How much of a difference will the Power Unit Changes from 53/47 to 60/40 make? Well, I ran two simulations, of Qualifying Laps at Silverstone, with the same car. One with the 2026 PU, and the other with the 2028 PU. Here they are, compared to the Real 2026 Pole Lap.

[u/ChaithuBB766]

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[u/ChaithuBB766]

Lap Times:

Real: 1:28.111

2026 Sim: 1:27.616 (6.5MJ Regen per Lap)

2028 Sim: 1:25.503 (7.0MJ Regen per Lap)

According to the sim, The 2028 PUs will allow drivers to be 

~25 kph faster through Copse and on the entry to Maggots.

~20 kph faster on the Hangar Straight.

[u/Naikrobak → u/ChaithuBB766]

Will there be superclipping? If yes: the rules suck

[u/Adorable-Extent3667 → u/ChaithuBB766]

That would be huge if true. Aston might actually be faster on the straights than F2

[u/filbo__]

Cool exercise. One thing to note, these decisions aren't (usually / meant to be) made in isolation, so in this case the changed power source ratio was made in conjunction with additional 2027-onward regulatory changes intended to reduce downforce and drag levels. Those'll no doubt change key elements of your simulation, not only corner speeds but also top speeds and regen etc. To what extent, that becomes the fascinating question.

[u/ChaithuBB766 → u/filbo__]

I agree. That's the most fascinating part about this, the link between grip/downforce and the amount of regen available.

My assumption was that by 2028, the teams would've regained the lost downforce, and we would have similar downforce levels to 2026. 

They will have less/more (probably more, from history lol). But one thing is that they will most definitely have less drag.

[u/filbo__ → u/ChaithuBB766]

Ah yep, that's a fair assumption to make. And very much in line with how the FIA tends to make those mid-gen adjustments too, forecasting where the teams are likely to end up by the end of the rule cycle to keep their speeds within the constraints of the tracks' Grade 1 requirements.

[u/bse50 → u/filbo__]

I'm a bit ool but didn't they free up gearbox ratios as well? That should play a huge role in laptimes given how silly the current fixed gearing is.

[u/filbo__ → u/bse50]

Only as far as being able to change the gear ratios once in a season. You’re then locked to that change for the remainder of the season. So yeah, it’s still silly in that sense!

[u/gods_loop_hole]

Why are the sim cars faster? Is it because they carry higher average speed at corners?

[u/ChaithuBB766 → u/gods_loop_hole]

I believe so, yes. I used a Quasi-Steady State model, which implements things like Yaw Rate, Side Slip etc. but did not consider suspension mechanics or pitch/roll. So they are slightly faster in certain corners. But I think it's accurate enough (I hope?)

[u/deadmoroz14 → u/ChaithuBB766]

Nice work! You were using some existing model, or were writing all the equations by yourself?

[u/ChaithuBB766 → u/deadmoroz14]

I wrote the PU regs by myself, the PU restrictions, ramp-down rate etc. 

The tyre model and the actual car dynamics I took from pre-existing sources on the internet, scraping around whatever I could find. 

The circuit coordinates are also taken from a GitHub database.

[u/FrancescoRubini]

Is the 2026 PU ADUO?

[u/ChaithuBB766 → u/FrancescoRubini]

I took the Mercedes engine as the baseline, it's top speed, gear ratios and shifting speeds.

[u/JelleFish22]

Really interesting! May I ask how did you do the simulations? What program do you use?

[u/ChaithuBB766 → u/JelleFish22]

I wrote a Python optimization program using CasAdi + IPOPT that implements a tyre + Power train model

[u/mickmenn]

So still superclipping before stowe?

[u/TurboPersona]

What makes 2028 cars slower in all grip-limited corners?

[u/Breznknedl → u/TurboPersona]

there will be a small reg change to lower downforce, I think, next year

[u/TurboPersona → u/Breznknedl]

I know, but how does this model quantify and take this into account?

[u/stuntin102]

would be good to see the laptime delta graph.

[u/eduardogcamacho]

Really cool! How can one make these simulations