[rcflyers]

If I am going along in traffic at say 30 - 40mph should I be in a gear that means the revs are a bit higher and the turbo is boosting a little or in a higher gear that means the turbo is not really doing anything for maximum efficiency?

[panthersteve]

I would say a higher gear so the revs are lower, but it will be interesting to see what others say 

[Dazzler]

I would say a higher gear so the revs are lower, but it will be interesting to see what others say 

I agree with Steve

[FatBoy]

Where the torque is at its highest. Don't over rev the engine or let the engine labour.

[Shambles]

It's a good question.

I prefer sympathy towards my engine, over any kind of economy or turbo concern. Between 30-40 mph I'll be in fourth, sliding up to fifth (and staying there) upto around 56mph, at which point I hit the top gear. Scares the shit out of the schoolkids as they cross the road

[Doggie 1]

Where the torque is at its highest. Don't over rev the engine or let the engine labour.

 

[The Gonz]

 

[rustynutz]

Labouring an engine will use more fuel and isn't terribly good for your engine either.
Much better to keep the revs up around where maximum torque is produced, eg around 1800-1900 rpm...

[VaerO]

I thought the higher the revs = more work for engine = more labor... I have a lot to learn. I always just assumed the higher to gear the less fuel I was using.

[The Gonz]

Labouring has a special meaning for when the engine is suffering from not enough revs for the load, so it always refers to the low end of the rev range, in any gear.

[Phil №❶]

Think of it like a geared bicycle. If you have ridden one, you know there are selectable gears made for different terrain. The Tour of France boys cruise along nicely on the flats but select low gears when climbing hills. Your engine is exactly the same, so a higher gear is only effective when the load on the car is low, the ground is flat and/or your acceleration requirements are reasonably low.

In an auto, the transmission senses engine load via throttle setting and other sensors etc. and it will drop down a gear under certain circumstances to provide more power, torque and acceleration.

All engines have a point in their revs by design, that produces the most power and the most torque, but not at the same revs. The secret to efficient driving, is to maintain the revs where the most torque is developed. This point is different for every type of engine and manufacturer. Diesel engines rev much lower than petrol engines and so to, the torque is developed at much lower revs.


BTW, Is Dita, Diesel or petrol

[VaerO]

Thank makes perfect sense thanks    Dita girl is petrol.

[FatBoy]

You'll also find that wherever they can, the cyclist in the Tour de France will try and keep the same cadence (same leg speed) and change gears so that their legs do that, regardless of speed (from memory it is about 80 rpm is the ideal cadence).  Think of that as their ideal "torque" band.  If their legs are going around too fast then they use more energy (fuel) for the same distance covered.  If they pedal too slowly, then the legs have to work harder to move the pedals around (i.e. they are labouring) and it is also inefficient.

Cadence - Wikipedia, the free encyclopedia(cycling)

[Dazzler]

You'll also find that wherever they can, the cyclist in the Tour de France will try and keep the same cadence (same leg speed) and change gears so that their legs do that, regardless of speed (from memory it is about 80 rpm is the ideal cadence).  Think of that as their ideal "torque" band.  If their legs are going around too fast then they use more energy (fuel) for the same distance covered.  If they pedal too slowly, then the legs have to work harder to move the pedals around (i.e. they are labouring) and it is also inefficient.

Cadence - Wikipedia, the free encyclopedia(cycling)

I didn't know that ( thanks Jamie)

[constipated]

I subscribe to the theory of keeping the car at maximum torque with lowest rpm, which for my FD is about 1900 rpm.

Therefore cruising in 5th gear at 1900rpm I find is better than 6th gear at 1700rpm.

I think a petrol car is different as torque arrives at much higher rpms and there are increased frictional losses that come into play. With my previous petrol car it was keep the car at the lowest rpm that didn't feel as if it was lugging.

[Doggie 1]

 

[Tourer_Guy]

I tend to worry less about revs and more about throttle position.  I use a gear where I have the lightest throttle opening, but where I could still accelerate if the throttle is increased slightly.  I have found that cruising at low speed on the flat I can use as few as 1400rpm, but below this the engine is not comfortable.  If going up hill I will select a lower gear, such that I can still use small throttle opening but have higher rpm.

Ideally, you should change gear at a point where the vehicle can maintain or increase speed on a smaller throttle opening than the gear you are currently in.

As a general rule of thumb, I drive between 1500 and 2000rpm in general driving, but occasionally go up to 3000rpm (or even a bit more) if accelerating onto freeway or into fast moving traffic.  There seems little point in going over 3500rpm, and indeed in opening throttle to the full position.

[The Gonz]

All my driving seems to happen between 1450 and 2100, accounting for idle achieving off-the-pedal cruise in 25 and 40 zones and driving up to 90 zones. I never speed so I've never gone beyond the 2100. My gear changes are very conservative, always before I get to 2000.

[Phil №❶]

Me 2, as in that's what the auto does for me.

[The Gonz]

So I'm changing gears within the dynamic range of the auto - sweet.
I'm a good boy.

[Phil №❶]

 

[Doggie 1]

All my driving seems to happen between 1450 and 2100

So what happens between 2100 and 1450 hours?   
Do you have a driver? 

[The Gonz]

That's when I hand over to my batman.

[FatBoy]

I thought that was after eight dinners.

[The Gonz]

I thought that was after eight dinners.

Dammit, that's what I've doing wrong. I've only ever done one or two dinners in one sitting. Eight? I'm not as young as I used to be.

[FatBoy]

That's so you have:

Dinner dinner dinner dinner dinner dinner dinner dinner batman

[The Gonz]

That's so you have:

Dinner dinner dinner dinner dinner dinner dinner dinner batman

Not even a dad joke but one straigjt out of my primary school days! 

[FatBoy]

I remain, Sir, your obedient servant.

[constipated]

All my driving seems to happen between 1450 and 2100, accounting for idle achieving off-the-pedal cruise in 25 and 40 zones and driving up to 90 zones. I never speed so I've never gone beyond the 2100. My gear changes are very conservative, always before I get to 2000.

I thought most efficient acceleration would be with turbo assistance within the peak torque range. So wouldn't the engine be lugging somewhat accelerating with such low revs thereby using more fuel?

[The Gonz]

I change down before it starts lugging. My economy results speak for themselves in all other respects. I don't drive with any awareness of turbo interaction.