engine braking

According to a couple of driving instructors I know, current thinking is to only select a lower gear when it is needed. The brakes on anything vaguely modern do not need any help, and when you are changing gear you can't steer effectively.

I find it difficult to fully embrace what they teach; I like to be in an appropriate gear for my current speed, so that I can accelerate quickly if there is an unexpected change in circumstances. I have modified my driving so that I don't automatically (!) go through every gear however.

Chris

I'm all for it.

Read the road ahead, and lift your foot off the accelerator to slow down as you approach the roundybout, change into the correct gear (usually 2nd for me) just as you near the 'line' and if all is *clear*, drive across without stopping.

Waste of time and effort IMHO - read the road as far ahead as possible, take notice of the road signs, use your right foot sensibly and you'll slow down enough to change gear only once. If you're afraid of being shunted from the rear when doing this, simply tap the brake pedal a couple of times to warn the traffic behind. BUT, if people don't tail-gate (as they seem to do these days) then there is no problem.

*IF* you driving at the legal speed limt, simply take your foot of the accelerator and let the engine do the braking (unless of course you're driving down something like Porlock hill in Somerest and then you use both engine and brakes to slow down).

Those that do, usually drive without looking and further than the end of their bonnet and lack a few brain cells.

Not to save 'brake pads' and most cars had inefficient drum and cable operated brakes (along with cross-ply tyres that barely gripped the road in some conditions) - as the braking systems got better, so the need for engine braking has reduced

I've never had a "wear and tear" problem using engine braking, but it is possible to cause problems of you change down the gears at too high an engine speed.

Been using 'engine' braking for the last 40 years or so.

I always 'read the road' as far ahead as possible (stay at least 3 seconds behind the car in front [more if possible]) and adjust my engine speed by use of the accelerator - and change gear only once I've reached the required speed to do so (I hate braking at every bloody traffic slow-down, roundabout approach, corner etc) and drive far more smoothly than many.

This is purely my system of driving (hammered into me by a driving instructor charging an exorbitant 1 a lesson some 45 years ago), and it may not suit others.

At what sort of speed do you change to fifth?

Makes no difference in terms of wear. Engine braking allows the drivers behind to see your brake lights come on if you do have to slow down.

The only time that engine braking is actually needed, is on very long descents and maybe, when towing. Block (gear) changing is the preferred method for the last 40 years.

If I'm aiming travelling at 60 and aiming to reach a roundabout at 20mph as the traffic clears, I'll be engine braking and then block changing. Even if I could coast for half a mile instead.

certainly take your foot off and let the speed ease off, but changing down to get the effect of putting your foot on the brake went out with the ark.

Yeah, you was robbed. I used to pay Jeff Allam's mum ten bob in 1967

Once upon a time the engine was the prime braking source. There was a long period between the brakes improving and the driving test recognising it. I doubt anybody under 60 has been taught about engine braking. Changing down while braking was once the practice though, which in the extreme leads to boy racer brrm brrm noises while slowing down, but hardly the same thing.

Strange how something like push pull steering is immediately forgotten after passing the test but the notion of "engine braking" still persists.

Not every roundabout needs to be entered in 2nd. Plan to use the gears to take you through as though there is no traffic and then adapt to the conditions as they occur.

If going from high gear to low gear it's probably a good idea to select an intermediate to balance wear on the synchro. No need to lift the clutch for the intermediates though. Whatever you do, the main thing is to do things smoothly.

The obverse is what gets me - going down a slope in a low gear and driving the car when they could glide down in a higher gear with foot hovering above the brake.

A modern engine provides so little retardation that it hardly makes a difference. Some drag is due to the engine being an air pump but in the olden days engines also had very high internal friction.

[...]

The biggest load of nonsense I've read this month.

The second biggest load of nonsense I've read this month.

Chris

critcher said....... not so, most modern engines fire on every stroke and there is little engine retardation like there used to be in carb. type engines.

ooh, even bigger nonsense.

Third.

Sounds wrong to me too. Apart from anything else, we have overrun fuel shut-off these days, so there's not even idling fuel injected above about 1200rpm. OK, the engines may have less friction, but I'd imagine the pumping action is more significant.

Funny that, when I started playing with 4 stroke engines I was taught that the system (in simple terms) to get the things to go was - Suck, Sqeeze,

*BANG* and Blow.

Or just in case you missed it - Intake, Compression, *IGNITION* and Exhaust. Admittedly I haven't messed with the workings of cars for a few years, so has that miraculously changed in these modern times then? ;-)

Now, if you're saying that one cylinder out of four (six or eight) will fire on every turn of the crankshaft - then you are probably right if I remember correctly. And I'm sure that Mrcheerful will confirm that (I hope anyway).

[...]

I would even question whether modern engines have less friction. If you look at something like the ubiquitous 'A' series engine, it had a three- bearing crank, and a single chain-driven cam operating overhead valves via push-rods. There was bugger-all to them!

Ancillary loads also account for a considerable amount of over-run resistance with modern cars; things like powerful alternators, power steering pumps and A/C compressors all add up.

When you then consider that modern engines have compression ratios perhaps 50% higher than those of the past, it's clear that engine braking will be significantly higher.

Chris

I haven't read the whole thread, so forgive me if I am going over old ground.

On a modern fuel injected engine all 4 phases of " Suck, Sqeeze *BANG* and Blow" apply, except that if you take your foot off the accelerator there's a spark but no bang. The reason is that the fuel injection does not feed any petrol into the system.

So, you've got all the friction from the engine turning over, but no band => braking.

HTH

critcher said....... not so, most modern engines fire on every stroke and there is little engine retardation like there used to be in carb. type engines.

Not so, carb type engines had centrifrugal weights in the distributor to advance or retard the timing. On the overun, it would be retarded so much that it would be pushing the pistons backwards, hence the large engine braking.

Fourth please. :)

Hmm. Care to define "past" in this context?

No, not really. Wasted spark ignition's been around since at least the '40s.