Avoiding BGOL around town

Topics relating to Advanced Driving in cars
Gareth
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Re: Avoiding BGOL around town

Postby Gareth » Fri Jan 29, 2016 6:20 am

waremark wrote:
Mr Cholmondeley-Warner wrote:Watch the rev counter and the speedo, and see if they actually drop in exact proportion.

How could it be otherwise?

The speedo and rev-counter 'follow' since they're not direct mechanical linkages. If there are magnetic components, they are more likely to be less linear than if they are corrected by electronics, which probably introduce greater lag.
there is only the road, nothing but the road ...

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jont-
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Re: Avoiding BGOL around town

Postby jont- » Fri Jan 29, 2016 7:06 pm

Gareth wrote:
waremark wrote:
Mr Cholmondeley-Warner wrote:Watch the rev counter and the speedo, and see if they actually drop in exact proportion.

How could it be otherwise?

The speedo and rev-counter 'follow' since they're not direct mechanical linkages. If there are magnetic components, they are more likely to be less linear than if they are corrected by electronics, which probably introduce greater lag.

The chap who reverse engineered the VW ECU while looking at dieselgate said the rev counter display value depended on a large number of factors, only one of which was engine speed :lol: (I think much of the fiddling was around the idle point so regardless of actual changes in engine speed due to load for aircon etc, the rev counter would show a constant, steady idle, which is apparently more reassuring to customers than telling them what the engine is actually doing).

I believe SWMBOs temp gauge on the Octy is much the same (ie very shortly after starting the car it sits perfectly in the middle, and I suspect would have to go outside a fairly wide range before reflecting this on the gauge). Apparently this is progress :twisted:

fungus
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Re: Avoiding BGOL around town

Postby fungus » Fri Jan 29, 2016 7:37 pm

jont- wrote:
Gareth wrote:
waremark wrote:
Mr Cholmondeley-Warner wrote:Watch the rev counter and the speedo, and see if they actually drop in exact proportion.

How could it be otherwise?

The speedo and rev-counter 'follow' since they're not direct mechanical linkages. If there are magnetic components, they are more likely to be less linear than if they are corrected by electronics, which probably introduce greater lag.

The chap who reverse engineered the VW ECU while looking at dieselgate said the rev counter display value depended on a large number of factors, only one of which was engine speed :lol: (I think much of the fiddling was around the idle point so regardless of actual changes in engine speed due to load for aircon etc, the rev counter would show a constant, steady idle, which is apparently more reassuring to customers than telling them what the engine is actually doing).

I believe SWMBOs temp gauge on the Octy is much the same (ie very shortly after starting the car it sits perfectly in the middle, and I suspect would have to go outside a fairly wide range before reflecting this on the gauge). Apparently this is progress :twisted:


Is that a deisel or petrol? My wifes deisel Octavia seems to take ages to get up to normal, where as the daughters Cooper S shows normal after about half a mile.

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Mr Cholmondeley-Warner
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Re: Avoiding BGOL around town

Postby Mr Cholmondeley-Warner » Fri Jan 29, 2016 8:08 pm

@jont - thanks. If I can, I'll rig up a camera and go and do the experiment and post a video. Some people obviously don't believe these things can happen.

@fungus - diesels take much longer to warm up than petrols. All of them, pretty much.
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TheInsanity1234
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Re: Avoiding BGOL around town

Postby TheInsanity1234 » Fri Jan 29, 2016 8:19 pm

fungus wrote:Is that a deisel or petrol? My wifes deisel Octavia seems to take ages to get up to normal, where as the daughters Cooper S shows normal after about half a mile.

Our Yeti will take about 10 minutes of normal driving before even registering a temperature on the gauge.

On the colder days, I've even resorted to switching off the heater completely to try and get the engine to warm up quicker.

Rick448
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Re: Avoiding BGOL around town

Postby Rick448 » Fri Jan 29, 2016 8:39 pm

After a number of years faffing about worrying about this I've concluded its more trouble than it's worth worrying about this. Ive yet to hear a well reasoned argument in favour of it that I can subscribe to. I can do it but I just don't think not doing it is unsafe at all. Especially at low speeds, I can see possible advantages at the limit but then heel and toe would be better in my opinion. Burn me!

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Mr Cholmondeley-Warner
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Re: Avoiding BGOL around town

Postby Mr Cholmondeley-Warner » Fri Jan 29, 2016 8:42 pm

Image
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Re: Avoiding BGOL around town

Postby Synchromesh » Fri Jan 29, 2016 9:12 pm

Mr Cholmondeley-Warner wrote:@jont - thanks. If I can, I'll rig up a camera and go and do the experiment and post a video. Some people obviously don't believe these things can happen.

I think that'll be your dials misrepresenting the truth of the situation (as other posters have mentioned, they 'follow' rather than display data in true real time).

I don't see how it's possible for the revs and speed not to move proportionally unless the clutch is down/slipping, since here there is a direct mechanical connection.

I may have spent far too much time playing with Lego Technic as a child ;)

Rick448
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Re: Avoiding BGOL around town

Postby Rick448 » Fri Jan 29, 2016 9:30 pm

Mr Cholmondeley-Warner wrote:Image

:lol: :mrgreen:

Gareth
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Re: Avoiding BGOL around town

Postby Gareth » Fri Jan 29, 2016 9:37 pm

TheInsanity1234 wrote:On the colder days, I've even resorted to switching off the heater completely to try and get the engine to warm up quicker.

If you haven't tried, consider using the recirculate setting.

In some cars it is helpful to switch to 'economy' mode during that last part of the journey, possibly with a higher temperature setting, then opening the windows during the last eighth of a mile or so. The aim is, first, to dry out the aircon system and, second, to allow moist air to escape the cabin.
there is only the road, nothing but the road ...


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