RE: Audi RS5 TDI: Driven
Discussion
All premium manufacturers have an e-boost ready for production within the next 3 years, some 42volt, some 12volt. 12volt is less efficient, but 48volt requires a lot of extra hardware which pushes weight up and economy down, bit of a balancing act.
What will define whether or not the RS5D sells is the sound insulation and generation systems. To be honest, if you take away the rev counter and sound, what fuel goes into the thing under the bonnet makes no difference, it's the engine performance characteristics that then define the drive. By giving the driver artificial sound, and damping out all the real engine noise, you can make the driver think he's in a high revving sports car instead of a dreary diesel, and with the torque of modern turbo diesels out-preforming their petrol counterparts, there's room to tune the engine to produce performance that matches the petrol equivalents.
Personally I've always felt that buying a car with fake noise is a bit like buying a GT40 replica, yes it looks the part, it may be identical in every way to the original, but it's not a GT40 and never will be and that's purely an emotional thing. It's that emotional element that I attach to real engine and exhaust notes, but I bet I'm in the minority.
What will define whether or not the RS5D sells is the sound insulation and generation systems. To be honest, if you take away the rev counter and sound, what fuel goes into the thing under the bonnet makes no difference, it's the engine performance characteristics that then define the drive. By giving the driver artificial sound, and damping out all the real engine noise, you can make the driver think he's in a high revving sports car instead of a dreary diesel, and with the torque of modern turbo diesels out-preforming their petrol counterparts, there's room to tune the engine to produce performance that matches the petrol equivalents.
Personally I've always felt that buying a car with fake noise is a bit like buying a GT40 replica, yes it looks the part, it may be identical in every way to the original, but it's not a GT40 and never will be and that's purely an emotional thing. It's that emotional element that I attach to real engine and exhaust notes, but I bet I'm in the minority.
sanctum said:
All premium manufacturers have an e-boost ready for production within the next 3 years, some 42volt, some 12volt. 12volt is less efficient, but 48volt requires a lot of extra hardware which pushes weight up and economy down, bit of a balancing act.
.
48 volt will always give the better economy gains regardless of weight, its the system cost thats the problem. .
Yet to see an e boost system of 12V though, the motor size would be too large even if you could provide the current. 24V is entry level shown by PSA iStars.
Stu R said:
Diesels are for torque. Economy is a just a plus in some cars where there's not a lot of work asked of them or weight to pull. My pick-up barely betters what the V8 petrol can do MPG wise, but it'll pull a house down and barely know it's there.
While I'd never choose one over a nice rev happy engine in a sports car application, the RS5 is not a sports car, it's a fast GT bloater. It'll probably work pretty well with a big diesel, and in the bigger stuff like Q7s where it's nice having sufficient poke to get to cruising speed in no time at all, in one effortless and smooth surge.
It's very much a case of horses for courses IMO. For non-enthusiastic, relaxed cruising it's perfect to me.
While that may be true, I don't agree with giving it an RS badge.While I'd never choose one over a nice rev happy engine in a sports car application, the RS5 is not a sports car, it's a fast GT bloater. It'll probably work pretty well with a big diesel, and in the bigger stuff like Q7s where it's nice having sufficient poke to get to cruising speed in no time at all, in one effortless and smooth surge.
It's very much a case of horses for courses IMO. For non-enthusiastic, relaxed cruising it's perfect to me.
Edited by Stu R on Tuesday 22 July 12:45
sleep envy said:
Stu R said:
TurboHatchback said:
I really don't understand the point of this. Diesels are for economy
Diesels are for torque. Economy is a just a plus in some of them where there's not a lot asked of them. My pick-up barely betters what the V8 petrol can do MPG wise, but it'll pull a house down and barely know it's there.While I'd never choose one over a nice rev happy engine in a sports car application, but the RS5 is not a sports car, it's a fast GT bloater. It'll probably work pretty well with a big diesel, and in the bigger stuff like Q7s where it's nice having sufficient poke to get to cruising speed in no time at all, in one effortless, smooth surge.
It's very much a case of horses for courses IMO.
Just to clear that up. The combustion process of a compression ignition engine is far more efficient than that in a spark ignition engine (about 50% vs 35% of energy created is actually turned into useful work). Currently, the only compression ignition engines in automotive mass production are diesel fuelled. That is going to change in the next 20 years.
The reason modern diesels produce such high torque levels is a by-product of that efficiency. You can run a larger turbo and push more fuel and air around to produce more power, but still deliver good fuel economy.
JonnyVTEC said:
sanctum said:
All premium manufacturers have an e-boost ready for production within the next 3 years, some 42volt, some 12volt. 12volt is less efficient, but 48volt requires a lot of extra hardware which pushes weight up and economy down, bit of a balancing act.
.
48 volt will always give the better economy gains regardless of weight, its the system cost thats the problem. .
Yet to see an e boost system of 12V though, the motor size would be too large even if you could provide the current. 24V is entry level shown by PSA iStars.
sanctum said:
sleep envy said:
Stu R said:
TurboHatchback said:
I really don't understand the point of this. Diesels are for economy
Diesels are for torque. Economy is a just a plus in some of them where there's not a lot asked of them. My pick-up barely betters what the V8 petrol can do MPG wise, but it'll pull a house down and barely know it's there.While I'd never choose one over a nice rev happy engine in a sports car application, but the RS5 is not a sports car, it's a fast GT bloater. It'll probably work pretty well with a big diesel, and in the bigger stuff like Q7s where it's nice having sufficient poke to get to cruising speed in no time at all, in one effortless, smooth surge.
It's very much a case of horses for courses IMO.
Just to clear that up. The combustion process of a compression ignition engine is far more efficient than that in a spark ignition engine (about 50% vs 35% of energy created is actually turned into useful work). Currently, the only compression ignition engines in automotive mass production are diesel fuelled. That is going to change in the next 20 years.
The reason modern diesels produce such high torque levels is a by-product of that efficiency. You can run a larger turbo and push more fuel and air around to produce more power, but still deliver good fuel economy.
Stu R said:
While I'd never choose one over a nice rev happy engine in a sports car application, but the RS5 is not a sports car, it's a fast GT bloater
"a growly burbly petrol-aping menace that is actually generated from a vibrating speaker within the exhaust pipe. The third is what you hear from within the car and it's gravellier noise that's no less appealing but references the diesel under the bonnet a bit better. This is synthesised and emanates from the car's interior speakers to exact match the revs. As a backdrop to pedal-down driving, it all sounds appropriate."
C'mon ffs
plus unfair surely to compare to petrol that hasn't got the electric wizardry!
TX.
C'mon ffs
plus unfair surely to compare to petrol that hasn't got the electric wizardry!TX.
Ugh.
Fake sound inside, fake sound outside. Give it a break, it's f
king pathetic.
A diesel doesn't necessarily sound bad, it just doesn't sound like a petrol engine, and that's fine. Don't try to tart it up, it's ghastly. Same goes for petrol turbos at the moment - no they don't sound like n/a petols, so don't try and copy them ffs! Did the various turbo versions of everything in the 80s sound that bad?! (answer: no, they sounded like turbos, ie, quite exciting).
But my biggest gripe with these cars now is this: two turbos, a turbo to spin the turbos, dsg's, hugely complicated stability systems, vast amounts of interior nonsense... It used to be that it was only really the s-class that was full of these gimmicks (and as a result I haven't seen one in years - no one can afford to keep them going). Now every single car on sale over £30k is full of "exciting" (irrelevant) technology. Not one of these cars will still be on the road in 15 years.
I bought an early 90s s-class as my first car - I ran it for around 6 months before the first "minor" issue cropped up (only a ten year old car at the time) - had to auction it.
All this st. It's all gonna break. And "Gus" down at the local shed won't be able to batter it back into life. Toys for toys sake. Does a diesel audi need better throttle response? Of course it doesn't, it's a fking diesel audi.
Fake sound inside, fake sound outside. Give it a break, it's f
king pathetic. A diesel doesn't necessarily sound bad, it just doesn't sound like a petrol engine, and that's fine. Don't try to tart it up, it's ghastly. Same goes for petrol turbos at the moment - no they don't sound like n/a petols, so don't try and copy them ffs! Did the various turbo versions of everything in the 80s sound that bad?! (answer: no, they sounded like turbos, ie, quite exciting).
But my biggest gripe with these cars now is this: two turbos, a turbo to spin the turbos, dsg's, hugely complicated stability systems, vast amounts of interior nonsense... It used to be that it was only really the s-class that was full of these gimmicks (and as a result I haven't seen one in years - no one can afford to keep them going). Now every single car on sale over £30k is full of "exciting" (irrelevant) technology. Not one of these cars will still be on the road in 15 years.
I bought an early 90s s-class as my first car - I ran it for around 6 months before the first "minor" issue cropped up (only a ten year old car at the time) - had to auction it.
All this s
t. It's all gonna break. And "Gus" down at the local shed won't be able to batter it back into life. Toys for toys sake. Does a diesel audi need better throttle response? Of course it doesn't, it's a fking diesel audi. sanctum said:
Actually no, not "nailed it" at all.
Just to clear that up. The combustion process of a compression ignition engine is far more efficient than that in a spark ignition engine (about 50% vs 35% of energy created is actually turned into useful work). Currently, the only compression ignition engines in automotive mass production are diesel fuelled. That is going to change in the next 20 years.
The reason modern diesels produce such high torque levels is a by-product of that efficiency. You can run a larger turbo and push more fuel and air around to produce more power, but still deliver good fuel economy.
I was being flippant, I'll use smilies next time. On reflection it did come across as if I was being serious. To clarify - I couldn't give a toss about economy so long as I get my beloved torque. Just to clear that up. The combustion process of a compression ignition engine is far more efficient than that in a spark ignition engine (about 50% vs 35% of energy created is actually turned into useful work). Currently, the only compression ignition engines in automotive mass production are diesel fuelled. That is going to change in the next 20 years.
The reason modern diesels produce such high torque levels is a by-product of that efficiency. You can run a larger turbo and push more fuel and air around to produce more power, but still deliver good fuel economy.
As for other compression ignitions coming to market, I'm intrigued, HCCI or similar I take it? I have a feint recollection Hyundai were working on something similar a couple of years ago.
JonnyVTEC said:
Looks like it will go in the Q7 first anyway which is more palatable powerful diesel offering; thats where we saw the bonker V12 diesel.
The problem with this engine is it has less power and less torque than the latest V8 diesel in the A8 (380bhp & 620lbft). I can only assume they are dropping the V8 diesel from the Q7. Maybe there's a new V8 on the way with this electric turbine thing and >450bhp.TobesH said:
My choice of fast diesel...
Performance
Acceleration 0-100km/h (s) 4.6
Top speed (mph (kph)) 173 (278)
Fuel consumption *
Urban (mpg) 47.1
Extra-urban (mpg) 57.6
Combined (mpg) 53.3
CO² emissions (g/km) 139
Efficiency category B
Sack those alloys off for something a bit more middle of the road and I am with you all the way on that one.Performance
Acceleration 0-100km/h (s) 4.6
Top speed (mph (kph)) 173 (278)
Fuel consumption *
Urban (mpg) 47.1
Extra-urban (mpg) 57.6
Combined (mpg) 53.3
CO² emissions (g/km) 139
Efficiency category B
Stu R said:
sanctum said:
Actually no, not "nailed it" at all.
Just to clear that up. The combustion process of a compression ignition engine is far more efficient than that in a spark ignition engine (about 50% vs 35% of energy created is actually turned into useful work). Currently, the only compression ignition engines in automotive mass production are diesel fuelled. That is going to change in the next 20 years.
The reason modern diesels produce such high torque levels is a by-product of that efficiency. You can run a larger turbo and push more fuel and air around to produce more power, but still deliver good fuel economy.
I was being flippant, I'll use smilies next time. On reflection it did come across as if I was being serious. To clarify - I couldn't give a toss about economy so long as I get my beloved torque. Just to clear that up. The combustion process of a compression ignition engine is far more efficient than that in a spark ignition engine (about 50% vs 35% of energy created is actually turned into useful work). Currently, the only compression ignition engines in automotive mass production are diesel fuelled. That is going to change in the next 20 years.
The reason modern diesels produce such high torque levels is a by-product of that efficiency. You can run a larger turbo and push more fuel and air around to produce more power, but still deliver good fuel economy.
As for other compression ignitions coming to market, I'm intrigued, HCCI or similar I take it? I have a feint recollection Hyundai were working on something similar a couple of years ago.
1.8 4 pot turbo petrol 235bhp and 300lbft 47mpg.
http://en.wikipedia.org/wiki/DiesOtto
Edited by dukebox9reg on Tuesday 22 July 14:59
Article said:
That extra weight, not just of the strengthened engine block, but also the flywheel and the stronger pistons and con-rods, is one drawback to getting diesels mentioned in the same breath as performance petrols. It takes more force to get them spinning and, if you come off the gas, the revs fall away more slowly. It's impossible to see diesel motors in track day weapons for example.
Mazda's latest diesel engine has gone the opposite way: with a lower compression ratio it can use lighter pistons, con-rods, crankshaft etc. so it revs more freely; I've driven one and it really shows; noise aside the main difference between it and the petrol car is simply the much earlier rev limit. It's not going to match some top-end sportscars with tiny flywheels for response, but its definitely a step forward IMO.Gassing Station | General Gassing | Top of Page | What's New | My Stuff