Diesel 'Sweetspot' ?Pedal to the Metal Vs Low Revs Coking Up?

2011abc

Ok so we all have diesels to save a few bob on fuel .But if you drive TOO 'steadily' you get that pile of black smoke the next time on your journey you floor it.Does that build up eventually cause problems over weeks and months ?Should you give her at least some welly every journey?Is it better to just average a slightly higher speed/revs to avoid this?Any advice appreciated.

(I drive an earlyish 1.3 Multijet with no dpf and can get up to an indicated 90mpg if REALLY slow (55mph on Mways)which brim to brim works out at about 76/78mpg.Normally get closer to 70mpg (actual mpg) though.Its a Panda which has started every morning for coming round to three years now (40-45k miles done to see 141k on clock now)Only oil changes (done every 6k miles) but Pre NCT work was a bit pricey at around 600 euro (front shocks and wishbones mostly and that was self sourcing parts and shopping around for labour)...These cars are fairly fond of front shocks (and tyres and tracking).But considering it probably saves me 50 a month compared with a one litre petrol Im keen on it.

Zcott

Correct me if I'm wrong, but low revs = more vibrations = more work for DMF = expensive repair bill. I usually sit around 2000rpm on the motorway and that's around 70mph.

CiniO

I use full throttle on my diesel daily, and that's not to clear up or prevent building a soot or something, but just because I like it.

Different in fuel consumption between my normal driving style (full throttling regularly) and crawling at low revs, is not that significant.

Normally I get about 6l/100km.
When I try really hard to drive as economical as possible I can get down to 5l/100km, but then there is no fun for driving - so what's the point in doing it.

Best I did on longer distance was 4.3 l/100km on distance of 250km, but it was driving at 1500rpm on 6th gear at 80km/h steady speed for nearly all this distance.


No point in damaging the car by driving at too low revs without flooring it, for sake of saving money, which you will need to spend on repairing the car anyway.

Y2KBOS86

I try not to drive below the turbo kickin ie 1800rpm.

I stay around 2000 - 3000rpm on most journey's.

At 100 km/h I leave it in 5th and only use 6th when doing 120km/h on the motorway, never use 6th on anything other than motorways.

Cleveland Hot Pocket

I use full throttle, usually in fifth gear at 1200 rpm going uphill.
Optimizing the smoke cloud!

christy02

Y2KBOS86 wrote: »

I try not to drive below the turbo kickin ie 1800rpm.

I stay around 2000 - 3000rpm on most journey's.

At 100 km/h I leave it in 5th and only use 6th when doing 120km/h on the motorway, never use 6th on anything other than motorways.

That's interesting that you only use 6th on motorways. I get into 6th as soon as I can. Anything over 80km car is happy to travel in 6th.

Should I not be doing this? Would be at about 1600rpm at 100km/hr.

CiniO

christy02 wrote: »

That's interesting that you only use 6th on motorways. I get into 6th as soon as I can. Anything over 80km car is happy to travel in 6th.

Should I not be doing this? Would be at about 1600rpm at 100km/hr.

If it's 1600rpm at 100km/h, then at 80km/h it's 1280rpm.

To be honest, I strongly doubt your car is happy to travel at that rev's.

I don't even think you are saving any fuel by driving that low. Most likely at 80-90km/h it is more economical to have it on 5th above 1600rpm than on 6th below 1500rpm.

Bpmull

I have only ever owned diesel cars. I find once you keep the revs over about 1500 (depending on the car) it's fine. Much less you will labour it a certain amount. Although at the same time I would floor it until about 1800-2000 rpm. As it's not great to be flooring the car when it's off boast. Other than that I can't really see any issue about driving diesels. None of mine have ever been smokey in the slightest bit certainly not when your accelerating maybe slight bit of smoke when their cold but minute enough and none when their warm. If the car is really smokey well then that's just down to bad maintenance.

christy02

CiniO wrote: »

If it's 1600rpm at 100km/h, then at 80km/h it's 1280rpm.

To be honest, I strongly doubt your car is happy to travel at that rev's.

I don't even think you are saving any fuel by driving that low. Most likely at 80-90km/h it is more economical to have it on 5th above 1600rpm than on 6th below 1500rpm.

Not sure rpm are linear to speed? Pulls away happily enough in 6th once accelerating over 80.

Don't do it to save fuel. I was always taught when learning how to drive to get up through gears as soon as possible. Just a habit.

Cleveland Hot Pocket

Bpmull wrote: »

I have only ever owned diesel cars. I find once you keep the revs over about 1500 (depending on the car) it's fine. Much less you will labour it a certain amount. Although at the same time I would floor it until about 1800-2000 rpm. As it's not great to be flooring the car when it's off boast. Other than that I can't really see any issue about driving diesels. None of mine have ever been smokey in the slightest bit certainly not when your accelerating maybe slight bit of smoke when their cold but minute enough and none when their warm. If the car is really smokey well then that's just down to bad maintenance.

Source?
There are straight diesels that don't have turbos and you can floor them anyway (I do it a lot, with c70bhp you need to floor it)

Bpmull

Cleveland Hot Pocket wrote: »

Source?
There are straight diesels that don't have turbos and you can floor them anyway (I do it a lot, with c70bhp you need to floor it)

Oh rep I know. They have plenty of sdi caddys where I work and anyone driving them basically has there foot to the floor all the time just going on this thread going on about efficiency and 6 speed gearboxes well then your talking modern diesels most likely. Which almost all modern diesel cars have a turbo of some sort. I know there is the odd exception but there fairly rare now.

cerastes

off boast?

I dont drive hard and I probably should from time to time,
definitely something up with the turbo, but no time to look it, mileage is ok, unless Im in a hurry, which is rare as it drops right down when I drive like that.

Bpmull

cerastes wrote: »

off boast?

I dont drive hard and I probably should from time to time,
definitely something up with the turbo, but no time to look it, mileage is ok, unless Im in a hurry, which is rare as it drops right down when I drive like that.

When you start a Diesel engine the turbo spins all the time. But when the car is idleing or at 1200 rpm it is only spinning at a fraction of its full capability. When you hit ca 1800 rpm the turbo boosts ie it spins to its full capacity and this helps the engine pull through the revs quicker and basically go faster. So if you floor a turbo diesel car at 1200 rpm then you will get lag (no rush of power) until ca 1800 rpm at which point the turbo will be on full boost and give that feeling of pulling you back in your seat. Obviously depends on the car and engine as to how much it will pull you back in the seat but you get the idea

CiniO

christy02 wrote: »

Not sure rpm are linear to speed?

Of course they are.

Pulls away happily enough in 6th once accelerating over 80.

Don't do it to save fuel. I was always taught when learning how to drive to get up through gears as soon as possible. Just a habit.

Quite bad habbit I must say.
Who taught you to drive?

Driving at too low revs just damages the car.

Interslice

Bpmull wrote: »

When you start a Diesel engine the turbo spins all the time. But when the car is idleing or at 1200 rpm it is only spinning at a fraction of its full capability. When you hit ca 1800 rpm the turbo boosts ie it spins to its full capacity and this helps the engine pull through the revs quicker and basically go faster. So if you floor a turbo diesel car at 1200 rpm then you will get lag (no rush of power) until ca 1800 rpm at which point the turbo will be on full boost and give that feeling of pulling you back in your seat. Obviously depends on the car and engine as to how much it will pull you back in the seat but you get the idea

Flooring it at 1200rpm would also put alot more strain on the clutch, flywheel and input shaft than the same acceleration at say 2000rpm. I was cringing sitting in fully loaded T5 with a lad the other week doing exactly that. A bout 30mph up a steep hill in 5th with about a tonne in the back :eek:. I'd have been in 3rd. Modern land cruisers have a big shift down light that comes on the the dash. They should put them in all cars . Ther would be less DMF failure's if they did.

Y2KBOS86

CiniO wrote: »

Quite bad habbit I must say.
Who taught you to drive?

Not his fault, that's the Irish way.

Don't rev it

Interslice

Y2KBOS86 wrote: »

Not his fault, that's the Irish way.

Don't rev it

Anymore than 5mph in first gear and you driving the ****e out of it :pac:

Y2KBOS86

christy02 wrote: »

That's interesting that you only use 6th on motorways. I get into 6th as soon as I can. Anything over 80km car is happy to travel in 6th.

Should I not be doing this? Would be at about 1600rpm at 100km/hr.

It doesn't feel right to me to be doing 100km in 6th at 1600rpm, feels like the engine is struggling, lacks acceleration compared to 5th.

I drive Avensis and Auris's pool cars now and again at work, find it very strange when the warning comes on the dash telling me to change gear between 1500rpm - 1800rpm, engine is only getting performance at those rev's.

Bpmull

Y2KBOS86 wrote: »

Not his fault, that's the Irish way.

Don't rev it

That seems to be the way. My driving instructor was like that. Constantly kk keeping the revs down. And no joke in my driving test I was driving a 1.6tdi octavia I got a blue mark for not being in fifth going up a hill at 70kmh. Like the car wasn't even at 2k rpm in fourth I'd have been labouring it. But it was the only mark I got and I was going to argue it out with the tester since I had passed. Lucky I knew enough to ignore all that don't rev it sh!t once I passed not that I drive around on the red line or anything but I don't go around at 1200 rpm all the time.

christy02

CiniO wrote: »

Of course they are.



Quite bad habbit I must say.
Who taught you to drive?

Driving at too low revs just damages the car.

No need to be smart. Learn how to spell also.
I was always taught to change revs at circa 2000 rpm. Which I do.

Car will be doing that at 80-90 in 5th. Car doesn't seem laboured at all at that speed in 6th.

I am sure you are the perfect driver with no bad habits.

Y2KBOS86

christy02 wrote: »

I was always taught to change revs at circa 2000 rpm. Which I do.

Car will be doing that at 80-90 in 5th. Car doesn't seem laboured at all at that speed in 6th.

I am sure you are the perfect driver with no bad habits.

You were taught wrong, like we all were.

Changing at circa 2000rpm is no better than changing at near 3000rpm, especially in petrols, where you can change much higher.

What diesel are you driving, modern 2.0l diesel's do labour in 6th at 80-90 compared to 5th, 4th, even 3rd.



I always try and get maximum performance from my diesel so would be in 4th sometimes even 3rd when I am accelerating from 80km when I need to overtake.

CiniO

christy02 wrote: »

No need to be smart. Learn how to spell also.

I'd love to.
I've been learning English for the last 24 years, but still far from good.
Where is a mistake in spelling btw?

I was always taught to change revs at circa 2000 rpm. Which I do.

It all depends on a car.
But in general driving at low revs in not good for an engine.
My golden rule with petrol engines is to never drive below 2000rpm in any gear except 1st. The higher the gear, the higher the minimum revs should be.
So f.e. in petrol engine I could change from 1st to 2nd that revs fall to say 1800rpm and I would still think it's acceptable, but I wouldn't drive below 2200 - 2400rpm on 5th on flat road, not even mentioning inclines.
There's no harm in using higher revs for an engine. Worst can happen is increased fuel consumption if you use too high revs. But if you go too low, you might just cause mechanical damage to an engine.

In diesels those limits would be lower, but again - I wouldn't really even try to drive at higher gears (3rd, 4th, 5th, 6th, etc...) below turbo kicking point usually around 1700-1800rpm.
On 1st and 2nd possibly driving at 1500rpm could be considered acceptable.

If you think driving at low revs saves you fuel or will make your engine last longer - you are wrong. It won't. It will do opposite.

Car will be doing that at 80-90 in 5th. Car doesn't seem laboured at all at that speed in 6th.

It might not seem or sound laboured, but believe me - it is.

I am sure you are the perfect driver with no bad habits.

Are you actually admitting here that driving with low revs is bad habit?
Looks like you are.
And yes - I'm trying my best not to have any bad habits when driving.

jimgoose

The whole lot of ye have the mechanical empathy of a bull-rhinocerous in heat, and should be driving space-hoppers.

christy02

So what no one actually has said is what revs you should actually drive at. I have a 2.2 diesel accord. To drive over 2000 revs all the time would be ridiculous as some have suggested. It is only doing 2000 revs on a motorway at 120kph.

A petrol is different. Obviously a petrol revs at a higher range.

I would assume if you drove a 3.0 diesel it would rev even lower.

All cars are not the same and a one for all rule does not work. I keep revs reasonably low but make sure I don't have the engine labouring. I have been driving for 20 years and never gone through a clutch.

Btw. If you rev too high when doing your driving test you WILL FAIL.....

_Kaiser_

This is another reason why I love driving automatics - takes all this guesswork/conflicting teachings out of it

My current A6 (3.0 TDI with tiptronic) and last Passat (2.0 TDI with DSG) had manual modes but I think the only time I used it was in the snow of 2010 to get out of the estate a few times. Aside from that they sit in D and do all the work. I don't even bother with S(port) mode.

Anyone who says modern auto's are "boring/slow/uninvolving" hasn't driven a decent one IMO. My current car jumps through the gears from standstill so fast that there's no way you could do it that quick yourself (unless maybe a professional rally driver), and generally sits in 5th in urban driving.

Out on the open road it's 6th all the way and even at optimal cruising speeds, she's still pulling less than 3000 rpm.

I could never go back to a manual myself

christy02

Kaiser2000 wrote: »

This is another reason why I love driving automatics - takes all this guesswork/conflicting teachings out of it

My current A6 (3.0 TDI with tiptronic) and last Passat (2.0 TDI with DSG) had manual modes but I think the only time I used it was in the snow of 2010 to get out of the estate a few times. Aside from that they sit in D and do all the work. I don't even bother with S(port) mode.

Anyone who says modern auto's are "boring/slow/uninvolving" hasn't driven a decent one IMO. My current car jumps through the gears from standstill so fast that there's no way you could do it that quick yourself (unless maybe a professional rally driver), and generally sits in 5th in urban driving.

Out on the open road it's 6th all the way and even at optimal cruising speeds, she's still pulling less than 3000 rpm.

I could never go back to a manual myself

So then an auto box is set up to drive the way some self titled experts on here (know it all's!) Say that you shouldn't drive.

Why is that?

CiniO

christy02 wrote: »

So then an auto box is set up to drive the way some self titled experts on here (know it all's!) Say that you shouldn't drive.

Why is that?

But is it really?
You really think any auto box would let car cruise below 1300rpm on 6th gear?

christy02

CiniO wrote: »

But is it really?
You really think any auto box would let car cruise below 1300rpm on 6th gear?

He doesn't say. He does say however that it is in 5th for urban driving.

If you are interested I never said I cruise in 6th at 1300 rpm. I said when I am accelerating past 80 I change to 6th. I would cruise at 100 in 6th. 1700 or 1800 rpm and I have seen no evidence to suggest that is bad for the car.

CiniO

Kaiser2000 wrote: »

This is another reason why I love driving automatics - takes all this guesswork/conflicting teachings out of it

My current A6 (3.0 TDI with tiptronic) and last Passat (2.0 TDI with DSG) had manual modes but I think the only time I used it was in the snow of 2010 to get out of the estate a few times. Aside from that they sit in D and do all the work. I don't even bother with S(port) mode.

Anyone who says modern auto's are "boring/slow/uninvolving" hasn't driven a decent one IMO. My current car jumps through the gears from standstill so fast that there's no way you could do it that quick yourself (unless maybe a professional rally driver), and generally sits in 5th in urban driving.

Out on the open road it's 6th all the way and even at optimal cruising speeds, she's still pulling less than 3000 rpm.

I could never go back to a manual myself

What's the lowest revs your auto box will let car accelerate or cruise?

CiniO

christy02 wrote: »

He doesn't say. He does say however that it is in 5th for urban driving.

I asked him so.

If you are interested I never said I cruise in 6th at 1300 rpm.

You said that:

I get into 6th as soon as I can. Anything over 80km car is happy to travel in 6th.

Should I not be doing this? Would be at about 1600rpm at 100km/hr.

So if at 100km/h on 6th, your engine revs at 1600rpm, then at 80km/h (when you change to 6th) it's down to 1280rpm.

I said when I am accelerating past 80 I change to 6th.

So that's even worse, as you are accelerating from 1280rpm.
Acceleration from such low revs is probably even worse than cruising at those low revs.

I would cruise at 100 in 6th. 1700 or 1800 rpm and I have seen no evidence to suggest that is bad for the car.

So now you changed your mind, and suddenly at 100km/h in 6th you have 1700-1800rpm, not 1600. Hmmm.


Driving at low revs would make sense in huge engine. F.e. 10 litre bus engine, would be happy to cruise at 1000rpm.
But not 2.2 litre car diesel, which you mentioned you drive.

fergus1001

CiniO wrote: »

I asked him so.



You said that:

So if at 100km/h on 6th, your engine revs at 1600rpm, then at 80km/h (when you change to 6th) it's down to 1280rpm.


So that's even worse, as you are accelerating from 1280rpm.
Acceleration from such low revs is probably even worse than cruising at those low revs.


So now you changed your mind, and suddenly at 100km/h in 6th you have 1700-1800rpm, not 1600. Hmmm.


Driving at low revs would make sense in huge engine. F.e. 10 litre bus engine, would be happy to cruise at 1000rpm.
But not 2.2 litre car diesel, which you mentioned you drive.

Lol owned

I drive a 1.4 hdi Peugeot 206 and I never let the car go below 1500 rpm as a rule use your gears !

christy02

CiniO I don't check my exact revs every time I change. I never cruise under 1600 or so which I feel causes no damage to the car unless it is labouring.

What I was asking at the start was is there any proof that it does? Despite a lot of trolling, the answer seems to be NO.

You are taking out of my comments what you like from them. Obviously what I meant was I am accelerating in 5th past 80 car is doing somewhere around 1800 rpm+ in 5th. I then change to 6th.

I would never cruise lower than 1600 or so. I am not overly conscious of MPG either. I am fairly new to having 6 gears so am probably driving as if it were a 5th gear.

I am sure if you drive a car with 5 gears that you don't drive in 4th at 100kph?

I suppose then that is really my question " should you drive a 6 speed car as if it were a 5 speed car with an overdrive for motorway driving only?"

I always felt that the gearing ratio was a bit lower to allow for normal driving in 6th. If you could answer that without the smart Alec comments it would be good.

CiniO

christy02 wrote: »

CiniO I don't check my exact revs every time I change. I never cruise under 1600 or so which I feel causes no damage to the car unless it is labouring.

What I was asking at the start was is there any proof that it does? Despite a lot of trolling, the answer seems to be NO.

You are taking out of my comments what you like from them. Obviously what I meant was I am accelerating in 5th past 80 car is doing somewhere around 1800 rpm+ in 5th. I then change to 6th.

I would never cruise lower than 1600 or so. I am not overly conscious of MPG either. I am fairly new to having 6 gears so am probably driving as if it were a 5th gear.

I am sure if you drive a car with 5 gears that you don't drive in 4th at 100kph?

I suppose then that is really my question " should you drive a 6 speed car as if it were a 5 speed car with an overdrive for motorway driving only?"

I always felt that the gearing ratio was a bit lower to allow for normal driving in 6th. If you could answer that without the smart Alec comments it would be good.

My answer is simple - avoid driving on too low revs.
Every car is bit different, and gear ratios are different - so there is no definitive answer to your question.
Once car might be OK to be driven at 80km/h in 6th, while other won't.

But driving below 1600-1700 in any modern diesel is just too low.
And it applies even more to accelerating.
So if you accelerate on 5th to 1800rpm, and then change to 6th where your revs fall to 1400rpm, and you keep accelerating to 1600rpm and then cruise at that, then you are doing it wrong.
Acceleration on 6th from 1400rpm to 1600rpm is really bad, both for your engine and flywheel.

What you should be doing is to accelerate to higher revs on each gear. F.e. accelerate to about 2000 - 2500rpm on each gear.
Once you are in 5th and reach 2500rpm, then change to 6th and keep crusing at 2000rpm.
If that's too fast, you might only accelerate to 2100rpm on 5th, and switch to 6th and keep crusing at 1700rpm if road is flat or downhill - that would still be probably acceptable for most modern diesels.
Also always increase revs on inclines. If you cruise on 6th at 1700rpm and encounter steep incline, reduce to 5th or 4th or even 3rd depanding on incline. You might need to use quite high revs on steep inclines, so don't be affraid to rev to 3000-4000rpm on inclines. Better going up steep incline in lower gear at 3000-4000rpm, then in higher gear at 2000rpm where your engine most like has highest torque and will cause higher forces going through the clutch, possibly shorting clutch's life.
For the same reasons avoid hard acceleration within max torque range revs - usually around 2000rpm in most modern diesels.

CJhaughey

The reason that they fit 6 spd boxes to modern diesel cars is because the powerband/torque peak is very narrow and to make the best use of it they need a gearbox with more ratios so you aren't always between gears.
6th in many cars (not all) is actually not far off 5th in a 5speed gearbox.
The exceptions are some repmobiles and French cars that have very tall 6th gear ratios for cruising on the Motorway.
Revs once an engine is warmed up won't do any harm, lugging an engine on the other hand has a lot of inherent problems like accelerated DMF failure and more worryingly failure of boundary lubrication.

ianobrien

Just to throw something into the mix. When Ford brought out a 5speed FWD gearbox in the old XR3i's some of the casings were wearing where the driveshafts entered the 'box (or was it the input shaft I can't remember). The problem was with drivers who engaged 5th gear below 45mph. The low engine speed set up a harmonic in the motions of the box causing either the input shaft or the driveshafts to wear the casing. The cure is a change of driver behaviour. The problem is so well known that most proper classic XR3 buying guides say to watch at what speed does the owner engage 5th at.

corkgsxr

ianobrien wrote: »

Just to throw something into the mix. When Ford brought out a 5speed FWD gearbox in the old XR3i's some of the casings were wearing where the driveshafts entered the 'box (or was it the input shaft I can't remember). The problem was with drivers who engaged 5th gear below 45mph. The low engine speed set up a harmonic in the motions of the box causing either the input shaft or the driveshafts to wear the casing. The cure is a change of driver behaviour. The problem is so well known that most proper classic XR3 buying guides say to watch at what speed does the owner engage 5th at.

06 yamaha r1's unscrew there oil filter over harmonics at round 170 mph

jca

CiniO wrote: »

But is it really?
You really think any auto box would let car cruise below 1300rpm on 6th gear?

It does. My 1.4 TSI Octavia regularly reaches 7th gear just driving around town. I don't bother with the + or - I just leave it in D and let it do its own thing. I give it the occasional lash in S mode to clear the cobwebs, usually at 4am when finished work;);). A fast little motor for a 1.4. If stuck behind a line of traffic being held to 70 km/h by the usual Toyota driver it would be in 7th gear and turning over at 1100-1200 rpm.

jca

ianobrien wrote: »

Just to throw something into the mix. When Ford brought out a 5speed FWD gearbox in the old XR3i's some of the casings were wearing where the driveshafts entered the 'box (or was it the input shaft I can't remember). The problem was with drivers who engaged 5th gear below 45mph. The low engine speed set up a harmonic in the motions of the box causing either the input shaft or the driveshafts to wear the casing. The cure is a change of driver behaviour. The problem is so well known that most proper classic XR3 buying guides say to watch at what speed does the owner engage 5th at.

Nissan Patrol's used to crack the headlight glass and that was only when it was idling.... Nissan diesels.... Junk..

gctest50

jimgoose wrote: »

The whole lot of ye have the mechanical empathy of a bull-rhinocerous in heat, and should be driving space-hoppers.

Be grand .....

https://www.youtube.com/watch?v=c8hqoE1_7bA

_Kaiser_

CiniO wrote: »

What's the lowest revs your auto box will let car accelerate or cruise?

Sorry just getting back to this now - it's not something I actally notice so I watched it today

At 50 km/h she's in 4th at around 1200 RPM. At 55 km/h she moves to 5th at just over 1200 (but less than 1300)

Cleveland Hot Pocket

Kaiser2000 wrote: »

Sorry just getting back to this now - it's not something I actally notice so I watched it today

At 50 km/h she's in 4th at around 1200 RPM. At 55 km/h she moves to 5th at just over 1200 (but less than 1300)

I had a manual TDI skoda superb but with gearchange suggestions on the dash.

She wanted to change up at about 1400 rpm, madness.

almostover

The father, a retired mechanic, always tells me the single worst thing you can do to an engine is labour it. Accelerates engine/clutch wear. Nothing p**ses me off more than being stuck behind someone constantly in 5th/6th who slows to a crawl when climbing any sort of incline. Just F***ing change down!

jimgoose

Any petrol-engined car I've encountered is quite happy changing gear at about 2,300 RPM. Drop that by 500 RPM for a diesel, and by another 500 RPM for big trucks. Most of them are quite frugal driven this way on the flat. Obviously feel quite free to focking floor it Fintan - you've let it warm up and heat-soak, right??

You'll know when your in the wrong gear - if you need more than around one-third throttle to maintain current speed, or the engine sound is more of a muffled "boom" as opposed to the usual sort of contented hum, change down.

jimgoose

Cleveland Hot Pocket wrote: »

I use full throttle, usually in fifth gear at 1200 rpm going uphill.
Optimizing the smoke cloud!

De job. Shoulder to the wheel and clouds of smoke. That's what they're for!

cerastes

Bpmull wrote: »

When you start a Diesel engine the turbo spins all the time. But when the car is idleing or at 1200 rpm it is only spinning at a fraction of its full capability. When you hit ca 1800 rpm the turbo boosts ie it spins to its full capacity and this helps the engine pull through the revs quicker and basically go faster. So if you floor a turbo diesel car at 1200 rpm then you will get lag (no rush of power) until ca 1800 rpm at which point the turbo will be on full boost and give that feeling of pulling you back in your seat. Obviously depends on the car and engine as to how much it will pull you back in the seat but you get the idea

Ok, Id wouldnt be flooring it in high gear to try accelerate, I dont labour it and it doesnt take long to get to 1800-2000 normally, Im sure there is a problem with my turbo and Im wondering if thats affecting my economy when I floor it, doesnt seem to take much flooring it to drive the economy down and there is no feeling of boost at 100-110kmh, just dies, Im sure the vanes are stuck as Ive looked it up, going to bring it to the NCT and then try clean the turbo (if I get time).

Interslice wrote: »

Flooring it at 1200rpm would also put alot more strain on the clutch, flywheel and input shaft than the same acceleration at say 2000rpm. I was cringing sitting in fully loaded T5 with a lad the other week doing exactly that. A bout 30mph up a steep hill in 5th with about a tonne in the back :eek:. I'd have been in 3rd. Modern land cruisers have a big shift down light that comes on the the dash. They should put them in all cars . Ther would be less DMF failure's if they did.

I wouldn't mind a light on the dash, just out of curiosity, but I dont think I need it, labouring an engine is a bad thing, I thought most people knew how not to, now I'm not so sure. Anyway, mnfg puts lights in dash, dmf failure reducing might not add up.

jimgoose

christy02 wrote: »

So then an auto box is set up to drive the way some self titled experts on here (know it all's!) Say that you shouldn't drive.

Why is that?

Automatics were always somewhat cognisant of throttle position, altering the shift-pattern (sometimes too subtly) depending on whether it was getting a bootful or a barman's fart. This was done via a vaccum sensor in the intake and in later incarnations often further modulated by "sport" and "comfort" modes, or similar. Also in the old, old days you had a switch on the floor under the accelerator pedal which whomped the thing down a cog con mucho gusto when it was floored. Nowadays of course you have sensors everywhere, everything connected to everything-else and fancy-dan dual-clutch automated manual setups, affording quite a degree of control even in an auto.

Gazzmonkey

I've often wondered this, if you had to drive at 80 for whatever reason..... would it be more economical to drive in 5th gear at 2000rpm or in 6th gear at 1500rpm taking into consideration that if you choose 6th gear you will have the gas pedal pressed a little further down!

CiniO

Kaiser2000 wrote: »

Sorry just getting back to this now - it's not something I actally notice so I watched it today

At 50 km/h she's in 4th at around 1200 RPM. At 55 km/h she moves to 5th at just over 1200 (but less than 1300)

That's quite surprising for me, as I would expect auto box not to let car travel at such low revs. Maybe fact that there is no DMF in auto cars, has something to do with it.

CiniO

I just made 2 videos.

1st is just normal acceleration 0-100km/h. I would rather not change gears any sooner than in this video, unless going downhill. Obviously if going uphill, changes would be at higher revs. But approximately what you can see on the video, I'd consider reasonable gear changes in diesel.

https://www.youtube.com/watch?v=vbw9QSNdkxY

2nd video shows acceleration trying to use maximum possible acceleration engine can provide. Obviously car could accelerate quicker is gear changes were quicker, but no point in making harm to gearbox, dmf and clutch when there's no need.

https://www.youtube.com/watch?v=h1_Vj5uxl6I

jca

CiniO wrote: »

That's quite surprising for me, as I would expect auto box not to let car travel at such low revs. Maybe fact that there is no DMF in auto cars, has something to do with it.

Mine has a dmf and actually runs at lower rpm when poodling along. I've often seen it in 7th gear at 60 km/h turning over at 1100 rpm.

christy02

CiniO wrote: »

I just made 2 videos.

1st is just normal acceleration 0-100km/h. I would rather not change gears any sooner than in this video, unless going downhill. Obviously if going uphill, changes would be at higher revs. But approximately what you can see on the video, I'd consider reasonable gear changes in diesel.

https://www.youtube.com/watch?v=vbw9QSNdkxY

2nd video shows acceleration trying to use maximum possible acceleration engine can provide. Obviously car could accelerate quicker is gear changes were quicker, but no point in making harm to gearbox, dmf and clutch when there's no need.

https://www.youtube.com/watch?v=h1_Vj5uxl6I

Nice dash. What car is it?

Was looking at my own driving style today also. Its actually hard to comment without spending a bit of time watching what you actually do. So much is habit you don't even notice.

Find I normally change up around 2500 rpm. Its probably then when I get into 6th I am doing 2000 rpm at 115 kph.

What I am probably a little wrong in doing is driving at 100 kph in 6th at ca 1750. Maybe a little low. Probably should stay in 5th until i go past 100.