This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Fiat Twin Cam engine" – news ·newspapers ·books ·scholar ·JSTOR(February 2010) (Learn how and when to remove this message)

Fiat Twin Cam engine
Overview
Manufacturer	Fiat/Lancia
Production	1966–2000
Layout
Configuration	I4
Displacement	1.3–2.0 L (1,297–1,995 cc)
Cylinder bore	76 mm (2.99 in) 76.1 mm (3.00 in) 78 mm (3.07 in) 80 mm (3.15 in) 82.6 mm (3.25 in) 83 mm (3.27 in) 84 mm (3.31 in)
Piston stroke	71.5 mm (2.81 in) 79.2 mm (3.12 in) 80 mm (3.15 in) 90 mm (3.54 in)
Cylinder block material	Cast iron
Cylinder head material	Aluminium alloy
Valvetrain	DOHC 2 or4 valves x cyl.
Combustion
Supercharger	In VX versions
Turbocharger	In some versions
Fuel system	Carburetor,Indirect injection,Direct injection
Fuel type	Gasoline, Diesel
Cooling system	Water-cooled
Chronology
Successor	Fiat Pratola Serra engine

TheFiat Twin Cam (also known as the Lampredi Twin Cam) is an advanceddouble overhead camshaftinline-four automobile engine produced from 1966 through 2000 as aFiat/Lancia engine. Designed by ex Ferrari engineerAurelio Lampredi, the engine was produced in a large number of displacements, ranging from 1.3 to 2.0 L (1,297 to 1,995 cc) and was used in Fiat,Lancia,Alfa Romeo,SEAT,FSO andMorgan cars. The Fiat Twin Cam engine has been widely used inmotorsport and has been the most successful engine in the history of theWorld Rally Championship. Fiat and Lancia won a total of tenWorld Rally Championships for Manufacturers using engines based on the Lampredi Twin Cam engine. It was replaced by the Fiat"family B" Pratola Serra engine series.

The Twin Cam uses the block of theoverhead valve124-series engine first found in theFiat 124 with some modifications to accept the belt drive for thedouble overhead camshafts (DOHC). The head itself is made in three pieces, one carrying thecombustion chamber and valves and one separate casting for each camshaft in tunnel typebearings. The valves had an included angle of 65 degrees. The engine featured a revolutionary new method for adjusting the valve clearance. Usually at that time in double overhead camshaft engines like fromAlfa Romeo orJaguar, small shims were placed on the valve stem inside thebucket tappets, thereby necessitating the removal of the camshafts to get access to these shims to adjust the valve clearance, making for time consuming and very expensive maintenance work.Lampredi’s design placed the shims on top of the tappets where they could be removed with the camshaftin situ after the tappets were pressed down with a special tool. This design was patented for Fiat and was used in the engines of the 128 and 130, and even theFerrari/Fiat Dino V6 engine was converted to this system.

Fiat was a pioneer in engine development during the time period, using toothed rubber belt driven camshafts andaluminium alloy heads. Earlier Fiat Twin Cam engines were actuallyO.S.C.A. designs.

One version was the CHT (for "Controlled High Turbulence"). This version was mainly used in the first generation Fiat Croma and used a special head and intake with auxiliary intake ducts to provide a better fuel and gas mixture under low or partial acceleration.^[1] This meant considerably improved fuel mileage.

Lampredi's twin cam engine was first seen in the Fiat 124 coupé of late 1966, but was later made available in a large number of cars.

The Fiat Twin Cam engine has been widely used inmotorsport and has been the most successful engine in the history of theWorld Rally Championship. TheWorld Rally Championship for Manufacturers has been won by Fiat and Lancia, using engines based on the Lampredi Twin Cam engine, for a total of 10 years.

The four valve version made its first appearance in the Group 4 competition version of the Fiat 124 Spider Abarth, where it had 1.8 litres. Group 4 regulations at that time allowed the use of a cylinder head of a "free" design. This engine still used a three-piece cylinder head design with an included valve angle of 46 degrees.

In later years motorsport regulations were changed so that the use of four valve heads was only possible when the homologated cars had four valve heads. Therefore, the homologation series of the Fiat 131 Rally Abarth came with a two-litre version of the four valve engine.

These engines were later used in the mid-engined Lancia 037, where they were supercharged and eventually enlarged to 2.1 litres.

In addition to the titles in the World Rally Championship, the Fiat Twin Cam equipped theLancia Beta Montecarlo turbo, that won theWorld Sportscar Championship for two consecutive seasons in 1980–1981.

The Fiat Twin Cam has also been used in hot rods and kit cars, with an aftermarket kit to swap one into the Morris Minor.

Constructor	Car used in World Championship	Seasons	Manufacturers' titles
Fiat	Fiat 124 Abarth	1970–1975	—
SEAT	SEAT 1430-1800	1974–1976	—
Lancia	Lancia Beta coupe	1974–1975	—
SEAT	SEAT 124D Gr	1977–1978	—
Fiat	Fiat 131 Abarth	1976–1982	3 (1977, 1978, 1980)
Lancia	Lancia 037	1982–1986	1 (1983)
Lancia	Lancia Delta HF 4WD andDelta Integrale	1987–1993	6 (1987–1992)

• Fiat Pratola Serra modular engines

Wikimedia Commons has media related toFiat Twin Cam engine.

• Fiat engines
• Straight-four engines
• Gasoline engines by model

• CS1 Italian-language sources (it)
• CS1 German-language sources (de)
• CS1 French-language sources (fr)
• Articles needing additional references from February 2010
• All articles needing additional references
• Articles with short description
• Short description is different from Wikidata
• All articles with unsourced statements
• Articles with unsourced statements from February 2010
• Commons category link is on Wikidata