M3 Diesel (M3d) ???

[mkoesel]

Originally Posted by Radiation Joe

Bottom line is I'd buy a diesel BMW with all of the M accoutrements.

Originally Posted by erhanh

I think that is possible in Europe, at least to some degree. I'd buy one too.

To bring things back on topic, how much performance would you guys be willing to give up to get the diesel?

Suppose the car performs at rougly 80% of the equivalent gasoline M3 on average, gets 25% better fuel economy on average, and costs the same. Buy?

(Obviously the performance differences are due to the engine. The suspension, brakes, differential, etc. are the same for both. Also assume the weight of the two is equal.).

[Erhan]

Originally Posted by mkoesel

To bring things back on topic, how much performance would you guys be willing to give up to get the diesel?

Suppose the car performs at rougly 80% of the equivalent gasoline M3 on average, gets 25% better fuel economy on average, and costs the same. Buy?

(Obviously the performance differences are due to the engine. The suspension, brakes, differential, etc. are the same for both. Also assume the weight of the two is equal.).

Just to make it clear, I didn't mean I'd buy a diesel M3. I'd buy a DD diesel (1 or 3 series) with M suspension.

[Uli_HH]

I owned an X3 3.0sd, and this car was an real monster! So if you go away from racetrack issues, I think most normal people on road would be faster with the massive torque of an diesel engine specially in thicker traffic.

And in the new market in china the buyers don´t know much about M history .. for them ist only an fast highpower car nice to own ... they don´t care about high rev and such issue why we love the NA M´s, what only counts is that the car is fast ... they will buy the car without asking if it has an special engine ... and like I wrote before most people in normal traffic, were torque counts, would be faster with an diesel engine.

So I am sure we would see diesel M´s in the near future, first in the SUV range and later also in the other cars.

Uli_HH

[mkoesel]

Originally Posted by erhanh

Just to make it clear, I didn't mean I'd buy a diesel M3. I'd buy a DD diesel (1 or 3 series) with M suspension.

Ok. So if I may offer an interpretation: in other words, you would be open to a higher performance BMW with a diesel, but you wouldn't pay M3-money for it, and you would still want another car for your "toy" or "weekend" car. Fair to say?

[FStop7]

I would be interested in a diesel M car if it had 500+ horsepower. I've been hoping to see Audi put the twin turbo V12 diesel R8 into production.

If BMW is eschewing high revving NA motors in favor of lower revving turbo motors then they may as well do it right and go diesel.

[bruce.augenstein@comcast.]

Originally Posted by SYT_Shadow

...Two cars with identical horsepower, where one has twenty times the torque of the other, will accelerate the same provided adequate gearing to each of their power deliveries. There is no getting around this...

This is true in simple theory.

However, all other things being equal (i.e. - car weight, rotational inertia, driveline friction, blah blah etc.) this is only true if both cars are operating at their power peaks, via cvt or at some specific speed.

In the real world, however, the torque-rich vehicle will win. This is because, after each shift, the torque-rich car will be making more power (i.e. - more torque) and will pull away.

A good example is the current M3 against the C63. The M3 has a slightly better power to weight ratio, but the C63 is a little quicker over, say, a quarter mile. This is in spite of the fact that the C63 loses some of its power before it gets to the ground because it has to run an additional oil pump for the automatic trans.

Bruce

[mjf6175]

This happens to be a very timely thread/discussion for me. I am new here (and to BMW) but actually an older guy who tinkers/mods his cars. I posted a couple of days ago in another section looking for info and guidance on a plan I had which was to mod a new 335d that has the M Sport pkg. Was looking to change out the sway bars for M3 convertible ones (they are the thickest) along with Koni Yellow Sports, BMW Performance Springs,M3 Strut Brace, and ultra-performance all season tires (non-RFT). Think it would be a sweet ride. Now yes some may find it hard to wrap their mind around the idea of M3+Diesel type of car but I think that the "future" of performance cars is going to go in somewhat in this direction. I believe in the not to distant future performance/sports cars are going to include some component of hybrid/electric technology. Such an idea or path for higher performance makes the same sense (to me at least) along the lines of a diesel vehicle as well. Just because we can afford to pay for gas does not mean we should not be concerned about how much we use, such an outlook helped get us where we are now when it comes to energy policies. I also like the idea of a M3/diesel just because it is different, doable, while getting performnce and economy at the same time. Not to mention that diesel engines can be modilfied somewhat easily. There is a member of this board who has a new 335d and has "chipped' it (a $279 add on box) and has posted the following performance: " 0-60 in 4.5 seconds, and 12.9 ETs".

Let me make it clear that I am not trying to argue the point but rather there is a logic behind the idea of a M3/diesel type. I am planning on ordering a new BMW in the next month. I am torn between the 335d and a M3-E90. Yes of course the M3 is the better performance car but between the simple idea of turning a 335d into something close to that for about $10k less gets my interest. Just one man's (NOOB) opinion.........

[Radiation Joe]

Originally Posted by mkoesel

Ok. So if I may offer an interpretation: in other words, you would be open to a higher performance BMW with a diesel, but you wouldn't pay M3-money for it, and you would still want another car for your "toy" or "weekend" car. Fair to say?

I believe the cost of a high performance diesel is probably close to the cost of a limited production engine like the S65. So apples to apples is probably a wash on price.

I think your estimates for performance trade-offs are close on power and pretty far off on efficiency. 80% of the S65s power or 330 hp sounds right, but probably 60% better mileage or 32 on the the highway considering fat, sticky tires.

The killer to an M-type of car would be the additional weight that comes with a diesel. Note that the curb weight of a 335d is about 200 lbs more than the 335i.

[Erhan]

Originally Posted by mkoesel

Ok. So if I may offer an interpretation: in other words, you would be open to a higher performance BMW with a diesel, but you wouldn't pay M3-money for it, and you would still want another car for your "toy" or "weekend" car. Fair to say?

That is true. I still want a proper high rev engine which delivers peak hp at/close to redline with performance oriented gearing.

The DD diesel doesn't need to be powerful, just handle good with decent brakes.

[bruce.augenstein@comcast.]

Originally Posted by erhanh

330lb-ft of torque at 1000rpm. Now that's a low end torque

Joking aside, that engine is impressive. It would be perfect it was able to keep the power going up all the way to redline.

Just curious. Other than a personal preference of some sort, why would that make it perfect?

Arguably, an engine that can rev well above its power peak makes better use of the power it has. As an example, if the M3 could rev to, say, 9200 rpm, with the identical power and torque curves it now has, obviously peaking at the same revs (295 @ 3900, 414 @ 8300), it would be a quicker car in a straight line if you shifted at the new red line.

The current Z06 has a red line approximately 10% above its power peak, which is, as a rule of thumb, ideal for getting the best acceleration out of the power it makes.

Bruce

[mkoesel]

Originally Posted by Radiation Joe

I believe the cost of a high performance diesel is probably close to the cost of a limited production engine like the S65. So apples to apples is probably a wash on price.

I disagree that effective cost is the same simply because sales numbers will not be the same. Also, total sales of non-diesel M3 will likely be effected (just how would be up to BMW to figure out). At best, you could say that you could increase the asking price on all M3 to account for the development of the second motor. This of course, means shrinking the total audience because you will price the car out of the range of some who would otherwise buy, and they will likely seek a competitors car with a lower price instead (such as C63).

I think your estimates for performance trade-offs are close on power and pretty far off on efficiency. 80% of the S65s power or 330 hp sounds right, but probably 60% better mileage or 32 on the the highway considering fat, sticky tires.

Better highway mileage, sure, but I was just taking a stab at overall efficiency gains. My assumption is that an M3 diesel will be driven hard just as a gasoline model will. In that case, the efficiency advantage of the diesel shrinks.

The killer to an M-type of car would be the additional weight that comes with a diesel. Note that the curb weight of a 335d is about 200 lbs more than the 335i.

But an M3 weighs about that much more than a 335i too. Now, that is obviously due in large part to the M3 specific parts that would be put on the diesel M3 as well. But my assumption is that an N55 and N57 should weigh about the same. I don't have an explanation for why the 335d outweighs a 335i by so much. Could some of it be difference in content? Again, I really don't see why a modern I6 diesel should weigh more than a comparable I6 gasoline motor.

Oh, and yes, I know the M3 has a V8, but the next generation one won't so the I6 vs. I6 comparison makes sense for this forward-looking discussion.

[mkoesel]

Originally Posted by mjf6175

I am planning on ordering a new BMW in the next month. I am torn between the 335d and a M3-E90. Yes of course the M3 is the better performance car but between the simple idea of turning a 335d into something close to that for about $10k less gets my interest. Just one man's (NOOB) opinion.........

I go back to a point I've made a couple times now in this thread. That is, you can get efficiency gains vs. an M3 very easily by going with a N55. So, just get a 335i, save yourself the money vs. a 335d, and install the same suspension and brake mods you were already planning. I'll bet a tuned N55 will offer better performance than a tuned N57. And the money you save by not getting the 335d will easily cover your higher gas bills.

You also get the option for 6MT or DCT.

[Radiation Joe]

Originally Posted by mkoesel

I go back to a point I've made a couple times now in this thread. That is, you can get efficiency gains vs. an M3 very easily by going with a N55. So, just get a 335i, save yourself the money vs. a 335d, and install the same suspension and brake mods you were already planning. I'll bet a tuned N55 will offer better performance than a tuned N57. And the money you save by not getting the 335d will easily cover your higher gas bills.

You also get the option for 6MT or DCT.

If he was totally concerned with economy of dollars, he wouldn't be considering the cars we're discussing. Diesel cars use significantly less fuel than gas powered equivalents. Many of us are willing to pay a little more to reduce our use of resources ... reduce our carbon footprint to use the parlance of the times.

[mkoesel]

Originally Posted by Radiation Joe

Many of us are willing to pay a little more to reduce our use of resources ... reduce our carbon footprint to use the parlance of the times.

Understood. I guess I just don't understand the notion of struggling between the 335d and the M3, when there's an elephant driving circles around the room in a 335i.

[bruce.augenstein@comcast.]

Originally Posted by mkoesel

...But an M3 weighs about that much more than a 335i too. Now, that is obviously due in large part to the M3 specific parts that would be put on the diesel M3 as well. But my assumption is that an N55 and N57 should weigh about the same. I don't have an explanation for why the 335d outweighs a 335i by so much. Could some of it be difference in content? Again, I really don't see why a modern I6 diesel should weigh more than a comparable I6 gasoline motor...

The reason an "equivalent" diesel is heavier is that its combustion process is essentially the same as a gasoline engine which is undergoing heavy knock. You can mitigate the issue to some extent with careful control of injector timing sequences, but in fact a diesel ignites its fuel more or less spontaneously. Therefore, cylinder pressures essentially "spike", much as they would in a current M3 with knock sensors disconnected, runing on regular. A few hundred miles of that and the current V8 would start to look like something Salvador Dali would be proud of.

The diesels have stronger (heavier) blocks, thicker and stronger piston tops, piston pins, rods, crank throws, etc. etc., all necessary for acceptable engine life. In addition, turbo diesels tend to make a bunch of torque per cylinder in order to get the power levels up with low rpm limits dictated by this type of combustion, so drive trains need to be beefy to stand up under the load.

"Beefy" is essentially code for "heavy".

Bruce

Edit: Almost forgot to mention the other elephant in the diesel engine room. With compression ratios typically running from as low as 14 to 1, to as high as 20 to 1, that's the other reason cylinder pressures are so high.

[Radiation Joe]

Originally Posted by mkoesel

Understood. I guess I just don't understand the notion of struggling between the 335d and the M3, when there's an elephant driving circles around the room in a 335i.

When I think of 3 series that I would buy, the 335i is always at the bottom of my list. In order of preference:

M3
335d
328i
335i

The 328i could be ahead of the 335d. I'd have to think about it. I think it is the best value of all the 3 series and it's much simpler and lighter than any of the others.

[Erhan]

Originally Posted by bruce.augenstein@comcast.

Just curious. Other than a personal preference of some sort, why would that make it perfect?

Arguably, an engine that can rev well above its power peak makes better use of the power it has. As an example, if the M3 could rev to, say, 9200 rpm, with the identical power and torque curves it now has, obviously peaking at the same revs (295 @ 3900, 414 @ 8300), it would be a quicker car in a straight line if you shifted at the new red line.

The current Z06 has a red line approximately 10% above its power peak, which is, as a rule of thumb, ideal for getting the best acceleration out of the power it makes.

Bruce

Yes you're right. But if you're loosing power very fast after peak power, wouldn't it be worse to shift at redline?

[bruce.augenstein@comcast.]

Originally Posted by erhanh

Yes you're right. But if you're loosing power very fast after peak power, wouldn't it be worse to shift at redline?

The ideal shift point is when the actual delivered power in the next gear just matches the actual delivered power in the current gear.

With the current M3, you get to around 5000 rpm in second gear at the 1-2 shift point (at red line). The car is making somewhere around 275 HP or so at that point, so acceleration is well off compared to what you were just getting in first gear with just under 414 HP being delivered. The power curve would have to drop like a rock in the M3 past 8300 rpm (i.e. - way the hell down close to 300 HP) before you'd want to shift. Given the power curves I've seen for the M3, the power just wouldn't drop very quickly past 8300 rpm.

A 9200 rpm shift point would drop you down to around 5500 or so, where the car is making a little over 300 HP.

The car would be faster, because you're making higher average HP during the run.

Of course, it might blow up.

The mitigating factor is that, with reduced rotating inertia in second gear, you might not need to go all the way to 9200 or so before shifting.

88-8900 might do it.

[kiwistu]

My 5c

Ok, as mentioned earlier I had a 335d, and now have an m3

Ran the d on track 5 or 6 times, drove away from suby's etc and was about equal with an average joe in an E46 m3, we probably both could have gone faster too.

Anyone knocking the d should drive one for weekend or take on on a long trip. Awesome.

I moved to an m3 because it's better for me now, IMHO you can't mod a normal 3 to get it up to m3 standard. A short drive in both back too back will show the difference. (the two cars don't many bits if you compare them...)

And yes I'd buy a m3d and no it wouldn't destroy the brand. Porsche make all sorts of rubbish (try a brown cayenne 3.0 on little wheels) but I still want a 911.

Cheers
stu

[mkoesel]

Thanks Bruce - helpful information.

All of that considered, it seems fair to say that the two engines should still be relatively close in weight. I can appreciate how all those measures that are needed to give the diesel more strength will add up, but given that they have the same basic dimensions and complexity, I would suppose the N55 and N57 should probably come within 50 lbs of one another. And I know there are differences in the turbo setup as well (single twin scroll turbo vs. dual sequential turbo). So, does anyone know the weight of the N55 and N57?

I agree with you on the drivetrain components too, but I suspect that they could design M3 parts to handle the diesel that would not weigh more than the M3 parts they need to support the gasoline M3 as well. That is to say that they are already beefing everything up so they would just need to make sure that in doing do they also account for the diesel's higher torque load in the process. Probably many of the revisions that need to be made regardless would already help in that goal.

Originally Posted by bruce.augenstein@comcast.

The reason an "equivalent" diesel is heavier is that its combustion process is essentially the same as a gasoline engine which is undergoing heavy knock. You can mitigate the issue to some extent with careful control of injector timing sequences, but in fact a diesel ignites its fuel more or less spontaneously. Therefore, cylinder pressures essentially "spike", much as they would in a current M3 with knock sensors disconnected, runing on regular. A few hundred miles of that and the current V8 would start to look like something Salvador Dali would be proud of.

The diesels have stronger (heavier) blocks, thicker and stronger piston tops, piston pins, rods, crank throws, etc. etc., all necessary for acceptable engine life. In addition, turbo diesels tend to make a bunch of torque per cylinder in order to get the power levels up with low rpm limits dictated by this type of combustion, so drive trains need to be beefy to stand up under the load.

"Beefy" is essentially code for "heavy".

Bruce

Edit: Almost forgot to mention the other elephant in the diesel engine room. With compression ratios typically running from as low as 14 to 1, to as high as 20 to 1, that's the other reason cylinder pressures are so high.

[mkoesel]

This is far from authoritative not least because its N54, rather than N55. And it is probably not apples/apple as far as part content. But this at least gives some basis for comparison:

http://bmwfans.info/parts/catalog/E9.../short_engine/
http://bmwfans.info/parts/catalog/E9.../short_engine/

N57 shows no valve cover, which could account for the fact that it shows the lower weight. I think the N57 will be slightly heavier in reality, but I bet not by much.

So in conclusion, while I still think M3d faces a limited audience and market, added weight vs. the gasonline equivalent probably would not ultimately be one of the major detracting factors.

[kmarei]

people are saying a diesel would ruin the M line
are these people aware all the new M engines will be turbocharged?
so the M line is already tarnished, at least give us fuel economy as well