Diesel just doesn't win me over....
Discussion
zeppelin101 said:
Fastdruid said:
1) Soot - Diesels clog up turbos and DPFs.
2) Particles - Petrols produce relatively few but GDI's have more so GPF's are only required on GDI cars and unlike diesels there are no complex regenerations required, for most regeneration is constant and there is no build up of soot or ash. Plus as a bonus they can actually replace silencers.
3) The way diesels make their power - kills DMF's (as well as vibration causing issues).
4) Cylinder pressure - far higher which means direct injection pressures are far higher (15000PSI up to 44000PSI against ~3000PSI) which means injectors are both far more expensive and more fragile and the same goes for pumps.
1) From the next round of legislation beyond EU6c where particulate regs will change again, filling GPFs up will be a problem for petrol engines where high filtration efficiencies will be a must.2) Particles - Petrols produce relatively few but GDI's have more so GPF's are only required on GDI cars and unlike diesels there are no complex regenerations required, for most regeneration is constant and there is no build up of soot or ash. Plus as a bonus they can actually replace silencers.
3) The way diesels make their power - kills DMF's (as well as vibration causing issues).
4) Cylinder pressure - far higher which means direct injection pressures are far higher (15000PSI up to 44000PSI against ~3000PSI) which means injectors are both far more expensive and more fragile and the same goes for pumps.
2) As gasolines improve in thermal efficiency (faster burn rates - less exhaust gas temperature) then the engine will have to be put under increasing load to regenerate. This is easy to implement with an auto gearbox but less so with a manual. Also, GPFs are not a requirement at any level, only if the engine out particulates cannot meet the relevant legislation. To my knowledge, only Mercedes have a gasoline engine in production with a GPF thus far.
3) There are any number of gasoline engines capable of producing 20+ bar BMEP from 1600 rpm or less - this is just as bad as any diesel in terms of DMF loading.
4) Injection pressure is a function of refinement and emissions, not solely combustion pressure. Gasoline injection pressures will increase in the next 3 years, and more so beyond - in excess of 500 bar in the near future.
Edited by zeppelin101 on Monday 20th April 07:38
2) As far as I'm aware it was direct injection only but I've not looked into what comes with one so you may be correct.
3) BMEP is not really relevant to DMF loading, the issue with diesels is the higher compression and type of power delivery which leads to a much "rougher" output.
4) Yes and no, diesel combustion pressure is way higher so needs more pressure to actually get the fuel into the cylinder, simple as. Plus 500 bar is only 7500PSI, miles away from 44000PSI!
The relevant point on injection pressure is that gasoline injection is almost exclusively in the intake stroke whereas diesel is not. That being said, peak firing pressures are typically no more than 80-100 bar higher than the equivalent petrol, whereas diesel injection pressures are 2000(ish) bar versus 200(ish) bar in gasoline at present.
Trust me, gasolines can take out DMFs just as easily as a diesel can. Think about it, the cylinder pressures required to achieve 20 bar + BMEP at 1500 rpm is not exactly going to be a smooth and progressive output to the crank is it?
Trust me, gasolines can take out DMFs just as easily as a diesel can. Think about it, the cylinder pressures required to achieve 20 bar + BMEP at 1500 rpm is not exactly going to be a smooth and progressive output to the crank is it?
E65Ross said:
the power seems to drop off considerably past 4k rpm.
Not surprising really, the best area for power is going to be 1500-3000 rpm, anything above that and the accelerator may as well be a volume pedal. There's really no need to redline a diesel unless it's on the way to the MOT station and you're a bit unsure whether it'll get a pass or not. It's just a different way of driving. I'd imagine comparing a car petrol engine to a bike petrol engine you'd see the same issue, a bike engine needs revs to make power. A diesel car engine doesnt.
I'm in two minds at the moment whether to go back to a diesel, it's the economy of it and the road tax. While signs in Sheffield seem to be saying 'drive ptrol not diesel' and certain diesels are being banned from some areas, the road tax doesnt reflect that, and the mpg makes it more worthwhile. I'm getting 300'ish miles to a 60 litre tank, It's a 4.0 V8 petrol, so it's never going to be great. I think I can get around 550-600 miles for roughly the same cost at the pumps by going for a diesel. The maintenance costs are roughly going to be similar (it's just oil and filters really) and if either engine went bang it'd write the car off in repair cost. I think I'd be OK risking a possible injector or flywheel issue, because while they're less common on petrols, they come with another set of problems. Bottom ends can go on petrols as much as injectors and flywheels can go on diesels
zeppelin101 said:
Trust me, gasolines can take out DMFs just as easily as a diesel can. Think about it, the cylinder pressures required to achieve 20 bar + BMEP at 1500 rpm is not exactly going to be a smooth and progressive output to the crank is it?
BMEP is a calculated figure and can be thought of as an *average* cylinder pressure so even a petrol vs a diesel with the same BMEP will have totally different "output" to the crank.Diesels have far higher peak cylinder pressures still so for a petrol and diesel with the same BMEP the diesel will still be far harder on a DMF.
TheJimi said:
My experience of diesels is that I'm yet to drive one with an degree of tractability.
Best one's I've driven so far are the 2.4 5cy Volvo lump, and while it sounds fantastic for a diesel, it's still not as tractable as a 1.6 Focus.
Try my A8 4.2 twin turbo TDi, it's stonking Best one's I've driven so far are the 2.4 5cy Volvo lump, and while it sounds fantastic for a diesel, it's still not as tractable as a 1.6 Focus.
Quiet, you can't tell it's a diesel from the inside and enough torque to pull your face off if you want to get a move on
It's completely redefined my opinion how a very fast sofa should drive...
Welshbeef said:
Diderot said:
That's the thing Ord - as you qualified, the nothing below 2k rpm doesn't afflict the x35/x40ds. I forget the precise figures but IIRC the x35d makes 90% torque at 1,750 rpm or something mad like that.
Which reminds me, I really must look into a remap
Exactly this is so often overlooked - though I guess most diesels are not sequential. However when you have diesels today which would demolish an E39 M5 or be doing 10-10.5 second to 100mph in near 2 tonnes you have to pay attention. Which reminds me, I really must look into a remap
Personally I cannot wait to get my hands on a Tesla P85D - but need comfort with the infrastructure and would like to have say a 1,000 mile range. 7 seater great looks destroys F10 M5's and hunts down Lambos. Perfect family car - then get a clip 172sport track slag for the noise thrills
Edited by theboss on Monday 20th April 12:00
I remain sceptical about these claims that petrols are close to diesels in mpg. I spent a day on Saturday in just such a car, but it was a brand new manual smart car and it was completely gutless. I'd say it was a little better than my ancient auto Bora tdi in terms of round-town mpg, (and of course petrol is cheaper than diesel), but has a lot less speed (and the Bora doesn't have much) space, comfort, practicality etc.
Fastdruid said:
1) Not from the articles I've read but they may be out of date. That said but diesels are going to be even more royally screwed come the next round of legislation.
You may well be right, but dear god, have i been reading that statement for what, 25 years now? I'd have loved a few quid for the countless times I've read that diesels will struggle 'next time'. charltjr said:
Welshbeef said:
One idea I've been having for a little while is to buy a cheap Renault Clio Sport 172/182 and have it strictly for the track. Strip it out and just have an absolute ball with it. They are fantastic cars loads of performance handling noise for very little money really. Sure it's nippy rather than fast but ragging it to within an inch of its life on the track would be great fun and if it goes pop get another for shed money and sell the other one for spares.
That's exactly what I do. Clio 182 for track/fun B road blasts and an Alpina D3 for everything else. I do 20k private miles a year so the D3 is an ideal car for that without being boring and the 182 covers all the other bases.Horses for courses.
I've a 1.6TDI Golf for the mundane runs, and a 2.8 VR6 engined Caddy for a bit of fun.
E65Ross said:
Been on holiday this week and a friend of mine is driving, a 2.0 diesel passat, the 170bhp one. It's not the performance that's the issue but it's so brash and unrefined. The noise is awful, the power seems to drop off considerably past 4k rpm.
Start stop REALLY doesn't work well either in this car. Every time the engine is stopped or started again the whole car shakes as the engine is rough. The only other car I've experienced stop/start in is a new M6, and it works very well as it has a nice smooth petrol engine.
Still, I suppose it's cheap on fuel and monthly payments.
Not too long ago I drove a 3.0 V6 TDI Audi A6 and that wasn't TOO bad, although at low speeds it is a bit unrefined but ok on the motorway. This 4 cylinder one is brash even on the motorway.
I'm not the only one who thinks this, am I?
I'd rather have a 6 cylinder diesel than a 4 cylinder petrol.Start stop REALLY doesn't work well either in this car. Every time the engine is stopped or started again the whole car shakes as the engine is rough. The only other car I've experienced stop/start in is a new M6, and it works very well as it has a nice smooth petrol engine.
Still, I suppose it's cheap on fuel and monthly payments.
Not too long ago I drove a 3.0 V6 TDI Audi A6 and that wasn't TOO bad, although at low speeds it is a bit unrefined but ok on the motorway. This 4 cylinder one is brash even on the motorway.
I'm not the only one who thinks this, am I?
There are some exceptions though, such as Alfa Romeo's 2.0 Twinspark engine.
daemon said:
Fastdruid said:
How many times do I have to repeat myself when both you and welshbeef bring up the same crap.
The difference is:
1) Soot - Diesels clog up turbos and DPFs.
2) Particles - Petrols produce relatively few but GDI's have more so GPF's are only required on GDI cars and unlike diesels there are no complex regenerations required, for most regeneration is constant and there is no build up of soot or ash. Plus as a bonus they can actually replace silencers.
3) The way diesels make their power - kills DMF's (as well as vibration causing issues).
4) Cylinder pressure - far higher which means direct injection pressures are far higher (15000PSI up to 44000PSI against ~3000PSI) which means injectors are both far more expensive and more fragile and the same goes for pumps.
While petrol cars have the same "technology" the different way the engines work mean that the technology is subject to different stress and you cannot tar petrol car technology with the diesel brush.
Well we'll see. The difference is:
1) Soot - Diesels clog up turbos and DPFs.
2) Particles - Petrols produce relatively few but GDI's have more so GPF's are only required on GDI cars and unlike diesels there are no complex regenerations required, for most regeneration is constant and there is no build up of soot or ash. Plus as a bonus they can actually replace silencers.
3) The way diesels make their power - kills DMF's (as well as vibration causing issues).
4) Cylinder pressure - far higher which means direct injection pressures are far higher (15000PSI up to 44000PSI against ~3000PSI) which means injectors are both far more expensive and more fragile and the same goes for pumps.
While petrol cars have the same "technology" the different way the engines work mean that the technology is subject to different stress and you cannot tar petrol car technology with the diesel brush.
Edited by daemon on Monday 20th April 13:15
The only "new" technology is GPF, DMF's, GDI, turbo's have all been on petrol cars for *years* and direct injection is the only one really known for issues now, the rest have had their issues pretty much ironed out.
Even then petrol (direct) injectors (and pumps) are a fraction of the cost of their diesel counterparts.
eg Anyone recall the issues everyone had with DMF's on mk3 petrol Mondeos? No because there weren't any (although I'm sure one or two isolated cases).
This thread is turning into every petrol vs diesel thread 
which I think is just an endless debate. To look at the OP's question I would agree I prefer to drive a petrol than a diesel and admit fully any downsides with that including mpg and mid range performance/having to be in right gear. Through work I have driven most current 1.6-2.0 diesel engines around right now and while I think the mpg is nice everything else is very utilitarian about them to me even though some have been refined to a good degree. The worst diesel I have come across so far in this period is the Vauxhall Astra 2.0 in its lower power guise I guess and here is why - fuel economy was miserable so the whole package felt pointless (I was doing 75mph on the M6 fyi). Had a ford focus ecoboost 1.0 too and got decent mpg. I think we are beyond 1.6 NA petrols which do not have enough overall performance for how heavy cars have become even with latest lighter models.
Because I don't do large mileage personally I feel I can justify an engine with a bit more character so choose a NA staright 6 petrol. I would never buy the 4 cyl petrol versions of my car. I am sure there are characterful diesels out there too but presume them to be 6 or 8 cylinder.
Somebody touched on the tractability of diesels and despite the good torque on paper I would agree diesels require a bit of care around the 1000-1500 rpm range to drive smoothly where petrols never some to stutter or seem to lack go. Also said by others that gearing is important which is totally the point. For a given performance the wheels are seeing the same power or torque so the 'I have more torque than you' argument means little if you have longer gearing.
which I think is just an endless debate. To look at the OP's question I would agree I prefer to drive a petrol than a diesel and admit fully any downsides with that including mpg and mid range performance/having to be in right gear. Through work I have driven most current 1.6-2.0 diesel engines around right now and while I think the mpg is nice everything else is very utilitarian about them to me even though some have been refined to a good degree. The worst diesel I have come across so far in this period is the Vauxhall Astra 2.0 in its lower power guise I guess and here is why - fuel economy was miserable so the whole package felt pointless (I was doing 75mph on the M6 fyi). Had a ford focus ecoboost 1.0 too and got decent mpg. I think we are beyond 1.6 NA petrols which do not have enough overall performance for how heavy cars have become even with latest lighter models.Because I don't do large mileage personally I feel I can justify an engine with a bit more character so choose a NA staright 6 petrol. I would never buy the 4 cyl petrol versions of my car. I am sure there are characterful diesels out there too but presume them to be 6 or 8 cylinder.
Somebody touched on the tractability of diesels and despite the good torque on paper I would agree diesels require a bit of care around the 1000-1500 rpm range to drive smoothly where petrols never some to stutter or seem to lack go. Also said by others that gearing is important which is totally the point. For a given performance the wheels are seeing the same power or torque so the 'I have more torque than you' argument means little if you have longer gearing.
Monkeylegend said:
Loudy McFatass said:
Monkeylegend said:
Loudy McFatass said:
Monkeylegend said:
I won't be buying another diesel. My latest has only done 267k miles in 4 years, has needed to be serviced every 18k miles, the water pump sprung a leak at 218k miles, I mean only 218k miles, Mercedes should be ashamed.
I have only managed to average 52mpg over 267k miles, and it never allows me to top up the oil between services. It cruises quietly at 75mph, I even have to tell my customers it's a diesel, how dare Mercedes make a diesel that runs so quietly and economically at cruising speeds pulling over 1600 kgs, plus several suitcases and very often 5 people.
I can't understand how Mercedes have got it so wrong, I mean the DPF should have gone kaput, the fuel pump should have gone kaput, the EGR should have gone kaput, the injectors should have the black death, at least one of the turbo's should have blown up by now. I will definitely be sending an e-mail to somebody high up to express my displeasure.
Yep, definitely the last diesel I will be buying, this one will only probably get me to 500k miles or so in the next few years, then after that another 500k. It's just not good enough.
Diesel, don't you just hate them.
Oh I forgot to mention the torque
Which model and engine is that!?I have only managed to average 52mpg over 267k miles, and it never allows me to top up the oil between services. It cruises quietly at 75mph, I even have to tell my customers it's a diesel, how dare Mercedes make a diesel that runs so quietly and economically at cruising speeds pulling over 1600 kgs, plus several suitcases and very often 5 people.
I can't understand how Mercedes have got it so wrong, I mean the DPF should have gone kaput, the fuel pump should have gone kaput, the EGR should have gone kaput, the injectors should have the black death, at least one of the turbo's should have blown up by now. I will definitely be sending an e-mail to somebody high up to express my displeasure.
Yep, definitely the last diesel I will be buying, this one will only probably get me to 500k miles or so in the next few years, then after that another 500k. It's just not good enough.
Diesel, don't you just hate them.
Oh I forgot to mention the torque
Edited by Monkeylegend on Saturday 18th April 22:24
And that's the rub, if you want mega miles diesel is the way to go. My car is used most days and usually does a minimum 220 miles per trip so none of the usual issues associated with low mileage usage.
I will admit though that when I buy another fun car it will be petrol
http://www.mercland.com/model/2122-2011(61)-MERCED...
Loudy McFatass said:
Monkeylegend said:
Loudy McFatass said:
Monkeylegend said:
Loudy McFatass said:
Monkeylegend said:
I won't be buying another diesel. My latest has only done 267k miles in 4 years, has needed to be serviced every 18k miles, the water pump sprung a leak at 218k miles, I mean only 218k miles, Mercedes should be ashamed.
I have only managed to average 52mpg over 267k miles, and it never allows me to top up the oil between services. It cruises quietly at 75mph, I even have to tell my customers it's a diesel, how dare Mercedes make a diesel that runs so quietly and economically at cruising speeds pulling over 1600 kgs, plus several suitcases and very often 5 people.
I can't understand how Mercedes have got it so wrong, I mean the DPF should have gone kaput, the fuel pump should have gone kaput, the EGR should have gone kaput, the injectors should have the black death, at least one of the turbo's should have blown up by now. I will definitely be sending an e-mail to somebody high up to express my displeasure.
Yep, definitely the last diesel I will be buying, this one will only probably get me to 500k miles or so in the next few years, then after that another 500k. It's just not good enough.
Diesel, don't you just hate them.
Oh I forgot to mention the torque
Which model and engine is that!?I have only managed to average 52mpg over 267k miles, and it never allows me to top up the oil between services. It cruises quietly at 75mph, I even have to tell my customers it's a diesel, how dare Mercedes make a diesel that runs so quietly and economically at cruising speeds pulling over 1600 kgs, plus several suitcases and very often 5 people.
I can't understand how Mercedes have got it so wrong, I mean the DPF should have gone kaput, the fuel pump should have gone kaput, the EGR should have gone kaput, the injectors should have the black death, at least one of the turbo's should have blown up by now. I will definitely be sending an e-mail to somebody high up to express my displeasure.
Yep, definitely the last diesel I will be buying, this one will only probably get me to 500k miles or so in the next few years, then after that another 500k. It's just not good enough.
Diesel, don't you just hate them.
Oh I forgot to mention the torque
Edited by Monkeylegend on Saturday 18th April 22:24
And that's the rub, if you want mega miles diesel is the way to go. My car is used most days and usually does a minimum 220 miles per trip so none of the usual issues associated with low mileage usage.
I will admit though that when I buy another fun car it will be petrol
http://www.mercland.com/model/2122-2011(61)-MERCED...
Are you thinking of buying it? Looks a nice car.
Edited to add Mercland have a very good reputation.
Edited by Monkeylegend on Monday 20th April 20:57
Monkeylegend said:
Yes, in the E class it develops 168 bhp, and about 290ftlb torque. I think it will be the same in that, but the C will be a bit faster and certainly as economical if not a bit better. Also has twin variable vane turbo so very little turbo lag.
Are you thinking of buying it? Looks a nice car.
Edited to add Mercland have a very good reputation.
Toss up between that and a C350. I've always wanted a Merc, however I now only do 12k miles per year though so I think a deasel will be pointless for me now. Are you thinking of buying it? Looks a nice car.
Edited to add Mercland have a very good reputation.
Edited by Monkeylegend on Monday 20th April 20:57
Loudy McFatass said:
Monkeylegend said:
Yes, in the E class it develops 168 bhp, and about 290ftlb torque. I think it will be the same in that, but the C will be a bit faster and certainly as economical if not a bit better. Also has twin variable vane turbo so very little turbo lag.
Are you thinking of buying it? Looks a nice car.
Edited to add Mercland have a very good reputation.
Toss up between that and a C350. I've always wanted a Merc, however I now only do 12k miles per year though so I think a deasel will be pointless for me now. Are you thinking of buying it? Looks a nice car.
Edited to add Mercland have a very good reputation.
Edited by Monkeylegend on Monday 20th April 20:57
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