cars with variable power output

[Calza]

McSam said:

hat's reasonable enough logic certainly for full throttle that's a fair assumption, though I would expect that most of these switchable maps would not differ at all until you got past 75% throttle, or at least half, to make it more driveable at normal speeds.

For the sake of argument, let's assume that the map is different all the way through the pedal travel, and the 500bhp map is always giving you 25% more power than the 400bhp one. Even if this is the case, you don't drive faster the driver innately adjusts themselves to the pedal response very quickly, and simply uses less travel, achieving the same acceleration and therefore the same fuel consumption as they would have done in the other map.

If you were using the exact same pedal positions all the time, then yes, it would make a difference. To how many speeding tickets you got, as well as your fuel consumption! It still takes the same amount of power to drive the car in the same manner, no matter what inputs you have to do to get it.

Shaoxter said:

No, the 400bhp mode doesn't shut down any cylinders or anything. The only time I ever use P400 is parking in a tight space. P500/P500S are a little bit jerky when trying to park.

That all makes sense, thanks!

[velocemitch]

danp said:

If a car has a switch/mechanisms to produce variable outputs I believe the NEDC test to obtain co2/mpg figures uses the default one it's in when started?.

My Alfa Giulietta does just that, on default N mode it develops less torque than it does when switched to D. I also very much suspect it blows it's 119 kg of co2 right out of the window too.

[troc]

velocemitch said:

My Alfa Giulietta does just that, on default N mode it develops less torque than it does when switched to D. I also very much suspect it blows it's 119 kg of co2 right out of the window too.

But I bet the mpg is pretty rubbish except downhill.

[Renovation]

TwigtheWonderkid said:

Renovation said:

I think having an electronic power restrictor is a good idea, it means you could lend your wife / kids / mum a 400bhp car but restrict it to say 150bhp.

I can understand restricting power for your kids, especially if they are young drivers. But restricting power for your mum or wife....why??

Because they aren't used to it and in my case with no traction control etc fitted, one prod on the peddle can have you sideways in a split second.

[velocemitch]

troc said:

velocemitch said:

My Alfa Giulietta does just that, on default N mode it develops less torque than it does when switched to D. I also very much suspect it blows it's 119 kg of co2 right out of the window too.

But I bet the mpg is pretty rubbish except downhill.

No it's not actually, the higher torque allows you to use a higher gear as it pulls better.

[troc]

velocemitch said:

troc said:

velocemitch said:

My Alfa Giulietta does just that, on default N mode it develops less torque than it does when switched to D. I also very much suspect it blows it's 119 kg of co2 right out of the window too.

But I bet the mpg is pretty rubbish except downhill.

No it's not actually, the higher torque allows you to use a higher gear as it pulls better.

I was alluding to the N for neutral vs the D for Drive in an automatic rather than the N and D in the Alfa DNA switch thing!

I suspect one of us needs a whoosh parrot but I'm not sure which

[velocemitch]

troc said:

velocemitch said:

troc said:

velocemitch said:

My Alfa Giulietta does just that, on default N mode it develops less torque than it does when switched to D. I also very much suspect it blows it's 119 kg of co2 right out of the window too.

But I bet the mpg is pretty rubbish except downhill.

No it's not actually, the higher torque allows you to use a higher gear as it pulls better.

I was alluding to the N for neutral vs the D for Drive in an automatic rather than the N and D in the Alfa DNA switch thing!

I suspect one of us needs a whoosh parrot but I'm not sure which

Ahh... I didn't make the Automatic connection.

[Paul671]

Starlet Turbos have a high/low boost switch for your choice of 115 or 133bhp, not sure why though?

[Buff Mchugelarge]

Defcon5 said:

If only there was some way to partially open the throttle

[Herman Toothrot]

Don't most of the new turbo BMWs have different boost profiles as standard, drove an M135i and Eco pro to sport make the car rather different. In sport it squirms a bit in the dry it you plant the throttle and keep it there through the gears, Eco pro and it'd struggle to pull the skin off rice pudding and is a lot more efficient 23mpg sport mode 30mpg Eco pro being typical the owner told me.

My old MX5 had a Link G3 motorsport ECU, had infinitely variable mapped boost on a dial. What makes this approach nice just like the BMW system is letting others drive the car. Trust me 265bhp and a mountain of torque in a 960kg Mx5 with 195 tyres on a cold wet winter night is unpleasant to drive, throttle application had to be very, very controlled. Twist of the dial and you loose 100bhp made it just like any sensible car to drive, no such pussy footing about required. People are not always in the mood for a car that's setup for being as fast as possible, sometimes it's nice for everything to be a bit smoother. Actual throttle pedal mapping is common these days as well so sport mode make give 10% more throttle opening at the same throttle position compared to normal mode.

[Vyse]

Honda with a VTEC engine. You can vary the power by either entering or not entering the VTEC zone.

[DKL]

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.

[McSam]

You could quite easily apply a setting that limited the maximum power for everyday use, but that would not improve the fuel consumption. The simple fact is that a high-performance engine designed to produce a lot of power cannot magically become efficient just by changing its mapping. Driving it gently is as close as you're gonna get.

[TwigtheWonderkid]

Renovation said:

TwigtheWonderkid said:

Renovation said:

I think having an electronic power restrictor is a good idea, it means you could lend your wife / kids / mum a 400bhp car but restrict it to say 150bhp.

I can understand restricting power for your kids, especially if they are young drivers. But restricting power for your mum or wife....why??

Because they aren't used to it and in my case with no traction control etc fitted, one prod on the peddle can have you sideways in a split second.

That could equally apply to your brother or your dad? But he said mum/wife as if women have some kind of inherent trouble with powerful cars. Sounds like sexist rubbish to me.

Edited by TwigtheWonderkid on Tuesday 23 September 08:55

[Renovation]

TwigtheWonderkid said:

Renovation said:

TwigtheWonderkid said:

Renovation said:

I think having an electronic power restrictor is a good idea, it means you could lend your wife / kids / mum a 400bhp car but restrict it to say 150bhp.

I can understand restricting power for your kids, especially if they are young drivers. But restricting power for your mum or wife....why??

Because they aren't used to it and in my case with no traction control etc fitted, one prod on the peddle can have you sideways in a split second.

That could equally apply to your brother or your dad? But he said mum/wife as if women have some kind of inherent trouble with powerful cars. Sounds like sexist rubbish to me.

Because my Dad has owned more powerful cars than I have and my brother was killed.

Your dad and brother may be morons like you, so in your case I wouldn't let them drive a fast car either.