Warming up an engine

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
261

Freight Dog:

newmercman:
Just skimmed over the last few posts, didn’t really take any of it in, I’ve just done a 700mile overnight shift, so I CBA, but the gist of it is that I agree with our resident lunatic, but from his posts we agree for different reasons, I like my engine up to temperature before setting off purely to thin the oil out so it can do it’s job better, all the rest of the apparent reasons are of little interest to me.

My engines sound smoother with a bit of heat and my completely free flowing exhausts on my CAT engined lorry blow out no visible smoke under load, save for a puff of black smoke when I change gear, that’s old school seat of the pants stuff and it makes me happy.

Sent from my SM-G930W8 using Tapatalk

The resident lunatic’s theory is a confusing hotchpotch of questionable deduction and misuse of terms such as piston slap that does not dovetail with accepted theory. Despite inward conflict and questionable arguments he is now a proponent of something that we all have been stating since the beginning by what appears, happy accident. Instead of defending idling a diesel to warm as per the original post, he has subtlety migtrated to the subjective term “high idle”.

What that means is running an engine at higher revs than idling, which we’ve all since post one stated the research shows is beneficial over idling and indeed appears in many manuals. In essance this is to take the engine out of the risk area associated with idling. Running under light load is an optimum method that does appear appear in some manuals. In light of the findings, it appears manufacturers are increasingly building in automatic engine start sequences that progress the engine schedule away from idle where the risk of glazing, bore scoring and wet stacking are most prominent.

A flick through my prior posts will spot a consitant personal approach. I have time and again advocated following manufacturer guidance above all else. Not least because manufacturers change the software and hardware in response to development and research. Which is why I find the staunch across the board advocates of “idle to warm” so hard to comprehend. Such an attitude shuts out reception to feedback. It is perhaps recognising that old habits die hard that has lead to manufacturers fitting automated engine regimes such as turbo timers and engine start sequencing to protect users from this stubborn trait.

It’s absolutely clear that I was referring to ‘high idle’ from my first post on the topic.

While it’s equally clear that you were/are referring to warming it up under ‘load’ by driving it off with a cold engine.In which case I’m still waiting for an answer to that question as to why the example in the video shows the least smoke ( unburnt fuel ) and therefore fuel wash at idle and the most under load ?.

IE this argument is all about warming up an engine using ‘idle’ as opposed to ‘load’.With both you and Rjan clearly being on the side of using ‘load’.Until I showed the real world results of such silliness just by looking at an open exhaust stack of a cold engine showing the results of what happens when you put diesel into a cold engine with idle being the least problematic and load being the most.

With you then seeming to be confusing engine speed with load when the two things are totally different and which is why I asked you if you could read a fuel map.Obviously not.Having also obviouly confused the fact that it’s the cylinder temperatures which totally wrecks the combustion process in a cold engine not the engine speed or the load factor of the engine.Chucking more fuel into a cold engine in the form of load just adding to the problems caused by the poor combustion not solving them.As shown in the video. :unamused:

262

Freight Dog:

Carryfast:
I thought I’d made the case my case being high idle to warm up clear.:

Absolutely not. In fact the opposite. So strong a proponent of idle to warm you posted a video of a Lancaster running in effort to attempt to discount what I had said and show an engine being warmed up by idling. I pointed out the Lancaster would not be sitting at idle power whilst warming. You didn’t answer.

I have pointed out three key areas. Idling a diesel can risk damage. Increasing engine speed can decrease the risk of wet stacking, bore scoring and glazing. Ideally Diesel engine combustion is improved when under load.

On face value you now appear to agree that idling a diesel to warm it up is undesirable. You seem to now agree on one of the points I raised. That increasing engine speed does have a beneficial effect on a diesel. Yet this was your response to my points:-

Carryfast:
At the expense of actually pushing in more fuel to create the bigger bang washing more oil off the same cold cylinder walls and any possible piston slap issues resulting from applying load to the larger clearance of the cold piston relative to the bore,while the engine is warming up ?

I sense some conflict in whether you believe increasing engine speed is beneficial over idling. Rather than being clear, if anything a rather confused opinion you are projecting?

:confused:

You’ve clearly said and continue to say that warming up an engine under ‘load’ is superior to idle.Seemingly because you can’t get your head around the fact that it’s the cold cylinder temperatures which wreck combustion process nothing to do with whether the thing is under load or idle.While applying load to a cold engine and therefore massively increasing the fuelling just massively adds to the combustion problems caused by the cold engine.

The Lancaster example clearly showed it being warmed up at high idle not under load.

For the umpteenth time engine speed is independent of load you said warm it up under load not idle.I’ve clearly said and continue to say warm it up using ‘idle’ ‘high’ idle being idle not load.

On that note I’d guess that this argument if anything will make people start to think what the warm it up using ‘load’,as opposed to ‘idle’ mantra is doing to DPF’s let alone EGR systems and let alone the long term life of engines.At least if they’ve got the sense to look at that video I posted and realise that all that unburnt fuel in the form of smoke,being kicked out,when he pointlessly used ‘load’ to just twist the chassis and rock the cab on its mountings,let alone accelerating a 44 tonner up to motorway speeds,goes into the DPF and/or back into the cylinders. :unamused:

263

Carryfast:
You’ve clearly said and continue to say that warming up an engine under ‘load’ is superior to idle.

I cited 2 scenarios where combustion is improved in a Diesel engine away from the risks of idle. Both increasing revs and light load.

Carryfast:
Seemingly because you can’t get your head around the fact that it’s the cold cylinder temperatures which wreck combustion process nothing to do with whether the thing is under load or idle.

This is fundamentally a misunderstanding of what has been said.

Diesel engines at idle ingest a quantity of air indepedant of the fuel injected. I have said this previously, but to recap - a diesel engine will suffer wet stacking through poor combustion if the intake air is cold enough and the fuel required for power is insufficient to maintain combustion chamber temperature.

It is accepted knowledge that a desirable condition of operating a diesel engine at light loads is the maintenance of combustion chamber temps adequate enough to support full combustion. It has been found that at both speeds above idle and under load full combustion is supported due to mechanical mixing of the air/fuel mixture, greater chamber turbulence and greater injection rate.

I have also pointed out that further to improved combustion the tendency for wet stacking (bore wash) is therefore negated by higher engine revelations and/or operating under load. This is also accepted knowledge.

Carryfast:
While applying load to a cold engine and therefore massively increasing the fuelling just massively adds to the combustion problems caused by the cold engine.

This is not true. See above reasons. Diesel Combustion is poor at idle. It is accepted that both increased engine speed and load have a positive effect on diesel combustion. The former through increased fuel injection rate and mechanical mixing. It is known that the likelood of fuel particle impingement on the cyclinder wall is greatly reduced at both speeds above idle, and conditions of load due to effective combustion. The associated risk of wet stacking, glazing and bore scoring are reduced compared to the poor combustion associated with idle conditions.

Carryfast:
The Lancaster example clearly showed it being warmed up at high idle not under load.

“High idle” seems to have been a subjective term you inserted after the fact. At the point of conversation regarding idling, I stated that we don’t warm piston aircraft engines at idle. It was a simple assertion and correct. The Lancaster is warmed at “warm up power”. On other piston aircraft engines for instance 1200 rpm for warm is a large part away from idle for an engine that is rated to perhaps only 2800. Idle is nearer 700 and sounds like a bag of spanners. 1200 for instance is not idle, it’s 1200 rpm. Idle was avoided for very specific reasons.

Carryfast:
For the umpteenth time engine speed is independent of load you said warm it up under load not idle.I’ve clearly said and continue to say warm it up using ‘idle’ ‘high’ idle being idle not load.

This is a misrepresentation. No one stated or defined the relationship of engine speed and load. With reference to Diesel engines I pointed out the risks of idling. I further cited two elements where the risks of idle can be mitigated. Both increased revolutions and running Diesel engines at light load. Both are accepted findings. I did not ever attempt to explore the relationship. This is a fundemental misunderstanding on your part.

Carryfast:
On that note I’d guess that this argument if anything will make people start to think what the warm it up using ‘load’,as opposed to ‘idle’ mantra is doing to DPF’s let alone EGR systems and let alone the long term life of engines.

I cant really assist as you appear to be mired in misunderstanding with the information before you. It’s pretty simple. I’ll say it again. Idling diesels can lead to to risk of wet stacking, glazing and bore scoring. Combustion is sub optimal at idle. I have pointed out two factors with supporting explanations. Increased revelations improves the combustion process. Diesels combustion is also far more effective under light load.

These two salient points are commonly understood. I have indicated this and also indicated methods where manufacturers have employed either, or both methods within their engines and/or guidance.

264

^^^^^^ Not quoting that lot :smiley:

A diesel under light load is more efficient and will warm up quicker than if left at idle, this is also where engine oil deteriorates far quicker with engine breathers filling the crankcase with moisture. Reasons i always pull away after starting, its easy to get up to speed under a light throttle, i just keep the revs under 1200rpm…

265

This topic is absolutely riveting… :unamused: :stuck_out_tongue:

266

AndrewG:
^^^^^^ Not quoting that lot :smiley:

A diesel under light load is more efficient and will warm up quicker than if left at idle, this is also where engine oil deteriorates far quicker with engine breathers filling the crankcase with moisture. Reasons i always pull away after starting, its easy to get up to speed under a light throttle, i just keep the revs under 1200rpm…

We’ll both have incoming mail now :laughing: . Brace yerself :smiley: .

Ive honestly tried to get my head around CF’s model of what’s been said.

In the first part of the chat all I pointed out was a lot of manuals say use to avoid idling to warm and that some promote the use of light load. Thinking of idling maladies I also recalled aircraft piston engines aren’t warmed up at idle. That caused a minor chaos. Crucially I also said it’s best to follow the operators manual for any car or lorry.

When the yacking progressed to the meat and potatoes of diesel ailments, I mentioned increased revs apart from use of light load also help a nice Diesel combustion. It went south from therein. Mind blown and springs everywhere :laughing:

I think this is what’s happened anyway.

267

switchlogic:
This topic is absolutely riveting… :unamused: :stuck_out_tongue:

Shame you were forced to click and read it :laughing: . So many other threads to read, shame you got stuck here :stuck_out_tongue: :wink:

To be fair this yacking is good fun but I feel the need to read something easy like a good roadside grub thread. :smiley:

268

Freight Dog:

switchlogic:
This topic is absolutely riveting… :unamused: :stuck_out_tongue:

Shame you were forced to click and read it :laughing: . So many other threads to read, shame you got stuck here :stuck_out_tongue: :wink:

To be fair this yacking is good fun but I feel the need to read something easy like a good roadside grub thread. :smiley:

I’m so sorry, are jokes not allowed now?

269

I myself was guilty of using the term idle at first, when I actually meant high idle, I’m sure I corrected that mistake quite early on in the thread. It does make a huge difference.

Sent from my SM-G930W8 using Tapatalk

270

switchlogic:

Freight Dog:

switchlogic:
This topic is absolutely riveting… :unamused: :stuck_out_tongue:

Shame you were forced to click and read it :laughing: . So many other threads to read, shame you got stuck here :stuck_out_tongue: :wink:

To be fair this yacking is good fun but I feel the need to read something easy like a good roadside grub thread. :smiley:

I’m so sorry, are jokes not allowed now?

Yeah course, why’d you think that? I was only kidding. I’m not down with the kids but I thought chucking in a few smileys gave that impression. Sorry if it didn’t. Maybe the wrong smiley faces. I’ll try again :laughing: :wink:

271

Freight Dog:

switchlogic:

Freight Dog:

switchlogic:
This topic is absolutely riveting… :unamused: :stuck_out_tongue:

Shame you were forced to click and read it :laughing: . So many other threads to read, shame you got stuck here :stuck_out_tongue: :wink:

To be fair this yacking is good fun but I feel the need to read something easy like a good roadside grub thread. :smiley:

I’m so sorry, are jokes not allowed now?

Yeah course, why’d you think that? I was only kidding. I’m not down with the kids but I thought chucking in a few smileys gave that impression. Sorry if it didn’t. Maybe the wrong smiley faces. I’ll try again :laughing: :wink:

God bless

272

Freight Dog:

Carryfast:
You’ve clearly said and continue to say that warming up an engine under ‘load’ is superior to idle.

I cited 2 scenarios where combustion is improved in a Diesel engine away from the risks of idle. Both increasing revs and light load.

Carryfast:
Seemingly because you can’t get your head around the fact that it’s the cold cylinder temperatures which wreck combustion process nothing to do with whether the thing is under load or idle.

This is fundamentally a misunderstanding of what has been said.

Diesel engines at idle ingest a quantity of air indepedant of the fuel injected. I have said this previously, but to recap - a diesel engine will suffer wet stacking through poor combustion if the intake air is cold enough and the fuel required for power is insufficient to maintain combustion chamber temperature.

It is accepted knowledge that a desirable condition of operating a diesel engine at light loads is the maintenance of combustion chamber temps adequate enough to support full combustion. It has been found that at both speeds above idle and under load full combustion is supported due to mechanical mixing of the air/fuel mixture, greater chamber turbulence and greater injection rate.

I have also pointed out that further to improved combustion the tendency for wet stacking (bore wash) is therefore negated by higher engine revelations and/or operating under load. This is also accepted knowledge.

Carryfast:
While applying load to a cold engine and therefore massively increasing the fuelling just massively adds to the combustion problems caused by the cold engine.

This is not true. See above reasons. Diesel Combustion is poor at idle. It is accepted that both increased engine speed and load have a positive effect on diesel combustion. The former through increased fuel injection rate and mechanical mixing. It is known that the likelood of fuel particle impingement on the cyclinder wall is greatly reduced at both speeds above idle, and conditions of load due to effective combustion. The associated risk of wet stacking, glazing and bore scoring are reduced compared to the poor combustion associated with idle conditions.

Carryfast:
The Lancaster example clearly showed it being warmed up at high idle not under load.

“High idle” seems to have been a subjective term you inserted after the fact. At the point of conversation regarding idling, I stated that we don’t warm piston aircraft engines at idle. It was a simple assertion and correct. The Lancaster is warmed at “warm up power”. On other piston aircraft engines for instance 1200 rpm for warm is a large part away from idle for an engine that is rated to perhaps only 2800. Idle is nearer 700 and sounds like a bag of spanners. 1200 for instance is not idle, it’s 1200 rpm. Idle was avoided for very specific reasons.

Carryfast:
For the umpteenth time engine speed is independent of load you said warm it up under load not idle.I’ve clearly said and continue to say warm it up using ‘idle’ ‘high’ idle being idle not load.

This is a misrepresentation. No one stated or defined the relationship of engine speed and load. With reference to Diesel engines I pointed out the risks of idling. I further cited two elements where the risks of idle can be mitigated. Both increased revolutions and running Diesel engines at light load. Both are accepted findings. I did not ever attempt to explore the relationship. This is a fundemental misunderstanding on your part.

Carryfast:
On that note I’d guess that this argument if anything will make people start to think what the warm it up using ‘load’,as opposed to ‘idle’ mantra is doing to DPF’s let alone EGR systems and let alone the long term life of engines.

I cant really assist as you appear to be mired in misunderstanding with the information before you. It’s pretty simple. I’ll say it again. Idling diesels can lead to to risk of wet stacking, glazing and bore scoring. Combustion is sub optimal at idle. I have pointed out two factors with supporting explanations. Increased revelations improves the combustion process. Diesels combustion is also far more effective under light load.

These two salient points are commonly understood. I have indicated this and also indicated methods where manufacturers have employed either, or both methods within their engines and/or guidance.

Wouldn’t you say that applying just enough load to rock the cab fits the description of ‘light’ load ?.

How are you going to accelerate a loaded truck up to motorway speeds even at that type of minimal load.

You did see the amount of unburnt fuel just that tiny bit of load applied to a cold engine created ?.

You’re not ‘maintaining’ any temperature at all in this case it’s just a choice of ‘how’ you ‘warm up’ the same ‘cold’ engine.

I didn’t need to define the ‘difference’ between engine speed v load because it’s a very simple fact.As shown by the fuel map which I posted.Engine speed being one side of the graph engine load being a totally different side of it.The resulting relative fuelling requirements v the cold cylinder temperature being the problem,at least if we’re worried about unburnt fuel washing the oil of the bores and soot contaminating what oil is left.Nothing whatsoever to do with any so called bs related to combustion supposedly being better/cleaner in a cold engine under load because,just like at idle,clean combustion in a cold diesel engine is mutually exclusive.Which just leaves the question how much diesel do want to chuck into it while the thing is warming up enough to a high enough cylinder temperature to support decent combustion.That having nothing to do with intake air temperature.Applying load actually creating the worst of all worlds situation of loads of fuel having to be chucked into the cold cylinders and unable to be burnt correctly just as shown in the video.Which is why nmm’s CAT will burn cleanly at -25 degrees or even less intake air temp ‘when’ the engine is warm.But try accelerating 65t or even 44t up to 65 mph or even 56 mph straight from cold then watch it smoke like a zb and possibly sound like a bag of bolts while its doing it.In which case I guess that he’d rather employ me to drive it than you or Rjan let alone Biking. :unamused:

273

Quite a tangle :laughing: . I can’t decipher most of that. I see you frequently mentioned your load/engine speed thing again. You lost me on rocking cabs. I think you’ve got the wrong end of the stick on some things and that makes it quite hard to discuss your responses when based on incorrect interpetation.

I’ll just say again like a stuck record in case some darts hit the spot. It’s pretty basic. Idling a diesel is bad crab for combustion. Increasing load on a diesel promotes better combustion. Increasing engine speed on a diesel, also promotes better combustion. I can’t see any point in going over again why combustion is improved. The pieces of background information are pretty much accepted. If you still disagree on the why, there’s not a lot I can do about that.

As an engine manufacturer, they play around with it as they see fit. Some engines use an automatic feature to increase the revs after start and some engine handbooks urge you to put the engine under load to warm it. Sometimes an engine has both. Automatic increased revs after start, and a line urging you to drive under load after start. Quite often it’s unhelpfully left to the user to work out what that means. In some manuals, a more detailed explanation is given.

Bit of related guff

logcom.marines.mil/Portals/1 … acking.doc

274

Freight Dog:
Quite a tangle :laughing: . I can’t decipher most of that. I see you frequently mentioned your load/engine speed thing again. You lost me on rocking cabs. I think you’ve got the wrong end of the stick on some things and that makes it quite hard to discuss your responses when based on incorrect interpetation.

I’ll just say again like a stuck record in case some darts hit the spot. It’s pretty basic. Idling a diesel is bad crab for combustion. Increasing load on a diesel promotes better combustion. Increasing engine speed on a diesel, also promotes better combustion. I can’t see any point in going over again why combustion is improved. The pieces of background information are pretty much accepted. If you still disagree on the why, there’s not a lot I can do about that.

As an engine manufacturer, they play around with it as they see fit. Some engines use an automatic feature to increase the revs after start and some engine handbooks urge you to put the engine under load to warm it. Sometimes an engine has both. Automatic increased revs after start, and a line urging you to drive under load after start. Quite often it’s unhelpfully left to the user to work out what that means. In some manuals, a more detailed explanation is given.

The rocking cab when he kicked the accelerator and resulting smoke was a perfect example of the difference between idle v load applied to a cold diesel engine.IE massive over fuelling based on the fact that the cylinder temperatures were too cold to sustain decent clean combustion.By your logic you’re saying lets apply even more load and thereby throw in even more fuel by accelerating a loaded truck with the same cold engine.

All based on the erroneous premise that the combustion issue is the result of insufficient load as opposed to the insufficient cylinder temperature.So let’s apply even more load thereby resulting in even more unburnt fuel. :unamused: As I said the stupidity of all this being hidden by modern day emissions crap.While the DPF suppliers and main dealerships are laughing all the way to the bank fixing all the resulting damage.When as anyone with any old school experience knows if you high idle the engine for a while the cylinders will eventually warm up enough to allow decent combustion.That’s even without getting involved in all the other variables referred to. :unamused:

275

Carryfast:
How are you going to accelerate a loaded truck up to motorway speeds even at that type of minimal load.

You’re not going right out onto the motorway though! Only in your imagination does every driver - or even an appreciable minority of drivers on an appreciable number of mornings - start their working day by turning the key, planting their foot to the floor, and keeping it there firmly until they reach their destination.

Only moderate throttle is required to move around at lower speeds, even fully loaded, and after a minute or two the issue of the engine being cold has disappeared.

You did see the amount of unburnt fuel just that tiny bit of load applied to a cold engine created ?.

You’re on shaky ground indeed if the best you can do is post some visual anecdote about a smoky engine as proof that any appreciable use of an engine whilst cold is seriously harmful for its health.

276

Rjan:

Carryfast:
How are you going to accelerate a loaded truck up to motorway speeds even at that type of minimal load.

You’re not going right out onto the motorway though! Only in your imagination does every driver - or even an appreciable minority of drivers on an appreciable number of mornings - start their working day by turning the key, planting their foot to the floor, and keeping it there firmly until they reach their destination.

Only moderate throttle is required to move around at lower speeds, even fully loaded, and after a minute or two the issue of the engine being cold has disappeared.

You did see the amount of unburnt fuel just that tiny bit of load applied to a cold engine created ?.

You’re on shaky ground indeed if the best you can do is post some visual anecdote about a smoky engine as proof that any appreciable use of an engine whilst cold is seriously harmful for its health.

^^^
A lot of perceived smoke will be just water vapour…

277

Carryfast:
By your logic you’re saying lets apply even more load and thereby throw in even more fuel by accelerating a loaded truck with the same cold engine.

It’s not logic you’re using. Where did I state that?

I pointed out that it is well known diesel combustion is poor at idle. I pointed out TWO well established key factors where combustion is improved.

1/Increased engine speed.

2/ Running a diesel under load

Where did I say you have to apply more load than that video?? Where did I say that increasing revs alone doesn’t improve combustion? Where did I say it has to be increased load? Where did I say about rocking cabs? Where did I explore what load is?

I have said that manufacturers seem to use 1 or indeed both the above in their guidance. Go away and read it all again and come back.

Carryfast:
All based on the erroneous premise that the combustion issue is the result of insufficient load as opposed to the insufficient cylinder temperature.

Where exactly did I say “combustion issue is the result of insufficient load as opposed to insufficient cylinder temp”? Please do quote me.

I said, combustion is improved under load. I also said it improves under increasing revs, but you left that bit out. I gave reasons why they both improved combustion. But I think you failed to read that part…

1/ I stated this of increasing revs:-

“an engine will normally operate at a somewhat higher temperature at higher engine speeds than at low idle because of the added fuel requirement. Atomisation of fuel improves at higher revs…”

Now see the bit about higher temps? Are are we still struggling? Now moving along :laughing: .

2/ I stated this about running under load:-

“operating Diesel engines at light loads maintains combustion temperatures adequate to support full combustion. The temperature is influenced by engine design such as compression ratio and environment like intake temp”

See again the bit about combustion temps? By the way if you don’t like the phrase “maintains” that phrase was also used in a study discussing diesel combustion so take it up with that :smiley:

278

CF. So now that’s cleared up, what are you proposing as a good working practice to warm a diesel then? I take it you now agree idling a diesel presents challenges. So are you an increased revs man then? Good. That’s one of the two points I raised. Like I said, some manufacturers do employ that in their engine mapping.

Personally, I’ve always said follow the book as some of it maybe automated for you, such as engine revs, my car does it after start. Revs for 1200 for a bit, Book wants you to drive away after start (you have to wait for the drop to engage reverse). It’s not a diesel though so it’ll be for different reasons.

279

Rjan:
You’re on shaky ground indeed if the best you can do is post some visual anecdote about a smoky engine as proof that any appreciable use of an engine whilst cold is seriously harmful for its health.

No the perfect ground of a truck without any emissions crap hiding the truth and which shows the idiocy of the eco warriors in thinking that applying load to a cold diesel engine is supposedly cleaner/better than letting it warm up at idle.Bearing in mind that the let’s drive off when it’s cold lot don’t even seem to understand the difference between idle v load. :unamused:

280

Freight Dog:

Carryfast:
By your logic you’re saying lets apply even more load and thereby throw in even more fuel by accelerating a loaded truck with the same cold engine.

It’s not logic you’re using. Where did I state that?

I pointed out that it is well known diesel combustion is poor at idle. I pointed out TWO well established key factors where combustion is improved.

1/Increased engine speed.

2/ Running a diesel under load

Where did I say you have to apply more load than that video?? Where did I say that increasing revs alone doesn’t improve combustion? Where did I say it has to be increased load? Where did I say about rocking cabs? Where did I explore what load is?

I have said that manufacturers seem to use 1 or indeed both the above in their guidance. Go away and read it all again and come back.

Carryfast:
All based on the erroneous premise that the combustion issue is the result of insufficient load as opposed to the insufficient cylinder temperature.

Where exactly did I say “combustion issue is the result of insufficient load as opposed to insufficient cylinder temp”? Please do quote me.

I said, combustion is improved under load. I also said it improves under increasing revs, but you left that bit out. I gave reasons why they both improved combustion. But I think you failed to read that part…

1/ I stated this of increasing revs:-

“an engine will normally operate at a somewhat higher temperature at higher engine speeds than at low idle because of the added fuel requirement. Atomisation of fuel improves at higher revs…”

Now see the bit about higher temps? Are are we still struggling? Now moving along :laughing: .

2/ I stated this about running under load:-

“operating Diesel engines at light loads maintains combustion temperatures adequate to support full combustion. The temperature is influenced by engine design such as compression ratio and environment like intake temp”

See again the bit about combustion temps? By the way if you don’t like the phrase “maintains” that phrase was also used in a study discussing diesel combustion so take it up with that :smiley:

For the umpteenth time you can’t ‘improve’ the ■■■■■■■■■■ of a cold diesel engine.It’s the same whether it’s idling or under load.IE total zb in either case and the more fuel the worse it is.You can only wait until the cylinders warm up before chucking in all the extra fuelling requirement associated with ‘load’.But it’s obvious that you can’t get your head around the difference between engine speed v engine load.That’s also ignoring all the other potential ‘issues’ of applying load to a cold engine.As I said the stupidity of all this eco bollox and steering wheel attendant ignorance is all being hidden,at great cost,by modern day emissions crap.Remove it and the resulting smoke trails,caused by diesels being driven off from cold,would make them think again.