The Road to the 50% Thermally Efficient F1 Internal Combustion Engine

[johnny comelately]

An expose by Pat Symonds.
Hopefully the beginning of a fruitful discussion of how this was achieved.

[johnny comelately]

Point 1.
The reduction of the unburnt fraction which is largely affected by the quench boundary layer. To my way of thinking this can only be achieved by higher combustion chamber wall temperatures. The only way that is possible is through coatings and materials, and then higher coolant temperatures, which seem to be indicated by the high system pressures of around 3.5 bar (is that correct)

[Zynerji]

Point 1.
The reduction of the unburnt fraction which is largely affected by the quench boundary layer. To my way of thinking this can only be achieved by higher combustion chamber wall temperatures. The only way that is possible is through coatings and materials, and then higher coolant temperatures, which seem to be indicated the high system pressures.

The Honda combustion chamber video changed that thought for me. Shooting a super-strong vortex loop out of the prechamber causes much higher mixing as well as self-ignition due to the shear against the cupped edge of the piston.



The dolphins in this vid are doing very similar in my opinion. It looked like that is what the Honda vid showed in cylinder.

[vorticism]

Good general overview. He mentioned there are dedicated piston cooling loops operating at their own temperature, separate from the crankcase oil. Does that mean they collect that same oil at the cylinder or is it lost to the crankcase?

Aiming for up to 50% electric propulsion at some point in the future. This seems at odds with their engine development freeze. Seemingly the easy route would be by lowering the cylinder count; just as with the V8s that would allow them to reuse most of their existing engine tech. How would nascent EV manufacturer Ferrari react? Given the state of the sport they might just add more batteries and increase car weight further. Bigger tyres. I think weight is their last concern, in modern F1. It's all about viewers and greenwashing claims, year to year laptimes are irrelevant.

Near the end (maybe 40-45:00 mark) he discusses fuels and we get an insight into the mindsets of the influential figures within the F1. They want a drop-in (standard) fuel, and plan to introduce one first to F2 & F3. Mentions there is a lot of money and development tied up in the current fuels and their production, expects one or two small plants to open to produce F1 fuels and presumably other niche syn fuels. They've painted themselves into a corner with this engine regulation, which requires what he calls an unnatural set of specifications to be met. Eight years in, huge money in the powertrains and niche fuel chemistry. I read that as: the current engine format will be sticking around til the end of F1 as we know it.

Then he puts his head down and starts whipping himself on stage. He says F1 needs to be something that "fans are proud of," and that if the sport loses interest by not becoming a moral role model, that the sport will "deserve it." I guess Pat has been guilt shamed by too many evocatively narrated nature documentaries. Why are they looking at themselves this way? The hobby became a sport, the sport became a livelihood, became a corporate enterprise, and became a church, apparently. No one was looking to F1 for pseudoreligious political guidance, and even if they were, they were misguided in thinking that F1 was a major source of environmental contamination. His mindset plays into the worst parts of consumerism and western democracies.

Pat laments his profession on stage; perhaps it's all for show. Does he cry every time his engines get flown across oceans? "The jet fuel, the jet fuel... *sob*"

[johnny comelately]

Point 1.
The reduction of the unburnt fraction which is largely affected by the quench boundary layer. To my way of thinking this can only be achieved by higher combustion chamber wall temperatures. The only way that is possible is through coatings and materials, and then higher coolant temperatures, which seem to be indicated the high system pressures.

The Honda combustion chamber video changed that thought for me. Shooting a super-strong vortex loop out of the prechamber causes much higher mixing as well as self-ignition due to the shear against the cupped edge of the piston.



The dolphins in this vid are doing very similar in my opinion. It looked like that is what the Honda vid showed in cylinder.

I'm not up to speed with the role of the Miller cycle as used here with its early IVC, and I am sure that it is bound up in the bore stroke ratio influence (and possibly why Pat mentioned they are looking at longer strokes), but if the the Miller is to help with turbulence then it is possible to do this another way.
In my experience with flame ignition the smaller the diameter of the hole the less distance the flame travels (to a point) and a bigger problem with prechamber evacuation and fill, something Pat alluded to. With the spark plug located vertically, or thereabouts there is a need for multiple holes which also suits the combustion chamber dimensions, which all in all creates a need for a fair degree of turbulence. Positioning the prechamber (one by regulation) somewhat horizontally and having one hole or maybe two (because we had two per cylinder) of the right diameter enables the flame (or its affect, shown by burn marks) to go right across the piston crown.
This seems to obviate the high requirement for turbulence. Indicated by a reduction of ignition advance down to around 22 degrees BTDC (10K RPM).
Getting back to the unburnt chamber under this described conditions there is a need to complete this to as near as possible to 100%.
The extinguishing happens because of the chamber itself , so if the chamber walls are hotter and the materials involved can cater for full burn and hotter temperatures we can entertain lambda 1.5 or thereabouts (Lambda 1.2 was the figure used in previous discussions, as supplied by the Honda affiliate here) and get close to 100% burn.

[gruntguru]

Point 1.
The reduction of the unburnt fraction which is largely affected by the quench boundary layer. To my way of thinking this can only be achieved by higher combustion chamber wall temperatures. The only way that is possible is through coatings and materials, and then higher coolant temperatures, which seem to be indicated by the high system pressures of around 3.5 bar (is that correct)

Unburnt charge is actually only a small fraction of the technology gain. Simply moving the AFR from about Lambda 0.85 to 1.4 will almost eliminate unburnt fuel. (Lambda 0.85 simply means you only have enough oxygen in the combustion chamber to burn 85% of the fuel so the engine must waste at least 15% of the fuel.)

[johnny comelately]

Point 1.
The reduction of the unburnt fraction which is largely affected by the quench boundary layer. To my way of thinking this can only be achieved by higher combustion chamber wall temperatures. The only way that is possible is through coatings and materials, and then higher coolant temperatures, which seem to be indicated by the high system pressures of around 3.5 bar (is that correct)

Unburnt charge is actually only a small fraction of the technology gain. Simply moving the AFR from about Lambda 0.85 to 1.4 will almost eliminate unburnt fuel. (Lambda 0.85 simply means you only have enough oxygen in the combustion chamber to burn 85% of the fuel so the engine must waste at least 15% of the fuel.)

Yes it does, but in doing so takes the boundary layer very close to the chamber walls, necessitating coatings. These have another advantage of putting more heat into the exhaust stream and piston.
Do you think the coolant temperature has to be raised for this to happen?

[gruntguru]

Good general overview. He mentioned there are dedicated piston cooling loops operating at their own temperature, separate from the crankcase oil. Does that mean they collect that same oil at the cylinder or is it lost to the crankcase?

I missed that bit. Do you remember where it is on the video?

Then he puts his head down and starts whipping himself on stage. He says F1 needs to be something that "fans are proud of," and that if the sport loses interest by not becoming a moral role model, that the sport will "deserve it." I guess Pat has been guilt shamed by too many evocatively narrated nature documentaries. Why are they looking at themselves this way? The hobby became a sport, the sport became a livelihood, became a corporate enterprise, and became a church, apparently. No one was looking to F1 for pseudoreligious political guidance, and even if they were, they were misguided in thinking that F1 was a major source of environmental contamination. His mindset plays into the worst parts of consumerism and western democracies.

No, F1 is reading the audience and looking at the future. The old songbook is fine for the the old congregation - who also comprise a large part of the current audience - but we are getting old and dying off. For today's youth to become F1 fans of the future requires the kind of changes Pat talks about. Formula E and Extreme E are examples of series that will be competing for their support.

[gruntguru]

Point 1.
The reduction of the unburnt fraction which is largely affected by the quench boundary layer. To my way of thinking this can only be achieved by higher combustion chamber wall temperatures. The only way that is possible is through coatings and materials, and then higher coolant temperatures, which seem to be indicated by the high system pressures of around 3.5 bar (is that correct)

Unburnt charge is actually only a small fraction of the technology gain. Simply moving the AFR from about Lambda 0.85 to 1.4 will almost eliminate unburnt fuel. (Lambda 0.85 simply means you only have enough oxygen in the combustion chamber to burn 85% of the fuel so the engine must waste at least 15% of the fuel.)

Yes it does, but in doing so takes the boundary layer very close to the chamber walls, necessitating coatings. These have another advantage of putting more heat into the exhaust stream and piston.
Do you think the coolant temperature has to be raised for this to happen?

Probably. As well as coatings, you have extreme dilution reducing cycle temperature, high expansion ratio reducing charge temperature during the power stroke and stratified charge all helping reduce heat flow to the coolant. 100 kW cooling system load from 1,300 kW total heat input is remarkable.

[vorticism]

Although you need an additional 110 kW heat dissipation in order to use to use it.

Good general overview. He mentioned there are dedicated piston cooling loops operating at their own temperature, separate from the crankcase oil. Does that mean they collect that same oil at the cylinder or is it lost to the crankcase?

I missed that bit. Do you remember where it is on the video?

11:50, dedicated pump

No, F1 is reading the audience and looking at the future. The old songbook is fine for the the old congregation - who also comprise a large part of the current audience - but we are getting old and dying off. For today's youth to become F1 fans of the future requires the kind of changes Pat talks about. Formula E and Extreme E are examples of series that will be competing for their support.

They are not reading the audience well. Many see through the pandering. Of those who don't, should suits be preying on their misguided views? EVs are a forced meme still (partly political, partly manufactures wanting cheaper components that are easier to warranty), and there's nothing inherent to liking them correlating with youth. I'm not against them totally but the scene at large and the greenwashing in motorsports shouldn't be lauded. If sport is to provide some sort of social function, it usually at a minimum is supposed to provide reminders for ethical behavior, through sportsmanship. PR, marketing, advertising and other forms of lying are at odds with that.

[gruntguru]

Some of the more interesting takeaways:
- lambda 1.3 - 1.4 Many (including myself) were suggesting 1.6 - 1.8. What we weren't counting on was EIVC Miller and the reduced VE associated with that.
- 20% (160 hp) from the turbine.
- Passive pre-chamber with rich mixture courtesy of DI aiming.
- Pre-chamber integral to spark plug.
- Spark plugs require indexing at installation (using shims) suggesting asymmetric placement of PC jet holes.
- Concerns around scavenging of PC. A mystery to me since even 12:1 effective CR and zero scavenging would produce only 8.5% passive EGR and 6% combustion product residual in the PC. Suggests the orifice diameter is so small that PC pressure significantly lags main chamber during compression and exhaust events.
- MAP as high as 5.5 bar to overcome inadequate intake camshaft lift-time area.
- EIVC Miller cycle. Short duration intake lobe results in acceleration-limited valve lift. I wonder if these intake valve trains are even capable of the 15k rpm limit? They were occasionally hitting 15k in the early days but I wonder if this is still the case? They certainly don't operate much above 11k for power reasons and the control system is certainly capable of preventing unintended overspeed.
- Very high sensitivity to octane number.

[gruntguru]

The Honda combustion chamber video changed that thought for me. Shooting a super-strong vortex loop out of the prechamber causes much higher mixing as well as self-ignition due to the shear against the cupped edge of the piston.



The dolphins in this vid are doing very similar in my opinion. It looked like that is what the Honda vid showed in cylinder.

Great video!
What I have seen regarding the PC jets from TJI suggests that it is more about heat and reactive species igniting the surrounding charge than mechanical agitation.

[johnny comelately]

Unburnt charge is actually only a small fraction of the technology gain. Simply moving the AFR from about Lambda 0.85 to 1.4 will almost eliminate unburnt fuel. (Lambda 0.85 simply means you only have enough oxygen in the combustion chamber to burn 85% of the fuel so the engine must waste at least 15% of the fuel.)

Yes it does, but in doing so takes the boundary layer very close to the chamber walls, necessitating coatings. These have another advantage of putting more heat into the exhaust stream and piston.
Do you think the coolant temperature has to be raised for this to happen?

Probably. As well as coatings, you have extreme dilution reducing cycle temperature, high expansion ratio reducing charge temperature during the power stroke and stratified charge all helping reduce heat flow to the coolant. 100 kW cooling system load from 1,300 kW total heat input is remarkable.

Do you mean lean of peak effect?

[gruntguru]

Yes it does, but in doing so takes the boundary layer very close to the chamber walls, necessitating coatings. These have another advantage of putting more heat into the exhaust stream and piston.
Do you think the coolant temperature has to be raised for this to happen?

Probably. As well as coatings, you have extreme dilution reducing cycle temperature, high expansion ratio reducing charge temperature during the power stroke and stratified charge all helping reduce heat flow to the coolant. 100 kW cooling system load from 1,300 kW total heat input is remarkable.

Do you mean lean of peak effect?

Extreme dilution (40% excess air) = much lower cycle temperature than stoichiometric.

[Hoffman900]

Some of the more interesting takeaways:
- lambda 1.3 - 1.4 Many (including myself) were suggesting 1.6 - 1.8. What we weren't counting on was EIVC Miller and the reduced VE associated with that.
- 20% (160 hp) from the turbine.
- Passive pre-chamber with rich mixture courtesy of DI aiming.
- Pre-chamber integral to spark plug.
- Spark plugs require indexing at installation (using shims) suggesting asymmetric placement of PC jet holes.
- Concerns around scavenging of PC. A mystery to me since even 12:1 effective CR and zero scavenging would produce only 8.5% passive EGR and 6% combustion product residual in the PC. Suggests the orifice diameter is so small that PC pressure significantly lags main chamber during compression and exhaust events.
- MAP as high as 5.5 bar to overcome inadequate intake camshaft lift-time area.
- EIVC Miller cycle. Short duration intake lobe results in acceleration-limited valve lift. I wonder if these intake valve trains are even capable of the 15k rpm limit? They were occasionally hitting 15k in the early days but I wonder if this is still the case? They certainly don't operate much above 11k for power reasons and the control system is certainly capable of preventing unintended overspeed.
- Very high sensitivity to octane number.

I wasn't counting on the Miller Cycle either.

Lambda compared to the DI Audi DTM engine is 1.15-1.38. Of course power wise, they are restricted to 3.5 bar and 90kg/hr. Probably not enough boost to really make the Miller Cycle work here.

The acceleration-limitation of the valvetrain in terms of valve time area (and the high boost to compensate) of the Miller cycle tells me they are NOT using metal valve springs, as was speculated about Honda. I do wonder if the rpm limits the teams use vs. rules has to do with the the dynamics, as you also noted.

I did like that they are running individual cylinder pressure sensors for each cylinder, at all time times. That's A LOT of data.