BMW to debut three-pot thumper

BMW will unveil its all-new three-cylinder engine family inside its Compact Activity Tourer concept car at this month’s Paris Motor Show, sources insist.

The Bavarian company has admitted to working on the three-cylinder family and while BMW officially refuses to comment, sources have no doubt the 1.5-litre engine will emerge in the engine bay of the brand’s first front-wheel drive car in a couple of weeks.

Don’t expect it to be a pure fuel-sipper, though, because BMW’s own proposed performance outputs hint at an eventual 165kW of power from the strongest of the smaller engines.

BMW will launch a diesel three-cylinder engine, too, offering no less than 135kW of power and an astonishing 330Nm from the strongest of the powerplants.

The engine, to be built on existing BMW production lines and with the ability to be employed in front-, rear- and all-wheel drive applications, is part of BMW’s strategy to slash its fuel consumption by 25 per cent by 2020.

Due on sale in the 1 Series within a year, the three-cylinder petrol engine is designed to share up to 60 per cent of its parts with its 2.0-litre four-cylinder and 3.0-litre six-cylinder cousins.

It will also share up to 40 per cent of its parts with the three-cylinder diesel, including its bore spacings, aluminium crankcase, timing chain and cylinder-head bolt layout, bore surface coatings, engine mounts, cooling circuits and intake and exhaust manifold interfaces.

The result will be that all of BMW’s mainstream three-, four- and six-cylinder engines will be built on the same production lines at the same time.

BMW has spent more than €300 million getting its manufacturing facilities ready for the new engine and motoring.com.au sources have been told BMW’s ultimate aim is to deliver 10 new petrol and diesel engines across its three basic engine sizes.

Sources insist the new three-cylinder engine is more like half of a six-cylinder engine (rather than a four-cylinder engine with one cylinder sliced off) and the technology reflects the claim.

It will come as a TwinPower engine, which means peak versions will carry technologies like direct fuel-injection, variable intake valve lift, continuously variable timing for both the intake and exhaust valves and even a twin-scroll turbocharger.

There will also be lower-performing versions of the engine with single-scroll turbocharging, and it will even find work as a range-extending generator for BMW’s upcoming hybrid model family.

While BMW is yet to make specific fuel consumption claims for the new engine, it has targeted a 25 per cent reduction in its across-the-board fuel economy by 2020, to back up the 25 per cent cut it achieved from 1995 to 2008.

More than 70 of BMW’s current models emit 140 grams of CO2/km or less, with 30 of them below the 120 mark. With a range of hybrid, plug-in hybrid, all-electric i-car and both petrol and diesel three-cylinder models coming, the number of economical BMWs is set to leap dramatically.

Sources have told motoring.com.au that all of its engines have been engineered around a single-cylinder design, multiplied by an engine’s cylinder count.

All of BMW’s future sub-V8 engines will have the same per-cylinder power and torque ranges, with sources revealing the petrol engines will produce between 30kW and 55kW per cylinder. They will back this up with between 60Nm and 80Nm of torque per cylinder.

The diesel engines have been organized along similar lines and will produce between 20kW and 45kW of power per cylinder, and between 75Nm and 110Nm of torque.

      
       
       
       
Of course, BMW being BMW, there will be a range of engine outputs spliced between the maximum and minimum ranges, as evidenced by BMW’s 3 Series range today.

“It’s not just about economy, this three-cylinder move,” a high-placed BMW source insisted.

“There are plenty of sound engineering moves behind it, too. For example, the 1.5-litre has high-revving characteristics, like the inline six, and it delivers a sporty sound and athletic responsiveness, too.

“The layout does a lot of technical things, like generating no free inertial forces or free moments of inertia. It’s also free of first and second order inertial forces and the balance shaft design eliminates any torque roll you could expect from this sort of engine.

“There’s also a torsional vibration damper to make it feel smoother, and the sound of a three-cylinder increases 50 per cent faster than a four-cylinder. That’s a significant side benefit of the layout,” he said.

BMW will offer the new three-cylinder engine range in its upcoming UKL (underclass) architecture, which will be home to the next MINI in 2014 and almost certainly the next 1 Series BMW in 2019, along with the production car that develops off the Compact Activity Tourer concept car.

Both the petrol and diesel versions of it will see duty in front-drive BMW and MINI models too.

Above that, the three-cylinder siblings will power the 1 Series, X1, 2 Series and 3 Series, and BMW has not ruled out sitting it inside an ultra-eco version of the 5 Series.

They will also sit inside plug-in hybrids, both for BMW’s upcoming i sub-brand and in standard BMW and MINI bodyshells. The new BMW triples will be built in Munich, Hams Hall (England), Steyr (Austria) and Shenyang (China).

BMW will combine the new engines with other fuel-sipping technologies, like its Eco Pro mode that is claimed to reduce consumption by up to 20 per cent by “training” drivers to use less fuel, a learn-as-it-goes eight-speed automatic transmission and intelligent energy management for cooling, heating, transmission and electrical systems.

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