# Engine configuration > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Engine_configuration > Markdown URL: https://mediated.wiki/source/Engine_configuration.md > Source: https://en.wikipedia.org/wiki/Engine_configuration > Source revision: 1351378001 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Categorization system of internal combustion engines The **engine configuration** describes the fundamental operating principles by which [internal combustion engines](/source/Internal_combustion_engine) are categorized. Piston engines are often categorized by their cylinder layout, valves and camshafts. [Wankel engines](/source/Wankel_engine) are often categorized by the number of rotors present. Gas turbine engines are often categorized into turbojets, turbofans, turboprops and turboshafts. ## Piston engines 1919 [Napier Lion II](/source/Napier_Lion) aircraft engine with three cylinder banks If a motor/engine is mounted in-line with the frame/chassis and in-line with the direction of travel of the vehicle it is a longitudinal motor. When the motor/engine is across the frame/chassis it is called a tranverse motor. Cylinder arrangement is not in the description of how the motor/engine is oriented. Therefore, a V4 motor/engine can be a transverse or an in-line. Where the cylinders are arranged in two or more lines (such as in [V engines](/source/V_engine) or [flat engines](/source/Flat_engine)), each line of cylinders is referred to as a 'cylinder bank'. The angle between cylinder banks is called the 'bank angle'. Engines with multiple banks are shorter than straight engines of the same size, and will often have better [engine balance](/source/Engine_balance) characteristics, resulting in reduced engine [vibration](/source/Vibration) and potentially higher maximum engine speeds. Most engines with four or less cylinders use a [straight engine](/source/Straight_engine) layout, and most engines with eight cylinders or more use a [V engine](/source/V_engine) layout. However, there are various exceptions to this, such as the [straight-eight engines](/source/Straight-eight_engine) used by various luxury cars from 1919-1954,[1][2][3] [V4 engines](/source/V4_engine) used by some marine outboard motors, [V-twin](/source/V-twin_engine) and [flat-twin](/source/Flat-twin_engine) engines used by motorcycles and [flat-four engines](/source/Flat-four_engine) used by various cars. ### Single cylinder bank 1928-1942 [Indian Four](/source/Indian_Four) straight-4 motorcycle engine [Straight engines](/source/Straight_engine) (also known as "inline engines") have all cylinders aligned in one row along the crankshaft with no offset. When a straight engine is mounted at an angle, it is sometimes called a "slant engine". Types of straight engines include: - [Single cylinder](/source/Single-cylinder_engine) example BMW R25 R26 R27 - [Straight-2](/source/Straight-twin_engine) example Sunbeam S7 - [Straight-3](/source/Straight-three_engine), also known as "inline-triple" - [Straight-4](/source/Straight-four_engine) - [Straight-5](/source/Straight-five_engine) - [Straight-6](/source/Straight-six_engine) - [Straight-8](/source/Straight-eight_engine) ### Multiple cylinder banks #### V engines V6 engine [V engines](/source/V_engine) (also known as "Vee engines") have the cylinders aligned in two separate planes or 'banks', so that they appear to be in a "V" when viewed along the axis of the crankshaft. Types of V engines include: - [V2](/source/V-twin_engine), commonly called "V-twin" - [V3](/source/V3_engine) - [V4](/source/V4_engine) - [V5](/source/V5_engine) - [V6](/source/V6_engine) - [V8](/source/V8_engine) - [V10](/source/V10_engine) - [V12](/source/V12_engine) - [V14](/source/V14_engine) - [V16](/source/V16_engine) - [V18](/source/V18_engine) VR5 and VR6 engines are very compact and light, having a narrow V angle which allows a single [cylinder block](/source/Cylinder_block) and [cylinder head](/source/Cylinder_head). These engines use a single cylinder head so are technically a straight engine with the name "VR" coming from the combination of German words “Verkürzt” and “Reihenmotor” meaning “shortened inline engine”. #### Flat engines [Douglas](/source/Douglas_(motorcycles)) flat-twin motorcycle engine [Flat engines](/source/Flat_engine) (also known as "horizontally-opposed" engines) have the cylinders arranged in two banks on either side of a single crankshaft. [Boxer engines](/source/Flat_engine#Boxer_engine) are a subtype of flat engines where opposing pistons move in and out in tandem. Types of flat engines include: - [Flat-2](/source/Flat-twin_engine), commonly called "flat-twin" - [Flat-4](/source/Flat-four_engine) - [Flat-6](/source/Flat-six_engine) - [Flat-8](/source/Flat-eight_engine) - [Flat-10](/source/Flat-ten_engine) - [Flat-12](/source/Flat-twelve_engine) - [Flat-16](/source/Flat-sixteen_engine) #### W engines Main article: [W engine](/source/W_engine) W engines have the cylinders in a configuration in which the cylinder banks resemble the letter W, in the same way those of a V engine resemble the letter V. Types of W engines include: - [W8](/source/W8_engine) - [W12](/source/W12_engine) - [W16](/source/W16_engine) - [W18](/source/W18_engine) W engines using twin "VR" engine banks are technically a V engine. These engine banks use a single cylinder head so are technically a straight bank with the name "VR" coming from the combination of German words “Verkürzt” and “Reihenmotor” meaning “shortened [inline engine](/source/Inline_engine_(aeronautics))”. #### Other layouts [Radial engines](/source/Radial_engine) have cylinders mounted radially around a central crankcase. [Rotary engines](/source/Rotary_engine) have a similar configuration, except that the crankshaft is fixed and the cylinders rotate around it. (This is different from the [Wankel engine](/source/Wankel_engine) configuration described below.) Radial and rotary engine designs were widely used in early [aircraft engines](/source/Aircraft_engine). [U engines](/source/U_engine) consist of two separate straight engines (complete with separate crankshafts) joined by gears or chains. Most U engines have four cylinders (i.e. two straight-two engines combined), such as [square four engines](/source/U_engine#Square_four_engine) and [tandem twin engines](/source/U_engine#Tandem_twin_engine). Similar to U engines, [H engines](/source/H_engine) consist of two separate flat engines joined by gears or chains. H engines have been produced with between 4 and 24 cylinders. An [opposed-piston engine](/source/Opposed-piston_engine) is similar to a flat engine in that pairs of pistons are co-axial but rather than sharing a crankshaft, instead share a single combustion chamber per pair of pistons. The crankshaft configuration varies amongst opposed-engine designs. One layout has a flat/boxer engine at its center and adds an additional opposed-piston to each end so there are two pistons per cylinder on each side. An [X engine](/source/X_engine) is essentially two V engines joined by a common crankshaft. A majority of these were existing V-12 engines converted into an X-24 configuration. The [Swashplate engine](/source/Cam_engine#Wobble_plate_engine) with the K-Cycle engine is where pairs of pistons are in an opposed configuration sharing a cylinder and combustion chamber. A Delta engine has three (or its multiple) cylinders having opposing pistons, aligned in three separate planes or 'banks', so that they appear to be in a Δ when viewed along the axis of the main-shaft. An example of this type of layout is the [Napier Deltic](/source/Napier_Deltic). ## Wankel (rotary) engines This section needs expansion. You can help by adding missing information. (August 2019) [Wankel engines](/source/Wankel_engine) (sometimes called 'rotary engines') can be classified based on the number of rotors present. Most production Wankel engines have two rotors, however engines with one, three and four rotors have also been produced.[4][5] Wankel engines can also be classified based on whether they are [naturally aspirated](/source/Naturally_aspirated_engine) or [turbocharged](/source/Turbocharger). Most Wankel engines are fueled by petrol, however prototype engines running on diesel and hydrogen have been trialed. The primary advantage of Wankel engines is the high power-to-weight ratio, as the rotational movement eliminates the need for heavy reciprocating parts like pistons and connecting rods. [Mazda](/source/Mazda) is most famous for using the Wankel engine in production, featuring it on the [RX-7](/source/Mazda_RX-7), [RX-8](/source/Mazda_RX-8), and other models. Mazda stopped using the Wankel engine in 2012 due to various issues such as the apex seal, although they brought back the Wankel engine in 2023 with the [MX-30](/source/Mazda_MX-30) as a range extender for the electric battery. ## Gas turbine engines This section needs expansion. You can help by adding missing information. (August 2019) [Gas turbine](/source/Gas_turbine) engines— mostly used for aircraft— are usually separated into the following categories: - [Turbojet](/source/Turbojet), gasses travel through a propelling nozzle - [Turbofan](/source/Turbofan), gasses travel through a ducted fan - [Turboprop](/source/Turboprop), gasses travel through an unducted propeller, usually with variable pitch - [Turboshaft](/source/Turboshaft), a gas turbine optimised for producing mechanical torque instead of thrust ## See also - [Powertrain layout](/source/Powertrain_layout) - [Car body style](/source/Car_body_style) - [Car classification](/source/Car_classification) ## References 1. **[^](#cite_ref-VVC70_1-0)** [Posthumus, Cyril](/source/Cyril_Posthumus) (1977) [1977]. "War and Peace". *The story of Veteran & Vintage Cars*. John Wood, illustrator (Phoebus 1977 ed.). London: Hamlyn / Phoebus. p. 70. [ISBN](/source/ISBN_(identifier)) [0-600-39155-8](https://en.wikipedia.org/wiki/Special:BookSources/0-600-39155-8). 1. **[^](#cite_ref-2)** ["Engine of the Day: Packard Inline Eight"](https://jalopnik.com/engine-of-the-day-packard-inline-eight-380781). *www.jalopnik.com*. Retrieved 15 November 2019. 1. **[^](#cite_ref-3)** *Hemmings Classic Car*. Vol. 6, no. 5. February 2010. p. 39. {{[cite magazine](https://en.wikipedia.org/wiki/Template:Cite_magazine)}}: Missing or empty |title= ([help](https://en.wikipedia.org/wiki/Help:CS1_errors#citation_missing_title)) 1. **[^](#cite_ref-4)** ["Technically Interesting: Dr. Wankel's Quad-Rotor Mercedes SL"](https://bringatrailer.com/2018/03/21/technically-interesting-dr-wankels-quad-rotor-mercedes-sl/). *www.bringatrailer.com*. 21 March 2018. Retrieved 31 August 2019. 1. **[^](#cite_ref-5)** ["How a Four-Rotor Wankel Engine Works"](https://www.roadandtrack.com/motorsports/videos/a31678/how-a-four-rotor-wankel-engine-works/). *www.roadandtrack.com*. 23 November 2016. Retrieved 31 August 2019. v t e Engine configurations for piston engines Type Atmospheric Axial Beam Cornish Rotative Bourke Cam engine Camless Compound Double-acting cylinder Flathead Free-piston Stelzer Hemi Heron head Intake over exhaust Oscillating cylinder Opposed-piston Overhead camshaft Overhead valve Pentroof Rotary Single-acting cylinder Split cycle Swing-piston Uniflow Watt Wedge Stroke cycle Two-stroke Four-stroke Five-stroke Six-stroke Two-and four-stroke Cylinder layout Inline – straight I1 I2 I3 I4 I5 I6 I7 I8 I9 I12 I14 Flat – boxer F2 F4 F6 F8 F10 F12 F16 V – vee V2 V3 V4 V5 VR5 V6 VR6 V8 V10 V12 V14 V16 V18 V20 V24 W W3 W6 W8 W12 W16 W18 W24 W30 Deltic H Radial Split-single U X v t e Internal combustion engine Part of the Automobile series Engine block and rotating assembly Balance shaft Block heater Bore Connecting rod Crankcase Crankcase ventilation system (PCV valve) Crankpin Crankshaft Core plug (freeze plug) Cylinder (bank, layout) Displacement Flywheel Firing order Stroke Main bearing Piston Piston ring Starter ring gear Valvetrain and Cylinder head Flathead layout Overhead camshaft layout Overhead valve (pushrod) layout Tappet / lifter Camshaft Chest Combustion chamber Compression ratio Head gasket Rocker arm Timing belt Valve Forced induction Blowoff valve Boost controller Intercooler Supercharger Turbocharger Fuel system Diesel engine Petrol engine Carburetor Fuel filter Fuel injection Fuel pump Fuel tank Ignition Magneto Compression ignition Coil-on-plug Distributor Glow plug Ignition coil Spark plug Spark plug wires Capacitor discharge ignition Engine management Engine control unit (ECU) Electrical system Alternator Battery Dynamo Starter motor Intake system Airbox Air filter Idle air control actuator Inlet manifold MAP sensor MAF sensor Throttle Throttle position sensor Exhaust system Catalytic converter Diesel particulate filter Gasoline particulate filter EGT sensor Exhaust manifold Muffler Oxygen sensor Cooling system Air cooling Water cooling Electric fan Radiator Thermostat Viscous fan (fan clutch) Lubrication Oil Oil filter Oil pump Sump (wet, dry) Other Knocking / pinging Power band Redline Stratified charge Top dead centre Portal Category --- Adapted from the Wikipedia article [Engine configuration](https://en.wikipedia.org/wiki/Engine_configuration) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Engine_configuration?action=history)). 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