cars with variable power output
Discussion
I wondered if there were cars out there that allowed the user to choose the performance level?
The E60 M5 has the M button for 400 or 500 bhp and I have a feeling some American cars have a valet setting that restricts performance. However I have no idea whether this is designed for general use or just the trip to the car park.
I just struck me that most of the time an engine map or no of cylinders used that gave adequate power but decent mpg would be fine but that sometimes another chunk of performance would be great.
Suspension would need to adapt and brakes would have to be good for the full power mode.
Say a 250 to 400 jump?
Anything out there?
The E60 M5 has the M button for 400 or 500 bhp and I have a feeling some American cars have a valet setting that restricts performance. However I have no idea whether this is designed for general use or just the trip to the car park.
I just struck me that most of the time an engine map or no of cylinders used that gave adequate power but decent mpg would be fine but that sometimes another chunk of performance would be great.
Suspension would need to adapt and brakes would have to be good for the full power mode.
Say a 250 to 400 jump?
Anything out there?
Very funny to those who jumped in with the obvious.
However you are still using an engine/software set up for maximum performance whether you use it or not. Otherwise no one would complain about about 20mpg as you could just go slower and get 60. Sadly it doesn't work like that. Drive an 8 cylinder car like Miss Daisy you you aren't going to get more than say 25mpg.
But with fewer cylinders used or possibly a different, leaner map (just a theory I've no idea if its actually possible) you could.
However you are still using an engine/software set up for maximum performance whether you use it or not. Otherwise no one would complain about about 20mpg as you could just go slower and get 60. Sadly it doesn't work like that. Drive an 8 cylinder car like Miss Daisy you you aren't going to get more than say 25mpg.
But with fewer cylinders used or possibly a different, leaner map (just a theory I've no idea if its actually possible) you could.
Edited by DKL on Sunday 21st September 23:32
McSam said:
The engine management isn't just a fixed thing, it's a huge and very complex map of settings. The car considers its operating condition and your demand, and goes for the most efficient solution. No modern car, whatever its power output, is "set up" for peak power when you're cruising around at 1/8th throttle. The injection strategy, valve timing and ignition points all move around to achieve as efficient a delivery as they can, there's no need to "change maps" to do this, all these different areas are included in the one map the car has already.
The reason you can't get 60mpg out of some firebreathing V8 is not because it's mapped incorrectly, and it's not anything a switch on the dash is going to solve - it's the fundamental characteristics of the engine, the compromises made in its design. Its layout, inertia, pumping losses, friction, cam settings, manifold designs, everything.. but rest assured that the OEM has already taken a few steps to make it not firebreathing and as gentle as possible when you've not got it pinned open!
Unfortunately you can't just leave behind half your engine or change its fundamental design when you don't need it.. widely variable valve timing and inlet manifold tracts are about as far as we've come in that respect, and then cylinder deactivation goes a step further.
Fair enough, that sounds a reasonable explanation. Out of interest which models have cylinder drop?The reason you can't get 60mpg out of some firebreathing V8 is not because it's mapped incorrectly, and it's not anything a switch on the dash is going to solve - it's the fundamental characteristics of the engine, the compromises made in its design. Its layout, inertia, pumping losses, friction, cam settings, manifold designs, everything.. but rest assured that the OEM has already taken a few steps to make it not firebreathing and as gentle as possible when you've not got it pinned open!
Unfortunately you can't just leave behind half your engine or change its fundamental design when you don't need it.. widely variable valve timing and inlet manifold tracts are about as far as we've come in that respect, and then cylinder deactivation goes a step further.
What is the US valet mode then? This sort of thing
http://www.post-gazette.com/auto/2014/06/26/Dodge-...
Edited by DKL on Sunday 21st September 23:43
Useful stuff, thanks. Not quite such a stupid question maybe..
I've done the 500bhp usable supercar daily and frankly it didn't work. But that car for weekends could be superb. It still seems to me that the option of be able to turn down the wick and up the mpg for weekdays and revert to full facepeeling power for the weekends has promise.
I've done the 500bhp usable supercar daily and frankly it didn't work. But that car for weekends could be superb. It still seems to me that the option of be able to turn down the wick and up the mpg for weekdays and revert to full facepeeling power for the weekends has promise.
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