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BMW and PSA Peugeot Citroën Introduce New 1.4-Liter Gasoline Engine

Engine partners BMW Group and PSA Peugeot Citroën have introduced a new, naturally aspirated 1.4 liter gasoline engine as part of a growing family. This new engine, which is applied in the upcoming new MINI One (earlier post) is directly derived from the existing 1.6 liter engine already applied in the MINI Cooper and Cooper S as well as on the Peugeot 207.

The new engine delivers 71 kW (95 hp) of power at 6,000 rpm. The torque varies from 136 Nm to 140 Nm depending on the application. It uses intake and exhaust variable valve timing and variable valve lift to optimize the output, while decreasing fuel consumption.

The variable valve lift system on the inlet valves allows the maximum valve lift to be adjusted gradually according to the position of the accelerator pedal. This technology removes the need for a throttle butterfly as the engine power is now controlled through the infinite adjustment of the inlet valve lift and intake valve opening times.

In a conventional engine the engine power output is controlled by means of a throttle butterfly. The required amount of air to be drawn into the engine is regulated by the position of the throttle butterfly; however, at certain engine speeds and throttle butterfly positions, the incoming air has to squeeze past the partially closed or closed butterfly, reducing the air flow into the engine.

Overcoming this resistance reduces potential power and overall engine efficiency and also increases fuel consumption.

The combination of the variable valve timing (VVT) system and the variable inlet valve lift system improves the engine’s efficiency and reduces fuel consumption. It also delivers improved engine responsiveness and greater engine flexibility.

The new engine has the same bore as its parent, but a reduced stroke.

As applied in the new MINI One, the 1.4-liter engine offers fuel consumption of 5.7 l/100km (41.3 mpg US), compared to 6.8 l/100km (35 mpg US) from its predecessor—a 16% reduction in fuel consumption. CO2 emissions are now 138 g/km, compared to 164 g/km produced by the previous model.

The companies plan full production of this engine family (1.4-liter and 1.6-liter) to reach one million units per year. The companies envision that of that, 40% will be the naturally aspirated 1.4-liter unit, 40% the naturally-aspirated 1.6-liter unit, and 20% will be a 1.6-liter turbocharged gasoline direct injection unit.

The PSA Peugeot Citroën plant of Douvrin (region Nord Pas de Calais) will manufacture all the engine’s components for both companies, and is also in charge of the engine assembly for PSA Peugeot Citroën. BMW will assemble the engines for MINI in its plant in Hams Hall (UK).

BMW Group and PSA Peugeot Citroën announced their partnership in Munich in December 2004. The joint development of the engines took place in the BMW Group R&D Centre in Munich with teams of engineers of both groups. R&D costs are shared by both partners.


Bud Johns

I'm impressed......they have pretty much eliminated pumping losses. I would love to know just how they control the valves so presicly!


The fuel consumption gains are impressive, but I'm betting there are still pumping losses--the piston is now sucking air past the partially-open valves instead of past the partially-open butterfly valve. You are still restricting the airflow based on engine load (unlike a diesel).

Bud Johns

Good point......


But the valves no longer have to open against a vacuum in the manifold.


What I find to be FAR more interesting is how BMW's 1 series 118i (1.8L 4 banger) gets 143hp with 40mpg fuel economy and 140g/km CO2 while this tiny 1.4L (also from BMW) with 95hp struggles to achieve 41.3mpg with 138g/km CO2.

Sorry, but I would automatically opt for the 118i over the Mini One any day. Similar fuel economy, similar greenhouse gas emissions, (one has to guess that other emissions are similar) and 50% more power.


You are still restricting the airflow based on engine load (unlike a diesel).

AIUI the idea is to open the valves fully until the necessary charge is drawn in, then fully close them. So for part of the intake stroke the piston is working against a vacuum, but for part of the compression stroke it's working with a vacuum: that is, the charge (at less than atmospheric presure) is acting like a gas spring. It's not quite adiabatic so it will be a bit lossy, but apparently less lossy than a throttle plate.

That said, the BMW diesels are 25-40% more fuel efficient than their gassers, VVT or no.

Rafael Seidl

Bud Johns -

BMW introduced its purely mechanical Valvetronic system several years ago. In a nutshell, a configurable guide mechanism allows some or all of the cam-driven motion to be "lost" to a spring without moving the valve stem. BMW's is just one of several possible implementations of this idea. Variable valve lift systems are usually only applied for the intake side of spark ignition engines and combined with cam phasers.

By now, the subcontractors that supply the high precision parts needed to very accurately control valve lift have obviously perfected their manufacturing technology to the point where it is economical even in a 1.4L engine destined for compact and sub-compact cars.

Patrick -

the new 1 series features zero idling, mild recuperative braking and several other fuel-saving features in the engine periphery. They may well choose to add those to the Mini at the next opportunity. People tend to buy it because they like its look and handling, though a 175hp turbocharged engine is available for serious gearheads.


A friend of mine has a 3-series BMW with the 2.5 litre engine with VALVETRONIC system, and the actual fuel economy is not goog. In Mexico city driving it only gets 6.5 km/litre = 15.3 MPG = 15.38 l/100km.
(with the air conditioning turned on)
So, who is right about the VALVETRONIC system,
Nick or cidi ?



You are right – there is no much difference between sucking air past partially closed throttle or partially closed intake valve. The trick is to close intake valve completely as early as possible, and this way pumping losses are greatly reduced, thought not eliminated. Variable valve lift is necessary to maintain good atomization of port-injected fuel. Theoretically variable valve lift is unnecessary on direct injection gasoline engine.

BMW engineers never stop to amaze me. How the hell they achieve such a precision?

Rafael Seidl

Jorge -

as long as a spark ignition is operated stoichiometrically, the mass of the fresh charge has to be managed by reducing its density relative to that needed at rated power, i.e. you need some form of throttling. Variable valve lift by itself buys you about 7% in terms of fuel economy, via reduced fluid dynamic losses and improved air-fuel mixture.

For those of you who are interested in the details of how the 2nd generation Valvetronic system works and the manufacturing challenges it presents (for-fee content):


Andrey's comment that variable valve lift is not necessary on GDI engines applies only if such engines are operated with globally lean mixtures in part load. While this is possible (cp. Mercedes M272 engine, BMW 335i), you do need to add a fairly expensive lean burn NOx aftertreatment system to meet emissions. Most GDI engines these days are actually operate stoichiometrically and throttle airflow in part load. The gains are then limited to the increased compression ratio (evaporative cooling by the fuel) and especially, the improved scavenging (greater negative valve operlap).


What a joke.
I drive a '96 Geo Metro and regularly get 37 mpg city. When I baby it I can get 41. The thing is 10 years old and I bought it for $1900 a few years back. Never done anything to it.
1.3 L 4 cyl, 70 hp, 74 ft-lbs torque
Something will fail on this Citroen little boy motor in three years.



This motor has more than 25% more power and nearly 50% more torque than your Geo Metro motor, all while getting the same fuel economy on nearly the same displacement. I'm impressed. As for reliability -- we'll know when we know. BMW has a good reputation, so I'm not inclined to believe such negative thoughts automatically.



I was actually referring that only variable valve lift could be unnecessary on GDI engine. Variable valve timing is great thing and benefits the engine on all counts. It is making the engine variable Atkinson (Miller with turbo) cycle!

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