BMW N20 and N26 Four Cylinder Turbocharged Engines

BMW N20 engine

N20 in an X1 xDrive28i


In 2011/12 BMW did something very radical indeed, they replaced their much loved straight six engines with a range of four cylinder turbos. In part the change was driven by ever tighter emissions laws and the desire to offer improved fuel economy. It remains a controversial decision, the only six in the range was the 3.0 turbo N55.

In its initial 2011 form the N20 was sold in the 320i 2.0 turbo and the 328i 2.0 with a bigger turbo. The traditionalists, myself included, were less than impressed by this. There's very little price difference between the models as there's not much engineering difference. The reasons some buyers opt for the cheaper model in the UK include lower annual road tax due to lower emissions, cheaper insurance, better economy and company car taxes.

By 2013 a 1600cc version had emerged to power the F10 520i. At the time of writing all other models use the two litre N20 although there are several levels of tune for the different Z4, X1, X3, three and one series.

Power figures should be taken with a grain of salt or three, especially on used cars. How effective the turbo and engine are will depend on how well it's been looked after and driven. If it's accumulated a lot of carbon deposits on the back of the valves power will be down a fair bit. With any range of turbo engines there will be variation in the state of tune from the factory and differences for regional markets. In addition a fair number of owners will have the cars re-chipped for greater output.

The N26 was produced for markets requiring a super low emissions N20. It has features such as all-metal fuel pipes instead of rubber and extra engine sensors.

BMW N20 engine

That's a nice big intercooler.


In many respects the N20 is two thirds of the six cylinder N55. The current BMW concept is for a series of 3, 4 and 6 cylinder engines with 500cc per cylinder. This is where the N20 sits. BMW believe cars under 1300kg should have the three cylinder N13, above that weight the N20 or for larger / higher performance models the six.

The turbo is a twin scroll model, that's why you see "Twin Power" on the engine's acoustic cover. Twin scroll turbos have two sets of inlets and nozzles, a small sharp angled one for fast response to reduce turbo lag and a large lower angled one for higher boost generation. It's bit like what they tried to do with the variable incidence turbos. Two cylinder exhausts feed each turbo nozzle section.

As you'd expect the engine is Valvetronic and had double VANOS. It uses Bosch direct gasoline injection (GDI) and a high pressure (200 bar) fuel pump which is driven from the exhaust camshaft. It has automatic stop / start and an electric coolant pump as part of BMW's Efficient Dynamics measures.

The block is aluminium and has iron cylinder liners made using a thin film deposition technology. The engine uses a strong forged crankshaft with four balance weights. In a measure to reduce piston friction the centre line of the crankshaft is offset from that of the cylinders above it, a first for BMW. The engine has twin balancer shafts to reduce vibration, a technology pioneered on the M43TU engine.

Initially on the N43 BMW had problems with direct injectors and ignition coils failing prematurely due to heat. To combat this the N20 had extra coolant passages in the head around the injectors. The engine featured a new design of crankcase ventilation system that was part of the valve cover, hopefully it'll clog up less.

BMW N20 engine

N20 in a 328i


Code Size Power
Made Bore x
Timing Weight
N20 1.6
168 @ 5000
154 @ 5000
181 @ 5000
215 @ 5000
241 @ 5000
184 @ 1500-4700
177 @ 1250-4000
199 @ 1250-4000
229 @ 1350-4800
258 @ 1250-4800
2013 on
2013 on
2011 on
2012 on
2011 on
Chain 100 Valvetronic
N26 2.0 241 @ 6500 258 @ 1250-4800 120 129 2012 on 84x90.1 Chain 100 Valvetronic


BMW N20 engine

N20 showing VANOS gear and direct injectors.


As this is a direct injection engine the intake valves aren't cleaned by fuel. They will build up carbon deposits which need to be cleaned by removing the intake manifold, possibly every 40,000 miles. All GDI engines do this, not just BMWs - it's the price we pay for lower emissions. It'll be worse on engines that don't get revved much and do a lot of short trips.

Turbo engines need clean, good quality oil in order to have a long life. Consider changing the oil before the factory recommended interval. Keep an eye on the oil level and never let it go below minimum.

There was a recall for oil starvation on the brake vacuum pump, without this brake servo assistance could be reduced. Valvetronic engines need a vacuum pump because they have no throttle plate so don't create much intake manifold vacuum.

Tuning one of these engines for more power is not a bad thing, so long as it's done professionally on a rolling road. Beware of "wonder chips" and miracle power chips from ebay.

There have been reports of cracked heads due to heat problems if after market tuners push things to far, a limit of 330lb/ft of torque has been quoted by several sources as a figure not to exceed.

In January 2015 BMW redesigned the timing chain to cure a problem found on some engines where it stretched. There was a TSB in 2012 to replace the oil seal on the chain tensioner.

There was a recall for 2014 model year engines due to failure of the high pressure fuel pump. Nickel plating inside the pump was not to the required standard, a supplier problem affecting several car manufacturers. Pumps in these engines seem to fail less than in the N54/N55 three litre engines.