Mercedes-Benz launches new V6 diesel engine

TDIMeister

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17th December 2004

A new Euro 4-compliant 224 bhp V6 diesel will replace Mercedes’ in-line five- and six-cylinder engines from spring 2005. It will boast a maximum torque of 510 Newton metres available from 1,600 rpm. Mercedes-Benz will offer the V6 engine with a particulate filter as an option in the UK.

At 208 kg the new engine is very slightly heavier than the previous five-cylinder engine, but its power-to-weight ratio has increased by more than 20 per cent to 1.08 hp/kg. Newly developed piezo injectors operate much more rapidly and precisely than the previous engines’ solenoid valves, making five injections per power stroke possible, at a peak pressure of up to 1600 bar.

- DaimlerChrysler's Chrysler Group expects to save $100 million a year by building four-cylinder engines in its Global Engine Alliance with Mitsubishi Motors and Hyundai at two plants in Michigan, Chrysler announced on 16 December. The "world engine" project, which will yield 2 million engines a year from five plants in South Korea, Japan and the USA.
 

Kabin

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For us metrically deprived, I'll try to decipher... 224bhp, 376ft-lb, and 23,200psi injector pressure. Sounds very nice, wonder how the fuel economy compares?
 

Tin Man

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Sounds like better specs than the 320 CDI (201 hp, 369 ft-lbs of torque). I still like the inline six better. One fewer head gasket to blow and smooth without balance shafts too.
 

Philip

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wondering why they are dropping the inline for a V design, I always thought the inlines were smoother and produced more torque then the Vs.
 

MrMopar

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wondering why they are dropping the inline for a V design, I always thought the inlines were smoother and produced more torque then the Vs.
Probably for packaging reasons - maybe for crash testing. Any time a car has a front-to-back engine layout with a long engine like an inline 6 it is harder to make sure the engine does not enter the passenger compartment in a crash. A few years ago GM was toying around with entirely overhauling the F-body platform, and having a brand new Camero/Firebird with the Vortec I-6 engine as the base, maybe with a turbocharged version as the mid-level upgrade. Safety concerns proved that it was hard to have a long engine and still be very safe in a crash.

Or maybe I'm just blowing smoke and MB has some other reason to switch to a V-6.
 

earthworm

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This term "safety" is blown all out of proportion in engineering reasoning.
The number one thing must be balance. The torque from a V engine or an I must be the same. With two heads, and more exhaust complexity, the I engine is less expensive to build. But the V has an advantage with a shorter crankshaft.
But only the bean-counters and designers know the exact values of each item.
I, for one ,would prefer that the car be just 6 inches longer and have the I engine.Consider the Volvo 740 or a Mercedes 300 or a Ford pickup with an Inline 6 - these all cost less to build and less to maintain, and the longer nose is ,IMO, psychologically nicer to drive.

And then there is the Volkswagen 15 degree VR engine, with but one head . But I think their new Inline 5 is better - but only the engineers really know..
 

Tin Man

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I believe Mercedes has some good experience with V6's, now that their V6 gasoline 3.2 liter problems are behind them (I hope). I believe its for fuel efficiency due to lighter engine and body. The cost savings of using such an engine in their smaller cars also comes into play.

I wish they could produce the inline 6 diesel along with the V6, though. Having only one common rail vs. two comes to mind as another advantage. Maybe the inline 5 will also work, but its not inherently balanced like the inline 6. Somehow BMW has managed to keep an inline 6 (they have more problems than Mercedes with head gaskets, so a BMW V6 may have even more problems).
 

likmywagon

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I've heard it said many times that the an inline 5 is inherently less balanced than a 4 or a 6 but I have to ask if it's in fact true? As side from 5 being a prime number is there any mathematical reason for a 5 pistons 72 deg apart to be significantly less balanced than 6 separated by 60 deg? Both of my Audi 5 cylinder engines, one 10V and one 20V, were very sweet smooth power plants.
 

Tin Man

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A balanced engine will have the same weight of moving parts going in opposite directions causing no large vibration on the motor mounts. The firing order and rotating weight of the pistons and crankshaft are not inherently even/balanced in a five like a six is. Engines larger than a certain displacement need a balance shaft, whether inline 3, 4, or 5 cylinders but not inline 6's or V8's. The horizontally opposed 4's and 6's are balanced while V6's are also somewhat more balanced. I'm sure your five is smooth because of special counterbalancing techniques and specially set firing rhythm. I think there must be some basic automotive reference that speaks to this.
 

TDIMeister

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Inline-5s are balanced for primary and seconday forces but have a rocking couple vertically along the crankshaft axis. Only on the latter factor is the inline-5 different from an inline-6, and it is still more balanced than a 90-degree V6 without balance shafts or inline-4.

There's nothing special in the counterbalancing of an inline-5 other than a 5-plane crank spaced 72-degrees apart for even-firing (an inline- and flat-6 have 3-plane cranks spaced 120-degrees apart, while 90-degree V6s and the VW VR6 engine have joined crankpins offset @ 30- and 15-degrees respectively to maintain an even firing-order.
 

Philip

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whatever works best for them, its also more of a pain to connect a turbo to 2 banks of 3 cylinders the one of 6.

hmm this seems to make no sense ATM, but only time will tell.

Whatever works best!
 

VWannabe

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This was probably done for packaging concerns, since the article states this will replace both the 5 and 6 cylinder inline engines. I bet this would fit nicely in the Dakota!
 

texsurfer

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I always thought inlines were lighter than V's? When Honda Motorcycles developed their V4 engines they produced gobs of good HP & torque but the inline Suzuki's weighed so much less that Honda couldn't win any races. That was then though. Now they race V2's all the time and win...
 

TDIMeister

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Inline engines are lighter insofar as only one cylinder is needed and one bank of camshafts, one set of cam sprockets, etc.

One head serving all 6-cylinders rather than 2 heads serving 3-each will have a negligible contribution to the weight difference, but most of the added weight of a V-type engine will found in the above, as well as extra material in the valley between the cylinder banks on the block.

Edit: The Mercedes V6 Diesel engine is lighter than the inline-6 only probably because of new technology like stronger materials that allow thinner walls to be used to retain the same strength.
 

Kabin

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When Honda Motorcycles developed their V4 engines they produced gobs of good HP & torque but the inline Suzuki's weighed so much less that Honda couldn't win any races. That was then though. Now they race V2's all the time and win...
I'm not aware of any currently successful Honda V2 designs in major motorcycle racing. In the MotoGP, Rossi won the previous year with Honda's V5. Since Rossi switched to Yamaha, he took Honda's winning ways with him on Yamaha's 1000cc, which I think is an inline 4. And in the AMA, inline 4's have been winning for years. And WSB doesn't count in my mind, as the Ducati V-twins are about the only major bike manufacturer in the series.
 

Matt_OToole

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Inline engines are lighter insofar as only one cylinder is needed and one bank of camshafts, one set of cam sprockets, etc.

One head serving all 6-cylinders rather than 2 heads serving 3-each will have a negligible contribution to the weight difference, but most of the added weight of a V-type engine will found in the above, as well as extra material in the valley between the cylinder banks on the block.

Edit: The Mercedes V6 Diesel engine is lighter than the inline-6 only probably because of new technology like stronger materials that allow thinner walls to be used to retain the same strength.
Actually the heaviest part of any modern engine is the crankshaft. Because an inline crank is longer, it has to be beefed up considerably to avoid torsional flex/windup. So the result is a much heavier crank than if length alone were considered, and perhaps a heavier engine.

However, the move toward V6s probably has more to do with packaging -- for crash engineering, and possibly having to fit a FWD chassis.
 

king908

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We have a few of the new E Class CDI's in our shop. We are currently bringing the cars to journalists and photographers.

I can get picks if anyone likes, or any other Benz, Maybach
 

Oldman

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mister is right, and the offset makes for a weak crank, which is going to be BAD on a diesel. The is no easy way to fix the offset as increasing the diameter increase bearing speed (not good, increasing the offset distance increases the lenght of the engine ( not good). You can change the angle to 60 degrees but then intake manifold ports become a nightmare and the head gets really small (not good). Um inline now you can have 7 main bearings, no offset on the crank between rod pairs as each rod can have a fully counter weighted cheek. All good the I6 is a really good setup, there are problems with crank whip at high RPM (not a problem with a diesel). There were problems with lots of valves driven off one cam as the cam would take a flex, and then a harmonic which could snap the cam or cause strange valve events down the block. Most new setups are of course twin OHC. Head warp could be bad, just don't overheat an 6 banger. I6 are very easy to work on in general and they are easy to package. Must be a real bear to put this into a FWD though unless it was a North South deal, but DC seems to headed back to RWD like the Hemi, what I'd do to have an I6 diesel in a Magnum station wagon RWD....
 

Ian F

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However, the move toward V6s probably has more to do with packaging -- for crash engineering, and possibly having to fit a FWD chassis.
That would be my guess - given the new European Pedestrian Impact standards...
 

earthworm

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I would say that at least 8 out of 10 drivers, running at normal speeds(not racing) cannot tell the difference between a 4 or a 6,thanks to balance shafts and engineered mounts. And the same holds true for a V engine vs the I type.
Of course, the V is more compact, but this can be a disadvantage with the turbocharger, I think.
Also, really newer engines may have no camshafts, that function taken over by computer controlled solenoids.
But, as I have said, only the bean-counters know the exact value of every aspect.
 

Tin Man

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I couldn't get the CDI out of the driveway due to 17 inches of snow let alone needing more ground clearance, so I drove my wife's ML320 to work for a few days. The smoothness of its V6 was remarkable compared to the more torquey I6 on the diesel. The SUV has 113,000 miles on it and the engine/transmission seem like they finally got "broken in!" I got 18-21 mpg with it with plenty of power too! Wonder how the direct injection gasser engines that are coming down the pike will be like. They reportedly will get at least 10% better fuel mileage and more power.
 

Oldman

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Only true of the even fire 90 degree V6, the odd fire ones with the non-off set crank did shake even at speed in a kind of pitter patter type of motion ba.ba.bump. Hence all the 90 degree V6 that I know of now are even fire, but as stated above the crank shaft is much weaker unless 3 cheeks are added to the rod bearing and even at 1 inch a cheek it would mean the entire engine would be 3 inches longer! Or not much shorter than an I6 say about what an I5 would be. Vovlo and Audi etc like the I5 and maybe this is most logical setup on a tight FWD setup. I should also note the I5 is at an angle so hood height is lower or as low as a V engine.
 

TDIBill

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IanF has it exactly right. They are doing it for packaging reasons to comply with European pedestrian impact safety regs taking effect in a few years. Inline engines are too long to allow a sufficient 'soft' inpact zone when a pedestrian is struck by a car.
 
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