Alfa Romeo Giulietta 1750 TBi

Alfa Romeo Giulietta 1750 Tbi is the most powerful version of the Giulietta model range. We already had a brief description of it in our Alfa Romeo Giulietta engines article. This model is also known as the Quadrifoglio Verde version due to the exclusive availability of this model with this trim. Quadrifoglio Verde means green cloverleaf and this is usually associated with the top performance models from a certain Alfa Romeo model range. The Alfa Romeo Giulietta 1750 Tbi is remarkable not only because it can reach 100 km/h in just 6.8 seconds, or because the engine has 235 HP but mainly because this performance levels are reached from a 1.75 litre engine packed with latest Alfa Romeo innovations. We are going to see which technologies are responsible for these results.

The scavenging technology

In classical terms a car fitted with a turbocharged engine should develop an increasing power especially on the high end of the engine speed, at high revs respectively. This means that at lower revs the driver should notice a lack of power compared with the engine response at higher rpm. This behavior is usually known as turbo lag. It seems that Alfa Romeo engineers have had this issue in their mind when they conceived the engine for the Alfa Romeo Giulietta Quadrifoglio Verde version and did their best to solve this problem. Amazingly they did a very good job, using the scavenging technology to increase engine torque at low engine speeds, minimizing the turbo lag to a level where it is unnoticeable which makes the car to respond better to acceleration. As a fact at 1750 rpm the Alfa Romeo Giulietta 1750 Tbi has a maximum torque value which is 70 percent greater than that coming from a classic turbocharger system. The secret of this result can be found in the improved engine management system and ECU. The engine operating parameters are permanently monitored and the engine response is optimized accordingly. High precision valve control allows an immediate activation of the turbocharger by generating a direct air flow from the intake manifold to the exhaust manifold. As a consequence the response time of the engine is now closer to that of an aspirated engine.

Direct injection technology

The direct injection system of the Alfa Romeo Giulietta 1750 Tbi uses a high pressure pump which can generate fuel pressures of 150 bar and also new injectors with seven holes for best possible fuel atomization. This improves both fuel efficiency and the output of the engine. The fuel injection is also controlled precisely to avoid fuel reaching the exhaust while the scavenging phase takes place.

Dual variable valve timing

The 1.75 litre engine has two continuous variable valve timing units on the intake and exhaust camshafts designed to continuously optimize the timing of the valves to achieve the best possible results in all conditions, including the variation of the engine speeds and loads. This makes it possible for the engine to adapt rapidly at the driving conditions and provide a quicker response even from lower engine revs.

The Turbocharger

Even the turbocharger was designed to make the best use of the exhaust pressure waves and ensure an increase in torque from low engine speeds through a new and innovative pulse converter exhaust manifold. Microcast steel has been used for the making of the manifold and the turbine which allows operation at temperatures as high as 1020 degrees Celsius and improves fuel consumption on motorways.

Fluid Dynamics optimization

In order to give the best performance level possible to the Alfa Romeo Giulietta 1750 Tbi a very fine and precise tuning of the engine was necessary even from the design phase. To optimize the efficiency of combustion it was necessary to make sure that all the fluids inside the engine – air and fuel – have the optimum dynamics. All critical areas like the intake ports, combustion chamber and exhaust ports have been optimized resulting a better mixture of air and petrol, increased combustion efficiency and better use of the exhaust gases by the turbocharger.

Internal engine friction

Obviously, after all these optimizations for obtaining a higher power it would be a pity to let it waste. A further optimization of the engine consisted in reducing friction related power losses throughout the entire engine. As an example, compared with a Twin Spark engine the cylinder heads of the Alfa Romeo Giulietta 1750 Tbi have 65 % less contact losses due to the use of new materials with low wear properties.

The result of the advanced technology used on the Alfa Romeo Giulietta 1750 Tbi

We believe that the engine of this Quadrifoglio Verde version of the Giulietta, as some people prefer to name it, is a wonderful achievement through perfect balance between exceptional performance and engine efficiency and economy. With 350 Nm of torque available from 1900 rpm this 1.75 litre engine is ready to make the Alfa Romeo Giulietta 1750 Tbi a worthy candidate for the premium performance class. The specific power and torque values of 134 HP/litre and 195 Nm/litre speak for themselves. The new technologies used by Alfa Romeo in the development of this engine also allow a EU5 compliance in terms of engine emissions and this is achieved with just a small catalytic converter.

Standard equipments for the Alfa Romeo Giulietta 1750 Tbi

235 HP would seem a high value for the front axle to handle, but the Alfa Romeo Giulietta 1750 Tbi comes standard with VDC with Hill holder including ABS, ASR and brake assistant, electronic Q2 to simulate the presence of a differential, Alfa dna to customize the driving experience and DST. This version, however is the only one in the entire Giulietta model range not fitted with a start and stop system. But it has 17” sports Quadrifoglio Verde alloy wheels with 225/45 tyres and if you want more, there are also 18” sports turbine patterned alloy wheels available as an optional for this model. The list of goodies also include full grain leather seats with microfiber inserts and red stitching, seats in leather and microfiber fabric with red stitching, steering wheel radio controls, white light Matrix Display, aluminium sport pedals, tinted windows, burnished brushed aluminium dashboard insert, sport ride settings, side skirts, red oversized brake calipers. Fog lights, dual zone automatic climate control, cruise control to name the most important ones. Add to this the fine design of the Alfa Romeo Giulietta, as well the excellent safety rating and you are going to face a hard to refuse offer. If you want to have a comparative view of all the available versions refer to the Alfa Romeo Giulietta specifications.