Audi V12 TDI: a quantum leap in diesel technology
Audi's stunning V12 bi-turbo diesel engine is truly the star of its new Le Mans effort.
Audi launched the direct-injection "TDI"-type engine in 1989. Today half of all new Audis carry a TDI powerplant,
with the top of the line production diesel engine a 4.2-liter V8 offering 326 hp and 650 Nm torque.
The all-aluminum V12 bi-turbo is a huge leap forward. Although limited by the Le Mans regulations to a maximum
displacement of 5.5 liters, a maximum boost of 2.94 bar, and a restricted air intake, the engine still develops 650 hp,
and a stump-pulling torque of 1,100 Nm.
The experience for drivers and spectators used to screaming small displacement V8s will be unique - the diesel power
band lies between 3,000 and 5,000 rpm. Equipped with diesel-particulate exhaust filters, the engine is said to be so
quiet that the drivers can't hear it when the car's up to speed, while spectators and photographers will miss not only
the howl of the engine, but also the off-throttle exhaust flames that have become a feature of night-time endurance
racing.
Audi has a track record of migrating racing technologies to production cars. It's not much of a stretch to predict that we will see aluminum-block high performance diesels in future production cars.
Full press release after the jump.
Audi Press Release: V12 TDI
The heart of the Audi R10 is a completely new V12 TDI engine with a cubic capacity of 5.5 litres the maximum
permitted at Le Mans. Audi ventures into previously unexplored diesel-engine terrain with power exceeding 650 hp and
torque of more than 1100 Newton metres from the V12 power plant. This engine is the specifically most powerful diesel
there is in the world and, up until now, the biggest challenge that Audi Sport has ever faced in its long history,
explains Ulrich Baretzky, Head of Engine Technology at Audi Sport. There has never been anything remotely comparable.
We started development with a clean sheet of paper.
The V12 TDI used in the R10 is the first Audi diesel engine with an aluminium crank case. The cylinder-bank angle is
90 degrees. The V12 TDI has, like Audi production car engines, four valves per cylinder and twin overhead camshafts.
The fuel induction is made by a modern Common Rail System. The injection pressure easily exceeds the 1600 bar
achieved in production cars. The ignition pressures also reach values never previously seen in any Audi engine.
The turbo pressure produced by the two Garrett turbochargers is limited by the regulations to 2.94 bars absolute, the
diameter of both engine air intake restrictors, stipulated by the regulations, is 2 x 39.9 millimetres. The engine
management is controlled by the latest generation of Bosch Motronic (MS14).
The engines power and the high torque are available to the driver practically from idling speed a speciality of
diesel technology, to which the Audi drivers must now become accustomed. The usable power band lies between 3000 and
5000 revs per minute.
Unfamiliar to the driver at this early stage, is the low noise level and, unique for a racing engine, the smooth
running V12 TDI power unit. At high speeds the powerful 650 hp engine can not be heard from the Audi R10 prototypes
open cockpit while there is also hardly any vibration. On the outside, the modern twelve-cylinder produces a faint,
but sonorous sound that quite possibly nobody would identify as a diesel power unit at first. The new R10 can only be
recognised acoustically as a diesel-powered sportscar during the warming-up process or in the pit lane.
There are no visual signs that a diesel power unit is at work in the back of the R10. It goes without saying that the
V12 TDI is equipped with a pair of diesel particle filters for the 24 Hours of Le Mans. Flashes of flame from the
exhaust, which are created by unburned petrol in spark-ignition engines, are not seen coming from the R10.
One of the diesel engines biggest advantages is the low fuel consumption, especially at part-throttle and overrun.
However, when compared to more classic circuits which demand a higher ratio of part throttle, the lower specific
consumption will hardly be noticeable at Le Mans because the quota of full-throttle is almost 75 percent.
The enormous torque of over 1,100 Newton metres not only posed previously unforeseen demands in the development of the
R10 drive train. Even the latest generation of engine dynamometers at Audi Sport had to be reequipped with special
gearboxes capable of withstanding the unusual forces.
Inside the V12 TDI, the extremely high pressures in particular create forces never seen before in a racing engine.
However, the main target of the Audi technicians is to reach the reliability level of the R8, which never recorded a
single engine failure in the 77 races it has contested to date.
[Source: Audi]
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Reader Comments (Page 1 of 1)
HardwareGuy 10:50PM (12/18/2005)
Hot.
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Ian 10:50PM (12/18/2005)
I wonder how quickly they can change gearbox at the LeMans 24 hrs?
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all_that 10:50PM (12/18/2005)
FYI: This is about 811 ft-lbs of torque. Nice...
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MikeW 10:50PM (12/18/2005)
I wonder if it is odd firing, or is the crank journals split (with the counterweight in between like V6s)
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JayP 10:50PM (12/18/2005)
"I wonder how quickly they can change gearbox at the LeMans 24 hrs?"
The quickchange rear clip was regulated out for the 2005 LeMans (I think- someone will correct).
With a redline of 5000rpm, the drivers will have to learn to drive the lower RPMs. Should be interesting.
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Rudolf Diesel 10:50PM (12/18/2005)
"With a redline of 5000rpm, the drivers will have to learn to drive the lower RPMs. Should be interesting."
Neah, if you are a trained diesel driver you will drive after "speed" and not "rpm"...
Like this: car standing, get into 1st, short acceleration (between 1 and 3 seconds , depending on the engine displacement and torque), and so on, until you are 1500-1800rpm in 4th, 5th or 6th at anything between 60 and 120km/h...
All of this while never fully accelerating, geting in front of many gasoline cars AND while doing 60mpg or more...
This year I drove only diesels: BMW 120d, 320d, 530d, Audi A4 2.0TDI, VW Golf 1.9TDI, Mercedes Benz C220 CDI, etc...some for more than 10.000km in less than 10 days...all over Europe...
The best and the most economical was the BMW 320d. You could do 130-140km/h constant, doing 1200km on a tank (5.6-5.8 l/100km) and never getting tired.
Did once Murcia-Cologne in one stint: departed at 18.00 and arrived at 17.25 next day with 2 hrs rest in a gas station near Dijon.
Etc, etc...
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grimey559 10:50PM (12/18/2005)
most powerful diesel in the world? what about the gale banks sidewinder truck, 700 hp and 1200 lbs ft. of torque
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m 10:50PM (12/18/2005)
can someone give more info on the flames that are produced when the naturally aspirated engines go off throttle, I would like to find out more about what causes this... thanks
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superjeff 10:50PM (12/18/2005)
While as an engineer I can appreciate the use of SI units, man it's hard to get used to reading Nm instead of foot-lbs. I just wonder how hp and Nm got used in the same sentence. Are Watts not used in the rest of the world for power?
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Car-la 10:50PM (12/18/2005)
A V12 diesel eh? "Vorsprung durch Technik" is all I can say. This is only a logical step considering that half of Audi's sales consist of diesels in Europe. After the BMW 3-series that won the 24h of the N?rgring some time in the 90's, this could be the breakthrough for the diesel in endurance racing. I'm really lookign forward to Le Mans next year, to see if the powerplant survives the race.
This is history in the making.
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Opposite Lock 10:50PM (12/18/2005)
M, on turbo gasoline race cars(rally cars i know for sure, i would assume sportscars as well), the flames that come out of the exhaust off throttle are caused by the anti-lag system. ALS consists of an air valve and fuel injector in the exhaust manifold that acts like a rocket engine to keep the turbo spinning, thus eliminating turbo lag.
This is not used on road cars because it destroys turbos in only a couple thousand miles and sucks through fuel very quickly.
Not sure what causes it on naturally aspirated engines beyond a short exhaust pipe and the fuel not burning completely in the combustion chamber.
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Sam Stone 10:50PM (12/18/2005)
Not quite-- the flames coming out the exhaust of racing engines--turbocharged or naturally aspirated--are a result of an extreme excess amount of fuel being dumped into the engine when the driver lets off of the gas for braking, which is then ignited in the exhaust.
Flames are also likely produced when the driver blips the engine to match revs on downshifts, as a large amount of fuel is injected for the rapid movement of the driver's foot (a tip in or acceleration enrichment)...the load on the engine isn't very high at this time, so once again a large amount of fuel goes unburnt until it hits the hot exhaust manifold.
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