# European vs American Diesel Engines



## TL2E90 (May 20, 2005)

I know both variants of 2018 BMW540d share the same engine - B57D30. While the European model is tuned to produce 320 hp /502 lb ft, the american variant is a detuned version producing only 265hp/457 lb ft.
Question: how can we update our engine specs to the Euro variant. Any ECU updates available as of yet?


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## floydarogers (Oct 11, 2010)

TL2E90 said:


> I know both variants of 2018 BMW540d share the same engine - B57D30. While the European model is tuned to produce 320 hp /502 lb ft, the american variant is a detuned version producing only 265hp/457 lb ft.
> Question: how can we update our engine specs to the Euro variant. Any ECU updates available as of yet?


The European 540d is a twin-turbo engine. The US engine is actually a 530d (or perhaps 535d) single-turbo. You're not going to get there with a tune.


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## TL2E90 (May 20, 2005)

floydarogers said:


> The European 540d is a twin-turbo engine. The US engine is actually a 530d (or perhaps 535d) single-turbo. You're not going to get there with a tune.


Take a look at https://en.wikipedia.org/wiki/BMW_5_Series_(G30) under Diesel Engines section. It appears we share the same engine altough the American version is de-tuned.


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## TL2E90 (May 20, 2005)

floydarogers said:


> The European 540d is a twin-turbo engine. The US engine is actually a 530d (or perhaps 535d) single-turbo. You're not going to get there with a tune.


Also Motor Trends states that for 2018 there is a complete new engine: "Under the hood is a new 3.0-liter turbodiesel I-6 with 261 hp and 457 lb-ft of torque, an increase of 6 hp and 44 lb-ft compared to the outgoing 535d. An eight-speed automatic is the only transmission available. Despite the extra horsepower and torque, the 2018 BMW 540d xDrive is one of most efficient 5 Series variant with an EPA rating of 26/36 mpg (9/6.5 L/100km) city/highway. "


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## edycol (Jul 8, 2015)

TL2E90 said:


> I know both variants of 2018 BMW540d share the same engine - B57D30. While the European model is tuned to produce 320 hp /502 lb ft, the american variant is a detuned version producing only 265hp/457 lb ft.
> Question: how can we update our engine specs to the Euro variant. Any ECU updates available as of yet?


I think we are getting single turbo version. Previous 3.5d was also 3.0d version from Europe. 
Only M57 in E90 and E70 are comparable to European 3.5d with bit different tune (265hp compared to 286 in Europe, but same torque) due to different NOx requirements in the US. 
And that is where the problem is. NOx requirements in the US are different and our version might have different EGR and its cooler even if it is same engine.

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## floydarogers (Oct 11, 2010)

TL2E90 said:


> Take a look at https://en.wikipedia.org/wiki/BMW_5_Series_(G30) under Diesel Engines section. It appears we share the same engine altough the American version is de-tuned.


If you look at realoem.com, the EU version shows twin turbo, but the US/CA version (both 2018) is a single turbo. Which do you want to believe? Real info or something written by someone posted by someone?

https://www.realoem.com/bmw/enUS/showparts?id=JD13-USA-01-2018-G30-BMW-540dX&diagId=11_6516
https://www.realoem.com/bmw/enUS/showparts?id=JD51-EUR-01-2018-G30-BMW-540dX&diagId=11_6606


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## TL2E90 (May 20, 2005)

floydarogers said:


> If you look at realoem.com, the EU version shows twin turbo, but the US/CA version (both 2018) is a single turbo. Which do you want to believe? Real info or something written by someone posted by someone?
> 
> https://www.realoem.com/bmw/enUS/showparts?id=JD13-USA-01-2018-G30-BMW-540dX&diagId=11_6516
> https://www.realoem.com/bmw/enUS/showparts?id=JD51-EUR-01-2018-G30-BMW-540dX&diagId=11_6606


Thanks!:thumbup:


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## TL2E90 (May 20, 2005)

Seems G-Power has something for us but very expensive. I sent them an email to confirm the module works on NA G30 engines.
https://www.g-power.com/artikeldeta...1-530d-g3x-315-ps_3689.php_3689.php?details=1


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## jck66 (Nov 28, 2017)

As stated above, the US "540d" is the same as the EU "530d". On the wikipedia page for the G30, it shows the 530d as having 265 PS, which is approximately 261 hp.


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## edycol (Jul 8, 2015)

jck66 said:


> As stated above, the US "540d" is the same as the EU "530d". On the wikipedia page for the G30, it shows the 530d as having 265 PS, which is approximately 261 hp.


American version of 530d will have different tune due to more stringent NOx requirements in the US.

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## alacey (Mar 14, 2018)

floydarogers said:


> The European 540d is a twin-turbo engine. The US engine is actually a 530d (or perhaps 535d) single-turbo. You're not going to get there with a tune.


I don't see why he couldn't get to with just a tune. Just because one engine has two turbos and the other is a singe doesn't necessarily mean they cannot make the same power. That depends on the what kind of turbo set up both have.

From the looks of the diagrams(not 100% sure), the EU engine looks to be a compound turbo set up, not a twin turbo. A high pressure turbo (smaller one) for low rpm and then a low pressure turbo (larger one) that takes over for higher rpm. The US version looks to have an actuator on it meaning that it is a VGT which does not require a high pressure small turbo since it can alter its aspect ratio to act as a smaller turbo. I don't know the specs, but if the big turbo on the EU engine is as big as the VG turbo on the US version, I don't see why it cannot be tuned to make the same peak power.

Of course I don't know if could do it and still be emissions legal due to the tighter NOx emissions requirement and different way of measuring NOx output in the US forcing BMW to keep the power low for less g/bhp-hr. Emissions is one of the reason why many US diesel have VGT's in the first place. Better control on NOx output throughout the whole rpm range.


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## Doug Huffman (Apr 25, 2015)

ALacey, still keeping Aufgeblassen company.


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## alacey (Mar 14, 2018)

Doug Huffman said:


> ALacey, still keeping Aufgeblassen company.


??????


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## edycol (Jul 8, 2015)

alacey said:


> I don't see why he couldn't get to with just a tune. Just because one engine has two turbos and the other is a singe doesn't necessarily mean they cannot make the same power. That depends on the what kind of turbo set up both have.
> 
> From the looks of the diagrams(not 100% sure), the EU engine looks to be a compound turbo set up, not a twin turbo. A high pressure turbo (smaller one) for low rpm and then a low pressure turbo (larger one) that takes over for higher rpm. The US version looks to have an actuator on it meaning that it is a VGT which does not require a high pressure small turbo since it can alter its aspect ratio to act as a smaller turbo. I don't know the specs, but if the big turbo on the EU engine is as big as the VG turbo on the US version, I don't see why it cannot be tuned to make the same peak power.
> 
> Of course I don't know if could do it and still be emissions legal due to the tighter NOx emissions requirement and different way of measuring NOx output in the US forcing BMW to keep the power low for less g/bhp-hr. Emissions is one of the reason why many US diesel have VGT's in the first place. Better control on NOx output throughout the whole rpm range.


You do know that single turbo engine is available in Europe as 3.0d and twin turbo (small + big) is available as 3.5 and 4.0d in Europe?
No, single one cannot deliver same power as twin in a manner BMW wants it.

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## alacey (Mar 14, 2018)

edycol said:


> You do know that single turbo engine is available in Europe as 3.0d and twin turbo (small + big) is available as 3.5 and 4.0d in Europe?
> No, single one cannot deliver same power as twin in a manner BMW wants it.
> 
> Sent from my iPhone using Tapatalk


Nope. I did not know that the EU diesel were of a larger displacement. I don't know to much about these small BMW diesels. Most of my diesel and racing experience is with US truck diesels with much higher power levels.

I was just going by the diagram that Floyd said posted which shows compound turbo set up with a small turbo pushing a larger one. Not a twin turbo configuration with two of the same size turbos used in conjunction.


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## floydarogers (Oct 11, 2010)

BMW uses (and has for 10 years or so) the same 3L block for engines designated 2.5, 3.0, 3.5. They recently started using the 4.0 label to designate the highest-power one - goes along with the gasser 340i B56 engine. Actually, there's a M50d designation that uses a tri-turbo setup, too. The small compound turbo setup is to get some torque down near 1200 rpm for step-off.

The 328d US actually is a 2L B47 engine (used to be N47), with a bigger intercooler and a few other things than the version sold in EU/etc as the 320d. Lots of marketing numbers...

There are certainly tunes and mods to get to very high peak power levels. It's pretty easy to get over 400hp on the older M57 engines if you want to run 12-second or better 1/4 miles... I'm sure that similar #s can be had with the B57. Of course, you pretty much have to run drag slicks to keep hooked up - 600 ft-lbs does want to spin them.


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## edycol (Jul 8, 2015)

alacey said:


> Nope. I did not know that the EU diesel were of a larger displacement. I don't know to much about these small BMW diesels. Most of my diesel and racing experience is with US truck diesels with much higher power levels.
> 
> I was just going by the diagram that Floyd said posted which shows compound turbo set up with a small turbo pushing a larger one. Not a twin turbo configuration with two of the same size turbos used in conjunction.


They are not larger displacement. I would say you are talking about something you don't know much about it.

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## alacey (Mar 14, 2018)

floydarogers said:


> BMW uses (and has for 10 years or so) the same 3L block for engines designated 2.5, 3.0, 3.5. They recently started using the 4.0 label to designate the highest-power one - goes along with the gasser 340i B56 engine. Actually, there's a M50d designation that uses a tri-turbo setup, too. The small compound turbo setup is to get some torque down near 1200 rpm for step-off.
> 
> The 328d US actually is a 2L B47 engine (used to be N47), with a bigger intercooler and a few other things than the version sold in EU/etc as the 320d. Lots of marketing numbers...
> 
> There are certainly tunes and mods to get to very high peak power levels. It's pretty easy to get over 400hp on the older M57 engines if you want to run 12-second or better 1/4 miles... I'm sure that similar #s can be had with the B57. Of course, you pretty much have to run drag slicks to keep hooked up - 600 ft-lbs does want to spin them.


Thank you for the clarification.


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## edycol (Jul 8, 2015)

alacey said:


> Oh, they are the same displacement? Well then what I said still stands then. The single VG turbo engine can make as much peak power as the compound turbo engine if the VG turbo is as big and puts out the same pressure as the low pressure turbo on the compound set up. I seen it happen on the dyno plenty of times.
> 
> I may not know the different designations of BMW diesels, but I do know turbos and I definitely know diesels.


You can achieve a lot of power with single turbo. Regardless of VG if turbo is too big you will have huge lag. I already told you, the way BMW wants to make engine and the way they want power to be delivered, it is impossible to achieve 35d and 40d numbers (Euro) with single turbo. 
One can achieve huge hp with 3.0ltr single turbo, question is how practical that is in real life. 
For BMW it is not hard to achieve 300+hp with single turbo. Question is lag. VG can help only so much. If it was that simple, all of these engines would have single turbo or twin scroll turbo.

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## alacey (Mar 14, 2018)

edycol said:


> You can achieve a lot of power with single turbo. Regardless of VG if turbo is too big you will have huge lag. I already told you, the way BMW wants to make engine and the way they want power to be delivered, it is impossible to achieve 35d and 40d numbers (Euro) with single turbo.
> One can achieve huge hp with 3.0ltr single turbo, question is how practical that is in real life.
> For BMW it is not hard to achieve 300+hp with single turbo. Question is lag. VG can help only so much. If it was that simple, all of these engines would have single turbo or twin scroll turbo.
> 
> Sent from my iPhone using Tapatalk


Being that the other diesel that I drive has a VG turbo over twice the size of what is on 3.0L and has almost no turbo lag. I find it hard to believe that BMW can't make a huge VG turbo without lag but Cummins can. I can view my trucks VGT opening position on my pillar mounted CTS2, and believe me it is quick. Very quick. I can go from the vanes being closed for exhaust braking to back on the throttle creating boost in a fraction of a second.

Then again, maybe your are right. One of the biggest complaints of this car is the lack of power and boost before 1,700 rpm, and the slow turbo response versus my truck. Maybe BMW can learn a thing or two from Cummins or GM on how to build a bigger turbo with quick VG reaction.


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## floydarogers (Oct 11, 2010)

alacey said:


> Being that the other diesel that I drive has a VG turbo over twice the size of what is on 3.0L and has almost no turbo lag. I find it hard to believe that BMW can't make a huge VG turbo without lag but Cummins can. I can view my trucks VGT opening position on my pillar mounted CTS2, and believe me it is quick. Very quick. I can go from the vanes being closed for exhaust braking to back on the throttle creating boost in a fraction of a second.
> 
> Then again, maybe your are right. One of the biggest complaints of this car is the lack of power and boost before 1,700 rpm, and the slow turbo response versus my truck. Maybe BMW can learn a thing or two from Cummins or GM on how to build a bigger turbo with quick VG reaction.


Don't know why you say 1700 rpm - my M57 has full torque (boost) available at 1200 rpm - look at the torque curves. (Granted, I only know the older E90 engine.)

There's a big (BIG) difference between exhaust flow on a 3L than on your 6.4L. A bigger turbo on the little engine won't spool very fast on 1/2 the flow. But because the DDE (ECU) and TCU (transmission) keep RPMs above 1200 rpm virtually all the time, the BMW diesel always has full boost and torque available, too.

I think you should consider that there are many reasons for the single or compound turbo setup that BMW uses.


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## alacey (Mar 14, 2018)

floydarogers said:


> Don't know why you say 1700 rpm - my M57 has full torque (boost) available at 1200 rpm - look at the torque curves. (Granted, I only know the older E90 engine.)
> 
> There's a big (BIG) difference between exhaust flow on a 3L than on your 6.4L. A bigger turbo on the little engine won't spool very fast on 1/2 the flow. But because the DDE (ECU) and TCU (transmission) keep RPMs above 1200 rpm virtually all the time, the BMW diesel always has full boost and torque available, too.
> 
> I think you should consider that there are many reasons for the single or compound turbo setup that BMW uses.


I have a 6.7L inline 6 with the outlet to the exhaust manifold toward the back three cylinders which does not have as good of flow as an engine with the outlet in the middle like the BMW 3.0L does. I do know from modifying and tuning Cummins and Duramax diesels that a big VG turbo can not only make as much power as a compound set up, it can spool just as fast if not faster depending on the vane configuration. Comparing BMW's configuration versus Cummins, I can see why it is not as responsive.

I also don't have a 3.0L(and I am now wishing I did). I have a 328D with the 2.0L diesel so that probably explains my gripes about lacking power. Going from a 513rwhp diesel that makes gobs of power and torque as low as 1,000 rpm to a 180 hp diesel that needs to be revved to 2,000 rpm to get any power out of it is big difference in terms of seat of the pants feel. I figured deleting and tuning it would make it better, but while it did add a lot of power at 2,000 rpms, it did not do much power wise below 1,700 rpm. I know I bought the 2.0L for fuel mileage on my 40+ mile one way commute, but I am seriously debating going to the 3.0L diesel next year.


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## edycol (Jul 8, 2015)

alacey said:


> I have a 6.7L inline 6 with the outlet to the exhaust manifold toward the back three cylinders which does not have as good of flow as an engine with the outlet in the middle like the BMW 3.0L does. I do know from modifying and tuning Cummins and Duramax diesels that a big VG turbo can not only make as much power as a compound set up, it can spool just as fast if not faster depending on the vane configuration. Comparing BMW's configuration versus Cummins, I can see why it is not as responsive.
> 
> I also don't have a 3.0L(and I am now wishing I did). I have a 328D with the 2.0L diesel so that probably explains my gripes about lacking power. Going from a 513rwhp diesel that makes gobs of power and torque as low as 1,000 rpm to a 180 hp diesel that needs to be revved to 2,000 rpm to get any power out of it is big difference in terms of seat of the pants feel. I figured deleting and tuning it would make it better, but while it did add a lot of power at 2,000 rpms, it did not do much power wise below 1,700 rpm. I know I bought the 2.0L for fuel mileage on my 40+ mile one way commute, but I am seriously debating going to the 3.0L diesel next year.


I would say you are comparing apples and oranges. 
I had numerous diesels with VGT and they all had obvious turbo lag. As far as I know single turbo set up is also VG on BMW. 
Comparing Cummins in a truck that barely holds road in a straight line with car that is made for dynamic driving is ridiculous. 
Multiple turbos on BMW are there so that manufacturer doesn't need to increase displacement and with that number of cylinders and with that weight, which would compromise perfect or in some models almost perfect weight distribution. BMW had V8 diesel but went away with it due to weight in front. MB and Audi still use V8 diesels but they are nowhere dynamic as BMW inline 6 with same power.

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## FaRKle! (Jun 18, 2016)

floydarogers said:


> The 328d US actually is a 2L B47 engine (used to be N47), with a bigger intercooler and a few other things than the version sold in EU/etc as the 320d. Lots of marketing numbers...


328d in the US never received the B47. It's still N47.


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## floydarogers (Oct 11, 2010)

FaRKle! said:


> 328d in the US never received the B47. It's still N47.


Yeah, I think you're right now that I think about it.


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## alacey (Mar 14, 2018)

edycol said:


> I would say you are comparing apples and oranges.
> I had numerous diesels with VGT and they all had obvious turbo lag. As far as I know single turbo set up is also VG on BMW.
> Comparing Cummins in a truck that barely holds road in a straight line with car that is made for dynamic driving is ridiculous.
> Multiple turbos on BMW are there so that manufacturer doesn't need to increase displacement and with that number of cylinders and with that weight, which would compromise perfect or in some models almost perfect weight distribution. BMW had V8 diesel but went away with it due to weight in front. MB and Audi still use V8 diesels but they are nowhere dynamic as BMW inline 6 with same power.
> ...


Have the numerous VGT diesels had all been BMW diesels? If so, that may explain a few things.

My truck may not do fast dynamic driving, but that does not mean it does mean the engine was not meant to perform under load with a responsive VGT. Let me paint a picture for you. Imagine taking an 8k lb truck and slapping another 10k to the back of it. Then imagine towing that 10k at 60 mph (1,650 rpm) down Texas hill country road with constant ups and downs along with a turns. The turbo has to go from a fully closed vanes with 0 boost for the exhaust brake on every down hill portion and then immediately building 30 psi boost to keep you at speed while going back up. This has to happen in a fraction of a second or you will loose speed and require you to downshift to gain back that momentum. If the big VGT on my truck is responsive enough to keep me at a steady speed in that type of situation and the one on the BMW isn't then there is something wrong with BMW's VGT set up.

Also, and compound turbo set up weighs more than a single VGT turbo while being able to have the same wide rpm range. Engineering Explained: 6 Different Types Of Turbocharger And The Advantages Of Each Setup


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## Doug Huffman (Apr 25, 2015)

Wow, on to the second page. Brother, we got us a convoy! Punt the hammer down and le***8217;s roll!


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## edycol (Jul 8, 2015)

Doug Huffman said:


> Wow, on to the second page. Brother, we got us a convoy! Punt the hammer down and le***8217;s roll!


I am having feeling this kid is related to someone.

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## alacey (Mar 14, 2018)

So is it common in this forum to insult those that don't agree with you?

Just because we have a difference of opinions based on our own knowledge and experience of the matter doesn't mean we should turn to insults. There may be a detail that I don't have experience with as Floyd corrected me earlier and I thanked him for it. But to try insult people are talk down to them just because they don't have the same opinion as you is a bit childish. So we don't agree with each other on this one thing, it is not that big of a deal to get mad.


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## Doug Huffman (Apr 25, 2015)

... and a projectionist too!


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## floydarogers (Oct 11, 2010)

alacey said:


> So is it common in this forum to insult those that don't agree with you?
> 
> Just because we have a difference of opinions based on our own knowledge and experience of the matter doesn't mean we should turn to insults. There may be a detail that I don't have experience with as Floyd corrected me earlier and I thanked him for it. But to try insult people are talk down to them just because they don't have the same opinion as you is a bit childish. So we don't agree with each other on this one thing, it is not that big of a deal to get mad.


Doug didn't "insult" you. You're just not able in such a short time to "read" our expressions from afar.

BTW, if you google messages by a user named TDIWyse - both here and on E90post - you'll be looking at posts from a guy with very extensive knowledge of these engines. He also has a Dodge Cummins; he's probably the best guy to answer any questions you have.


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## alacey (Mar 14, 2018)

floydarogers said:


> Doug didn't "insult" you. You're just not able in such a short time to "read" our expressions from afar.
> 
> BTW, if you google messages by a user named TDIWyse - both here and on E90post - you'll be looking at posts from a guy with very extensive knowledge of these engines. He also has a Dodge Cummins; he's probably the best guy to answer any questions you have.


The "Aufgeblassen" comment made it seem so. Although I am less of a passive aggressive or beat around the bush and am more direct.

Sorry, I have just seen too many people in other forums who take it personal if you disagree with them or their assessment. I on the other hand don't mind people disagreeing with me and them stating why they do so. Lord knows I don't know everything about everything and if someone disagrees then I welcome a knowledgeable debate. Who knows, I may learn something from it just like I have from many other conversations that started the same way in other forums.


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## edycol (Jul 8, 2015)

alacey said:


> So is it common in this forum to insult those that don't agree with you?
> 
> Just because we have a difference of opinions based on our own knowledge and experience of the matter doesn't mean we should turn to insults. There may be a detail that I don't have experience with as Floyd corrected me earlier and I thanked him for it. But to try insult people are talk down to them just because they don't have the same opinion as you is a bit childish. So we don't agree with each other on this one thing, it is not that big of a deal to get mad.


This is not insult. Your argument comes along the lines: why ship cannot fly? It can, I know it can. 
You do not understand (and this is not insult, you truly do not as you never needed to understand that) why BMW or other European manufacturers build this kind (small) diesel engines. 
For the record, I owned Lancia Lybra 2.4JTD, Skoda Octavia 1.9tdi (two of them), Peugeot 508 2.2hdi GT, BMW E61 525d. These cars are made to save money and still drive fast. They all had VGT, that is not some achievement. VW 1.9tdi from 1997 had it. But they still have turbo lag. You cannot spin turbo that fast regardless of VGT because of the law of physics. One could increase displacement to generally increase power, and with that torque. 
You are comparing truck that first of all has huge displacement and has different emissions schedule. On top of that it is modified. You took into consideration EPA NOx standards? All these things manufacturers like BMW have to take into consideration. 
What I said and you obviously didn't read is that BMW could put torque much lower with bigger engine and small VGT. But, it increases the weight in the hood, consumption (reason why people drive small diesels), mess up dynamic (reason why people buy BMW) etc. 
And your 6.7ltr Cummins too has lag, it is just hidden due to displacement.

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## alacey (Mar 14, 2018)

edycol said:


> This is not insult. Your argument comes along the lines: why ship cannot fly? It can, I know it can.
> You do not understand (and this is not insult, you truly do not as you never needed to understand that) why BMW or other European manufacturers build this kind (small) diesel engines.
> For the record, I owned Lancia Lybra 2.4JTD, Skoda Octavia 1.9tdi (two of them), Peugeot 508 2.2hdi GT, BMW E61 525d. These cars are made to save money and still drive fast. They all had VGT, that is not some achievement. VW 1.9tdi from 1997 had it. But they still have turbo lag. You cannot spin turbo that fast regardless of VGT because of the law of physics. One could increase displacement to generally increase power, and with that torque.
> You are comparing truck that first of all has huge displacement and has different emissions schedule. On top of that it is modified. You took into consideration EPA NOx standards? All these things manufacturers like BMW have to take into consideration.
> ...


I guess we will have to agree to disagree because I know that a VGT can perform as well as or even better than a compound setup depending on how it is mapped. I have seen it on the dyno and driven both on the street.

Engine displacement is not really a factor in regards to turbo lag because you can alter the size of the turbo along with engine displacement. What does factor into how much turbo lag a VGT(or any turbo) has is the turbos A/R ratio, blade size and wheel trim, compressor/turbine housing size, type of bearing used(journal or ball), and vane set up(rotating or sliding vane). All these things can effect a turbos compressor map which will dictate how much lag it has, compressor speed, and max boost when mated to an engine of proportional size.

From looking at the specs of the 3.0L diesel's Garrett turbos, it seems they(and many Euro diesel VGT's) are rotating vane which I am not a fan of because the response time is slower in comparison to sliding vane VGT's like what is on my Cummins. They are also easier to collect carbon buildup on the vanes.

Another thing I noticed in one article N57 engines was the the compound turbo set up also had higher max fuel pressure. The VGT was maxed out at 26,000 psi and the compound was maxed out at 29,000 psi from what I read. This would allow for higher power numbers if true. A tune would be able to fix that if they used the same HPFP and injectors.

Also, my car is deleted and tuned just like my truck.


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## edycol (Jul 8, 2015)

alacey said:


> I guess we will have to agree to disagree because I know that a VGT can perform as well as or even better than a compound setup depending on how it is mapped. I have seen it on the dyno and driven both on the street.
> 
> Engine displacement is not really a factor in regards to turbo lag because you can alter the size of the turbo along with engine displacement. What does factor into how much turbo lag a VGT(or any turbo) has is the turbos A/R ratio, blade size and wheel trim, compressor/turbine housing size, type of bearing used(journal or ball), and vane set up(rotating or sliding vane). All these things can effect a turbos compressor map which will dictate how much lag it has, compressor speed, and max boost when mated to an engine of proportional size.
> 
> ...


Mapping, what mapping? You are looking at this from maximum performance disregarding the fact that these small engines have to meet very strict emissions standards, make 300k+, have decent consumption since gallon of diesel in Europe is $6-7 etc. 
since you are comparing it with 6.7ltr Cummins, then there is no other way but for Cummins to built 2.0ltr or 3.0ltr diesel and show BMW how it is done. Or even better, you pack your bag, get on the plane to Munich and explain ignorant engineers.

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## alacey (Mar 14, 2018)

edycol said:


> Mapping, what mapping? You are looking at this from maximum performance disregarding the fact that these small engines have to meet very strict emissions standards, make 300k+, have decent consumption since gallon of diesel in Europe is $6-7 etc.
> since you are comparing it with 6.7ltr Cummins, then there is no other way but for Cummins to built 2.0ltr or 3.0ltr diesel and show BMW how it is done. Or even better, you pack your bag, get on the plane to Munich and explain ignorant engineers.
> 
> Sent from my iPhone using Tapatalk


Compressor mapping. Every turbo will have a different compressor map dictating where they are most efficient and such.

Something like this.









Cummins(my old employer) does build a 2.8L, 3.8L, 4.5L and 5.0L. All use a very responsive sliding vane VGT in their applications accept for the pick up version of the 5.0L. It uses a two-stage single turbo for packaging reasons. All other 5.0L applications use a VGT.


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## edycol (Jul 8, 2015)

alacey said:


> Compressor mapping. Every turbo will have a different compressor map dictating where they are most efficient and such.
> 
> Something like this.
> 
> ...


And BMW uses VGT, and two stage turbos and twin turbos. I would say BMW engine would be better choice then Cummins in ANY car. 
Again, you are DISREGARDING other parameters and only looking from performance perspective. 
Also, all diesel engines have turbo lag including Cummins.

Sent from my iPhone using Tapatalk


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## alacey (Mar 14, 2018)

edycol said:


> And BMW uses VGT, and two stage turbos and twin turbos. I would say BMW engine would be better choice then Cummins in ANY car.
> Again, you are DISREGARDING other parameters and only looking from performance perspective.
> Also, all diesel engines have turbo lag including Cummins.
> 
> Sent from my iPhone using Tapatalk


Nope I don't think I am disregarding the performance aspect. There are VGT's on many performance cars like Porche 997, Koenigsegg Agera, and more. Although it is mainly limited to mostly diesels due to the high exhaust temps of gasoline engines requires exotic metals in the vanes of VGT's so they can handle the heat which also increases cost.

You are disregarding the difference between being forced to select a turbo that best fits their engine design versus one specifically designed for an engine. It is like the difference of having a custom tailored suit versus just picking the best one that fits off the shelf. In my many years working for different engine and auto manufacturers I can understand BMW is limited to what their suppliers have unless they want to pay for a custom part which increases costs especially if it is not a high volume product.

BMW does not make their own turbos so they rely on picking a supplier's turbo that best fit what they want out of the engine. They will look at the various compressor maps (that I mentioned earlier) to choose one depending on what their priority for that engine is. If the supplier does not make a big enough VG turbo(or any turbo) for their performance needs for that engine, then they have to go with that suppliers dual or triple turbos and design the engine around that.

I am not sure what your knowledge or experience is with adding turbos to an engine is, but if you have done it before then you will know that there is a give and take with every turbo from each supplier. Each turbo may be made for a displacement range(say between 2.5L and 3.5L) and their compressor maps may not be exactly what you want. So you either have to compromise with what is most important to you(i.e more peak power at the expense of lag) or go dual turbos if they don't make a single big enough for what you are looking for. I have no doubts that if BMW did make their own turbos then they would go VGT on almost all engines.

Cummins on the other hand makes their own turbos and I can tell you first hand that they not only design them for a specific engine and application, but they also make them for different power levels in that application. This leaves you with less compromises since you have the ability to design a turbo for specific engine, response, and performance you want to achieve rather than being forced to pick one that fits many different applications. Like I said, custom tailored suit versus one that is off the shelf.

You can either pick one of these from a suppler (Link to Garrett turbo catalog) or make one for a specific engine and another five more for different power levels for that engine.


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## Thecastle (Feb 5, 2016)

I'll also add one other thing being left out of this discussion on the differences between a BMW diesel and a Cummins 6.7L diesel. The Cummins and BMW engines are optimized to do different things. 

RPM operating range, the Cummins is a very low reving engine redlining typically in modern form at 3000rpm. So it has an extremely narrow operating range and very low volumetric efficiency because it can't rev. As compared to a BMW diesel which redlines (M57) at 5000rpm, and makes real power at 4500-5000rpm. 

Or another way to say it, the cummins has a very narrow power band, basically its peak torque is in a vary narrow operating range, peak torque (full spool) at 1400rpm, and it drops off a cliff at 2800 rpm, so it only has a 1400rpm operational range. Pretty easy for a single turbo to be optimized for that (no need for high flow, as you can't rev). So basically its a puke, then die engine, power, then no power. But fine if your into steady state high loads (towing at a constant speed), not so awesome for acceleration, area under the curve is small and narrow. 

BMW on the other hand has a much wider operating range than the cummins, the 335d can achieve full spool of the small turbo at 1200rpm, and the large turbo at 2000rpm, making the torque curve much flatter and it makes real power from 1200-4800 rpm. Its power doesn't fall off a cliff (like the cummins), giving you a broader power range, more volumetric efficiency, and more hp for the displacement due to higher revs.

Trucks are slow, but can tow. Their engines are optimized for that narrow duty. BMW's engines are optomized to be performance gasoline alternatives.


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## Thecastle (Feb 5, 2016)

I'll also add one other thing being left out of this discussion on the differences between a BMW diesel and a Cummins 6.7L diesel. The Cummins and BMW engines are optimized to do different things. 

RPM operating range, the Cummins is a very low reving engine redlining typically in modern form at 3000rpm. So it has an extremely narrow operating range and very low volumetric efficiency because it can't rev. As compared to a BMW diesel which redlines (M57) at 5000rpm, and makes real power at 4500-5000rpm. 

Or another way to say it, the cummins has a very narrow power band, basically its peak torque is in a vary narrow operating range, peak torque (full spool) at 1400rpm, and it drops off a cliff at 2800 rpm, so it only has a 1400rpm operational range. Pretty easy for a single turbo to be optimized for that (no need for high flow, as you can't rev). So basically its a puke, then die engine, power, then no power. But fine if your into steady state high loads (towing at a constant speed), not so awesome for acceleration, area under the curve is small and narrow. 

BMW on the other hand has a much wider operating range than the cummins, the 335d can achieve full spool of the small turbo at 1200rpm, and the large turbo at 2000rpm, making the torque curve much flatter and it makes real power from 1200-4800 rpm. Its power doesn't fall off a cliff (like the cummins), giving you a broader power range, more volumetric efficiency, and more hp for the displacement due to higher revs.

Trucks are slow, but can tow. Their engines are optimized for that narrow duty. BMW's engines are optimized to be performance gasoline alternatives.


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