Citroen 'Common Rail' HDi engines

HDi Diesel Technology

I learned about the HDi 'Common Rail' Diesel technology in 2005 and was surprised to discover that it was first introduced in 1998. It's incredible that this technology has been around for over two decades and is still used in many Citroen Diesel engines. I was particularly impressed to learn that the 1.4HDi 16v (89hp), 1.4HDi (69hp) and the 1.6HDiF (108hp) all use this technology. It's clear that HDi Diesel technology has stood the test of time and is still a reliable choice for many drivers today.

Common Rail

High-pressure direct injection (HDi) uses Common Rail technology to inject fuel under very high pressure (up to 1800 bars on the 1.4HDi 16v (89hp) hence pulverising the fuel to increase the efficiency of the burn. The benefits to the driver and the environment are many and include:

Increase of power, performance and torque

HDi engines develop high torque at low engine speeds and, as a result, are quick to respond in all circumstances to bring the driver increased safety, driving pleasure and peace of mind. For instance, the 1.4 16v HDi 89hp engine is turbocharged with an air-to-air intercooler and a capacity of 1398cc. It develops maximum power of 66kW (89bhp) at 4000rpm with a torque of 200Nm at 2000rpm.

Improved fuel consumption

Due to the pulverisation of the fuel in the combustion chamber, more complete and uniform combustion is achieved, resulting in considerably improved fuel consumption compared to conventional indirect injection diesel engines. For instance, the 1.4 16v HDi 89hp, when fitted to the Citroen C3 5-door manual, delivers an impressive 65.7mpg (4.3 litres/100km) in the combined cycle, 53.3mpg (5.3litres/100km) in the urban cycle and 76.3mpg (3.7 litres/100km) in the extra-urban cycle (N.B. official government test fuel consumption).

Reduced C02 emission

The efficiency of the burn and reduced fuel consumption considerably reduce pollutant emissions to make the engine more environmentally friendly. Emissions of C02 gas, the leading cause of the greenhouse effect, are therefore considerably lower than similar-sized petrol and indirect injection diesel engines. For instance, in the Citroen C3 5-door manual, the 1.4 HDi 69 hp engine only emits 110 grams per kilometre, which put it into the lowest diesel Government Excise Duty (Road Fund Licence) group at the time.

Reduced particulate emissions

All Citroen HDi engines significantly reduce particulate emissions compared to the previous generation of indirect diesel engines. This reduction in emissions is taken even further with the 1.6 HDiF engine with its integrated state-of-the-art Diesel Particle Filter (DPF), which periodically burns off the remaining particles, virtually eliminating diesel smoke and far exceeding current E.U. environmental standards.

Reduced engine running noise

Noise emission reductions are tackled on 3 fronts – first; noise reduction is at the source through a pre-injection of fuel that gradually increases the temperature in the combustion chamber, reducing the 'bang' or 'diesel knock' generally associated with diesel combustion. Secondly, the engine is stiffened by ribbing to reduce vibration noise, and finally, the engine is encapsulated for the well-being and acoustic comfort of the occupants.

Instant start-up

The high injection pressure means that HDi engines can start without preheating when the outside temperature is above O°C.