Fiat twin cam engine
| Fiat Twin Cam engine | |
|---|---|
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| Overview | |
| Manufacturer | Fiat/Lancia |
| Production | 1966–2000 |
Designed by Aurelio Lampredi, the Fiat Twin Cam (also known as the Lampredi 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" series of engines. The engine uses the block of the OHV engine 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. The engine was produced in a large number of displacements, ranging from 1,297 cc to 1,995 cc 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. 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.
Fiat was the pioneer in engine development during the time period, using a monoblock technology, belt driven camshafts and aluminium alloy heads. Earlier Fiat Twin Cam engines were actually O.S.C.A. designs. Curiously, the first directly injected diesel engine in a passenger car, the 1929cc engine powering the Fiat Croma Turbo D i.d, also derives from the Lampredi Twin Cam, despite being a SOHC design.
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