The History of the Fiat Twincam


At the 1966 Motor show of Turin, a new type of engine was unveiled. The work of one of the brightest sparks of the period, Aurelio Lampredi, the engine started a dynasty which lasted over 30 years. During this time it powered everything from family saloons to high powered rally cars, like the Lancia 037 featured here. The engine is the Fiat Twincam (or TC) engine, and it’s history is something that needs to be shared, to understand it’s placing in the engine hall of fame.
At the Fiat factory in the 1960s, Aurelio Lampredi was the man in the know when it came to engines. With a history designing Formula 1 engines for Ferrari, Lampredi possessed a vast knowledge in powerplant design when he started at Fiat, after being ousted from the Scuderia Veloce team. It was due to his efforts and ingenuity that the Twincam became such a popular engine, even to this day.
Taking the rather pedestrian Fiat overhead valve engine, Lampredi & his design team gave it a proper workover. The OHV head was swapped out for a aluminium twin cam cylinder head, and although Hemi heads could be fitted (and some special TC engines received this treatment) the standard heads contained pentroof combustion chambers. The intake valves were inclined at 31.5 degrees to the vertical, the exhaust valves mounted at 33.5 degrees. This valve angle setup helped allow for much better flow in the Twincam, and power increase over the OHV engine it was based on. Fueling duties were taken care of by a Weber 2 barrel 34DFH, while the exhaust was a 4 into 1 system.
The first of the Twincam engines had a bore of 80mm & a stroke of 71.5mm, the long stroke compared to bore diameter allowing for short combustion time and increased torque. 5 main bearings, teamed up with forged conrods & crank allowed for a rather strong bottom end, straight from the factory. In a first for a mass production car, a toothed single-belt drive system was utilised on the engine. This arrangement helped to make timing adjustments easier, and made for quieter engine operating noise. On the downside, the drive belt had to be changed every 36000 miles, according to Fiat.
From a performance point of view, the TC was far ahead of it’s OHV stablemate. To put it in figures, the OHV put out 65hp@5600rpm, while the TC pumped out 96hp@6500. In terms of torque, the TC had 82.5ft/lb versus the OHV 70ft/LB. When looking for comparisons against other car makes, the power output of the Twincam put it on the same hp/ltr standing as a Porsche 911T of the same period. This was quite an achievement for an engine which was to be used in family haulers as well as the sports orientated models in Fiat’s lineup.
Over the years, the displacement of the Twincam fluctuated. The original 1438cc model, unveiled at the Turin show made way for a 1608ccengine, but was dropped back to 1592cc in 1973, by reducing the bore by a millimetre. This was done to dodge a European tax targeting cars displacing more than 1600cc. Eventually the TC settled at 1585cc, the bore measuring at 84mm. Still more variants were produced over the years, of 1756cc and 1995cc.
The original 1438cc powerplant was a sales hit when it was first released, the fact it didn’t much modification to meet American emissions standards made sure it was an easy sell in the United States. The tightening of emission laws changed this though, with European and American cars having to be designed to different standards. When the Twincam was in 1608cc form, the Europeans top of the range cars had 125hp, whereas the American ‘desmogged’ engines had to make do with 104hp. In 1967, Wheels Magazine tested a Twincam Fiat 125, it had been fitted with a 1608cc Twincam engine, specific output was reduced but no exact figure given. This, according to Wheels, was a reason to ‘cry together now, those of us anticipating low cost sedan racing’.
During it’s production run, the Twincam found it’s way into many different models of Fiat, Lancia, and even some Alfa Romeo cars as well. The fact it was so far ahead of it’s time when released allowed it to stay on the market for such an extended amount of time. As well as this, the TC only got better with the advent of fuel injection and turbocharging. Or in the case of the 037, supercharging. The Lancia featured here is fitted with the Fiat TC, with a supercharger setup on it it is putting out somewhere over 300+bhp, not bad for a two litre engine.
In the late 1980s the last major upgrade for the TC engine came, in the form of swapping the exhaust & inlet valves on the head, in order to fit the engines in front wheel drive cars. This allowed for memorable models such as the Lancia Delta Integrale, which had a Garrett T3 turbocharger, contra rotating balancing shaft and fuel injection all added to the power of this marvellously engineered powerplant.
The end of the Fiat Twincam’s period as a production engine came at the end of 1999, when the Nuova Delta was dropped from the Lancia lineup. For over three decades, Aurelio Lampredi’s ‘little engine that could’ had been winning motor races, as well as giving the motoring public a chance to drive something interesting to the shops, should they be in the mood for some more spirited driving. In numerous guises, powering various cars, it is testament to Signore Lampredi’s talent as an engine designer. It is due to his desire to have a mass produced Twincam engine, the Fiat engine has such a standing today.

4 thoughts on “The History of the Fiat Twincam

  1. Great article!

    I’m from Brazil and i’m studying about this engine (Fiat Twin Cam / Bialbero Lampredi) and i’m each time more and more fascinated!

    I had a Fiat Tempra 2.0 16V with 135hp. Amazing setup to an daily use car (here in Brazil, at least).

    Best regards.

  2. The Lampredi TC cylinder head is not a Hemi, it is a Pent Roof similar to the majority of modern cylinder heads including the now common four valve cylinder head. Lampredi understood well the problems with a Hemi head. Historically the Hemi head problem of non-uniform burn was addressed by using two spark plugs, The Pent Roof chamber addresses this problem without the need for two spark plugs.

    This Lampredi engine along with the Single Over Head Cam engine designed about the asme time remains two of the best low cost high performance engines built to date.

    Both engine design suffered from the being among the first production engines to use cog belt cam drive which mandated replacement, a service requirement the majority of American wrenchers could not accept and was totally alien to them at the time. This lack of understanding and lack of respect for this mandatory required service became part of the gear head myth of why Fiat’s were un-reliable, fragile and more..

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