Straight-four engine

Diagram of a DOHC straight-four engine
1989-2006 Ford I4 DOHC engine with the cylinder head removed
2006-2009 Nissan M9R diesel engine

A straight-four engine (also referred to as an inline-four engine) is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.

The majority of automotive four-cylinder engines use a straight-four layout[1]: pp. 13–16  (with the exceptions of the flat-four engines produced by Subaru and Porsche)[2] and the layout is also very common in motorcycles and other machinery. Therefore the term "four-cylinder engine" is usually synonymous with straight-four engines. When a straight-four engine is installed at an inclined angle (instead of with the cylinders oriented vertically), it is sometimes called a slant-four.

Between 2005 and 2008, the proportion of new vehicles sold in the United States with four-cylinder engines rose from 30% to 47%.[3][4] By the 2020 model year, the share for light-duty vehicles had risen to 59%.[5]

  1. ^ Cite error: The named reference Nunney was invoked but never defined (see the help page).
  2. ^ "Performance: The new 718 Boxster". Porsche. 2016. Retrieved 2016-11-01.
  3. ^ Schembari, James (2010-10-15). "A Family Sedan Firing on Fewer Cylinders - 2010 Buick LaCrosse CX - Review". The New York Times.
  4. ^ Ulrich, Lawrence (2010-08-13). "Four-Cylinder Engines Are Smaller, Quieter and Gaining New Respect". The New York Times.
  5. ^ "Explore the Automotive Trends Data". November 2021. Retrieved 2021-11-25.