The government have won. Selling my diesel for a petrol.....

[havoc]

xjay1337 said:

2) Assuming it's an older non turbo NA vtec unit, they have no torque anywhere in the rev range, and only really get a shuffle on in a relatively narrow powerband (about 3k rpm - which is no different to the 1500-4500rpm powerband of most modern 2.0 4 pot diesels).

Bullst. Ignore the physical rpm numbers (i.e. adjust for gearing), put the two curves side-by-side, and see which looks better.

A good example (because the gearing makes it easy) is vs the BMW 2.0d motor - it's the same capacity as the Civic and is broadly lauded as one of the best 2.0 diesels:-
- The Civic has gearing which is approximately half that of e.g. a 320d (20mph/1,000rpm vs c.40mph/1,000rpm in top, and the same proportion in peak rpm - 8,700 vs c.4,500).
- The Civic has ~153lb ft peak, of which as I've said above >135 lb/ft is available for a range of >6,000rpm (or >75% of the rev-range).
- The 320d has 295 lb/ft, but you need to halve it to adjust for the gearing effect between the cars, and get c.150lb/ft for the same wheel-speed - almost the same peak torque as the Civic. Close enough to say they're the same.
- Except the 320's curve drops a LOT sooner (starts to drop at ~2,900rpm, which is 65% of peak rpm. The engine only delivers >85% of peak torque between 1,500rpm and 4,000rpm, so 55% of the rev-range).


So if you're considering the wheel-torque curves, the Civic delivers the same or more wheel-torque vs the 320d for an extra 20%+ of the rev-range. Which means the Civic's engine is more flexible than the 320d.


The 335d isn't any better either in terms of engine flexibility, as the curve here shows - 85% of peak torque available from ~1,300 to 3,900, so 2,600 usable revs out of a redline of ~5,000rpm (again, maybe 55% of the rev-range):-

(Contrast the 335i, which has 85% of peak torque available from c<1,200rpm up to ~5,700rpm, so 4,500rpm out of a 7,000rpm rev-range, so 65% of the rev-range.)

Of course, both the blown 3.0 6-pots are bigger engines so have more grunt anyway, which means you don't NEED to be at 85% of peak torque - so in the real world the 335d engine is pretty good (335i is still better, by this measure). But comparing similarly-sized engines, a diesel is always less-flexible than a petrol.



Whether you enjoy one engine's delivery over another's is a separate point (each to their own) - I'm talking about engine flexibility, and diesels lose out to petrols in this regard. Always have, always will.

Edited by havoc on Friday 26th January 11:33

[Ares]

Mr Tidy said:

Ares said:

Don't forget, most people bhing about diesels being st to drive have only every driven a sub-150bhp, st diesel.

Well my 1st diseasel was a BMW 320td with just 150 bhp, but my 2nd was a 123d with "only" 201 bhp.

But then I got a Z4 Coupe with 265 bhp and I really couldn't give a sh*t about road tax or economy! A "tractor" will always be a tractor!

You're telling me the 123d was dull?

[Ares]

havoc said:

Bullst. Ignore the physical rpm numbers (i.e. adjust for gearing), put the two curves side-by-side, and see which looks better.

A good example (because the gearing makes it easy) is vs the BMW 2.0d motor - it's the same capacity as the Civic and is broadly lauded as one of the best 2.0 diesels:-
- The Civic has gearing which is approximately half that of e.g. a 320d (20mph/1,000rpm vs c.40mph/1,000rpm in top, and the same proportion in peak rpm - 8,700 vs c.4,500).
- The Civic has ~153lb ft peak, of which as I've said above >135 lb/ft is available for a range of >6,000rpm (or >75% of the rev-range).
- The 320d has 295 lb/ft, but you need to halve it to adjust for the gearing effect between the cars, and get c.150lb/ft for the same wheel-speed - almost the same peak torque as the Civic. Close enough to say they're the same.
- Except the 320's curve drops a LOT sooner (starts to drop at ~2,900rpm, which is 65% of peak rpm. The engine only delivers >85% of peak torque between 1,500rpm and 4,000rpm, so 55% of the rev-range).


So if you're considering the wheel-torque curves, the Civic delivers the same or more wheel-torque vs the 320d for an extra 20%+ of the rev-range. Which means the Civic's engine is more flexible than the 320d.


The 335d isn't any better either in terms of engine flexibility, as the curve here shows - 85% of peak torque available from ~1,300 to 3,900, so 2,600 usable revs out of a redline of ~5,000rpm (again, maybe 55% of the rev-range):-

(Contrast the 335i, which has 85% of peak torque available from c<1,200rpm up to ~5,700rpm, so 4,500rpm out of a 7,000rpm rev-range, so 65% of the rev-range.)

Of course, both the blown 3.0 6-pots are bigger engines so have more grunt anyway, which means you don't NEED to be at 85% of peak torque - so in the real world the 335d engine is pretty good (335i is still better, by this measure). But comparing similarly-sized engines, a diesel is always less-flexible than a petrol.



Whether you enjoy one engine's delivery over another's is a separate point (each to their own) - I'm talking about engine flexibility, and diesels lose out to petrols in this regard. Always have, always will.

Edited by havoc on Friday 26th January 11:33

Might be me, but that graph its wrong. The Torque and BHP lines are the wrong way around, and the 335d puts out 313bhp?

[havoc]

You're right on the key, but I took that as wheel-hp rather than an adjusted figure (using coast-down or otherwise), as both cars are 'too low', but proportionately they're about right.

Same as the Civic chart above - it's a whp / wheel-torque chart.

[Ares]

havoc said:

You're right on the key, but I took that as wheel-hp rather than an adjusted figure (using coast-down or otherwise), as both cars are 'too low', but proportionately they're about right.

Same as the Civic chart above - it's a whp / wheel-torque chart.

Yes....but shouldn't the 335i and 335d be pretty much the same peak bhp? If anything the 'd' should be higher than the 335i? (313 vs 303 IIRC)? Or does a diesel have significantly more losses to the wheel?

[havoc]

Looks like there's only about +/- 16whp in it - not that far off the on-paper relationship. Maybe the 335i was particularly fit / maybe the 335d wasn't that fit...or maybe that comment is more broadly true of those engines.
(e.g. the F10 M5's always made well above stated power...it's possible the 335i's are the same / it's possible they used a blueprinted 335d to get the advertised power and a customer vehicle is a little light)

[greenarrow]

To answer the original post. No I've not. Its all bks as far as I am concerned. I am keeping my oil burning motorway muncher until I find an electric car with a suitable range with which to complete my weekly commutes.

I really don't buy this "petrol is the saviour" stuff. Lower NOX maybe, but higher CO2, less real world MPG. I don't do much town driving so don't really think my diesel is a great danger to anyone. I say this as someone who's other car is a petrol powered MX-5, which I try and use for my local trips.......

[rxe]

I'm very happy in my 51 plate 5 pot diesel. If 4 pots are agricultural and 6 pots are OK, what is a 5 pot?

Anyway, I've recently picked up a very dull 30 each way commute. Nearly all motorway, in the morning when everyone is bimbling along at 50. The mpg is astounding, best is 650 miles on a tank. It's cheaper than my old commute which was a few stops on the tube.

Not planning on changing it any time soon.

[Coolbanana]

greenarrow said:

I really don't buy this "petrol is the saviour" stuff.

But it isn't, who it telling you that it is?

Both petrol-only and diesel-only ICE are for the scrapheap; eventually.

The future is in Hybrids and EV until something even better comes along in the very distant future.

[Ares]

greenarrow said:

To answer the original post. No I've not. Its all bks as far as I am concerned. I am keeping my oil burning motorway muncher until I find an electric car with a suitable range with which to complete my weekly commutes.

I really don't buy this "petrol is the saviour" stuff. Lower NOX maybe, but higher CO2, less real world MPG. I don't do much town driving so don't really think my diesel is a great danger to anyone. I say this as someone who's other car is a petrol powered MX-5, which I try and use for my local trips.......

Let you into a secret..... we don't think petrol is the saviour either, but it makes a bloody good excuse to wives/accountant/man maths recipients to swap a 300bhp diesel with a 500bhp petrol

[Pica-Pica]

V88Dicky said:

To the OP; the Government have won twice, no?

Government then: Buy a diesel

OP: Ok


Government now: Buy a petrol

OP: Ok

You missed the next step
Government next year: petrols produce micro-particles, petrol not OK.

[bmwmike]

I regularly check the WBAC of my petrol f10 (530) and it's gone up £800 in the past couple of months (11k to 11.8k).

Admittedly it was 13.5 as recently as June lol.

[Pica-Pica]

Mr2Mike said:

heebeegeetee said:

Diesels are better for co2, aren't they?

Yes but that is pretty much irrelevant when they also pump out a shed load of NOx and particulates which are actually proven toxins/carcinogens.

NOx of Euro 6 are pretty close for diesel and petrols, but CO2 are about half for diesel.

[bmwmike]

Pica-Pica said:

NOx of Euro 6 are pretty close for diesel and petrols, but CO2 are about half for diesel.

Not sure I'd call it pretty close looking at this article, but no doubt huge improvement's to both SI and CI engines over the years.

Disclaimer.. I only skim read and looked at the pretty graph

https://www.theengineer.co.uk/fact-check-are-diese...

[Number 97]

yep, saw this coming last year and traded in my Citroen Ds3 1.6 TDI for a Mazda 3 2.0

[Pica-Pica]

Mr2Mike said:

heebeegeetee said:

Diesels are better for co2, aren't they?

Yes but that is pretty much irrelevant when they also pump out a shed load of NOx and particulates which are actually proven toxins/carcinogens.

..and the finer particulate size of petrol engines more so.
Also shed load of NOx? My EURO 6 diesel is below the EURO 6 petrol limit for NOx

[WJNB]

You would have to be pretty thick or resident on another planet not to have realised YEARS ago that the diesel was dying.
A diesel engined car was never going to have any cache or class irrespective of the badge on the bonnet. Diesels were for tractors & delivery vans. Rattle around in a smelly diesel in 2018 & you're a laughing stock.
There are going to be many thousands of owners weeping at the cost of their mistake come the time to off-load their derv machines. In fact how belong before they are worthless?

[Ninja59]

WJNB said:

You would have to be pretty thick or resident on another planet not to have realised YEARS ago that the diesel was dying.
A diesel engined car was never going to have any cache or class irrespective of the badge on the bonnet. Diesels were for tractors & delivery vans. Rattle around in a smelly diesel in 2018 & you're a laughing stock.
There are going to be many thousands of owners weeping at the cost of their mistake come the time to off-load their derv machines. In fact how belong before they are worthless?

Depends what your miles are and where. When you do motorway miles of any significant distance there is still very few real replacements for a diesel.

Many diesels are pushing 500 - 600 miles+ between refills. I mean plonk my 640 on a motorway it goes over 40 MPG and returns about 550 - 600 miles. In that time a Tesla would need charging 2 - 3 times, cheaper to charge yes, but on a long trip who really wants to stop and charge.

Also in my case very few of the petrols actually sold or have been sold.

[Ninja59]

havoc said:

Bullst. Ignore the physical rpm numbers (i.e. adjust for gearing), put the two curves side-by-side, and see which looks better.

A good example (because the gearing makes it easy) is vs the BMW 2.0d motor - it's the same capacity as the Civic and is broadly lauded as one of the best 2.0 diesels:-
- The Civic has gearing which is approximately half that of e.g. a 320d (20mph/1,000rpm vs c.40mph/1,000rpm in top, and the same proportion in peak rpm - 8,700 vs c.4,500).
- The Civic has ~153lb ft peak, of which as I've said above >135 lb/ft is available for a range of >6,000rpm (or >75% of the rev-range).
- The 320d has 295 lb/ft, but you need to halve it to adjust for the gearing effect between the cars, and get c.150lb/ft for the same wheel-speed - almost the same peak torque as the Civic. Close enough to say they're the same.
- Except the 320's curve drops a LOT sooner (starts to drop at ~2,900rpm, which is 65% of peak rpm. The engine only delivers >85% of peak torque between 1,500rpm and 4,000rpm, so 55% of the rev-range).


So if you're considering the wheel-torque curves, the Civic delivers the same or more wheel-torque vs the 320d for an extra 20%+ of the rev-range. Which means the Civic's engine is more flexible than the 320d.


The 335d isn't any better either in terms of engine flexibility, as the curve here shows - 85% of peak torque available from ~1,300 to 3,900, so 2,600 usable revs out of a redline of ~5,000rpm (again, maybe 55% of the rev-range):-

(Contrast the 335i, which has 85% of peak torque available from c<1,200rpm up to ~5,700rpm, so 4,500rpm out of a 7,000rpm rev-range, so 65% of the rev-range.)

Of course, both the blown 3.0 6-pots are bigger engines so have more grunt anyway, which means you don't NEED to be at 85% of peak torque - so in the real world the 335d engine is pretty good (335i is still better, by this measure). But comparing similarly-sized engines, a diesel is always less-flexible than a petrol.



Whether you enjoy one engine's delivery over another's is a separate point (each to their own) - I'm talking about engine flexibility, and diesels lose out to petrols in this regard. Always have, always will.

Edited by havoc on Friday 26th January 11:33

Bit unfair the 3.0 diesel 335D is an older generation design M57 v a newer 335i N54 series engine...

[sgtbash]

Ninja59 said:

Bit unfair the 3.0 diesel 335D is an older generation design M57 v a newer 335i N54 series engine...

Exactly. The newer 335d's have loads more power.