RE: BMW Z4 Gets New 4-Pot Option
Discussion
doogz said:
It does? Please, do explain, how peak torque by 1800rpm can be viewed as artificially limited?
You think it makes more torque down there, but they limit it to the amount it makes at 5k rpm?
Well the torque curve is perfectly flat for most of its length. That can't be natural, surely? Many of these high powered forced induction engines do have a torque limiter to protect the gearbox and/or diff. You think it makes more torque down there, but they limit it to the amount it makes at 5k rpm?
It's only likely to be torque limited to the extent that is how it's been mapped for smoother power delivery. If you were to push the engine to its limits at every RPM point it would likely follow a more natural power curve. A torque limit because of the transmission would likely not show up on the published power curve, as it would not be operational in every gear.
Hey, at least BMW haven't gone down the Aston route and rolled some bland little appliance turd in glitter in order to bring down average co2 numbers. (stop there iQ owners - I'm sure your car is great, but in the context of sporting cars on an enthusiast website it counts as a turd - so please don't waste time telling us how good it is)
I'm generally of the opinion that anything less than 6 cylinders isn't a proper engine, but...is it really so bad to have a 240bhp turbo/4 in the Z? You don't have to buy that version; go for your 6's until your heart is content, but if BMW can continue to become evermore efficient whilst still delivering the goods, surely that's got to be a positive thing, right? Different approaches to improved efficiency:
Aston = Polish a turd so we can keep making cars (that look almost exactly the same) with engines that are curiously underpowered for their vast displacment and inefficiency. (still want one though)
BMW = Make 'proper' models with ever more efficient engines/drivetrains whereby little turbo/4s +ED makes it so we can build big turbo v-8s that have power appropriate to their displacement.
VAG = Make every possible car/engine combination (with 4 basic platforms spawning 23,467 different models/badges) from tiny little 4s to mahoosive quad turbo 16's and hope it all balances out.
I'm generally of the opinion that anything less than 6 cylinders isn't a proper engine, but...is it really so bad to have a 240bhp turbo/4 in the Z? You don't have to buy that version; go for your 6's until your heart is content, but if BMW can continue to become evermore efficient whilst still delivering the goods, surely that's got to be a positive thing, right? Different approaches to improved efficiency:
Aston = Polish a turd so we can keep making cars (that look almost exactly the same) with engines that are curiously underpowered for their vast displacment and inefficiency. (still want one though)
BMW = Make 'proper' models with ever more efficient engines/drivetrains whereby little turbo/4s +ED makes it so we can build big turbo v-8s that have power appropriate to their displacement.
VAG = Make every possible car/engine combination (with 4 basic platforms spawning 23,467 different models/badges) from tiny little 4s to mahoosive quad turbo 16's and hope it all balances out.
PMKeates said:
It's only likely to be torque limited to the extent that is how it's been mapped. If you were to push the engine to its limits at every RPM point it would likely follow a more natural power curve. A torque limit because of the transmission would likely not show up on the published power curve, as it would not be operational in every gear.
Surely that depends on which end of the gearbox it's trying to protect? doogz said:
It does? Please, do explain, how peak torque by 1800rpm can be viewed as artificially limited?
You think it makes more torque down there, but they limit it to the amount it makes at 5k rpm?
Whaddya want, proof?You think it makes more torque down there, but they limit it to the amount it makes at 5k rpm?
I think this makes it perfectly clear that torque has been artificially limited, don't you?
No amount of internet forum hypothesising can dispute the cold hard FACTS, clearly illustrated in the equation above.
kambites said:
Surely that depends on which end of the gearbox it's trying to protect?
Of course, by transmission I really meant the drivetrain. 'Limiting' torque because you are mating it to a certain transmission is just mapping and packaging, I wouldn't really call it limiting. Almost every engine can produce more power than it is packaged to, especially turbocharged engines. Not producing maximum power for reasons of internal reliability, potential damage to other components etc. is just standard practice for automakers.doogz said:
Like PMKeates says, that's not likely to be the case. This graph originated from MINI, apparently, it's most likely from an engine dyno, but either way, i severely doubt the torque curve as we see if there, is artificially limited at lower revs. That makes no sense.
Many engines these days have a flat portion to the torque curve, where they make peak torque right through a certain rev range, that's not limited to FI engines either.
If that's the case (and I have no reason to believe that you're wrong about that), I still hold that it's a limit - whether it's simply "part of the map" or not is rather a question of semantics. No engine, if allowed to breath to the best of its ability, would ever have a perfectly flat section to its torque curve like that. Many engines these days have a flat portion to the torque curve, where they make peak torque right through a certain rev range, that's not limited to FI engines either.
That engine could generate more torque if the manufacturer had wanted to and indeed it looks as if the manufacturer has gone out of their way to avoid it. Perhaps to make it feel more sporty and less diesel-like? Or maybe to protect things. I guess with a fuel injected turbo, there isn't really such a thing as a "natural" torque curve though, manufacturers can do pretty much what they want.
Maybe BMW will get this right and it'll be the first turbocharged engine that I'll like...
Edited by kambites on Wednesday 20th April 12:49
I may be being naive here but isn't this the best of both worlds?
With new restrictions on emissions and the simple fact that a lot of people (I'm not going to point fingers at any demographic) only want a nice looking car which is relatively cheap to run. These sell in droves which then allows BMW to keep hold of its six cyl plants in the hotter versions.
Stop whinging, they need to sell cars, not please the few people who are genuinely interested in them.
With new restrictions on emissions and the simple fact that a lot of people (I'm not going to point fingers at any demographic) only want a nice looking car which is relatively cheap to run. These sell in droves which then allows BMW to keep hold of its six cyl plants in the hotter versions.
Stop whinging, they need to sell cars, not please the few people who are genuinely interested in them.
doogz said:
The one i posted meets those criteria, what's the issue with it?
Nothing at all if they do that and it really feels like it needs to be revved. It's a good solution to the problem. It's also one that I've never known to work in any of the turbocharged cars that I've driven (including the MINI), although that's probably mostly because they've been shopping cars rather than sports cars. Maybe BMW can make this feel wonderful... I certainly have nothing about I4 engines if they can get around the turbo issues. I'm not holding my breath, though.I certainly have nothing against this car existing, it sounds like a viable addition to the range. I just can't help but feel that we're seeing the end of BMW's I6 engines in their smaller cars.
Edited by kambites on Wednesday 20th April 12:56
kambites said:
otolith said:
kambites said:
I think tripples can sound quite nice.
They sound different...doogz said:
So, you don't like torque?
Basically, you want something that has to be ragged, to go anywhere in a hurry, yeah?
If so, that's fair enough, i'm just trying to figure out your angle.
In sports cars yes, I suppose that just about sums it up. Torque is a wonderful thing in a car that you want to be very little effort to drive; but a sports car that's very little effort to drive seems a bit of an oxymoron to me. Basically, you want something that has to be ragged, to go anywhere in a hurry, yeah?
If so, that's fair enough, i'm just trying to figure out your angle.
I think turbochargers suit barges and GTs very well.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff