Fiat Twin Cam engine

Designed by ex Ferrari engineer 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" Pratola Serra engine series. 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 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.

Fiat Twin Cam engine
Overview
ManufacturerFiat/Lancia
Production1966–2000
Layout
ConfigurationInline-4
Displacement1.3–2.0 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)
  • 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)
Block materialCast iron
Head materialAluminium alloy
ValvetrainDOHC 2 or 4 valves x cyl.
Combustion
TurbochargerIn some versions
Fuel systemIndirect injection, Direct injection
Fuel typeGasoline
Cooling systemWater-cooled
Chronology
Successor"family B" Pratola Serra

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 1.9 L (1,929 cc) diesel (both the regular indirect-injected unit and the direct-injected one, the first direct-injection diesel appeared in a production passenger car, the Fiat Croma Turbo D i.d.) and 1.7 L (1,698 cc) 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 CHT engine in a Croma

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.

Displacements
Displacement Bore x Stroke Models
1.3 L (1,297 cc)76 mm × 71.5 mm (2.99 in × 2.81 in)Lancia Beta, Fiat 131 Supermirafiori
1.3 L (1,301 cc)76.1 mm × 71.5 mm (3.00 in × 2.81 in)Lancia Beta
1.4 L (1,367 cc)78 mm × 71.5 mm (3.07 in × 2.81 in)Fiat 131 Supermirafiori[2]
1.4 L (1,438 cc)80 mm × 71.5 mm (3.15 in × 2.81 in)Lancia Beta; Fiat 124 Special T/coupe/Spider
1.6 L (1,585 cc)84 mm × 71.5 mm (3.31 in × 2.81 in)Fiat 131 Supermirafiori/132/Argenta/Ritmo 105TC; Lancia Beta/Delta GT/Delta HF/Prisma
1.6 L (1,592 cc)80 mm × 79.2 mm (3.15 in × 3.12 in)Fiat 124 Special T/coupe/Spider, Fiat 132; Lancia Beta, Polski Fiat 125p Monte Carlo
1.6 L (1,608 cc)80 mm × 80 mm (3.15 in × 3.15 in)Fiat 124 coupe/Spider, Fiat 125
1.7 L (1,698 cc)82.6 mm × 79.2 mm (3.25 in × 3.12 in)Fiat Duna/Fiorino/Ritmo/Regata/Uno (turbo) diesel
1.8 L (1,756 cc)84 mm × 79.2 mm (3.31 in × 3.12 in)Fiat 124 coupe/Spider, Fiat 132/Tipo/Tempra; Lancia Beta/Delta/Prisma/Dedra, Polski Fiat 125p Akropolis
1.9 L (1,929 cc)82.6 mm × 90 mm (3.25 in × 3.54 in)Fiat Bravo/Brava/Croma/Ducato/Ritmo/Regata/Tipo/Tempra; Lancia Delta/Dedra/Prisma (turbo) diesel[3]
2.0 L (1,995 cc)84 mm × 90 mm (3.31 in × 3.54 in)Fiat Spider 2000/131/132/Argenta/Strada/Ritmo/Regata/Croma/Tipo/Tempra/coupé; Lancia Beta/Delta/Prisma/Dedra/Thema, FSO Polonez
2.1 L (2,110 cc)85 mm × 93 mm (3.35 in × 3.66 in)Lancia 037 Evo II (also supercharged)

Engine Codes
Engine typeEngine volumeEngine power
124AC3.0001438ccm90HP
124AC.0001438ccm90HP
124AC.0401438ccm96HP
132A.040.41592ccm95HP
132AC.0001592ccm95HP
132A9.0001592ccm98HP
132AC.040.31592ccm87HP
125BC0001608ccm110HP
125BC0401608ccm110HP
132AC1.0001756ccm114HP/118HP
132A1.031.51756ccm83HP
132A1.040.41756ccm86HP
132A1.040.51756ccm86HP
131A1.0401756ccm87HP
132AC4.0001756ccm128HP
132C2.0401995ccm83HP
132C2.0311995ccm87HP
132C3.0311995ccm102HP/105HP
132V3.0311995ccm135HP
125A.0001608ccm90HP
125B.0001608ccm100HP
131B.0001297ccm77HP
131B7.0001301ccm77HP
131C1.0001367ccm77HP
131B1.0001585ccm95HP/98HP
131C3.0001585ccm97HP
132A1.0401756ccm87HP
132C2.0311995ccm80HP
132C2.0401995ccm86HP
132C3.0311995ccm102HP
132C3.0401995ccm80HP/105HP
131B2.0001995ccm115HP
131C4.0001995ccm115HP
132DB.0001995ccm187HP
131AR.0001995ccm140HP/215HP
132A.0001592ccm98HP
132B.0001592ccm98HP
132C.6001585ccm90HP
132C.0001585ccm98HP
132A1.0001756ccm105HP
132B1.0001756ccm107HP/111HP
132CB.0A01585ccm98HP
132C2.0001995ccm112HP
132D.0001585ccm98HP
132D1.0001995ccm113HP
132D4.0001995ccm122HP
132C3.0001995ccm122HP
132D7.0001995ccm135HP
132E.0001995ccm135HP
828B3.0001297ccm82HP
828C3.0001301ccm84HP
828D3.0001367ccm83HP
828A2.0001438ccm90HP
828A.0001592ccm100HP
828AC.0001592ccm108HP
828B.0001585ccm100HP (>82)
828B.0001585ccm108HP (82>)
828A1.0001756ccm110HP
828A1.04051756ccm86HP
828AC1.0001756ccm120HP
134AS.6001756ccm82HP
134AS.03161756ccm82HP
828B1.0001995ccm115HP (->78)
828B1.0001995ccm119HP (79->)
828B1.04051995ccm87HP
134AS.0001995ccm120HP
828B4.0001995ccm122HP
828B4.04051995ccm108HP/106HP
828B7.0001995ccm135HP
?1995ccm205HP (037 stradale)
?2110ccm325HP (competition engine)

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.

Fiat 131 Abarth of Walter Röhrl at 1980 Rallye Sanremo
Constructor Car used in World Championship Seasons Manufacturers' titles
Fiat Fiat 124 Abarth 1970–1975 —
Lancia Lancia Beta coupe 1974–1975 —
Fiat Fiat 131 Abarth 1976–1982 3 (1977, 1978, 1980)
Lancia Lancia 037 1982–1986 1 (1983)
Lancia Lancia Delta HF 4WD and Delta Integrale 1987–1993 6 (1987–1992)

See also

Footnotes
  1. "CHT". Dizionario Tecnico dell'Automobilismo [Technical Automotive Dictionary] (in Italian). Archived from the original on 2013-06-10. Retrieved 2013-05-01.
  2. Büschi, Hans-Ulrich, ed. (March 3, 1982). "Automobil Revue '82" (in German and French). 77. Berne, Switzerland: Hallwag, AG: 296. ISBN 3-444-06062-9. Cite journal requires |journal= (help)
  3. "Fiat Tempra 1.9 Tds Turbo-diesel" (PDF). www.theaa.com.
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