42 replies to this topic

[Captain Mainwaring]

Ive always used the gears to slow down, when the road speed drops to allow the next gear down to be selected, i do so, using the brake a little to slow the car a little more so the engine isnt revving highly in the lower gear, its a nicer way to slow down, instead of braking hard like a lot of drivers do, but you do tend to get the late brakers over taking you as you slow down, but they look stupid when you cruise to a stop directly behind them lol

 For a while I thought the same thing until, for various reasons I started to drive STGO Cat 3 vehicles.....Try that with 150 tonnes up your plughole and you'll swap ends....

Not sure it would be an issue in a mini...

[adam_93rio]

I find that the way you learn to drive is based around modern cars and it does rely on the brakes. They teach you to brake until slow enough for second, I haven't down shifted from 4th to 2nd since my first month of driving a mini about 4 years ago now. I always work my way down the gears because it helps you keep on par with the ever changing condition of what is happening on the road. Eg, coming upto and open roundabout, I don't slow to go from 4th to 2nd as by the time I've slowed down its clear to cross in 3rd.
I always blip the throttle on down shifts whilst braking and release the clutch at the right revs for the gear I'm changing down to. The clutch in a mini doesn't have loads of travel so is almost on/off. So releasing the clutch when changing down without a blip of the throttle ends up making you and passengers feel like you're all going through the windscreen. It just simply doesn't feel nice for anyone. Blip of the throttle on down changes on bends on backroads puts you straight back on the power out of the corner too instead of waiting for the engine braking effect to dissapear

[Ethel]

 

 

 

Toe & heel is just double de-clutching (changing down, so blipping the throttle in neutral to speed up the gear hub) while braking at the same time.

 Noooo...it can be with a double de-clutch, but it doesn't have to be.....used to work nicely on a Rallye Imp to get the power on early and the tail wagging coming out of a tight corner.....

 

You could do that, but if you aren't using the clutch to change gear you have a spare foot to operate the brake pedal.

[Ethel]

I tend to do both, (braking and down shift).

 

One thing I have been thinking about though... I am teaching my girl friend to drive at the moment, over here in Sweden we need to attend a 3 hour training lecture to be approved as a 'teacher'. 

 

They are big on what the call eco driving - Part of which is thE use of engine braking (down shifting). Does that save fuel? Cant really figure it out. 

 

On a side note, thdespito promote skipping a gear when accelerating, despite a long winded debate with the instructor, I am sure that doesn't save fuel either. yeah you dint accelerate as hard, but you accelerate for longer. 

Braking turns you kinetic energy into heat, changing down at least stores some of it in the flywheel & other moving engine parts. Driving in the highest gear possible is generally the most economic as the lower revs equate to less friction losses. Power is also directly related to the amount of fuel/air mixture going through the engine; lower revs mean you need more mixture per rev, so a more open throttle and higher combustion chamber pressure, which also help mpg (à la diesel). Of course, if you miss out a gear, you'd usually have to take it to higher than optimum revs in the lower gear before you change up - so more useful in an unladen hgv than a Mini.

[timmy850]

 

I tend to do both, (braking and down shift).

 

One thing I have been thinking about though... I am teaching my girl friend to drive at the moment, over here in Sweden we need to attend a 3 hour training lecture to be approved as a 'teacher'. 

 

They are big on what the call eco driving - Part of which is thE use of engine braking (down shifting). Does that save fuel? Cant really figure it out. 

 

On a side note, thdespito promote skipping a gear when accelerating, despite a long winded debate with the instructor, I am sure that doesn't save fuel either. yeah you dint accelerate as hard, but you accelerate for longer. 

Braking turns you kinetic energy into heat, changing down at least stores some of it in the flywheel & other moving engine parts. Driving in the highest gear possible is generally the most economic as the lower revs equate to less friction losses. Power is also directly related to the amount of fuel/air mixture going through the engine; lower revs mean you need more mixture per rev, so a more open throttle and higher combustion chamber pressure, which also help mpg (à la diesel). Of course, if you miss out a gear, you'd usually have to take it to higher than optimum revs in the lower gear before you change up - so more useful in an unladen hgv than a Mini.

 

And modern fuel injected cars cut fuel to the engine when coasting which is the most efficient a car can be.

 

You also tend to have more control over the car when braking in gear - you can speed up to avoid things etc

[oli8925]

 

 

I tend to do both, (braking and down shift).

 

One thing I have been thinking about though... I am teaching my girl friend to drive at the moment, over here in Sweden we need to attend a 3 hour training lecture to be approved as a 'teacher'. 

 

They are big on what the call eco driving - Part of which is thE use of engine braking (down shifting). Does that save fuel? Cant really figure it out. 

 

On a side note, thdespito promote skipping a gear when accelerating, despite a long winded debate with the instructor, I am sure that doesn't save fuel either. yeah you dint accelerate as hard, but you accelerate for longer. 

Braking turns you kinetic energy into heat, changing down at least stores some of it in the flywheel & other moving engine parts. Driving in the highest gear possible is generally the most economic as the lower revs equate to less friction losses. Power is also directly related to the amount of fuel/air mixture going through the engine; lower revs mean you need more mixture per rev, so a more open throttle and higher combustion chamber pressure, which also help mpg (à la diesel). Of course, if you miss out a gear, you'd usually have to take it to higher than optimum revs in the lower gear before you change up - so more useful in an unladen hgv than a Mini.

 

And modern fuel injected cars cut fuel to the engine when coasting in gear which is the most efficient a car can be.

 

You also tend to have more control over the car when braking in gear - you can speed up to avoid things etc - That's why it's still taught to keep the car in gear until you're almost at your stop, out of gear coasting is a big no no as you're not fully in control.

 

I would have thought theoretically, using the gears when accelerating would be more economical. You'd want to keep the engine operating at it's most efficient speed, hence to do that as your road speed is increasing you'll need to use your gears. In practice, and depending on your car, you may find it more economical to give a quick blast in second to 30mph and then cruise in 4th for example, rather than using 3rd as well. I know a lot of people with modern turbo diesels find this to give better results

[Teapot]

I just like making an a-rumm noise when changing down

But it does keep things smooth, especially uphill when the revs can drop abruptly when you come out of gear. Better still to change down a bit earlier, speed permitting.

I can't heel 'n' toe in Huey with me legs bent.

 

@AVV IT The other issue is that using you brakes alerts drivers behind you that you are slowing down via your brake lights, using the gears to slow doesn't do this

Good point.

[Captain Mainwaring]

 

I tend to do both, (braking and down shift).

 

One thing I have been thinking about though... I am teaching my girl friend to drive at the moment, over here in Sweden we need to attend a 3 hour training lecture to be approved as a 'teacher'. 

 

They are big on what the call eco driving - Part of which is thE use of engine braking (down shifting). Does that save fuel? Cant really figure it out. 

 

On a side note, thdespito promote skipping a gear when accelerating, despite a long winded debate with the instructor, I am sure that doesn't save fuel either. yeah you dint accelerate as hard, but you accelerate for longer. 

Braking turns you kinetic energy into heat, changing down at least stores some of it in the flywheel & other moving engine parts. Driving in the highest gear possible is generally the most economic as the lower revs equate to less friction losses. Power is also directly related to the amount of fuel/air mixture going through the engine; lower revs mean you need more mixture per rev, so a more open throttle and higher combustion chamber pressure, which also help mpg (à la diesel). Of course, if you miss out a gear, you'd usually have to take it to higher than optimum revs in the lower gear before you change up - so more useful in an unladen hgv than a Mini.

 

Hehehe...yes but for how long and how much? Certainly not enough to be of use for anything, and ultimately only turns that kinetic energy into heat. I'd have to disagree that power is directly related to the amount of fuel entering the engine, there is a lot more to be considered such as BMEP and cylinder scavenging.

If only the rest were as simple as you suggest, but it's not.

Remember, people desire power but they drive torque.

Yes...fuel injected cars cut fuel when on the over-run, but if you say coasting, coasting used to me rolling with the car in neutral or the clutch dipped. That certainly won't save juice. Some say it's against the law in the UK, but it's probably off the books now with the number of vehicles that are designed to coast.

i do know for a fact that whilst I have enjoyed getting 53 MPG at an average speed of 72 MPH (as calced by the computer) from a 150 hp merc common rail, I don't enjoy someone who piss farts about in and out of gear - this is a very Chinese thing, and having sat with a coach driver who would try and coast down a hill and half way up the other side, to miss 3 gears and get stuck behind a lorry for 2 miles going back up the other side, I had a desire to launch a pork and chilli dumpling at the back of his head every time he tried it......

[ianclark1275]

 

 

 

I tend to do both, (braking and down shift).

 

One thing I have been thinking about though... I am teaching my girl friend to drive at the moment, over here in Sweden we need to attend a 3 hour training lecture to be approved as a 'teacher'. 

 

They are big on what the call eco driving - Part of which is thE use of engine braking (down shifting). Does that save fuel? Cant really figure it out. 

 

On a side note, thdespito promote skipping a gear when accelerating, despite a long winded debate with the instructor, I am sure that doesn't save fuel either. yeah you dint accelerate as hard, but you accelerate for longer. 

Braking turns you kinetic energy into heat, changing down at least stores some of it in the flywheel & other moving engine parts. Driving in the highest gear possible is generally the most economic as the lower revs equate to less friction losses. Power is also directly related to the amount of fuel/air mixture going through the engine; lower revs mean you need more mixture per rev, so a more open throttle and higher combustion chamber pressure, which also help mpg (à la diesel). Of course, if you miss out a gear, you'd usually have to take it to higher than optimum revs in the lower gear before you change up - so more useful in an unladen hgv than a Mini.

 

And modern fuel injected cars cut fuel to the engine when coasting in gear which is the most efficient a car can be.

 

You also tend to have more control over the car when braking in gear - you can speed up to avoid things etc - That's why it's still taught to keep the car in gear until you're almost at your stop, out of gear coasting is a big no no as you're not fully in control.

 

I would have thought theoretically, using the gears when accelerating would be more economical. You'd want to keep the engine operating at it's most efficient speed, hence to do that as your road speed is increasing you'll need to use your gears. In practice, and depending on your car, you may find it more economical to give a quick blast in second to 30mph and then cruise in 4th for example, rather than using 3rd as well. I know a lot of people with modern turbo diesels find this to give better results

 

its not really "explainable" very well with a few quotes, but a few things to note in "tuning the a series engine" is the VE (volumetric efficiency)  of a mini engine is not at "low" revs.  also theres that  french man, mr carnot. which when you put numbers in the formula, actually turns out turbocharged large capacity engines are more efficient at turning petrol into power. not your small mini engine     

 

in racing you do all sorts of cruel things to the transmission.

 

flat out acceleration on loose while pressing brake (Slight effect of LSD) amongst others.

[Scorp]

i do it because i sound like a racing driver

brummmmmm (change down) brummmmm off we go

[1984mini25]

Ive always used the gears to slow down, when the road speed drops to allow the next gear down to be selected, i do so, using the brake a little to slow the car a little more so the engine isnt revving highly in the lower gear, its a nicer way to slow down, instead of braking hard like a lot of drivers do, but you do tend to get the late brakers over taking you as you slow down, but they look stupid when you cruise to a stop directly behind them lol

witch is the same way I was taught. As  rather than screeching to a stop at a roundabout etc.. and finding its clear and screeching off again, your already in the right gear to match the road speed, so if it is clear your good to carry on.

[Mrpeanut]

I find the brakes are an amazing tool for slowing the car down, it's like they were designed for the job.... 

Quite. Pads/discs/shoes are a wee bit cheaper than lifting your engine and rebuilding your box.

[Ethel]

Big engines have better  thermal efficiency by virtue of being bigger. It's the same basic surface area to volume ratio that gives an elephant a lower metabolic rate than a mouse. It's still a bit wasteful to feed an elephant if a mouse produces enough power for the job in hand though.

 

God knows how we got here, wasn't it a discussion about the relative merits of changing gear or using your brakes to slow down 

 

In those circumstances you have a limited choice of engines: just the one under your bonnet.