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

[vorticism]

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.

They may have smaller intake valves relative to the exhaust valves to address this.

[Zynerji]

What's this Omega piston design?

[vorticism]

What's this Omega piston design?

Piston crown shape. Four bosses offset 90* radially, combined with a diesel bowl geometry. Four omega shapes result.

[Hoffman900]

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.

They may have smaller intake valves relative to the exhaust valves to address this.

I doubt that. With a Miller Cycle engine, they are limited on valve open time area. Shrinking the intake valves just makes it worst.

I’m pretty certain the “Omega” pistons are a bowl with a raised center. Center point may be slightly recessed as well.

[vorticism]

Could have a raised center, some diesel bowl pistons do. Would depend on prechamber shape and other factors. But the name is a reference to the bosses which provide the squish turbulence.

As for the valves, it's an educated guess. Valve diameter vs valve mass vs valve acceleration. Inlet area vs opening duration. Given the high boost and the importance of exhaust flow it my be inverted from typical layouts (exhaust vs intake diameters). Otherwise from what I've seen they are at least near equal.

[saviour stivala]

Could have a raised center, some diesel bowl pistons do. Would depend on prechamber shape and other factors. But the name is a reference to the bosses which provide the squish turbulence.

As for the valves, it's an educated guess. Valve diameter vs valve mass vs valve acceleration. Inlet area vs opening duration. Given the high boost and the importance of exhaust flow it my be inverted from typical layouts (exhaust vs intake diameters). Otherwise from what I've seen they are at least near equal.

Do you mean you have actually seen at least some valve sizes of any of the four present 1.6l engines?.

[johnny comelately]

For relativity, let’s see if this is right:

You have a bent 8 of yesteryear.
It has, say, no. 72 main jets in the holley giving .87 lambda.
The compression ration is 11:1.
Ignition timing is set for MBT and safe from knocking.

Then the configuration is changed to adding a turbo that pumps 4 bar.
But also the geometric compression ratio is upped to 18:1.
And then the difficult part, replace the main jets with 41’s
And it has to be competitive and last.

[coaster]

You could solve F1's cost issues and just give them 22 old chevy small blocks every year.

[johnny comelately]

Point 2.

The wholesale change:

From the focus on inlet systems, where the tradition has been cylinder fill from valve sizes, port design, cam timing, turbos, etc
Squeeze it and light the wick
With some just adequate attention to exhausts mainly so as to not impede and aid fill.

To:
A complete burn creating an extremely energized exhaust to focus on recovering the maximum from that.
All the fuels worth has been found and does its usual but now better job on the piston/crank

The indicators are the Miller cycle coupled with the dreary 220 degrees of inlet duration and only 8mm of cam lift.
The 5.5 bar of boost is apparently providing the right balance of delivery and useful exhaust energy.
Pumping losses come to mind with the enormous pressures before ignition but again the Miller cycle slightly mitigates this.
The reduction in ignition advance from the jet ignition style is a major reduction in pumping losses (technically not accurate, but the work involved by the piston pushing against the combustion BTDC)
The part HCCI plays in all this would seem to be one of the many keys in these fantastically revolutionary engines.

[gruntguru]

. . . . The reduction in ignition advance from the jet ignition style is a major reduction in pumping losses (technically not accurate, but the work involved by the piston pushing against the combustion BTDC) . . . .

The more important benefit of rapid combustion is getting the charge combusted as soon after TDC as possible. Combustion that occurs later in the stroke has less ability to contribute to pushing the piston down.

[coaster]

Compressing through a small intake port would not raise the temperature?
Why flog the 2 valve horse when 4 valve is the undisputed king?

[vorticism]

. . . . The reduction in ignition advance from the jet ignition style is a major reduction in pumping losses (technically not accurate, but the work involved by the piston pushing against the combustion BTDC) . . . .

The more important benefit of rapid combustion is getting the charge combusted as soon after TDC as possible. Combustion that occurs later in the stroke has less ability to contribute to pushing the piston down.

In the vid he said delayed or slow combustion (iirc) contributes to knocking, but this did not make sense to me. I thought knocking was more about premature or too quick (detonation) combustion. Do you know what he meant?

[gruntguru]

. . . . The reduction in ignition advance from the jet ignition style is a major reduction in pumping losses (technically not accurate, but the work involved by the piston pushing against the combustion BTDC) . . . .

The more important benefit of rapid combustion is getting the charge combusted as soon after TDC as possible. Combustion that occurs later in the stroke has less ability to contribute to pushing the piston down.

In the vid he said delayed or slow combustion (iirc) contributes to knocking, but this did not make sense to me. I thought knocking was more about premature or too quick (detonation) combustion. Do you know what he meant?

Knocking occurs when the last bit of unburned charge gets hot enough to all ignite (almost) simultaneously. Slow combustion makes knock more likely because there is more time for the radiation from the flame to heat the "end gas" (unburnt remaining charge).

[Hoffman900]

The more important benefit of rapid combustion is getting the charge combusted as soon after TDC as possible. Combustion that occurs later in the stroke has less ability to contribute to pushing the piston down.

In the vid he said delayed or slow combustion (iirc) contributes to knocking, but this did not make sense to me. I thought knocking was more about premature or too quick (detonation) combustion. Do you know what he meant?

Knocking occurs when the last bit of unburned charge gets hot enough to all ignite (almost) simultaneously. Slow combustion makes knock more likely because there is more time for the radiation from the flame to heat the "end gas" (unburnt remaining charge).

This.

To piggy back, when this happens it produces a spike in pressure that wrecks pistons (typically between the face and the too ring land), and / or the top ring, and / or main / rod bearings, etc.

A big part of modern engine design is about building in knock resistance by having very big focus on tumble strength and preservation beyond IVC.

[johnny comelately]

About a 16cc chamber makes very little room for omegaing the chamber or crown, extraordinary!
But of course this does produce a very small surface area for heat loss.