Engine revolution

[CORZZA]

ENGINE REVOLUTION: The badge says GT and that means power but VW's latest GT is kitted with only a 1.4-litre engine - with 127kW on tap!

Specifications

Price: From £18 095 (about R234 000). On sale in Europe. South Africa might have to wait until 2008.

Engine: 1390cc, four cylinders, 16 valves, supercharger and turbocharger, 127kW at 6000rpm, 240Nm from 1750-4750rpm.

Transmission: Six-speed, front-wheel drive.

Performance: 220km/h, 0-100km/h 7.7sec.

Claimed fuel consumption: 7.43 litres/100km.

The petrol engine fights back. Diesel has been in the ascendant for a while now with its easy-driving nature, its fuel economy and - often nowadays - a greater power output than a same-sized petrol engine

Though modern diesels can be quiet, they really don't sound very nice

.

Modern diesels are invariably turbocharged, of course, but it's still a staggering state of affairs when you think how sleepy diesels used to be.

All is not perfect in dieselworld, however. They are good on CO2 emissions but poor on other pollutants and need expensive particulate filters to render them acceptably clean. They have a narrow usable torque band and run out of steam at quite low engine revs so you need lots of gears to get the best from them.

And, though modern diesels can be quiet, they really don't sound very nice. Whatever, diesels have rocketed in popularity as petrol engines, especially small ones, feel ever more feeble as they struggle to cope with heavier cars and tighter emissions legislation.

This, though, is set to change because Volkswagen has launched a petrol engine so capable that it rewrites the rules of what is possible

The engine delivers a big-muscled 240Nm of torque all the way from 1750rpm to 4750rpm

. Meet the Volkswagen Golf TSI.

(VW SA says the TSI won't be here this year and probably not in 2007 either. A spokesman said there might have to be a mindset change among local drivers who, he said, were still obsessed with cubic capacity.)

Its little 1.4-litre engine produces up to 127kW – no, that's not a typo. To get an engine to produce so much more than 100bhp/litre normally means manically high revs and minimal low-speed pulling ability - fine for a racetrack, hopeless on the road.

Not here, though: the engine delivers a big-muscled 240Nm of torque all the way from 1750rpm to 4750rpm. It has the low-end thrust of a good diesel and the high-end eagerness of a highly tuned petrol engine. Cake is simultaneously had and eaten, and all with an official combined-cycle fuel economy figure of about 7.4 litres/100km.

So we have a reasonably hefty Golf GT TSI able to reach 100km/h in 7.7sec and to keep accelerating right up to 220km/h, given the opportunity. All from 1.4 litres.

How on earth…? Read on…

The T in TSI stands for Twincharger. That means two "chargers": a supercharger, belt-driven by the engine, and a turbocharger, driven by the exhaust gases.

Turbocharging is used by many engines, petrol and diesel, but a turbo can take a while to spin quickly enough to provide meaningful boost pressure, especially in a small engine. That can make it frustrating to drive: foot down – nothing - then surge of energy.

A supercharger gives a quicker, more consistent, response but it saps a lot of energy at high speed so it's bad for fuel efficiency.

VW approach

Put the two technologies together and you have an engine capable of miracles. Lancia did this with its Delta S4 rally cars two decades ago but fuel efficiency wasn't uppermost in that company's mind.

The VW approach is different and driven by the commitment among major automakers to have average CO2 emissions, across the fleet of vehicles sold, of only 140g/km by 2008.

The supercharger comes in whenever you accelerate from a low engine speed. It spins five times faster than the engine's crankshaft but its efforts tail off above 2500rpm and by 3500 it's out of the picture, its electromagnetic clutch disengaged and its air supply bypassed.

This is because from 2500rpm the turbocharger is making a useful contribution and by the time the engine is producing its maximum power it is relying on the turbocharger alone.

That what is, by then, simply a turbocharged 1.4-litre engine can produce so much power is down to several factors:

The turbo runs at a high boost pressure.

The engine has a high compression ratio.

Being a direct-injection engine, it can run at that high compression ratio without destroying itself.

That is because injecting the fuel directly into the cylinder has the effect of reducing the temperature inside the cylinder because the vaporisation of the fuel soaks up heat. And this is why the Golf TSI can run at high speed on freeways without needing the extra fuel normally needed in a turbo engine to keep them cool.

So that's another way it gains in fuel economy.

Little click

This is downsizing at its most intelligent. A small engine is a light engine, even with two boost devices. A light engine means a lighter car, which uses less fuel and can have lighter brakes and wheels. And this little TSI engine is cheaper to make than a two-litre turbodiesel while offering similarly easy low-speed pull.

Fine. Does it work? You bet it does!

As you move off in the TSI you hear a little click as the supercharger clutch engages. There's a tiny delay in the accelerator's response because the engine's air supply has such a long journey from air filter to the four cylinders (the pipework almost encircles the engine: filter, supercharger, turbocharger, intercooler, intake port, cylinder) but then you hear a deep, guttural snort like that of an old rally car on Weber carburettors as the supercharger does its stuff.

That snort, never loud but pleasingly characterful, fades as the turbo takes over, but the thrust is insistent right through the speed range.

It really does feel like a two-litre engine, and a very punchy one at that. The accelerator response does soften when the turbo alone is in play but the way you can amble along in high gears and know there's effortless overtaking urge always available is a new experience with such a small engine.

I found a tight uphill hairpin bend on my test route. It involved slowing to about 25km/h in second gear before accelerating away. The Golf TSI powered out of the corner as if pulled by a steam engine.

Better compromise

Yet this is an engine that will pull past 7000rpm. Its breadth of ability is extraordinary and gives a delightful driving experience. The Golf GT to which it is fitted suits the characteristics perfectly, with a ride supple enough to soak up our crumbling road infrastructure yet steering and handling precise enough to satisfy a keen driver.

It's a better compromise all round than even the excellent Golf GTI because it lacks that car's underlying firmness and tiresome tyre roar. As you might expect, the interior trim and the exterior styling are halfway between a regular Golf and a GTI - sporty-ish but not racy.

There's also a 105kW version of the engine for lower-range Golfs and the Touran MPV. Eventually variations on the theme will replace the existing two-litre engines, although the turbo version will continue for the Golf GTI and other cars in the VW group.

It's not often we can hail the arrival of a new engine that does so many things so well but we can do so here. The Golf TSI is nothing short of an automotive miracle

[Daniel]

welcome to a few months ago.

I'd never trust something that has to run 2 bar of boost standard. How the hell would you boost it up?

[CORZZA]

supercharger gets it into turbo boost.

i presume the power would feel like the surge you get in turbo diesel cars with huge torque figures

[selyaT]

How the hell would you boost it up?

You aren't meant to, presumably - seems like they were going for fuel economy

[sportiyo]

i reckon is one interesting engine, 127kw from a 1.4, and there shouldnt be any lag too

Edited February 22, 2007 by sportiyo

[CORZZA]

lets wait for more reviews

[Daniel]

Do people not get it? 7 psi puts alot of strain on most turbo cars. This thing runs like 30 psi on the SC and 35 on the Turbo. It may be a great car when new but own it for more than 50-100 thousand kms and I reckon ull be sitting on a time bomb. save an extra 3 grand and buy the GTi. Thats my thoughts.

[selyaT]

When you're going for more power on a turbo car you strengthen the engine internals before any serious winding up of the boost... You would expect a car that runs such high boost from factory to be strong enough to handle it for an extended period of time straight out of the box. Pretty sure if these things starting being "time-bombs" after 100,000kms then VW would be in a fair bit of trouble. Having released this car you'd imagine they'd have tested it pretty thoroughly and are confident it isn't going to cost them any law suits.

[CORZZA]

exactly!^^

This engine has been engineered to have high boost and last!

[sportiyo]

thats what i thought too, in the game of modifying maybe its too high boost, but if its from the factory, they would of have all the other parts to match the higher boost, its stupid not to, just like golf gti for example, they have a turbo engine in them and more power than 'standard' golfs, its stupid not too have better handling and brake package to match it

[SILVABULLIT]

Mate it's a Volkswagen not a missin Nissan.....

VW's are built to last unlike disposable Nissans and the like....

[Guest JDM y0 !]

the only reason diesel engine is thought to have better torque per liter versus a petrol engine is coz the diesel engines always have a turbo on them now days. i mean TDI 1.6 versus a NA 1.6 is not really a fair comparrison. petrol turbo 1.6 could proberly make better power and torque per liter than a TDI 1.6

im proberly wrong but i just thought i would voice my oppinion... my 2c anways.

but this 1.4 engine sounds really good, really promising engine.

Edited February 24, 2007 by JDM y0 !

[CHA54]

have you seen the fuel economy of the TDI's V's the turbo petrols??

[Guest JDM y0 !]

lol tue... i was owned by that :)

[CORZZA]

Turbo diesel will make more torque than a turbo petrol!

[Guest JDM y0 !]

ah damn lol.

i always thought turbo petrol was better and make more power....how wrong i am.

[CORZZA]

hang on sorry! i meant make more torque! il change it

[Daniel]

Diesels always have turbos because they need to run hot. Remember old petrol cars on hot days, out of tune and under load "ping"? well thats how a diesel car runs. No spark plugs to ignite the fuel just high temperature and high compression ratios. Turbos add to compression ratio as they put more air/fuel mixture into the cylinders and also run hot. Thats why turbos are always used with diesel as it is a perfect match. They are not catagarised by insurance companies as performace cars only "low pressure turbos".

Also the reason why diesels are more fuel efficient is because instead of having to run a 12:1 air/fuel mixture they run a 20:1 or something mixture. This coupled with they fact they dont rev hard and they idle low.

As for the torque - diesel will always have more torque and less power than petrol of the same capacity turbo or not turbo. We'll use the golf as an example seeings as thats what this topic is about.

Golf 2.0 FSI - 110kW / 200NM

Golf 1.9 TDI - 77kW / 250NM

Golf 2.0 TDI - 103kW / 320NM

Golf 2.0 FSI Turbo - 147kW / 280NM

And if you think it is just VW have a look at any comparison. Holden Astra:

Astra 1.9L Turbo Diesel - 110kW / 320NM

Astra 2.0L Turbo Petrol - 147kW / 262NM

Astra 2.2L N/A Petrol - 110kW / 210NM

So summing up, Diesel will always have more torque, better fuel economy, less power and less revs than a petrol equivalent and there are very few if any exceptions.

As for the comment about nissan's. I've owned a skyline GTST. You cant knock a car that will do 0-100 in 6.2 and the quarter mile in 14 flat all day every day even after thousands of kms. I ringed that car's neck every time i drove it and never had a problem. You're also talking about the company that made a factory car in 1989 that did 0-100 in 4.8 seconds (1989 Skyline GTR). A 2007 model HSV wont even go that fast. They also were the first production car to break the 8 minute barrier around the Nuhrenburg circuit (R33 Skyline GTR) and that included supercars like porsche, etc. They do still produce a 350Z which is more of a performance car than what? Do Toyota even make a sports car anymore? oh hang on - no they dont!

So in summing up that one - no nissans are not crap.

[selyaT]

I tend to agree with your Nissan sentiments.

[CAP]

Golf 2.0 FSI - 110kW / 200NM

Golf 1.9 TDI - 77kW / 250NM

Golf 2.0 TDI - 103kW / 320NM

Golf 2.0 FSI Turbo - 147kW / 280NM

And if you think it is just VW have a look at any comparison. Holden Astra:

Astra 1.9L Turbo Diesel - 110kW / 320NM

Astra 2.0L Turbo Petrol - 147kW / 262NM

Astra 2.2L N/A Petrol - 110kW / 210NM

Also the max torque figures of the diesels are developed and sustained at much low rpms in comparison to the petrol equivalent.

[CORZZA]

exactly! and when re tuned the torgue figures jump up even more!

[gengo]

daniel is right ,too many know it alls in here this turbo supercharged vw was covered months ago anyways

Edited February 26, 2007 by gengo