Ferrari Power Unit Hardware & Software

[PlatinumZealot]

I've professional experience with steel sintered parts in toolmaking industry (for plastic injection moulds components).
The resulting part has approximately 80% of the toughness of the same steel forged, same hardness, can be post-machined where necessary.
Besides what some of you are pointing out about the heat dissipation I see no big problems on using this technology to manufacture pistons for F1 engines.
On the other side, I understood and read on this and other engine related threads that lean combustion leads to lower temperature, lower heat transferred to the cylinder walls, piston crown and head. Correct me if i'm wrong.

Found the article!
Motorcyle pistons though.

http://www.cycleworld.com/2016/03/01/st ... gy-feature

[Tommy Cookers]

.....steel sintered parts in toolmaking industry ......has approximately 80% of the toughness of the same steel forged, same hardness ......see no big problems on using this technology to manufacture pistons for F1 engines.
On the other side, I understood and read on this and other engine related threads that lean combustion leads to lower temperature, lower heat transferred to the cylinder walls, piston crown and head. Correct me if i'm wrong.

good info rgava
fwiw my guess why steel is needed .....
the engine has about the same fuel-heat rate per cylinder as NA F1 but about 50% more heat rate per cycle (the rpm being much less)
so despite the heat dilution from 40? % leaning the temperature will be no lower than usual ie we're still at the stress limit for alloy pistons
(the temperature is of course lower than it would be unleaned, ie afaik proportionately more energy linked to pressurised gas not gas temp)
but by the greater heat rate and greater efficiency the combustion pressure will be higher than usual, ie probably enough to overstress alloy pistons

[godlameroso]

There's also the possibility of using ceramic heat reflective coating on the crown.

Perhaps these problems can be solved, but they are formidable. Large marine Diesel pistons (some are 48-inches in diameter) and their sealing rings are cooled by continuous circulation of liquid coolant through complex passages behind the rings and under the dome. In many cases this liquid is delivered through telescoping pipes. It is hard to imagine such pipes reliably serving a Ducati Panigale’s 112mm pistons during 11,000-rpm operation, and it is not reasonable to imagine taking enough oil for that job from the already hard-working connecting-rod bearing. Therefore the oil would have to be delivered by oil jets and captured by “scuppers” made as part of the piston, then sent to pass through cooling galleries behind the piston rings.

Interesting, maybe that hypothetical thing Wazari was talking about in the Honda engine thread has something to do with this. Maybe they(Honda) are ahead of the curve?

[roon]

There's also the possibility of using ceramic heat reflective coating on the crown.

Perhaps these problems can be solved, but they are formidable. Large marine Diesel pistons (some are 48-inches in diameter) and their sealing rings are cooled by continuous circulation of liquid coolant through complex passages behind the rings and under the dome. In many cases this liquid is delivered through telescoping pipes. It is hard to imagine such pipes reliably serving a Ducati Panigale’s 112mm pistons during 11,000-rpm operation, and it is not reasonable to imagine taking enough oil for that job from the already hard-working connecting-rod bearing. Therefore the oil would have to be delivered by oil jets and captured by “scuppers” made as part of the piston, then sent to pass through cooling galleries behind the piston rings.

Interesting, maybe that hypothetical thing Wazari was talking about in the Honda engine thread has something to do with this. Maybe they(Honda) are ahead of the curve?

With internal channels you could feed oil through the reciprocating components. Crank journal>crank>conrod>gudgeon pin>piston. Maybe this is already done somewhere. Could probably be pulled of with traditional drilling & plugs. Printed parts would offer more internal voids though for more oil capacity.

A supply of oil flowing through the piston would be provide cooling, but I would also consider piping it through an array of small holes on the piston skirts to provide a constant fluid film for the skirts to glide against. Seems like it would be great for minimizing friction. The skirt would never contact the cylinder, and the fresh oil flow would help cool the inner cylinder wall. I understand regular pistons already do this to a degree—oil gets trapped between the piston & cylinder wall for lubrication. But a constant pressurized flow might provide an air-hockey table effect.

[godlameroso]

That's what I said.

[roon]

Cool. Let's file a patent together. Mind covering the lawyer?

[godlameroso]

I'm of the opinion that if I've thought about it, there's at least 100 people smarter than me have already thought about it, and why it wouldn't work because of at least one critical factor I neglected.

Like why hasn't anyone used a Tesla turbine(boundary layer turbine) as a turbocharger turbine.

[roon]

You might be surprised. Define smart.

Tesla turbine seems more voluminous & heavy than a modern centrifugal, bladed turbine. That it works primarily via viscosity seems like a handicap in an automotive application, compared to a rotor deflecting a gas stream, in that requires a lot of working surface area compared to a bladed rotor. You have to divide the gas stream into multiple thin flows to take advantage of viscocity & the coanda effect. I imagine there would be some tradeoffs between getting the disks as thin as possible to keep the package dimensions down, while keeping them durable enough to receive exhaust pulses.

Just my conjecture. In the end it might just be lacking optimization details from being dormant so many decades.

[shady]

Theres nothing to be said of the load you can place on that kind of turbine. However; a thin, light strong, and heat resistant enough material and you could create a lot of surface area with an excessive amount of layers.. seems like a lot of work and research.

[stevesingo]

With the ability to create void spaces within the structure, would it be feasible to use sodium filled voids for cooling similar to exhaust valves?

[gruntguru]

A few thoughts regarding piston crown temperature, heat dissipation etc.
- Gas temperatures are generally lower (due to leaning) although peak values are probably higher due to high peak pressures and rapid combustion near TDC.
- A cooler piston crown means greater heat loss from the gas and lower TE (a win for steel)
- Rate of heat transfer is a function of thermal conductivity but also thinness of the section. Thinner crown = faster heat flow.
- Piston crown stress is inversely proportional to thickness squared and deflection is inversely proportional to thickness to the third power (http://www.roymech.co.uk/Useful_Tables/ ... lates.html) so the main problem with a steel crown is the strength and rigidity when reduced to the same weight as aluminium (about 33% of the thickness so about 9 times the stress and 9 times the deflection despite being 3 times the stiffness)
- The answer is to "fatten" the crown with lightweight voids between upper and lower "skins" - a bit like an "I" beam. I suppose a "waffle slab" underside as proposed by PZ would be a part-way solution.

[Brian Coat]

Since we are talking pistons, I thought people might find this MAHLE publication on the general subject interesting.

It's a few years old but offers good information about the fundamentals ... from the best piston company in the business.

https://www.fsb.unizg.hr/miv/MSUI/KonMo ... r-2012.pdf

[Brian Coat]

With the ability to create void spaces within the structure, would it be feasible to use sodium filled voids for cooling similar to exhaust valves?

Good thinking.

Yes.

That is an active research area.

http://www.bine.info/fileadmin/content/ ... x_engl.pdf

[Tommy Cookers]

- Rate of heat transfer is a function of thermal conductivity but also thinness of the section. Thinner crown = faster heat flow.

surely heat flow will be faster with a thicker section ? ..... (eg consider electrical conduction, or why steel wool burns)
this is part of the reason why Al alloy gives much lower crown temperature

and the coefficient of thermal expansion will be much lower with steel - potentially useful to the designer

[Brian Coat]

Diesel Fe/Al piston design comparison.

Clearly not a direct F1 surrogate but interesting.

http://gasturbinespower.asmedigitalcoll ... 6_f003.png

Piston engines with the very highest pressure ratios (big cross-head 2T) sometimes employ an iconel layer on top of the piston. That's interesting, too, I think.