Oil jet piston cooling (just marketing hype?)

[djones]

I was reading some really interesting facts about the 1998 Honda Integra Type-R and couldn't help but think a lot of it was marketing.

Things like:

"To help ensure long-term durability and reliability, the Type R engine uses an oil jet cooling system. A jet of pressurized engine oil is directed to the underside of the piston to help dissipate the extreme heat generated during sustained high rpm operation. This technology has proven itself in Formula One and other top-level racing engines."

http://www.itrsport.com/technical.html

It sounds really impressive but is that anything special or does pretty much every engine have that?

[DaveKillens]

This procedure is common, and been around for a long time. Honda didn't invent it, they just hype it. You can find this application on anything from lawn mower engines to heavy duty diesels to aircraft engines.
All is required is an oil passage inside the connecting rod and an oil nozzle at the end. An oil cooler is supplimental and recommended. And the principle is simple, to use oil to cool one of the engine components that is of aluminum and hard to cool.

[Belatti]

I don´t know exactly the origin of that technology, but is commonly applied in heavy duty turbo-diesel engines and is not a new technology. As I recall in was known in the 80´s (and maybe before, too). In HD diesels it was needed when direct injection high boost turbos were introduced massively, to cool down piston crown: Without oil cooling internal gallery this is what happens:


At 340 C° engine oil would be carbon!

So this is the solution:


(Light vehicle diesel example)

This is the difference:



And this is how it works:



Also I would like to tell you how the hell do you manufacture such an internal complicated geometry: salt!
You have to "bake" under big pressure some salt grains to conform a solid mould that will be introduced into the piston casting dies. Then you fill with liquid aluminum (+720°c) you let it all cool down, you take the "gross" piston and with hot water you dissolve the salt till oil gallery is salt empty. Then you just apply the commonly known processes (thermal and surface tratments, machining, etc)
and vuala!

[checkered]

Also I would like to tell you how the hell do you manufacture such an internal complicated geometry: salt!

Good thinking Belatti, you

anticipated my emerging question! The manufacturing process sounds quite energy intensive, though. I'm just wondering how that compares to any savings in fuel economy/engine durability vs. more "primitive" engines. (Naturally, I'm kinda hoping it's not a zero sum game, or worse.) This as I've come to wonder generally about the attention paid to the energy consumed in manufacturing/recycling a vehicle vs. its operating energy expenditures.

[DaveKillens]

Thank you Belatti, I was not aware of running cooling passages inside of the piston. New casting technology must make this feasible.

[Belatti]

Good thinking Belatti, you

anticipated my emerging question! The manufacturing process sounds quite energy intensive, though. I'm just wondering how that compares to any savings in fuel economy/engine durability vs. more "primitive" engines. (Naturally, I'm kinda hoping it's not a zero sum game, or worse.) This as I've come to wonder generally about the attention paid to the energy consumed in manufacturing/recycling a vehicle vs. its operating energy expenditures.

Well, "direct" savings in fuel are usually because lighter pistons or a decrease in friction (both due to materials developments)
Here you can see the fatigue strenght evolution through years that made posible mass reductions:



Then, other "indirect" savings come when engine performance is increased by adoption of new technologies. With the raise in combustion chamber pressures you must adopt the cooling gallery, all that justo to get a better HP/liter ratio plus durability.



To make a proper energy balance between fuel savings vs. "cooled pistons" production energy increase, you must consider energy used to extract and transport the salt, the machine that manufactures the mould, the machine that dissolve the salt once the piston is casted and (as salted water is considered industrial waste) the energy to build and maintain a wastewater treatment plant.
Thats a hard job to do. Anyway, the market is moved by money and energy efficience is not considered as a whole. After all, many new jobs were given with the implementation of such thing.

One more technical aspect I forgot to mention: you can only have galleries in die casted pistons. In racing (thus forged) pistons oil is just directed to the underside of the piston, as djones said.

[checkered]

All very interesting, now

isn't it? These are just the sorts of considerations I was thinking about. Ideally, savings in energy will also get corporations a competitive advantage, hopefully also reflecting in consumer prices. See, saving the environment is profitable! I guess with this, it is like with most things - the good news and the bad news are one and the same:

"There's a lot of work to be done."

[Fiero Brick]

All is required is an oil passage inside the connecting rod and an oil nozzle at the end.

GM does this via an oil squirter mechanism near the bottom of the cylinder with a little J-shaped tube to direct the oil without interfering with the piston. On their gasoline engines. I suppose each would have its own advantages for difference engines.