2.2 hdi 5th gear at 30mph

[exec406]

Set the cruise at 30mph in 5th gear and noticed the fuel computer was giving me 60mpg, much more than 4th gear.

The engine is hardly making 1,000 revs at that gear and that speed - is that OK?

[Welly]

Not really ok to be honest, you will be labouring the engine to an extent - it will be hauling the car around with decreased oil pressure and the mechanical shock loading of the downward piston stroke is not good for the dual mass flywheel at those revs.

You should use more 'favourable' revs of, say, 1500 as a minimum (so the engine's still off-boost).

[Doggy]

You will get better economy at low engine speeds, but I would agree with welly that a few more revs is sensible. (It's a fair tribute to the DW12's balancer shafts etc. that it doesn't rattle your teeth loose).
Mine reminds me of a petrol straight six in terms of low speed smoothness and lugging ability - you sometimes think it's a bit sluggish, then discover it's in 5th, not 3rd.

Good to hear from you again, welly.

[exec406]

OK thanks for that, the car almost drives itself with no throttle when in 5th at 30mph, maybe it's the high torque (314)

[DiscoPol]

maybe it's the high torque (314)

only 314, oh well never mind

[Doggy]

only 314, oh well never mind

Some newer ones are only 370, oh well never mind

[OdinEidolon]

IMHO as long as you don't do that for too long it's fine for short periods. As said don't keep those revs for too long. I don't usually set the cc at lower engine speeds than 1400.
I also found that if I use cruise while the engine has little to no load (for example at 40mph descending a small hill) the consumption can go up to the sky (down to 30mpg). I also prefer not to use cruise when climbing a hill

[exec406]

only 314, oh well never mind

Some newer ones are only 370, oh well never mind

Yeah but in the 406? The car I have is a Jul 2003 - maybe it has that 370? Accoridng to the handbook (dated 16 Dec 2001) it states the 314.

[OdinEidolon]

only 314, oh well never mind

Some newer ones are only 370, oh well never mind

Yeah but in the 406? The car I have is a Jul 2003 - maybe it has that 370? Accoridng to the handbook (dated 16 Dec 2001) it states the 314.

He's talking about remapped ones, all 2.2s are 314 Nm

[Doggy]

DW12BTED4 2.2 twin turbo, (407 HDi GT 175 / Disco's C5) - 370 Nm.

Remapped 406 2.2 HDi - 398 Nm.

[OdinEidolon]

DW12BTED4 2.2 twin turbo, (407 HDi GT 175 / Disco's C5) - 370 Nm.

Remapped 406 2.2 HDi - 398 Nm.

Oh, i thought the twin turbo was more than that.

[DiscoPol]

DW12BTED4 2.2 twin turbo, (407 HDi GT 175 / Disco's C5) - 370 Nm.

Remapped 406 2.2 HDi - 398 Nm.

Doggy are you suffering "Turbo Envy" again?
I wonder what mine would be like remapped, I bet the bugger would proper fly, I tanked with that super duper doozil the other day and decided i would drive it like i stole it for a day or two, it scared me silly

[Welly]

Remapped 406 2.2 HDi - 398 Nm**.

**Please note; Custard proof required, all figures quoted are based upon 'pub' estimates only.

Anyhoo all this talk of torque is all very well but it is Brake Horse Power that makes a proper quick car - for which I am in the lead

[Doggy]

Anyhoo all this talk of torque is all very well but it is Brake Horse Power that makes a proper quick car - for which I am in the lead

On the contrary, my dear Welton, 'Brake Horse Power' is what gives you a high top speed.
Doubtless, your trusty Volvo will rocket from 0-60 in sub 7 seconds & exceed 150 mph, which none of the quicker diesels can do, but we can't equal 4 mpg or £250+ per hour like you either.

What we can do is everyday sensible stuff darn near as rapidly, with the addded advantage, (especially in my case due the the age / image of a 406 estate), of giving other road users the WTF experience.

[Doggy]

Doggy are you suffering "Turbo Envy" again?
I wonder what mine would be like remapped, I bet the bugger would proper fly, I tanked with that super duper doozil the other day and decided i would drive it like i stole it for a day or two, it scared me silly

I don't imagine for a second the numbers tell the whole story - yours produces max torque from 1500 rpm well up the rev range, whereas all the gains on mine are above 2000. I would expect yours to be quicker in practical terms and probably easier to drive quickly - mine wriggles a bit and re-defines torque-steer on occasions.
Initially I decided the remap wasn't worth it because there was no benefit below 2000 and not much gain in the area you use all the time - as it was 'free' curiosity got the better of me and I was pleasantly surprised at the results.