When did diesel cars get complicated?

[Avocet]

You could stop them making it, if you wanted.

Stick to the speed limit.

Sorted.

I'm more keen to try and save lives and injuries than limiting any kind of damage to my wallet though...

 

[Avocet]

We're going to have to disagree then, something I very rarely do with your comments.

You are mixing up petrol and diesel emissions for 1, but also not allowing for the volume of emissions. Fairly easily demonstrated by running a petrol car and then a diesel car in a small workshop with ventilation and extraction closed off. Within minutes (2 or r 3) the diesel exhaust fumes are noticeable and then progressing to choking. Increased revs worsens it quickly, very quickly.
Whilst with (modern) petrol engine doing the same it is not as noticeable for maybe 10 minutes, but again increased revs worsens it.

Not something I'd recommend you do, but have experienced above and can tell you if 1 diesel car can do that , I actually worry what the volume of traffic in built up areas is really doing, to all of us, but some must really suffer.

A quick look at many diesels that emit a cloud of black smoke as they accelerate is a visual proof of the emissions volume increasing

We have to compare like with like though. Assuming they're both current "Euro 6d" cars, you shouldn't see ANY smoke out of a diesel on acceleration - absolutely none! If we're talking about older cars, before cats and DPFs, then diesels are better on CO and HC but worse on NOx and particulates.

If you're talking about the first 10 minutes after startup, petrol engines tend to run hotter, so from a cold start, you'll see a small improvement earlier from the petrol engine as its cat "lights up" sooner and starts working, but both of them have to do their emissions tests starting from the same "cold" start temperature, though, and they both have to drive the same WLTP drive cycle. Limits for both are identical apart from the NOx limit for diesels - which is very slightly higher. That is proposed to be addressed in the Euro 7 regs, but some pundits seem to think it will just kill-off diesels altogether because they'll need massive amounts of AdBlue to get the NOx down enough.

My gut feeling (and I wish the government would do some actual research on it), is that if all vehicles were correctly maintained Euro 6d (RDE) or later, we wouldn't really have that bad an air quality problem. That goes for petrol AND diesel. However, in practice, that means banning anything powered by an ICE, built before about the end of 2020, and given the backlash against ULEZ requirements as it is, that's just not going to happen. What we really DO need to come down hard on, (IMO) are post-registration modifications to engines ( de-cats, DPF and EGR deletes, Remaps, etc) that take them out of compliance. They're (again IMO) what's dragging us back. Our MOT emissions test just isn't "fit for purpose". It can't check emissions under load and it can only (in any meaningful sense) look for CO and HC at no load. Particulates testing with a smoke meter, is a joke, and they can't test for NOx at all!

 

[norseman]

That poor little engine! Wouldn't pull the skin off a rice pudding, and someone is deluded enough to think that it's "perfectly happy" at about 1200 revs in 4th... Now THAT'S the sort of crime that I think should be deserving of a custodial (in fact, possibly even capital)penalty...



In your self-righteous (but utterly impotent) rage, you are confusing "being held up" with "deserving to be held up". It goes without saying that I don't give the proverbial flying f*&^ whether you think folk "deserve" to be held up or not, it doesn't really change the fact that they ARE being held up...



At least you got that right...



I certainly hope never to grow any like yours, at any rate!



As I've said before, I am motivated to try and reduce deaths and serious injuries on our roads. You, on the other hand, appear to be motivated by a short-sighted desperation for "compliance", more than anything else. (Not that you have much to show for it again this year...)

View attachment 366762

Interesting, the big dip around 2020?

 

[carmanmemoranda]

We have to compare like with like though. Assuming they're both current "Euro 6d" cars, you shouldn't see ANY smoke out of a diesel on acceleration - absolutely none! If we're talking about older cars, before cats and DPFs, then diesels are better on CO and HC but worse on NOx and particulates.

If you're talking about the first 10 minutes after startup, petrol engines tend to run hotter, so from a cold start, you'll see a small improvement earlier from the petrol engine as its cat "lights up" sooner and starts working, but both of them have to do their emissions tests starting from the same "cold" start temperature, though, and they both have to drive the same WLTP drive cycle. Limits for both are identical apart from the NOx limit for diesels - which is very slightly higher. That is proposed to be addressed in the Euro 7 regs, but some pundits seem to think it will just kill-off diesels altogether because they'll need massive amounts of AdBlue to get the NOx down enough.

My gut feeling (and I wish the government would do some actual research on it), is that if all vehicles were correctly maintained Euro 6d (RDE) or later, we wouldn't really have that bad an air quality problem. That goes for petrol AND diesel. However, in practice, that means banning anything powered by an ICE, built before about the end of 2020, and given the backlash against ULEZ requirements as it is, that's just not going to happen. What we really DO need to come down hard on, (IMO) are post-registration modifications to engines ( de-cats, DPF and EGR deletes, Remaps, etc) that take them out of compliance. They're (again IMO) what's dragging us back. Our MOT emissions test just isn't "fit for purpose". It can't check emissions under load and it can only (in any meaningful sense) look for CO and HC at no load. Particulates testing with a smoke meter, is a joke, and they can't test for NOx at all!

Agree and disagree with that but.

You are not allowing for volume of emissions. More fuel in more emissions out, no matter how clean or dirty

 

[morqthana]

In your self-righteous (but utterly impotent) rage, you are confusing "being held up" with "deserving to be held up". It goes without saying that I don't give the proverbial flying f*&^ whether you think folk "deserve" to be held up or not, it doesn't really change the fact that they ARE being held up...

Being "held up" means that someone's progress is being impeded, delayed. It presupposes that an unimpeded, undelayed progress would be possible were it not (in the context used by norseman & ReganAndCarter) for drivers adhering to the limit.

Being delayed is being made late, or slow. Slow can only exist in a frame of reference which must include what the speed limit is, as travelling at the speed limit can only be regarded as normal. Being made late? If a driver is made late because of speed limits the fault is entirely his, not the speed limit, and not other drivers who are adhering to it.

The only way faster progress would be possible would be via driving illegally.

The way you describe the situation of people driving according to the law is highly pejorative, and clearly shows that you do not respect the law.

(Not that you have much to show for it again this year...)

You've been shown the evidence of the efficacy and desirability of 20mph speed limits many times. There's no point me showing any of it to you yet again because you are one of those people who, when presented with facts which contradict your existing beliefs, decides to ignore the facts rather than accept that his existing beliefs were mistaken

 

[Avocet]

Interesting, the big dip around 2020?

Covid lockdowns.

 

[Avocet]

Agree and disagree with that but.

You are not allowing for volume of emissions. More fuel in more emissions out, no matter how clean or dirty

But higher RPM in itself, isn't the only determinant of the amount of fuel going in. With a petrol engine, under no load in neutral, you can get very high RPM without injecting much fuel. Conversely, you can run low RPM on a wide open throttle and high load but get through a great deal more fuel. The diesel doesn't have a throttle plate to restrict air, but it can run at air : fuel ratios of 60 or 70 :1 so it achieves the same thing (more so, in fact), where it can run at light load and high RPM, using very little fuel, or High load and low RPM where it will use a lot more fuel.

With both engines, if you keep the same load, then yes, I agree, higher RPM = more fuel in, and more CO2 out. I don't think the other pollutants are quite so linear though. NOx, for example, is formed when combustion chamber temperatures get high (i.e. at larger power outputs).

 

[Avocet]

Being "held up" means that someone's progress is being impeded, delayed. It presupposes that an unimpeded, undelayed progress would be possible were it not (in the context used by norseman & ReganAndCarter) for drivers adhering to the limit.

Being delayed is being made late, or slow. Slow can only exist in a frame of reference which must include what the speed limit is, as travelling at the speed limit can only be regarded as normal. Being made late? If a driver is made late because of speed limits the fault is entirely his, not the speed limit, and not other drivers who are adhering to it.

The only way faster progress would be possible would be via driving illegally.

The way you describe the situation of people driving according to the law is highly pejorative, and clearly shows that you do not respect the law.

More tedious, semantic ****** to try and obfuscate your way out of the hole you're digging yourself. None of that lengthy diatribe changes the fact that a slower driver in front, "holds up" a faster driver behind. The issue around breaking the law is a separate one.

You've been shown the evidence of the efficacy and desirability of 20mph speed limits many times. There's no point me showing any of it to you yet again because you are one of those people who, when presented with facts which contradict your existing beliefs, decides to ignore the facts rather than accept that his existing beliefs were mistaken

I guess I ought to be thankful for small mercies then! Yes, you (and others) have presented all sorts of cherry-picked "evidence" in your attempts to back up your claims that slower = safer. It must be a constant irritation to you that the number of deaths and serious injuries on our roads changes very little as a result of ever-increasing speed limit reductions and automated enforcement. Come back when that graph has a decent downward slope on it and we can continue the conversation, eh? I expect the new crop of driver assistance systems to have a far greater effect than anything the hysterical "speed kills" lobby has managed to achieve.

 

[morqthana]

More tedious, semantic ****** to try and obfuscate your way out of the hole you're digging yourself.

Categorising the use of the actual definitions of words as "semantic ******" is a tactic of failure.

None of that lengthy diatribe changes the fact that a slower driver in front, "holds up" a faster driver behind.

No, they don't do that.

This concept of being "held up" does not exist. It is a pejorative term which you are using because you do not like the law, you do not want the law, you do not respect the law.

I guess I ought to be thankful for small mercies then! Yes, you (and others) have presented all sorts of cherry-picked "evidence" in your attempts to back up your claims that slower = safer. It must be a constant irritation to you that the number of deaths and serious injuries on our roads changes very little as a result of ever-increasing speed limit reductions and automated enforcement. Come back when that graph has a decent downward slope on it and we can continue the conversation, eh? I expect the new crop of driver assistance systems to have a far greater effect than anything the hysterical "speed kills" lobby has managed to achieve.

1) There is no "cherry-picking". Have you looked at the data comparing just 20mph areas before and after the change? Have you looked at the evidence from other countries? The more you try to deal with facts which contradict your prejudiced narrative by simply denying them the more you confirm that you simply do not like 20mph limits, you simply do not want 20mph limits, you simply do not want society to have the benefits of 20mph limits, and you will lie in defence of your bigotry.

2) If people other than me are telling you the same thing that's because there are people other than me who believe in facts.

3) As you have been told over and over and over and over and over again, 20mph limits are about more than just reductions in KSI, so even if that reduction was zero (it isn't) they would still be worthwhile.

 

[carmanmemoranda]

With both engines, if you keep the same load, then yes, I agree, higher RPM = more fuel in, and more CO2 out. I don't think the other pollutants are quite so linear though. NOx, for example, is formed when combustion chamber temperatures get high (i.e. at larger power outputs).

And that really was my point

Assuming (it's a big assumption) people are in the correct gear for the engine speed, slow moving constant traffic is better for efficiency and emissions than stop start, and high revving faster moving traffic. Just the fact of being in a lower gear, on its own, doesn't increase emissions

Nowhere have I said I agree with lower speed limits, but I can understand some of the arguments for them. The real issue is that too many people don't care about emissions, they want to keep taking dirty vehicles into built up areas. Too many would also try to travel at excessive speeds for the circumstances, so we all get saddled with the easiest, cheapest control, low speed limits.