Diesel engine pistons!

RINGER

RINGER

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Hi.

Sorry, I am a sceptic by nature.

A claimed 25% reduction in fuel consumption cuncurrent with a 5% increase in torque and horsepower.

Sounds to good to be true.

But interesting nevertheless. A *typical diesel truck engine is approximately 45% efficient in terms of converting the energy in the fuel to power out the flywheel. So any gains that are claimed by the SoA technology will need to come from the 55% of fuel energy that is currently wasted, mostly as heat.

Therefore a 25% fuel reduction plus a 5% power increase, 25 x 5 = 26.25%.
Therefore 26.25% of 55% is 14.43% which is the gain needed to result in less heat generated by the engine fitted with the SoA pistons.
SoA technologies are making the claim, not me, but it seems to be a lot of gain to my sceptical mind.

* https://en.wikipedia.org/wiki/Diesel_engine

Cheers.
 
I absorbed this article with a similar take, initially ~ BUT ~ on investigation & interpretation it seems like a better air fuel mix thus more complete & even fuel burn especially closer to the colder cylinder walls [mentioned] is meant to be taking place. Especially relevant to all & any CI engines.
It's not beyond the realms of possibility this slight move away from 'what's considered normal' can have such consequences.
 
I suspect it's about swirl and squish in mostly large capacity V engines with simple inlet ports.

The high speed engines we are familiar with in our cars produce a lot of output for their size, and have two ports per cylinder each with a different path, one causing helical motion, to promote even fuel mixing over the firing period from computer controlled injector opening.. The shaped recesses in the piston top combine with swirl to get maximum combustion benefit.
 
PSA's discussion of the improvements in the 2.0L RHH motor over the 2.0L RHR are interesting, as these subtle changes aren't obvious to look at. These were part of passing from Euro IV to Euro V pollution limits.

Torque at 2000 RPM - up 6%
Torque at 1250 RPM - up 10%
Power at 4000 RMP - up 20%

SA measured a 6.3% reduction in consumption when fitted to a C5, and 10.2% fitted to a Picasso. They didn't describe the laboratory "drive" except that for all bodies with the engines it was the same.

The subtlety of the changes can be seen in this diagram.
piston crowm.png

Compression ration was lowered and turbo pressure raised. With the shape changes and more injector holes PSA states there was improvement of combustion on the wall.
 
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Golf ball dimples more swirl better mixing, flogging a dead horse. Well not quite, loving thermodynamics, the diesel max 50% is a pipe dream but the closer you get the better. Electric for me. Where is maggot when you want to castrate something.
 
If diesel engines in cars get too efficient their heaters will never warm the cabin.

People in cold countries will then install diesel heaters, thus cancelling out the engine fuel savings.

Just sayin...
 
Armidillo said:
If diesel engines in cars get too efficient their heaters will never warm the cabin.

People in cold countries will then install diesel heaters, thus cancelling out the engine fuel savings.

Just sayin...
Click to expand...
Hi.

I suspect that diesel heaters would consume significantly less fuel in absolute terms than the 55% of fuel energy that is wasted as heat in a typical diesel truck engine.

So I hope that the SoA claims are true and that the combined three technologies do reduce fuel consumption, as the otto cycle heat engines need all the help they can get.

Cheers.
 
Many years ago, Perkins engines installed a laser doppler anemometer in their R&D department with which they were able to study in real time the combustion processes in their diesel engines via crystal windows. The Perkins Phaser engines were a direct result of these studies, providing much increased horsepower and torque over the preceding 6-354 series of similar displacement, along with a significant reduction in fuel consumption and engine noise. The bulk of these benefits were due to piston crown design. I believe these engines still used mechanical injection.
 
Whippet said:
Hi.

I suspect that diesel heaters would consume significantly less fuel in absolute terms than the 55% of fuel energy that is wasted as heat in a typical diesel truck engine.

So I hope that the SoA claims are true and that the combined three technologies do reduce fuel consumption, as the otto cycle heat engines need all the help they can get.

Cheers.
Click to expand...
I think the cooling system temperature would still be regulated to the same temps as now for consistency in the thermal expansion of critical components? Any reduction in heat wastage would be via the exhaust.
 
Yes, but modern diesels already take a long time to reach operating temperature and open the thermostat, making bleeding a slow process. If they (diesels) get much more efficient, the manufacturers might have to reduce the volume of the cooling system, as it can't be good for engine life if they never reach operating temperature in winter!

What do they do in Russia (apart from old tales of lighting a fire under the sump)?
 
Armidillo said:
Yes, but modern diesels already take a long time to reach operating temperature and open the thermostat,
Click to expand...
A bit off topic I admit, but...
Did Pug 307 diesels have some sort of electric boosting of the interior heater?
We have a 250 m driveway, on a really cold morning, say 5 degrees C, I could start off in the morning really cold, by the time I reached the front gate, I had hot air blowing on the windscreen. I was impressed with that, couldn't believe how fast it heated up.
The car was a 1.6 Hdi 2007 model with the Ugly Betty grille.
 
simca1100 said:
A bit off topic I admit, but...
Did Pug 307 diesels have some sort of electric boosting of the interior heater?
We have a 250 m driveway, on a really cold morning, say 5 degrees C, I could start off in the morning really cold, by the time I reached the front gate, I had hot air blowing on the windscreen. I was impressed with that, couldn't believe how fast it heated up.
The car was a 1.6 Hdi 2007 model with the Ugly Betty grille.
Click to expand...
If it was electric I would say it would be almost instant heat? More likely a 2 stage thermostat where all the initial engine heat generated is directed into a small volume of coolant in the cylinder head and heater.
My son has a diesel Dualis and my daughter a diesel Carnival and they both have good cabin heat available within a couple of minutes of a cold start.
 
From memory, i recall from my MI16 days, that the thermostat when cold introduces a passageway for coolant direct to the heater matrix ,passage to radiator blocked .to assist de frosting in cars operated in cold European climate ,as the coolant worms up the passage to the rad opens up and the shortcut to the heater closes ,somehow the heater stays in the loop but now in the larger loop , including the rad i tried ,removing a thermostat from a BMW my son had [ presumably with a similar system ],as it was faulty but it still overheated, till we replaced it with a new one PS the t stat has two baffles one opens when the other closes !
 
In the diesels the big coolant line at the back of the engine from the water box to the pump has two branches in it - one to the heater and one to the turbocharger. The thermostat valve controls the radiator circuit.
 
Thinks to self: only on Aussiefrogs could the topic stray so far away from Diesel Engine Pistons.......
 
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