Petrol or Diesel

[tofufi]

Originally Posted by Laird Scooby

Thing is, to really argue the case for diesels you need to understand they still produce just as much rubbish as they always have done but a lot of it is now trapped by DPFs etc.

Also, this really isn't true at a combustion level, even before we look at the aftertreatment systems.

More precisely controlled fuel injection strategies (some using up to 8 injection pulses per cycle now), introduction of EGR, improved piston and combustion chamber design to improve swirl, higher diesel injection pressures, have all contributed to improvements in diesel engine efficiency and emissions performance over the years.

Compare what comes out of the cylinders on my D24T engine to a brand new diesel engine, and the combustion [in the brand new engine] will be notably cleaner even before after-treatment systems get involved.

[tofufi]

Originally Posted by Whippy

The first, I remember Audi fitting Adblue devices in mid 2014. Obviously HGV 's have been using it for a while but it's a relatively new tech in cars.

As Zebster says, EGR reduces NOx formation, it became commonplace on diesels in the mid-late 90s from memory. The additives (adblue etc) came in around 2014-15 as you say.

NOx is primarily caused under high combustion temperatures and pressures - so under acceleration, steep hills etc.

EGR reduces the combustion temperature by reducing the amount of combustible matter in the engine cylinder (the used exhaust gas should have nominal amounts of oxygen left to burn as it goes through the engine the second time).

Adblue is added downstream of combustion to mop up NOx.

[Whippy]

I think this explains it in a simple to understand way.

https://www.autocar.co.uk/opinion/te...ficient-petrol

[Zebster]

Originally Posted by tofufi

As Zebster says, EGR reduces NOx formation, it became commonplace on diesels in the mid-late 90s from memory. The additives (adblue etc) came in around 2014-15 as you say.

NOx is primarily caused under high combustion temperatures and pressures - so under acceleration, steep hills etc.

EGR reduces the combustion temperature by reducing the amount of combustible matter in the engine cylinder (the used exhaust gas should have nominal amounts of oxygen left to burn as it goes through the engine the second time).

Adblue is added downstream of combustion to mop up NOx.

EGR is more about limiting the necessary excess of air (e.g. oxygen and nitrogen) by displacing the fresh air cylinder fill with exhaust. It's this excess of air that leads to the formation of NOx, very much more so in a diesel, where this excess is required to completely fill the cylinder to maximise compression (not necessary in a petrol engine which, in any case, is throttled anyway). The reduction of combustion temperature is a result of EGR but not the purpose.

[tofufi]

Originally Posted by Zebster

EGR is more about limiting the necessary excess of air (e.g. oxygen and nitrogen) by displacing the fresh air cylinder fill with exhaust. It's this excess of air that leads to the formation of NOx, very much more so in a diesel, where this excess is required to completely fill the cylinder to maximise compression (not necessary in a petrol engine which, in any case, is throttled anyway). The reduction of combustion temperature is a result of EGR but not the purpose.

Well spotted. I shouldn't be trying to multi-task

That said, NOx formation does increase rapidly above 1500-1600 deg C.

[tofufi]

Originally Posted by tofufi

Also, this really isn't true at a combustion level, even before we look at the aftertreatment systems.

More precisely controlled fuel injection strategies (some using up to 8 injection pulses per cycle now)...

Stumbled across a graphic to show the influence of multiple injections on pollutant emissions...



From: https://dieselnet.com/tech/engine_fi.php

[anotheruser]

I've gone from a petrol to a diesel.

> Now having to commute 60 miles a day
> £0 tax
> 66 plate. Likely to last me 10 years. By then, we'll have figured out what we're doing about electric cars.
> Both cars are now diesel in our household so means less than the half a second of confusion at the pumps.

[anotheruser]

Originally Posted by andy_d

whilst Rightly criticising Diesels Please DO bear in mind that the Nastys they chuck out HAS been know about since the 1970s, and Nothing , no dpf/add blue/eu emissions rating has or can EVER change that.

you can Not defend the un-defendable so dont bother trying

as for the "EV" or "scifi" methods that you meantion

Please do have a Big cup of coffee, and wake up in the real world sometime soon eh
closed minds - not needed in 2021

Such as the closed mind of diesel = the worst?

The facts are... there are no facts.
Absolutely nobody has done any sort of study taking into account all factors. Perhaps the rise of cleaning products has contributed to people being more ill these days. So much to consider.
But banging on about how bad diesels are isn't going to change someone's mind rather just make you look like an extremist and nobody likes those!

Originally Posted by Laird Scooby

... when there have allegedly been inventions of vehicles that run on water only (apparently petrochemical companies bought the Patents and buried them)...

Please provide any scrap of evidence of this because if you can't, people will assume it's a lie and then put everything you've typed into doubt.
If you can't provide any evidence, then best not bother saying something quite "out there"

Originally Posted by Laird Scooby

The big problem is you can't change the Laws of Physics or Chemistry. That is a simple fact. Diesel + combustion = heat + various waste products of combustion. Those waste products have not changed since Otto Diesel first created the compression ignition engine.
It doesn't matter what you hang on the exhaust like DPFs etc, the fact remains the same.

Let's split the hairs here, yes, you're right.

However the waste products can be made significantly cleaner and thus what comes out the back is quite different.

Take railways.
Old HST engines were fitted with a Valenta (very old) or Paxman VP185 engine. Now all of them currently operating are running with an MTU engine.
Same old diesel going in but completely different smoke coming out.

Somewhere along the way, those waste products have been changed to be not as harmful. Yes, still there to some degree but if you're basically trying to say a 1970s diesel car will provide the same emissions as a 2020 diesel car, nobody will believe you as (while I have no facts to back this up), I bet my next payslip it's not true.
You even said it yourself, a lot is trapped by the DPF or other such filters. If the bas gasses can be changed into soot, that's completely different to it coming out the back of the car.



At the end of the day, no matter what the poor people of the 80s and 90s were told, that was 30/40 years ago.
The young drivers of today care about price, style and electrical gizmos. Perhaps to an extent environmental factors but I suspect both modern petrol and diesels are about the same in the tests by which they are measured for pollutants.

[anotheruser]

I also found the part of this thread discussing electric vehicles and how "we're not ready" interesting.

Like it or not, it's likely they'll become mainstream.
There are many silly questions that were asked about those in terraced houses, or what happens if you don't work or this or that.
The answer simply is that some people will miss out.
Yes, amazing to say but that's the truth.

There was a proposal that people in the future wouldn't own cars but pay some sort of fee to "rent" one. If going on holiday, when it gets nearly empty, you drive to a service station and swap it for a new one.
Yes, this means lugging all the luggage between the two cars but that's the best answer so far. Remember, it's not "if" electric vehicles will take over but "when".

Instead of asking the question, work out a solution.
If you put your hands up and say there isn't one, it's that you're not really interested in finding one really.


Because many of the questions could be asked of things like the internet or telephones.
The answer is that the industry will find a way. They found a way to upgrade copper wires to fibre optic (to the cabinet at least!) (and there's still a long way to go on that), just like they found a way to install phone lines to begin with. When demand increases, companies will want to make money so will invest and make their billions.

[Laird Scooby]

Originally Posted by anotheruser

Such as the closed mind of diesel = the worst?

The facts are... there are no facts.
Absolutely nobody has done any sort of study taking into account all factors. Perhaps the rise of cleaning products has contributed to people being more ill these days. So much to consider.
But banging on about how bad diesels are isn't going to change someone's mind rather just make you look like an extremist and nobody likes those!

I found facts from research in a school library book in the early 80s - when i went to check something else in the same book it had been removed and destroyed. I was too young and naive then to think it might be a deliberate ploy on the part of the govt but i later (namy years later) learned that about the same time, oil companies were telling the govt NOT to use diseasel as the new "green" fuel because it wasn't. It really was "1984" coming to life!

Just because YOU have never found such facts does NOT mean they don't or never existed! Think about it! You'll be telling me next Curly-Wurlys have always been as small as they are these days!



Please provide any scrap of evidence of this because if you can't, people will assume it's a lie and then put everything you've typed into doubt.
If you can't provide any evidence, then best not bother saying something quite "out there"


Look up the definition of the word "Allegedly".........................



Let's split the hairs here, yes, you're right.

However the waste products can be made significantly cleaner and thus what comes out the back is quite different.

Take railways.
Old HST engines were fitted with a Valenta (very old) or Paxman VP185 engine. Now all of them currently operating are running with an MTU engine.
Same old diesel going in but completely different smoke coming out.

Somewhere along the way, those waste products have been changed to be not as harmful. Yes, still there to some degree but if you're basically trying to say a 1970s diesel car will provide the same emissions as a 2020 diesel car, nobody will believe you as (while I have no facts to back this up), I bet my next payslip it's not true.
You even said it yourself, a lot is trapped by the DPF or other such filters. If the bas gasses can be changed into soot, that's completely different to it coming out the back of the car.



At the end of the day, no matter what the poor people of the 80s and 90s were told, that was 30/40 years ago.
The young drivers of today care about price, style and electrical gizmos. Perhaps to an extent environmental factors but I suspect both modern petrol and diesels are about the same in the tests by which they are measured for pollutants.

The soot is still there, hence the DPFs - a 1970s diesel could easily achieve similar emissions levels if a DPF was fitted and/or other measures were used to clean the exhaust up. The fact it wouldn't pull the skin off a rice pudding with that lot on is irrelevant to your argument.