2007 International Engine

The  2007 International Engine of the Year awards announced recently in Britain again highlight the fact that while the clock is ticking on the internal combustion engine it does still have plenty of life and development potential left in the short/mid term.

In several categories, petrol and diesel engine technology has been further refined to improve performance and fuel economy/emissions, proving that the two objectives are not necessarily mutually exclusive.

It has been done by taking technology from the petrol and diesel genres, using smaller capacities and applying traditional performance engineering, including forced induction, high compression ratios and variable valve timing, to extract high outputs without the attendant high fuel consumption and emissions.

The International Engine of the Year awards, now in their ninth year, are judged by 62 motoring writers from 30 countries. The Australian representatives are mynrma.com.au's Bill McKinnon and John Carey from Wheels magazine.

There are eight categories for specific capacity groupings, from Sub 1.0 litre to Above 4.0 litre, plus categories for Best Fuel Economy, Best Performance Engine and Best New Engine of the Year. The overall International Engine of the Year is chosen from the category winners.

The envelopes, please...

Sub 1.0 litre

This category is big in Japan and to a lesser extent Europe, where engines of less than 1.0 litre are much more common than they are here.

This year's winner is the Toyota 1.0 litre three-cylinder petrol engine found in the Aygo, a tiny hatch (smaller than the Yaris) that's not sold yet in Australia. The same engine is also used in the Citroën C1 and Peugeot 107, plus a Yaris variant in Europe.

The Toyota 1-litre is the lightest internal combustion engine on sale today. Weighing 69kg, its designers employed an all-aluminium construction and made the throttle body and fuel pipe out of resin instead of metal.

A small cylinder bore-to-bore distance makes for a very compact engine block - the wall thickness between the bores is just 7mm, thinner than on any other Toyota engine - and the air intake system and engine cover are integrated into a single unit, a design first for the Japanese firm.

With 50kW of power and 93Nm of torque at 3,600rpm, the engine has impressive performance for a 1-litre. And with a potential consumption of 4.6 litres/100km, it also has the lowest combined cycle fuel consumption for a petrol engine in its segment. 

1.0-1.4 litre

Volkswagen has again taken the money in the 1-litre to 1.4-litre class, for the second consecutive year, with the 1.4-litre TSI Twincharger, an engine that has just been introduced to Australia in the new Golf GT.

Twincharger refers to the fact that the VW engine uses a supercharger and a turbocharger. It's the only production engine to employ both forms of forced induction. Direct injection and a high 10:1 compression ratio are other significant features that enhance performance and economy.

The belt driven supercharger operates from idle to enhance low speed tractability and responsiveness. The turbocharger takes over at midrange revs, delivering a lag-free top end kick that's comparable with a sporty 2.0 litre engine.

So are the 1.4's numbers. It produces 125kW of power at 6000rpm and 240Nm of torque from 1750-4500rpm. Matched with the six speed automated manual DSG transmission, it averages 9.9 litres/100 km in town and 5.8 litres/100 km on the highway, according to European standard tests. CO2 emissions are 176g/km.

The Twincharger is a remarkable piece of machinery. Across the bottom half of the rev range, it feels almost like a diesel in its effortless torque delivery. At the top end, though, it also spins smoothly and willingly to 7000rpm, driving the Golf to 100 km/h in just 7.2 seconds. Not bad for 1.4 litres.

1.4-1.8 litre

This award goes to an engine that's also designed to maximise performance from a small, frugal capacity.

It's the 1.6 litre turbo petrol engine, developed by BMW and Peugeot/Citroën, available here in the Peugeot 207 GTi and Mini Cooper S.

The 1.6 is as high tech as they come. It's constructed from light alloy and features a twin-scroll turbocharger, direct injection, twin overhead camshafts, roller-type drag arms optimised for minimum friction, and hydraulic valve adjusters. The outlet valves are filled with sodium to aid cooling, while the intake camshaft comes with infinite timing adjustment, setting the engine's valve timing to the driver's power and performance requirements.

It produces 128kW of power at 5500rpm and 240 Nm of torque from 1600-5000rpm, with up to 260Nm available under hard acceleration.

Yet it also returns a claimed 20 per cent improvement in fuel consumption over the 125kW supercharged 1.6 in the previous Cooper S. It averages just 8.9 litres/100 km in town and 5.7 litres/100 km on the open road. CO2 emissions are 164g/km.

1.8-2.0 litre

No surprises here - the VW/Audi 2.0 litre direct injection turbo petrol (TFSI) engine has taken this class for the third consecutive year.

It's available in several local models, including the VW Golf GTi, Eos and Passat, plus Audi's A3, A4, A6 and TT. It produces 147kW of power at 5100-6000 rpm and 280Nm of torque from 1800-5000rpm.

A high performance version, with 194kW, has just been released in the new Audi S3.

The 2.0 litre pulls with surprising ease from idle, then segues without the usual turbo kick into a punchy, flexible midrange and crisp, responsive top end. It's impeccably smooth throughout, makes deliciously fat four cylinder blat noises and can return very good economy - albeit on recommended 98 octane premium.

Its average consumption (in the Audi TT) is just 7.8 litres/100 km, with CO2 emissions of 183g/km. Expect 10-12 litres/100 km in town.

2.0-2.5 litre

Stand by for an avalanche of BMW engines, which is fair enough because as far as six cylinder and V8 engines go, BMW usually delivers the best blend of performance, economy and refinement.

It's the six cylinders that really shine, with beautiful smoothness, responsiveness and technical sophistication. The fact that BMW is one of the few manufacturers that also pays serious attention to minimising the weight of its cars only enhances the efficiency of its powerplants.

This class was won by the 2.5 litre petrol straight six, found here in the 325i sedan and coupé, 525i, Z4 Roadster and X3.

It produces 160kW at 6500rpm and 250Nm from 2750-4000rpm. The 325i coupé auto averages 12.9 litres/100 km in town and 6.7 litres/100 km on the highway; CO2 emissions are 218g/km.

Making use of other BMW innovations first seen in the 2,497cc unit's 3-litre sibling, parts of the crankcase, bedplate and cylinder head cover are complex castings comprising a stiffer, lighter, magnesium alloy, and an aluminium alloy.

When installed in the 325i, the engine's low mass contributes to the car's 50:50 weight distribution and helps limit the car's unladen kerb weight to 1,450kg. Light weight means better performance: the 325i auto coupé accelerates to 100km/h from a standstill in a claimed 7.6 seconds.

2.5-3.0 litre, Best New Engine and 2007 International Engine of the Year

BMW has taken this year's top honour, plus two other category wins, with its new 3.0 litre twin turbo six, found in the 335i sedan, convertible and coupé.

It employs two phased turbochargers, direct injection and, like the 2.5, has a magnesium/aluminium alloy construction. BMW wanted to deliver V8-like performance without the economy or weight penalties inherent in a larger capacity.

The 3.0 produces 225kW of power at 5800 rpm and 400Nm of torque from 1300 rpm all the way to 5000 rpm.

Apart from a trace of lag when you squeeze the pedal in the higher gears at low revs, there is no obvious sign from the driver's seat that you're working with a forced induction engine.

The 3.0 goes and sounds like a BMW six should. It's satin smooth, well mannered in the tedium of traffic and relatively quiet.

Across the midrange and top end, from 3000-7000 rpm, it is also seriously mean and gives away virtually nothing in sheer performance to the mighty M3. It drives the 335i six speed auto coupé to 100 km/h in just 5.7 seconds.

Yet it averages 13.8 litres/100 km in town and 7.0 litres/100 km on the highway according to European standard tests, and emits 228g/km of CO2.

3.0-4.0 litre

After taking this class for the past six years (plus the IEOTY and Best New Engine categories in 2001) the most successful engine ever in the IEOTY awards, BMW's 252kW 3.2 litre straight six S54 engine, as used in the M3, has finally been knocked off by Porsche's formidable new 3.6 litre twin turbo horizontally opposed six, as used in the 911 Turbo.

This thing is a beast. It produces 353kW of power at 6000rpm and 620Nm of torque from 1950-5000rpm. The optional Sports Chrono package includes an overboost function, which increases torque to 680Nm from 2100-4000rpm.

It uses two turbochargers with variable vanes, two intercoolers, dry sump lubrication, variable inlet valve timing and lift. The engine takes eleven litres of oil. Servicing is required only at 30,000 km intervals. So why does a Camry need to be serviced every 7,500 km?

It drives the 911 Turbo to 100km/h in just 3.9 seconds. Fuel consumption figures are not pretty, but economy is at least better than most V8s: 18.8 litres/100 km in town and 9.5 litres/100km on the open road. It produces 307g/km of CO2.

Above 4.0 litre and Best Performance Engine

The overall winner of the International Engine of the Year title for the past two years, the 5-litre V10 from BMW that powers the M5 and M6, returns in 2007 to secure the Above 4-litre category title, and the Best Performance Engine category, for the third consecutive year. The victory means that in all, the unit has now won eight 'Engine Oscars'.

It produces up to 373kW of power at 7750rpm and 520Nm of torque at 6100rpm. It is basically a race spec engine for the road, with a radically oversquare bore and stroke (92.0 x 75.2 mm) that allows it to rev to 8250rpm.

It boasts one-piece, four-valve, aluminium cylinder heads, while the valve train components, such as the 5mm valve shafts, have been engineered for low mass. There are 10 individual throttle butterflies. Production techniques have also played their part in keeping the weight low - the cylinder crankcases are cast using the low pressure gravity die method and made from a lightweight hypereutectic aluminium silicon alloy.

Matched with a seven-speed sequential manual gearbox, it drives the M5 to 100km/h in 4.8 seconds. It uses 22.7 litres/100 km in town and 10.2 litres/100 km on the highway. CO2 emissions are 357g/km.

Best Fuel Economy

It's a fourth straight year at the top of the Best Fuel Economy category in the International Engine of the Year Awards for Toyota with the 1.5-litre Hybrid Synergy Drive unit. The result means that Prius's power train, which was voted International Engine of the Year in 2004, has now garnered nine awards.

The hybrid powerplant's consistently strong performances at the Awards are due in no small measure to its wide fan base: 35 of the 62 judges awarded it points, helping it finish 114 points clear of the second-placed Honda Hybrid 1.3-litre IMA, as used in the Civic Hybrid.

The anatomy of the Hybrid Synergy Drive is now familiar. The 1.5-litre petrol motor with 57kW of power and 115 Nm of torque is engineered to run on the Atkinson cycle, allowing the compression and expansion strokes to be independently set. An electric motor works in tandem with the internal combustion engine, providing a combined output of 82kW and a V8 like 478Nm of torque from startup. The combination propels the Prius from zero to 100km/h in under 11 seconds while averaging just 4.4 litres/100 km and emitting just 106g/km of CO2.

Prius II has become the best-selling hybrid car to date, with 500,000 of them now on the road around the globe. Toyota plans to make 280,000 Prius IIs in 2007, forming the lion's share of its 430,000 annual total hybrid production target.

Article by Bill McKinnon, June 2007.