BMW introduces new 6-cylinder in-line diesel with 3 turbochargers for new M Performance models

Greencarcongress ^ | 1/26/2012

[Jack of all Trades]

BMW has introduced a new range of M Performance Automobiles featuring a new 6-cylinder in-line diesel developed exclusively for those applications. The engines, which feature three turbochargers, deliver maximum output reaching 280 kW/381 hp and peak torque of 740 N·m (546 lb-ft).

The new engine is applied in the BMW M550d xDrive Sedan, BMW M550d xDrive Touring, BMW X5 M50d and BMW X6 M50d. The vehicles are also equipped with an eight-speed sports automatic gearbox and the intelligent all-wheel-drive system BMW xDrive tuned to suit each model, as well as BMW EfficientDynamics technologies, including Auto Start-Stop and ECO PRO mode.

The BMW M550d xDrive Sedan, the most fuel-efficient of the new series, accelerates from 0 – 100 km/h (62 mph) in 4.7 seconds and has a top speed of 250 km/h (155 mph). Average fuel consumption is 6.3 liters/100 kilometers (37.3 mpg US), with CO2 emissions of 165 g/km. The vehicle meets Euro 6 exhaust standards.

Output and torque diagram for the new diesel. Click to enlarge. M Performance TwinPower Turbo diesel with tri-turbo. The market launch of the first BMW M Performance Automobiles also marks the premiere of the most powerful diesel engine ever fitted in one of the brand’s models. With maximum output of 280 kW/381 hp, the 2,993 cc engine has a specific output of 93.6 kW/127.3 hp per liter of displacement. The maximum torque of 740 N·m (546 lb-ft) is on tap as low down as 2,000 rpm.

Playing a central role in this increase in power is M Performance TwinPower Turbo technology. The engine developed for the BMW M Performance Automobiles will, for the first time, see two comparatively small high-pressure chargers working with a larger low-pressure unit. The integration of an additional high-pressure turbo increases the engine’s capability when it comes to generating charge pressure, a key ingredient in taking the engine’s power output to the next level.

The M Performance TwinPower Turbo technology—including the requisite charge air cooling—is integrated into a small space in the main unit. Its compact construction puts the engine in a position to meet future pedestrian protection stipulations, while the arrangement of the three turbochargers is also part of an intelligent system.

Both the exhaust inflow to drive the turbos and the supply of fresh air, plus the channelling of compressed air to the combustion chambers, have been designed to ensure that the three compression units work as a team as effectively as possible at all engine speeds. Efficiency is further optimized by the variable turbine geometry of the two high-pressure chargers, which allows them to react even more precisely to the driver’s power needs.

One of the two small turbos is activated at engine speeds just above idle. Its low moment of inertia allows it to respond without delay to slight movements of the accelerator and therefore supply the combustion chambers with compressed air at an early stage. As revs increase, the flow of exhaust gas also reaches the larger turbocharger, which announces its arrival with the engine spinning at just 1,500 rpm. Working together with the small charger, it ensures that the peak torque of 740 Newton metres (546 lb-ft) is generated at this low engine speed and maintained up to 3,000 rpm.

To further increase the performance of the large turbocharger, a greater volume of exhaust gas is required at around 2,700 rpm. If the driver calls up additional power, a vacuum-modulated exhaust flap instantly opens up another supply route, allowing extra exhaust gas to flow past the already active high-pressure charger to the large low-pressure turbo. The third turbocharger—integrated into this bypass line—also has a low moment of inertia and variable compressor geometry, which allow it to spring into action as soon as the exhaust flap opens. The result is additional charge pressure, generated by two sources at the same time. The large turbocharger is able to deliver its full output, while the second small turbo builds on the effect of its two active colleagues by supplying even more compressed air to the combustion chambers.

This arrangement allows the turbocharging system to drive the engine with sustained thrust to its maximum output, which it achieves up between 4,000 and 4,400 rpm. The maximum engine speed of the new diesel powerplant is 5,400 rpm. In order to ensure that charge pressure is developed as effectively as possible, both the exhaust flow and supply of fresh air to the turbos and the channelling of compressed air into the combustion chambers is regulated with precision.

If the large turbocharger is spinning at particularly high speeds, a vacuum regulator opens a wastegate valve to relieve the pressure and so avoid unwanted exhaust backpressure. The supply of fresh air is also controlled according to need by means of pneumatically activated flaps. For example, at low revs a bypass flap ensures that the air is channelled directly to the high-pressure charger, which spins into action very early. At less than 2,700 rpm a change-over flap keeps the air away from the third turbo, which is not yet active, to prevent unnecessary fluctuations in pressure.

Indirect charge air cooling enables the temperature of the air compressed by the three turbos to be reduced to the optimum level for increasing engine output. Both the main radiator positioned immediately in front of the combustion chambers and the intercooler behind the low-pressure charger are supplied by a low-temperature water circuit with separate electric pump.

Increased combustion pressure. Maximum combustion pressure in the engine has risen from the 185 bar of the most powerful diesel engine in the existing BMW line-up to 200 bar. As part of this development, the crankcase in the new 3.0-liter diesel engine features a novel tie rod concept for the assembly of the main bearing caps and cylinder head. The sintered main bearing caps are given extra strength by a central screw. Like the crankcase, the cylinder head is also subjected to a special high-pressure compression process.

This “HIPen” manufacturing concept sees the aluminium castings heated to solution annealing temperature and the casting pores created during manufacturing welded under high pressure. This process gives the finished component additional strength. A double diagonal bore ensures the interbore bridges have high thermal stability.

The geometry of the crankshaft and connecting rods has been further optimized and they are now made from higher-strength materials. Added to which, hub bushings and bowl rim remelting enhance the effect of the increase in piston compression height.

Fuel injection system. Higher pressure also raises the efficiency of the injection system. The injection system of the new six-cylinder in-line diesel engine has also benefited from further development. The upgraded system raises the injection pressure of the piezo injectors to 2,200 bar. During each power stroke, three pre-injections, one main injection and four post-injections of fuel take place.

An ultra-high-performance pump channels the fuel to the combustion chambers through a common rail made from forged stainless steel.

The output and capacity of the cooling system have been given another boost, too. An additional low-temperature circuit supplied by an electric water pump controls the temperature of the intercoolers. The exhaust treatment system includes a diesel particulate filter and oxidation catalytic converter, which is located close to the engine in the same casing. More efficient exhaust cooling, meanwhile, minimises the formation of nitrogen oxides. Standard-fitted BMW BluePerformance technology, which includes a NOx storage catalytic converter, helps the new diesel engine powering the BMW M550d xDrive to meet the EU6 exhaust standard not due to come into force until 2014.

Eight-speed automatic. The configuration of the transmission management system for the BMW M Performance Automobiles promotes dynamic acceleration. The M-specification gearshift dynamics enable extremely rapid gear changes with an almost uninterrupted flow of power. The eight-speed Sports automatic transmission offers the driver two automated shift programs—D and S modes—as well as the option of changing gear manually (in M mode). The automatic gearbox is operated using an electronic gearshift lever on the centre console adorned with an M logo. Manual mode allows the driver to change gears sequentially using either the gearshift lever or the paddles on the steering wheel.

In keeping with M fashion, the right-hand paddle changes up a gear and the left-hand paddle is used for downshifts. If the driver activates manual mode using the gearshift lever, the transmission holds the gear selected until the engine’s revs hit the limiter. By not shifting up automatically in this mode, the gearbox gives the driver maximum control over the car when pushing the dynamic boundaries. The driver can also switch instantaneously from automatic gear changes to M mode with a nudge of one of the gearshift paddles; if M mode is selected in this way, the gearbox’s automatic shift-up function remains active. The transmission also restores automatic mode if the gearshift paddles are not used again following an upshift or downshift.

[nascarnation]

Diesel has more energy content per gallon.
No suprise they can get more $$ for it vs gasoline.

Diesel may well be overtaken by nat gas.
If nat gas stays this cheap for a couple years, you’ll see lots of commercial vehicles switching to nat gas, especially ones that run a daily route and can put in a refueling station at home base.

[Eye of Unk]

I cannot see why they just cannot build a two cycle diesel, its not like the idea isn’t new. The first GM Detroit Diesel came out in the late 1920’s, and won WW2 for us.

Just have to rethink the materials and exhaust gas scavenging.

[Clay Moore]

UPS is running a bunch of their trucks on CNG. I suppose it would be like LPG in that you drain out oil after 5K miles or so and it would still be as clean as new.

Our city was running some police cars on CNG but got tired of hauling them home on a rollback after a chase because they ran out of fuel...

With nat gas at ~$2.50 per million right now and rarely over $4 lately, I have thought of looking into it.

[Clay Moore]

“I cannot see why they just cannot build a two cycle diesel, its not like the idea isn’t new. The first GM Detroit Diesel came out in the late 1920’s, and won WW2 for us.”

Maybe the EPA said something about the great pools of oil underneath the Detroit’s... I always wondered if they actually leaked or were just marking their territory. (^;

[nascarnation]

They build nat gas Honda Civics here in Indiana. I considered buying one, but there’s only a couple refuel stations here in Indy. Unfortunately the home refueling station is pretty pricy, so if you only use it for one vehicle the payback isn’t there.

[Eye of Unk]

Tell me about it, I have been a diesel mechanic my whole life and I happen to have a certificate of attending a Detroit Diesel 71 engine series overhaul and tuneup training seminar, a course I attended for 5 days at Stewart and Stevenson in Houston Texas in the mid 1980’s.

[Clay Moore]

We had a 6/92 in a firetruck some years ago. It ran great till they set the rack back and then it would hardly pull itself up the ramp in the morning. Of course, it didn’t block out the sun with smoke either.

We all griped about it to no avail. One day when we were over at the garage I was met by the manager who greeted me with “if you are over here to complain...”

I said “no, just waiting for a slow night to reset the rack myself.” He started acting like a long tailed cat in a room full of rocking chairs and speaking incoherently! LOL

[Clay Moore]

Yes access to refill is a problem. I can hit several wells from my property with a rock but don’t have gas available.

I cannot imagine not being able to build my own small compressor station for a lot less than the commercial ones.

[Pete-R-Bilt]

I wonder what you’d get doing that to one with propane injection?

I’m guessing liftoff, or a mushroom cloud.

The vids at the bottom are nice.

fwiw i wouldn’t think you could do that to a post accert engine, with the exhaust routing back into an EGR and/or a DPF, I would guess you’d splode the combustion chamber(s) the first time you hit the throttle!

your prolley good with your cummins but I’m sol with my stroker

Thanks...

[Pete-R-Bilt]

The twin turbo cats are a plumbing nightmare...

3? UNNGGH!

whats in yer wallet?

[Moonman62]

Never could afford a BMW. Still can’t!!

I think Warren Buffett should be forced by law to buy us one. He can also get one for his secretary who he claims pays more taxes than he does.

[Clay Moore]

I think they have DPF deletes, excuse me, test pipes, if you click on the buttons on the left.

[Squantos]

Hey hope yer well !

[dennisw]

Diesel: Why is it more expensive than gasoline?

This is part one of a three-part series on diesel in the United States. Part two is about why diesel vehicles make up such a small part of the American consumer vehicle fleet. And part three is about what diesel options are coming soon to America.

Many years ago, diesel was cheaper than gasoline. However, since about 2004, that has not been the case. The additional requirement that refineries produce diesel very low in sulfur has also contributed to the increase in price. The U.S. Energy Information Administration has a nice great page focused on Diesel Fuel Prices.

The reason diesel is more expensive in the United States is a bit difficult to nail down. Diesel has historically been cheaper than gasoline in the U.S., but it’s currently cheaper than gasoline in many countries. Take the Netherlands, for example: a gallon of gasoline runs about $7.52 per gallon and diesel about $5.40 per gallon. These same Department of Energy charts show diesel costing about 30 cents more per gallon than gasoline here in the United States, at about $2.92 per gallon. (This is about the time when you realize that you’re getting a great deal on fuel costs!)

Supply and demand issues contribute greatest to the diesel price premium. FactCheck.org has a great overview that explains the diesel price situation. The page talks about historical price trends, but one of the most intriguing explanations of why diesel is more expensive is because gasoline is “cheap.” The Energy Information Administration pointed out that Americans decreased their amount of driving because of gasoline costs. About 97% of consumer automobiles in the U.S. are gasoline-powered, which resulted in great decrease in gasoline demand when gas prices started hitting consumer pocketbooks. However, diesel usage remained much steadier; we still needed all those trains and jets and ships to get goods from one place to another, and all those trains, jets, and ships use diesel (or a fuel very close to diesel in form). Ultimately, demand for gasoline decreased, so price decreased; demand for diesel didn’t decrease, so its price didn’t decrease. This allowed gasoline prices to fall below diesel prices, and that’s where we’re at today.

When looking at worldwide diesel demand, it’s growing rapidly. More than 30% of India’s new vehicle sales are diesel, and that number is expected to hit 50% by next year. In the European Union (page 13), there are several countries in which diesels make up more than 50% of new car sales (Austria, Belgium, Italy, Portugal), and nearly all the remaining countries are at 30% or more. Don’t forget about China, Russia, and Brazil, which are also quickly growing economies that demand more and more oil.

There of course are other factors influencing the price of diesel, such as taxes and production issues, but supply and demand is the biggest issue.

[nascarnation]

If the nat gas price stays low, I’m betting a bunch of low price home compressors will come to market. It’s certainly isn’t going to require new technology, just some clever design and development for low cost and reliability.

The “Phill” system previously marketed by Honda has a reputation for short life and poor after sales support.

[NVDave]

It isn’t difficult to nail down. It’s simple as this: When we went to ULSD, our diesel became exportable to the EU for their use. Before that, our 50 to 500ppm sulphur diesel wasn’t allowed to be used in their market(s).

They have increased diesel consumption, since over 40% of their new car sales are diesel vehicles. Their refiners have an over-supply of gasoline, since you can “tune” a refinery’s output only so far in the gas/distillate split.

So we export diesel fuel to the EU, and import gasoline on the flip side.

[CapnJack]

Very nice to see a Inline 6 diesel in cars (inlines are best for torque).

Only thing to change on these cars is to get rid of the automatic trans and put in a 6 speed manual. Or at least offer a 6 speed manual.

[Jack of all Trades]

Don't 2 stokes have an issue with uncontrollable runaways under certain conditions? That might put a damper on them.

I'm not a combustion engineer, my field is fuel injection, but I believe the advances in diesel efficiency are coming from the growing ability to precisely control air and fuel flows, timing quantity and distribution. In a 4 stroke, there's more time and and dedicated hardware available to give full authority over optimizing each parameter. In a 2 stoke, the focus is sort of on making each component perform as many functions as possible.

That said, take a look at the OPOC engine. That's a new spin on a 2 stroke diesel.

[ecomcon]

Its compact construction puts the engine in a position to meet future pedestrian protection stipulations..

WTH

[PapaBear3625]

It is true that Europe has no government-issued mileage requirements, hard as that is to believe.

They don't need regulation. They have extremely heavy fuel taxes there. diesel prices in Germany average around $1.36 per liter, or $5.23/gal. At those prices, you look for fuel economy.