[Drivaar]

Although it's rated at 425 ft-lb, the final drive is 19% weaker than in the 335i, and the 335d weighs about 6% more than the 335i also...

So in the end, the engine's massive torque rating shows up as only about 11% more in terms of "push that you feel" when compared to the 335i.

Still a ton of torque, of course! But far less than you'd expect just based on the engine's torque rating.

And this is matches up with how it felt on a test drive... It's not nearly anything like 42% more "push that you feel" that you might expect based on a naive torque ratio comparison.

Note that this post is not saying anything subjective or opinion-related about the 335i or 335d... They are both great cars, and the differences have been discussed everywhere. I just want to share this important factoid, which may be helpful for people choosing between the two cars.

[caradd]

Yeah, people forget gear ratio and weight when it comes to HP and TQ. They just see numbers and blah blah blah.

[MrPig]

BMW is notorious for publishing underrated numbers. Diesel Power Magazine dyno'd the '09 335d at 421 lb/ft of torque at the wheels. While I know dyno numbers vary from dyno to dyno it's still pretty impressive. At the end of the day, people should just test drive both vehicles and choose based on that, not just looking at print material.

[Drivaar]

Totally agree... test-driving is always the best advice.

I would say that in practice, it did feel like almost exactly 10% or thereabout in terms of the difference between 335d and 335i "push you feel". MAYBE 15%, but they are pretty close. And in highway cruise, the MPGs didn't seem that far apart either. But in city driving, I think the 335d's MPG whallops the 335i's.

[Insider]

And of course that 11% is only at low RPM's. When revving the engine up under full throttle, the 335i actually produces more torque, and that is verified by its faster acceleration times.

[maswastage]

Originally Posted by Drivaar

Totally agree... test-driving is always the best advice.

I would say that in practice, it did feel like almost exactly 10% or thereabout in terms of the difference between 335d and 335i "push you feel". MAYBE 15%, but they are pretty close. And in highway cruise, the MPGs didn't seem that far apart either. But in city driving, I think the 335d's MPG whallops the 335i's.

Can you give any higher praise to the D, though? I think that's the whole point, is that it really doesn't feel radically different from a turbocharged gasoline engine - it is a bit more torquey and runs out of breath a bit earlier, but as a whole it drives just as well as the N54/55, two of the finest examples of a modern gasoline engine. The difference being that it is also 40-50% more fuel efficient.

So it's a win-win, in my eyes - you get all the driving pleasure of a high powered gas engine with the fuel efficiency of a fuel sipping subcompact or hybrid.

[ErvGotti]

It's funny the same facts that you bring up to compare torque to the ground between the 335i and 335d is the same argument that the E9x M3 folks make comparing torque between the S65 and N54/55.

[Thud]

Originally Posted by Drivaar

So in the end, the engine's massive torque rating shows up as only about 11% more in terms of "push that you feel" when compared to the 335i.

Still a ton of torque, of course! But far less than you'd expect just based on the engine's torque rating.

11% is definitely something you can feel in the seat of your pants. People pay good money for an equivalent amount of "push" in their 335i's!

The main point is that it has that extra grunt where you'll use it every day. The motor feels much bigger than it is. You sacrifice some on the top end, but as a nice bonus you can go longer between refueling.


However, I'm expecting our french Canadian contingent to chime in soon (he just can't stay away from diesel threads), at which point all rationality in this thread will go out the door.

[Drivaar]

Originally Posted by Thud

11% is definitely something you can feel in the seat of your pants. People pay good money for an equivalent amount of "push" in their 335i's!

Yup, you can definitely feel the 11%. But FYI, the difference in "push" (gearing + weight diff) between 335i and 328i is about 40% in any gear.

[Coolieman1220]

cute mathematical calculations. you forget to account that the Torque at peak comes at only 1750 RPM and before that number you still have almost all the torque there. Therefore its always there when you need, no downshift, it just gets up and goes and says, "KAYY>>>>BYE!!!!"

[DesiRoc]

You guys are silly.

[galahad05]

Originally Posted by Coolieman1220

cute mathematical calculations. you forget to account that the Torque at peak comes at only 1750 RPM and before that number you still have almost all the torque there. Therefore its always there when you need, no downshift, it just gets up and goes and says, "KAYY>>>>BYE!!!!"

Are you speaking of the 335i or the 335d? Both are tuned to produce peak torque at just over idle (~1400 rpm for the n54).

[Drivaar]

Originally Posted by galahad05

Are you speaking of the 335i or the 335d? Both are tuned to produce peak torque at just over idle (~1400 rpm for the n54).

Yup, exactly... both cars do the same thing -- torque comes in very early and lasts deep through the rev range.

[DnA Diesel]

Originally Posted by galahad05

Are you speaking of the 335i or the 335d? Both are tuned to produce peak torque at just over idle (~1400 rpm for the n54).

?

335i - 300 ft-lbs from 1200 to 5000rpm. (335i specs)

335d - 425 ft-lbs, 1750-2250rpm. (335d specs)

The N55 has a huge-wide flat-rated torque 'curve', so even though it has 'only' 300 ft-lbs, compared to 425, that 300 is available over a 3800rpm-wide peak torque band, vs. the 335d's narrower 500-rpm peak torque band.

In assessing overall acceleration performance (re-arranging F=ma into a=F/m) it is actually the integration of available torque (which is rotational Force) over the entire acceleration speed-range (and various gears as the transmission shifts), that results in the 335i accelerating faster than the 335d...otherwise known as "area under the (torque) curve". The gasser still wins on this integration over speed-band function, while at individual sample points, the far higher peak torque of the diesel gives windows of phenomenal acceleration sensation.

Diesels have always had relatively narrower torque-bands compared to gasoline engines, which is why they do better with a transmissions with greater numbers of gears (Class 8 trucks with 15-18 speeds are the norm). If there was such a beast as a CVT that could handle all the diesel's torque, that would be the best, the worst being a widely-spaced, manual transmission that didn't allow the engine to be used most often towards its peak torque.

Cheers
D.

[Drivaar]

DnA Diesel: I agree with most of what you've written, except that the 335d's "peak torque" rating of 1750-2250 doesn't mean it isn't VERY close to that torque level right after the drop-off. All it means is that the absolute peak is in that range. In reality, it delivers pretty solid thrust throughout, though yes it drops a little after 2250 rpm.

[cssnms]

Originally Posted by Drivaar

DnA Diesel: I agree with most of what you've written, except that the 335d's "peak torque" rating of 1750-2250 doesn't mean it isn't VERY close to that torque level right after the drop-off. All it means is that the absolute peak is in that range. In reality, it delivers pretty solid thrust throughout, though yes it drops a little after 2250 rpm.

Right, the d is producing over 300lb ft at 3500 rpm just around the point of peak hp.

Otherwise this is a silly thread.

[statelax3]

i had a d as a loner a few weeks ago. even with down pipes and tune the d felt like it had more torque. butt dyno for the win!

[Inspired]

What is the quarter mile on the 335D?

[maswastage]

Originally Posted by twinturbo335

What is the quarter mile on the 335D?

It's a few ticks slower than a 335i, but still plenty fast. Hotrod, one of our forum members, clocked his at 13.7 and 102 mph when it was running stock.