° -90 ° -180 °, which results in the intended non-uniform torque output through shorter (90 °) and longer (270 °) intervals between the force-generating strokes.

The V four-cylinder engine of the Ducati Desmosedici and Ducati Desmosedici RR has a cylinder bank angle of 90 ° and a crank pin offset of 70 °. This results in an ignition offset of 200 ° -90 ° -340 ° -90 °, while a conventional V-4 engine would have more uniform ignition intervals of 90 ° -270 ° -90 ° -270 °. This modification of the Big Bang principle is referred to by Ducati as Twin Pulse .

Web links

Individual evidence

  1. ↑ MotoGP: What is a Big Bang Engine? Article on Speedweek Germany from April 20, 2010 , accessed on May 25, 2016
  2. ↑ Presentation of the Ducati Desmosedici RR , article on motorradonline.de ( Memento of the original from May 26, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed May 26, 2016 @1@ 2Template: Webachiv / IABot / www.motorradonline.de