Max power, at 10500RPM or higher than 10500RPM?

[Tommy Cookers]

Truth be said, in practice they often are at 10300 after an upshift.
I have seen this umpteen times while collecting gearing data.
But talking of 10500 simplifies the discussion at hand.

given the nature of sampling and consequent rpm value presented .....
doesn't this suggest that the real rpm on completion of upshift is ? ....

10200 rpm ?
or 10100 rpm ?
or ?

[hollus]

Probably yes.

[gruntguru]

I agree. There is little doubt that the optimum shift would land the rpm somewhere slightly below 10,500 for two reasons.
1. There is a small energy release from the inertia of the engine and the rpm drop during the shift
2. An ideal shift results in the same power before and after. The power below 10,500 approximates a constant torque characteristic, so 10,200 rpm would represent a 3% drop in power from 10,500. It is likely that the power at 11,000 or 11,500 is similar.

[saviour stivala]

"max 'power speed' is @ 10500rpm, or higher then 10500 rpm?". Burning fuel gets you power, burning more fuel gets you more power. where will the extra fuel needed to burn to make more power over and above the maximum fuel flow rate (100kg/h @ 10500rpm coming from?.
Upshifts are traditionally made above the max power speed (10500rpm) so as the drop in RPM will not drop below maximum power speed.

[Dr. Acula]

"max 'power speed' is @ 10500rpm, or higher then 10500 rpm?". Burning fuel gets you power, burning more fuel gets you more power. where will the extra fuel needed to burn to make more power over and above the maximum fuel flow rate (100kg/h @ 10500rpm coming from?.
Upshifts are traditionally made above the max power speed (10500rpm) so as the drop in RPM will not drop below maximum power speed.

You do realise, that the PU ist still reving up? Powerout in simple terms is engine speed multiplied with torque output. As long as the percentual rpm gain is higher than the percentual torque "loss" you still gain power. The torque output of an engine isn't proportinal to it's amount of fuel burnt per rpm, the behaviour is not even strictly linear.
Also, you wan't to be a fair bit under the max. power rpm after an upshift. What you wan't to achieve is to rev through the point of max. power in every gear. You wan't to maximize the area under the curve so to speak. You don't do that when you keep the revs over this point nearly all the time.

[Jolle]

There is I think another reason why the used rev range starts below 10.500.

Up to 10.500 rpm the fuel injected per combustion is the same, only to get less per bang above that. If you optimise your PU for that amount of fuel and mixture, your PU will be at its most efficient for the longest. In this fuel restricted formula, efficiency is king.

So, with the PU optimised for this amount of injected fuel, it would suggest that top power is at 10.500.

[henry]

...
So, with the PU optimised for this amount of injected fuel, it would suggest that top power is at 10.500.

That seems unlikely for the reason @gruntguru gave. You want the power to be the same before and after a gearchange*. If max power were at 10,500 the power at change up speed, around 11,800 would match a power at a speed after the gearchange well below 10,500 and that’s not what we see.

FWIW I analysed the Ferrari at Singapore using data researched by @mudflap. The power peak was around 11,200. It moved around a bit depending on variable values I chose but never got anywhere near 10,500.

* this is a requirement in order to keep the Tractive effort constant allowing drivers to change during cornering. Last year there were examples of drivers up shifting at the entry to Campsa at Barcelona.

[gruntguru]

Upshifts are traditionally made above the max power speed (10500rpm) so as the drop in RPM will not drop below maximum power speed.

No. Upshifts are made at a point above the max power speed such that the rpm will drop to below the max power speed at approximately the same power level. The object is to maximise operate in a speed range that maximises the average power output.


Ideal shift points occur where rear wheel torque is the same before and after changing gear. Because road speed is also the same, the rear wheel power (and therefore engine power) is the same.

[saviour stivala]

Unless a driver is driving in ‘save fuel mode’ upshifts are made above max power speed, was always done like that, and I don’t see why it has changed. Up to the NA 2.4L V8 (2013) with the 18000rpm limit imposed but with no fuel flow limit, max power speed was 17500rpm, and upshifts were made at 18000rpm. With the present 1.6l turbocharged power unit being fuel flow rate limited to 100kg/h at 10500rpm, above which no more power can be produced by the ICE, The max power speed is 10500rpm, and I expect that upshifts are made anywhere up to 2-3 times above max power speed of what was the practice in the NA 2.4L V8 era.

[hollus]

With the V8s we had an "air limited" engine, yet you say that the max power point was below the max air point of 18000 rpm.
Now we have a fuel limited formula, yet you say that the max power can only be exactly at the point of max fuel.

What is the difference? Combustion chemistry can be equally limited by fuel or by air. So what makes an air limited formula conceptually different from a fuel limited formula in your eyes?

P.S. In the current formula max fuel is not at 10500rpm, it is at 10500-15000 rpm.

[J.A.W.]

With the V8s we had an "air limited" engine, yet you say that the max power point was below the max air point of 18000 rpm.
Now we have a fuel limited formula, yet you say that the max power can only be exactly at the point of max fuel.

What is the difference? Combustion chemistry can be equally limited by fuel or by air. So what makes an air limited formula conceptually different from a fuel limited formula in your eyes?

P.S. In the current formula max fuel is not at 10500rpm, it is at 10500-15000 rpm.

I think perhaps that S.S. fails to take into account the relative gearing advantage enjoyed by
the current formula, whereby the max-rpm range of the engine is effectively only ~55-60% of
the prior super-high revving N/A engines, yet sans any reduction in effective ratios available.

[saviour stivala]

The formula 1 NA engine in whatever make/configuration and capacity plus year of manufacture was always designed and optimised to attain its maximum power speed 500rpm below the maximum RPM it could operate at for at least a race distance, and or below the imposed maximum RPM limit. The NA engines that had no fuel flow restrictions imposed where optimised to reach the so called ‘lovel factor’ (max induction air speed) at the targeted maximum power speed, above which speed no more power could be produced because of (diminishing air volume). Using regular pump fuel the strongest combustion can be had at a fuel/air ratio of 14.7:1. Moving one of the two, fuel or air up or down in numbers, the combustion can only gat weaker/less powerful.
Burning fuel makes power, burning more fuel makes more power.

[Tommy Cookers]

....The NA engines that had no fuel flow restrictions imposed where optimised to reach the so called ‘lovel factor’ (max induction air speed) at the targeted maximum power speed, above which speed no more power could be produced because of (diminishing air volume). Using regular pump fuel the strongest combustion can be had at a fuel/air ratio of 14.7:1. Moving one of the two, fuel or air up or down in numbers, the combustion can only gat weaker/less powerful.
Burning fuel makes power, burning more fuel makes more power.

none of this applies to current F1

yes 'my' 6 year old thorny question still seems valid (for the Sunday race anyway) .....
ie rpm climbing 16% up from 10500 must give an efficiency disadvantage somewhere (when full fuel rate used from
10500)

but if the rpm climb after upshift started (let's imagine) at 10000 the efficiency problem seemingly would be smaller
and in this case something over 10000 would be the lowest apparent on our TV screens

RETRO-EDIT
Note to self - the 'efficiency problem' is less than in 2014 etc because variable length inlet tracts were since allowed

[saviour stivala]

“None of this applies to the current F1 (power unit)”. On the contrary, all of it applies to the current F1 (power unit). We are still talking about an ICE that burns fuel to make power. The differences, while the NA ICE was always air restricted by design/optimised/tuned to achieve maximum power speed at a point 500rpm bellow the maximum RPM it could safely withstand for at least a race distance, and or whatever maximum RPM that was imposed. The present forced induction ICE is fuel restricted to a maximum power speed of 10500rpm, which is 4500rpm below its permitted maximum RPM of 15000.

[hollus]

The fuel and the oxidizer are equally important to make power. We take the O2 for granted, but it is no less important.
It is not true that the energy content is in the fuel. The energy content is in the difference between energy states of fuel and oxidizer compared to that of combustion products.