Fiat Twin Cam engine


Designed by ex Ferrari engineer Aurelio Lampredi, the Fiat Twin Cam was an advanced inline-four automobile engine produced from 1966 through 2000 as a Fiat/Lancia engine until it was replaced by the "family B" Pratola Serra engine series. The engine was produced in a large number of displacements, ranging from and was used in Fiat, Lancia, Alfa Romeo, SEAT and Morgan cars. The Fiat Twin Cam engine has been widely used in motorsport and has been the most successful engine in the history of the World Rally Championship. Fiat and Lancia won a total of ten World Rally Championships for Manufacturers using engines based on the Lampredi Twin Cam engine.

Design

The engine uses the block of the OHV 124-series unit first found in the Fiat 124 with some modifications to accept the belt drive for the camshafts. The head itself is made in three pieces, one carrying the combustion chamber and valves and one separate casting for each camshaft in tunnel type bearings. 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 DOHC engines like from Alfa Romeo or Jaguar, small shims were placed on the valve stem inside the bucket 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 camshaft in 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 the Ferrari/Fiat Dino V6 engine was converted to this system.
Fiat was a pioneer in engine development during the time period, using belt driven camshafts and aluminium alloy heads. Earlier Fiat Twin Cam engines were actually O.S.C.A. designs. Despite being SOHC designs, the diesel and blocks are derived from the Lampredi Twin Cam.

Applications

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.

Fiat

One version was the CHT. 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. This meant considerably improved fuel mileage.

Displacements

Engine Codes

Motorsport

The Fiat Twin Cam engine has been widely used in motorsport and has been the most successful engine in the history of the World Rally Championship. The World 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 the Lancia Beta Montecarlo turbo, that won the World Sportscar Championship for two consecutive seasons in 1980-1981.
at 1980 Rallye Sanremo
ConstructorCar used in World ChampionshipSeasonsManufacturers' titles
FiatFiat 124 Abarth1970–1975—
LanciaLancia Beta coupe1974–1975—
FiatFiat 131 Abarth1976–19823
LanciaLancia 0371982–19861
LanciaLancia Delta HF 4WD and Delta Integrale1987–19936

Footnotes