Avoiding BGOL around town

[TheInsanity1234]

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.

But what I'm trying to do is trap all the heat possible in the engine, with recirculate, it's still taking heat out of the engine to warm the cabin up. The car puts warming up the cabin first, then warming the engine second.

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 isn't an 'economy' mode... The whole car is supposed to be in a permanent 'economy' mode. But it doesn't do it awfully well

[Mr Cholmondeley-Warner]

@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 remember posting that the mechanical difference would be all that great, and the original post was about a perceived drop in revs, for a small change in indicated speed. You chose to pooh pooh my post without actually testing it, based on an idealistic view of a perfect mechanical linkage. Have you never noticed how you can apparently speed up the engine of a car without it speeding up noticeably on the road? Try just pootling along and giving the accelerator a nudge - watch the rev counter as you do this. Think of all the flexible parts in the transmission - springs in the clutch driven plate, elasticity in the driveshafts, slop in the gears and CV joints, and big squidgy rubber things between the wheels and the road ...

So there are two effects you see - a loss in the mechanical transmission somewhere, and a lag in the instruments' indication of the proportional change in road speed. Added together they change the proportion of rpm/mph displayed by the two instruments, that Rainmaker noticed. It's particularly noticeable at low rpm, hence (I believe) Rainmaker's observed anomaly.

[Horse]

I NEVER have to BGOL for any other gear

If braking too much then the chances are that too high a gear has been selected

A junction I commute through is traffic lights at the end of a motorway off slip.

In my little car, with its 1.6TD, top gear seems reasonable for 70mph, doesn't it?

At the lights, if I try to brake to a halt in top gear, declutching just before stopping, the engine will stall.

So what should I do?

[Rick448]

I NEVER have to BGOL for any other gear

If braking too much then the chances are that too high a gear has been selected

A junction I commute through is traffic lights at the end of a motorway off slip.

In my little car, with its 1.6TD, top gear seems reasonable for 70mph, doesn't it?

At the lights, if I try to brake to a halt in top gear, declutching just before stopping, the engine will stall.

So what should I do?

Take the Devils dollar and change down first or just stop and choose first gear. No nuns or kittens are likely to die.

[Horse]

I NEVER have to BGOL for any other gear

If braking too much then the chances are that too high a gear has been selected

A junction I commute through is traffic lights at the end of a motorway off slip.

In my little car, with its 1.6TD, top gear seems reasonable for 70mph, doesn't it?

At the lights, if I try to brake to a halt in top gear, declutching just before stopping, the engine will stall.

So what should I do?

Take the Devils dollar and change down first or just stop and choose first gear. No nuns or kittens are likely to die.

As I said, it'll stall if I try your 2nd option. Guessing, 3rd is probably the highest gear I could try that.

[Gareth]

A junction I commute through is traffic lights at the end of a motorway off slip.

In my little car, with its 1.6TD, top gear seems reasonable for 70mph, doesn't it?

I change down a gear or two before entering the off-slip.

[Gareth]

There isn't an 'economy' mode...

I found an online Yeti Owners Manual - all the systems that are described as 'air conditioning' have a mode where the cooling function can be disabled.

[Gareth]

But what I'm trying to do is trap all the heat possible in the engine, with recirculate, it's still taking heat out of the engine to warm the cabin up. The car puts warming up the cabin first, then warming the engine second.

It's generally more important to keep the windows clear than it is to warm the engine.

If the windows are properly clear, helping the engine warm up quicker might improve fuel economy for the journey.

The main reason for wanting the engine to be fully warmed is to be able to use higher engine speeds without causing unnecessary wear.

[IcedKiwi]

Hotter engines definitely have better fuel consumption. It means less in cylinder hear transfer to the walls and hence more fuel energy is converted useful power. Also hotter oil means thinner oil which reduces friction and give fuel savings.
Lots of new engines on or coming to the market that have zero coolant flow conditions in the block initially to help speed up warm up. They're also using electric thermostats which means they can control coolant temperature to ~110-115degC over the legislative cycles but then lower to 90degC at higher power to protect the engine.
All this is purely for fuel consumption, they don't care whether you can use more revs faster. There's a lot of work going into speeding up warm up. Think the ball park number we use for the difference between at hot NEDC and one starting from cold (25degC) is about 10%. That's a 20minute cycle - the percentage benefit obviously decreases the longer the drive.

[Astraist]

Also, the metal expands so you get less pressure leaking into the sump and contaminating the oil. The absence of this benefit in cars that only drive for short distances in towns is very evident when changing oils, and requires changing it much sooner.

I wouldn't think too much into accelerating the rate at which the engine is heated up. As for heating in particular, what you do by opening the heater is effectivelly elongating the track which the coolant runs around, so it despereses more heat.

However, in some cars it traverses the same route anyhow, and all that the heater does is to expose a part of that piping to the passenger compartment, so in that case (and it's becoming the case for more cars because it heats the cabin quicker at the start of the journey) there is little difference in the rate at which engine heat increases.

Anyhow, it's clear from the very outset that demisting and creating a comfotable environment for the driver is top priority. I'd hate to use the better part of my effort "budget" (and thus my concentration) on shivering to generate body heat, and I'd equally hate to drive with a thick coat.