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Diesel engines, then and now

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Diesel engines, then and now

Old 10th May 2021, 21:23
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Diesel engines, then and now

I was watching some video of diesel hauled trains on YT recently and was struck by how much visible pollution they were throwing up into the air. Contrast that with modern diesel cars which were, not so long ago, promoted as better for the environment than petrol. Unbelievable! But visibly less polluting than diesel locos.

Just a few years ago diesel trucks used to surround themselves with a smoke screen when started on cold mornings. When I were a lad I understand that diesel trucks used a decompression system to make them easier for the electric starter to crank them over and, once churning at some speed, the compression was re-enabled and the engine would crawl into life. Cue loads of smoke. This all took a good number of seconds on the starter button, a lot longer than required to kick a petrol engine into life. They must have had good batteries in those days.

And then I came across
YT video of a class 50 railway loco engine start on a cold day. It is cranking over from the start of the video and it is about 4 minutes in before the engine might be self sustaining although exactly when it takes over from the electric starter is unclear. Just look at the clouds of clagg and even some flames coming from the exhaust. Impressive battery performance, again.

A sobering detail though, the Class 50 loco had a 246 litre engine developing 2700 Hp (11 hp per litre), my car has a 2 litre petrol engine developing 150 hp (75 hp per litre) or about 6.5 times as much and with much less smoke.

Rans6.............

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Old 10th May 2021, 21:53
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One thing with diesel (compression ignition) engines that is not universally understood is that it is not just compression that allows the injected fuel to burn but that in compressing the air in the cylinder(s) it is heated to a temperature above the ignition point of the diesel fuel.

Unfortunately, when cranking a cold engine in arctic conditions a lot of heat is lost initially through transfer to the cold cylinder walls and the lower surface of the cylinder head.
It is only when the engine has cranked long enough to heat the cylinder walls and reduce the heat transfer that ignition will occur.

Alternatively, a starting aid might be incorporated in the design such as ether injection or electrical pre-heaters.
We didn't need ether on E-E 16CSVT's in Oz but looking at the flame coming out of the muffler on your Class 50 I suspect that ether might be the reason.

Charles' Law

Boyle's Law

Sorry, I couldn't find one for the Combined Gas Law

But just for comparison, a Cummins QSK60 (60 litre engine) is now rated at up to 2850 BHP and complies with Euro Stage V
From new to first overhaul these engines will consume 4.2 million litres of diesel fuel plus a couple of buckets of AdBlue.
That equates to about three years in a mining truck.
What a difference 50-60 years makes.

Last edited by WingNut60; 10th May 2021 at 22:22.
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Old 10th May 2021, 22:47
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Leave the locos alone.

Want to draw attention to something - take a look at tractor pulling contests or burn-out contests, particularly those with diesel powered equipment.
Spectacular emissions and completely pointless....
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Old 10th May 2021, 23:53
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Paxman Diesels was a major employer in Colchester.

Where did it all go?

I'd never owned and rarely driven diesel until I owned a BMW six series. The twin turbo was a thing to behold. Really miss it, and the economy.
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Old 11th May 2021, 00:14
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Back in the mid 90's I did my Army service running a refueling rig for a Nordic brigade of the Swedish Army. Halfway through someone came up with the great idea of swapping out the 2 stroke pumps we used for a diesel variant, big spiel that the fancy new pump even comes with an electric starter motor so no more need for hand starting it.
Shame the boffin that came up with the idea forgot that all the NATO leads on the rigs had been disabled due to the risk of sparks when plugging things in. Lots of "fun" were had trying to hand start those darn diesel pumps in the cold and dark of a Swedish winter.
From memory they had a mechanical lifter that limited compression and allowed you to turn the motor over, lifter closed after a few revolutions. If you had managed to yank hard enough on the starter rope there was just enough inertia for one stroke with compression.
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Old 11th May 2021, 00:18
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Old British motorbikes had valve lifters. In some cases, a little valve that had to be ground in.
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Old 11th May 2021, 01:24
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Originally Posted by rans6andrew View Post
I was watching some video of diesel hauled trains on YT recently and was struck by how much visible pollution they were throwing up into the air. Contrast that with modern diesel cars which were, not so long ago, promoted as better for the environment than petrol. Unbelievable! But visibly less polluting than diesel locos.

Just a few years ago diesel trucks used to surround themselves with a smoke screen when started on cold mornings. When I were a lad I understand that diesel trucks used a decompression system to make them easier for the electric starter to crank them over and, once churning at some speed, the compression was re-enabled and the engine would crawl into life. Cue loads of smoke. This all took a good number of seconds on the starter button, a lot longer than required to kick a petrol engine into life. They must have had good batteries in those days.

And then I came across THIS YT video of a class 50 railway loco engine start on a cold day. It is cranking over from the start of the video and it is about 4 minutes in before the engine might be self sustaining although exactly when it takes over from the electric starter is unclear. Just look at the clouds of clagg and even some flames coming from the exhaust. Impressive battery performance, again.

A sobering detail though, the Class 50 loco had a 246 litre engine developing 2700 Hp (11 hp per litre), my car has a 2 litre petrol engine developing 150 hp (75 hp per litre) or about 6.5 times as much and with much less smoke.

Rans6.............
It isn't just horsepower, torque counts for a lot when hauling stuff or, in the case of diesel locomotives, generating electricity.
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Old 11th May 2021, 02:18
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Torque and rpm are analogous to amps and volts. You need both to make power in watts.
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Old 11th May 2021, 02:26
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Serious visual diesel exhaust emissions are much more rare than they used to be where I live and move; most probably due to improved technology and probably under pressure of more stringent compliance requirements. The last grain harvester I owned used to throw a huge if short burst of serious black smoke upon startup, due, (as I discovered) that the injector pump had to be - and was - set internally at full throttle for the initial turn over. After that, the exhaust stream it was almost invisible. It used to give me a serious fright at times because as this black cloud drifted through the field of the rear vision mirrors, my immediate reactor was "Hell! A bushfire in this paddock or the next one .. ! ". Happily that never happened.
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Old 11th May 2021, 05:58
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It physically hurts to see and listen to a loco diesel being cold started. At sea we would not consider starting a diesel engine that had not been preheated and I always had heaters installed in my diesel engined cars as well.
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Old 11th May 2021, 06:29
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Drove a dumper in the 60s during East Anglian winters....now that was a challenge to swing the starting handle fast enough. No easy start in those days.
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Old 11th May 2021, 07:08
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Originally Posted by Loose rivets View Post
Old British motorbikes had valve lifters. In some cases, a little valve that had to be ground in.
Yes, my Royal Enfield is kickstart only and it has a separate decompressor valve. I use it every time I start the bike. This model was still in production up to 2007.

In my youth (almost half a century ago!) I worked for a building company as a labourer. Part of my job on one site was to drive a dump truck which had a single cylinder Diesel engine. It was hand start only. One had to open the exhaust valve lifter, using a lever on the cylinder head, crank the engine over on the starting handle and then flick the valve lifter lever back when you had got the revs up high enough for it to go over compression. If you got it wrong it could kick back like a mule and was quite capable of breaking your wrist or fingers. The truck always lived outside. I worked through two winters and when it was very cold and the engine oil was thick it was especially hard work cranking the engine over, especially for the first start of the day.
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Old 11th May 2021, 07:49
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" If you got it wrong it could kick back like a mule and was quite capable of breaking your wrist or fingers "

Before modernisation arrived, as in electricity and other useful forms of starting, the RAF had several pieces of vintage ground equip designed with just this in mind.

Notably the Hyd test rig / the cabin px test rig, and, everybody's favourite as it combined all of the above, plus the option to get squashed and cause carnage all around, the infamous two lumps of concrete with an engine on top used for towing. Met several engineers who proved your suggestion above worked perfectly !
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Old 11th May 2021, 07:59
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Originally Posted by Krystal n chips View Post
" If you got it wrong it could kick back like a mule and was quite capable of breaking your wrist or fingers "

Before modernisation arrived, as in electricity and other useful forms of starting, the RAF had several pieces of vintage ground equip designed with just this in mind.

Notably the Hyd test rig / the cabin px test rig, and, everybody's favourite as it combined all of the above, plus the option to get squashed and cause carnage all around, the infamous two lumps of concrete with an engine on top used for towing. Met several engineers who proved your suggestion above worked perfectly !
Ah yes the 'Yellow Peril',usually started by filling the priming pot with oil and then swinging it hopefully without breaking fingers etc.
There was the famous patched hole in a Hangar roof at Brawdy caused by a 'Yellow Peril' cyl head exiting the hangar through the roof after some bright spark primed the pot with AVPIN instead of the more usual engine oil.
The Hyd Test rig was not too bad to start as long as one locked the throttle to idle,although the handle was unpleasantly close to ones teeth if it slipped out of the 'dog'.
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Old 11th May 2021, 08:18
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Had a VOR 400 enduro until 3 years ago; forward kick start with a valve lifter as the compression was so high that I couldn’t turn in through TDC without inertia. Had to wear motocross boots to start it as if it back fired it would either break your ankle or get you airborne. Not unlike the Panther my dad had.
Now have the luxury of electric start and 175bhp along with sophisticated computer that stops me looping.
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Old 11th May 2021, 09:09
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Thanks LR, that is the best and most concise illustration I have seen.
Many years ago, I was frustrated by a statement that "hill climbing ability is a function of torque, not power". True, in that with lots of torque but little power you will eventually get up the hill.. But for hill climbing performance, you need power.
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Old 11th May 2021, 09:13
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Once had a vehicle with a Perkins diesel.
The starting device was a thing which allowed
fuel into the inlet manifold, where there was a small
electric element. Press the button for a while, then start.
A small fire is started in the manifold, and sucked into
the engine which bursts into life. Filled the airport car park with
white smoke once.
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Old 11th May 2021, 09:14
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Originally Posted by rans6andrew View Post
I was watching some video of diesel hauled trains on YT recently and was struck by how much visible pollution they were throwing up into the air...........Just a few years ago diesel trucks used to surround themselves with a smoke screen when started on cold mornings......Just look at the clouds of clagg and even some flames coming from the exhaust. Impressive battery performance, again.

A sobering detail though, the Class 50 loco had a 246 litre engine developing 2700 Hp (11 hp per litre), my car has a 2 litre petrol engine developing 150 hp (75 hp per litre) or about 6.5 times as much and with much less smoke.

Rans6.............
Yes, but how much torque does the train engine produce and at what revs does it achieve it ? Ship engines run even more slowly, yet produce squillions of torque.

Cars and vans do produce lots of Diesel smoke sometimes - I see them while driving.

Lack of visible smoke does not mean that an engine is not producing pollution ! Lots of nasties are colourless and odourless. e.g. Carbon Monoxide, Carbon Dioxide.
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Old 11th May 2021, 09:43
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Originally Posted by esa-aardvark View Post
Once had a vehicle with a Perkins diesel.
The starting device was a thing which allowed
fuel into the inlet manifold, where there was a small
electric element. Press the button for a while, then start.
A small fire is started in the manifold, and sucked into
the engine which bursts into life. Filled the airport car park with
white smoke once.
You just reminded me of being on a gliding course 'somewhere in yorkshire' in the winter of 1969/70,the GC had a Fergie Diesel Traccor,the cold start device had been disabled as I believe people had tended to leave it 'on',there was just the cold start push button on the inj pump for enriching the mixture.Our course instructor who had just left the RAF (Radio Tech ?) came up with the idea of a lighted 'torch' held near the air intake,after setting the air inlet trunking on fire we retired a few yards and threw snowballs at it to extinguish the fire
I guess we got it started somehow eventually
Although I had already left school - I had been invited on this school trip to make up the numbers LOL,we travelled from Peterborough -ish up to Thirsk in a J4 diesel van - no seats or anything in the back of course .
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Old 11th May 2021, 10:01
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Originally Posted by ShyTorque View Post
Part of my job on one site was to drive a dump truck which had a single cylinder Diesel engine. It was hand start only. One had to open the exhaust valve lifter, using a lever on the cylinder head, crank the engine over on the starting handle and then flick the valve lifter lever back when you had got the revs up high enough for it to go over compression. If you got it wrong it could kick back like a mule and was quite capable of breaking your wrist or fingers. .
Similarly, National Diesel canal boat engines were two-cylinder jobs with an exhaust-valve lifter. You wound it up to as many r.p.m. as you could and the rotating inertia of the heavy flywheel would take it over at least two compressions when you flicked the lever.
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