Ferrari Power Unit Hardware & Software

[izzy]

Distortion will be a function of the underlying structure. The coating has little effect.

Weight for weight aluminium will distort less than steel.

the temperature is the thing tho isn't it? Aluminium actually melts at 655 degrees, and alloys even less apparently, so at some point well below that its stiffness must cross over and become less than steel. And by the sound of it Ferrari are trying to run the combustion chamber hotter, is the idea

[henry]

If the objective is to run the combustion chamber hotter I imagine an associated objective would be to eliminate hot spots. I imagine, obviously don’t know, that an inserted prechamber might be a potential location for a hot spot given that any cooling passageways will be separated from the chamber by enough material to meet mechanical requirements either side of the screwed joint.

If, by 3D printing, they could form the prechamber directly in the cylinder head they could provide it with its own cooling galleries, and potentially form it without any additional discontinuities in the surface form of the combustion chamber.

Obviously they would need to be very sure of the prechamber design, and I’m not sure how easy it would be to form the jet orifices, assuming they are quite small and close toleranced.

[subcritical71]

If the objective is to run the combustion chamber hotter I imagine an associated objective would be to eliminate hot spots. I imagine, obviously don’t know, that an inserted prechamber might be a potential location for a hot spot given that any cooling passageways will be separated from the chamber by enough material to meet mechanical requirements either side of the screwed joint.

If, by 3D printing, they could form the prechamber directly in the cylinder head they could provide it with its own cooling galleries, and potentially form it without any additional discontinuities in the surface form of the combustion chamber.

Obviously they would need to be very sure of the prechamber design, and I’m not sure how easy it would be to form the jet orifices, assuming they are quite small and close toleranced.

You could AM it, and then use traditional manufacturing (like lasers, or EDM) to open up the bores which are exposed to the cylinder.

[henry]

....

Obviously they would need to be very sure of the prechamber design, and I’m not sure how easy it would be to form the jet orifices, assuming they are quite small and close toleranced.

You could AM it, and then use traditional manufacturing (like lasers, or EDM) to open up the bores which are exposed to the cylinder.

I think the jets are likely to be pretty much radial, given the shallow nature of the combustion chamber at combustion initiation. So positioning a laser or EDM head would be difficult. But it sounds a reasonable possibility.

[saviour stivala]

Assuming a pre-chamber is being used, of which one type that had been actually claimed to have been used, the original (Mahle TJI) which actually the direct injection rules does not allow. The same goes for steel liners and steel pistons ‘assuming’ if they are being used.

[izzy]

If the objective is to run the combustion chamber hotter I imagine an associated objective would be to eliminate hot spots. I imagine, obviously don’t know, that an inserted prechamber might be a potential location for a hot spot given that any cooling passageways will be separated from the chamber by enough material to meet mechanical requirements either side of the screwed joint.

If, by 3D printing, they could form the prechamber directly in the cylinder head they could provide it with its own cooling galleries, and potentially form it without any additional discontinuities in the surface form of the combustion chamber.

yes, and I'm just going on instinct but in my mind they won't have galleries or hotspots they'll have a foam or matrix type structure for the cooling, with an enormous surface area and they AM build it directly onto the back of the solid steel surfacing. Then they actually want the lower heat transfer of steel, and they run the coolant extremely hot as well, with its carbon nanoparticles, huge boiling point, smaller radiators... And with all that they can basically just dial in a temperature, and it's all really compact

[subcritical71]

Assuming a pre-chamber is being used, of which one type that had been actually claimed to have been used, the original (Mahle TJI) which actually the direct injection rules does not allow. The same goes for steel liners and steel pistons ‘assuming’ if they are being used.

Mahle says Ferrari F1 are using a Mahle Jet Ignition system on their website...

[saviour stivala]

“Mahle says FERRARI are using a ‘Mahle jet ignition system’ on their website”. If FERRARI are using ‘Mahle jet ignition system’ Mahle must have removed the injector from inside of what they call/name TJI pre-chamber because all four engines on the grid uses exhaust side mounted injectors injecting direct into the combustion chamber as per the rules. In such case this this Mahle (branded as turbulent jet ignition) system is known to have simply been met with just a spark-plug complete with pre-chamber at its front (spark-plug-non-fouler/spark-plug cap). Something which is in common use not only in F1 but also in WEC racing.

[63l8qrrfy6]

Weight for weight aluminium will distort less than steel.

I disagree with this.
Young's modulus of Aluminium is roughly a third that of steel and so is its density.
Intuitively, since the volume of a liner (assuming it is a perfect cylinder) is proportional to the square of its outer diameter (bore is fixed) the steel liner should be the same or lighter.

Let's say the liner thickness is 6 mm for aluminium, E=70000 MPa , bore is 80 mm and internal pressure is 200 bar. Hoop strain (assuming the liner behaves as a thin wall pressure vessel) is 1.9 milistrain. A steel liner of the same bore, E=200000 MPa will have to be 2.1 mm thick to achieve the same strain.

Densities are about 2700 kg/m^3 for aluminium and 8000 kg/m^3 for steel so for any liner length the steel liner would weight about 1% less.

Doing this again for 3 mm thick aluminium would produce a liner that is about 1% lighter than a steel one (square of the OD has decreased significantly).

I think that in the range of practical thicknesses there is virtually no difference in weight between steel and aluminium.

When thermal effects are considered though, Young's modulus decreases much faster with temperature for aluminium while its coefficient of thermal expansion is roughly twice that of steel.
At the usual operating temperatures there is just no way an aluminium bore could weigh as much as a steel one for the same stiffness.

[63l8qrrfy6]

Assuming a pre-chamber is being used, of which one type that had been actually claimed to have been used, the original (Mahle TJI) which actually the direct injection rules does not allow. The same goes for steel liners and steel pistons ‘assuming’ if they are being used.

which rule bans steel pistons and liners ?

[saviour stivala]

Assuming a pre-chamber is being used, of which one type that had been actually claimed to have been used, the original (Mahle TJI) which actually the direct injection rules does not allow. The same goes for steel liners and steel pistons ‘assuming’ if they are being used.

which rule bans steel pistons and liners ?

I haven't claimed rules ban steel liners, I asked who are using them and asked for any possible links.

[subcritical71]

Assuming a pre-chamber is being used, of which one type that had been actually claimed to have been used, the original (Mahle TJI) which actually the direct injection rules does not allow. The same goes for steel liners and steel pistons ‘assuming’ if they are being used.

which rule bans steel pistons and liners ?

I believe it was 2013 rules that excluded it. Since then it has not been an excluded material. This has been debated many times and on several threads with no current rule being shown to exclude it.

[gruntguru]

Weight for weight aluminium will distort less than steel.

Young's modulus of Aluminium is roughly a third that of steel and so is its density.
Intuitively, since the volume of a liner (assuming it is a perfect cylinder) is proportional to the square of its outer diameter (bore is fixed) the steel liner should be the same or lighter.

Let's say the liner thickness is 6 mm for aluminium, E=70000 MPa , bore is 80 mm and internal pressure is 200 bar. Hoop strain (assuming the liner behaves as a thin wall pressure vessel) is 1.9 milistrain. A steel liner of the same bore, E=200000 MPa will have to be 2.1 mm thick to achieve the same strain.

Densities are about 2700 kg/m^3 for aluminium and 8000 kg/m^3 for steel so for any liner length the steel liner would weight about 1% less.

Doing this again for 3 mm thick aluminium would produce a liner that is about 1% lighter than a steel one (square of the OD has decreased significantly).

I think that in the range of practical thicknesses there is virtually no difference in weight between steel and aluminium.

I agree there is little difference when loaded only with cylinder pressure and/or tension/compression along the cylinder axis. Loading of the cylinder is of course much more complex than that and all the other loading vectors (piston side-loads, localised thermal stress) will favour the aluminium cylinder due to the greater wall thickness. Further, the higher thermal conductivity results in lower temperature gradients and lower thermal stress.
.

When thermal effects are considered though, Young's modulus decreases much faster with temperature for aluminium . . .

Yes but not in the normal temperature range for a cylinder. Having said that I am sure the F1 bore runs at a higher temperature than normal so presumably the temperature gradient from bore to coolant is also higher than normal. Whether this is achieved with insulating surface treatment, steel liners or some other means is an interesting topic.
.

. . . . while its coefficient of thermal expansion is roughly twice that of steel. At the usual operating temperatures there is just no way an aluminium bore could weigh as much as a steel one for the same stiffness.

Isn't that what I said?

[izzy]

When thermal effects are considered though, Young's modulus decreases much faster with temperature for aluminium . . .

Yes but not in the normal temperature range for a cylinder. Having said that I am sure the F1 bore runs at a higher temperature than normal so presumably the temperature gradient from bore to coolant is also higher than normal. Whether this is achieved with insulating surface treatment, steel liners or some other means is an interesting topic.

if it's being AM'd, then it won't be a single 'wall thickness' will it, it'll be a super thin skin as the inside face of the cylinder, then some kind of lattice or foam type structure on the back to give it stiffness that'll be much lighter and they can flow coolant through, to give the right temperature gradient as you say even if it's steel, as thermal conductivity is generally linear with thickness

then the flame temperature will be about 2000 degrees or something? They want to run the combustion chamber hotter as that gives a bit more expansion of the charge and reduces heat rejection. Their limits are the oil, i guess, and fuel and avoiding pre-ignition, but aluminium's stiffness falls off a cliff with temperature:

[Tommy Cookers]

Izzy

again you are saying plastic deformation is the issue ....
what is the meaning of stiffness ?
the others are talking only about elastic deformation ?

steel or part-steel pistons exist for use at temperatures where the fatigue strength of al-alloy pistons is inadequate
you are saying this also applies to the cylinder ?
yield strength being the step beyond fatigue strength (and what we might call elastic strength)