Dimpled Pistons: 20%+ better (Diesel) fuel economy!??

[Logic]

Firstly; I don't 'see it', but there seem to be a good number of indipendant tests proving this works. (in Diesel engines)

Some links to get you started:
https://www.carexpert.com.au/car-new...diesel-engines

https://dfcdiesel.com/2023/05/02/how...iesel-engines/

Home Page:
https://www.speedofair.com/

Youtube:
https://www.youtube.com/results?sear...impled+pistons

I have yet to research this properly but for the moment:
IF they work; How and Why??
aerohead??

This seems pretty easy to DIY.

[freebeard]

In another test conducted by Olsen Ecologic Lab in Fullerton, California, a stock Cummins 5.9-liter engine was compared to one with only a set of SoA pistons installed. The report showed a 15.5 percent increase in horsepower and a 15.2 percent increase in torque.

That closing in on 'extraordinary claims' territory.

But it reminds me of drilling holes in the piston top. www.onallcylinders.com: Part 2: Power-Packed Piston Tech You Can Use!

Gas Porting
One exception to vertical clearance is when gas ports are used in the piston. Gas ports provide a means to supply combustion pressure directly to the backside of the piston ring. As a result, ring vertical clearance can be reduced, and simultaneously, ring flutter can also be reduced significantly. Ring seal goes up along with horsepower. Unfortunately, gas ports are only suited for use with engine combinations where frequent teardowns are common. This means gas ports don’t see use in street-driven vehicle applications. Carbon tends to plug the gas port holes and ring and cylinder wall wear is much faster than more conventional setups.

Typically gas ports consist of 12 to 16 0.040 to 0.060-inch holes drilled vertically through the piston deck. They intersect with the backside of the compression ring groove. Gas porting is most advantageous when a narrow face, lightweight piston ring (such as the 0.043-inch ring) is used. MAHLE uses a different setup. They make use of lateral gas ports, consisting of 8 to 12 horizontal holes drilled into the top flank of the top ring groove. This allows combustion gases to the backside of the ring groove. MAHLE notes it can add vertical ports on a custom basis, but it primarily provides lateral gas ports (they’re an option on a select few pistons in their PowerPak lineup).

[Piwoslaw]

[Impatiently waiting to see whether to pull out drill]

[jakobnev]

Reduced oil change intervals by 50%

Hey, that's a bad thing!

[Isaac Zachary]

I don't know if I'd believe those "studies." "NOx reductions saw reductions as high as 80 percent, and the ability to extend oil change intervals jumped by 50 percent due to decreased soot and fuel dilution," and "15.5 percent increase in horsepower and a 15.2 percent increase in torque," seem kind of hard to believe to me.

From what I understand you could benefit from dimples but if only they're put in the right places. Just randomly guessing probably won't help. And there are other geometric changes in a combustion chamber that may help more than just dimples.

The way air, fuel and flame flow through a combustion chamber is quite complex. This is one reason why engines keep getting more efficient, the combustion chamber, piston and intake designs do better and putting air and fuel where they need to be and moving in the direction they need to be. That's a lot harder to do than one would think.

Note that the treatment also includes thermal barrier ceramic coatings, so how much of the extraordinary improvements are the dimples and how much is due to the coatings?

[jakobnev]

Maybe I'm reading the charts wrong, but @2100rpm there was 30%(?) increase in power with 6% improvement in BSFC, which means 23% more fuel was injected. It's not apples to apples and if you don't isolate your variables - you are not doing science!

[freebeard]

Dimples are what you do before you have 5-axis CNC mills.

[Piwoslaw]

So, do we use these improvements from the dimples to efficiently move this thread to the Unicorn Corral?

[aerohead]

Originally Posted by Logic

Firstly; I don't 'see it', but there seem to be a good number of indipendant tests proving this works. (in Diesel engines)

Some links to get you started:
https://www.carexpert.com.au/car-new...diesel-engines

https://dfcdiesel.com/2023/05/02/how...iesel-engines/

Home Page:
https://www.speedofair.com/

Youtube:
https://www.youtube.com/results?sear...impled+pistons

I have yet to research this properly but for the moment:
IF they work; How and Why??
aerohead??

This seems pretty easy to DIY.

I'm not current on Diesels, as I've lost interest in internal combustion, but the last time I looked, the most efficient diesels were in ocean-going cargo ships.
The one reported, was manufactured by HITACHI, of Japan, which ran on bunker fuel, was compound-turbocharged, and operated at a maximum, 130-rpm.
The pistons are as tall as an adult male.
The brake thermal efficiency is 42% ( 58% of the thermal energy is lost ).
The ships can stay at sea for 3-months per 'tank.'
--------------------------------------------------------------------------------------
These engines would have already undergone intense investigation for combustion efficiency, and without exacting specificity, the claims of a 20% improvement in mpg would require third-party laboratories corroborating the same extraordinary evidence.
--------------------------------------------------------------------------------------
My initial reaction to the claim is that it is highly dubious!

[Logic]

Originally Posted by aerohead

I'm not current on Diesels, as I've lost interest in internal combustion, but the last time I looked, the most efficient diesels were in ocean-going cargo ships.
The one reported, was manufactured by HITACHI, of Japan, which ran on bunker fuel, was compound-turbocharged, and operated at a maximum, 130-rpm.
The pistons are as tall as an adult male.
The brake thermal efficiency is 42% ( 58% of the thermal energy is lost ).
The ships can stay at sea for 3-months per 'tank.'
--------------------------------------------------------------------------------------
These engines would have already undergone intense investigation for combustion efficiency, and without exacting specificity, the claims of a 20% improvement in mpg would require third-party laboratories corroborating the same extraordinary evidence.
--------------------------------------------------------------------------------------
My initial reaction to the claim is that it is highly dubious!

Ships also use the waste heat in exhaust ( and cooling system?) to turn steam engines/turbines, greatly increasing the efficiency per liter of fuel burned.

My Initial reaction is the same, but I still haven't researched this much at all.
The ceramic coating on top and low friction coating on the skirts further muddy the results.

I am interested in what you think might happen to the flame front etc when encountering said dimples..?