View Single Post
      04-22-2014, 11:49 AM   #2
Boss330
Major General
Boss330's Avatar
No_Country
1712
Rep
5,108
Posts

Drives: BMW
Join Date: Mar 2012
Location: Earth

iTrader: (0)

Great technical info

I found a few parts especially interesting:

Quote:
One difference is that with naturally aspirated engines, there is a stronger intonation of intermediate positions of the accelerator pedal. If you increase the acceleration slightly, the engine immediately sounds different. A naturally aspirated engine acknowledges the request for more power with a change in sound. But with a turbo engine, this is not resolved acoustically in such detail, because the noises on the intake and exhaust sides are heavily damped by the turbo. It is this lack of acoustic feedback that creates the subjective perception of the engine's response.
I do agree that the sound phenomenon actually takes place, but it surely doesn't account for everything... It might help exaggerate the felt lag in response, but a engine with turbo lag will still have lag. However it will be interesting to see how the S55's response really is.


Quote:
Another important point is that we normally have to take the drive train into consideration when it comes to building up torque. As a rule, the engine is able to build up torque at a speed that is much faster than that with which the drive train can cope. You can imagine that the drive train then begins to behave like a torsion spring, which is first stretched out and then vibrates, resulting in juddering. To prevent such judders, it is necessary to dampen the engine's build up of momentum to allow a harmonic progression of its response characteristics.
Torque management is obviously nothing new, but interesting insight anyway

Quote:
The rigid drive train of the new BMW M3 and BMW M4 is, however, optimised for a fast build-up of momentum, similar to a racing car, with a carbon fibre drive shaft, rear axle rigidly bolted to the body, suitably dimensioned drive shafts, etc. This means that the rigid drive train is also an important factor of the spontaneous entrance of the new BMW M3 and BMW M4. In EFFICIENT mode, everything is more levelled out, with a high orientation towards comfort. In stark contrast is the SPORT PLUS mode, which pays absolutely no attention to any comfort factors. In SPORT PLUS, all filter functions are deactivated and the engine responds directly to movements of the accelerator pedal – but this also requires someone behind the wheel who really knows what he is doing. In SPORT PLUS, everything is transmitted as sharply as a knife, in terms of what the engineering can do to facilitate fast lap times – whether in the engine, transmission, chassis or control systems.
All the reviewers have been warned, you need to be able to handle a performance car! Chris Harris, please step forward and drive the car please

Over on the M5 forum there is a debate concerning exactly this point about the M5

Last edited by Boss330; 04-22-2014 at 11:57 AM..
Appreciate 0