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

[henry]

maybe very off topic from the original question, but I think this fuel flow limit is one of the key things mercedes got right compared to Renault and Ferrari in 2014. It is very counter intuitive that with every extra rpm above 10.500 the fuel per cycle is less. To keep the golden 1/14 fuel/air ratio, they have to limit the air above that rpm (lower boost) or run less then a 1/14 ratio. This combined that no fuel must go to waste. Compared to more rpm = more power and unburned fuel is no problem (even good for cooling) in the old N/A era

this is one of the reasons I do like the latest formula, a whole new way of thinking.

They run a long way from 14:1. Probably in the region of 22:1.

[stevesingo]

Suggesting that a particular formula car/one engine peak power was being produced at 11500 rpm means that car/engine maximum fuel flow has been shifted from the mandatory 10500 rpm to 11500 rpm.

Conventionally you would expect peak power to coincide with the lowest rpm where max fuel flow is available.

These engines are not conventional. Add in the effects of MGU-K and MGU-H in particular and I don't suppose it is clean cut.

[saviour stivala]

Suggesting that a particular formula car/one engine peak power was being produced at 11500 rpm means that car/engine maximum fuel flow has been shifted from the mandatory 10500 rpm to 11500 rpm.

Conventionally you would expect peak power to coincide with the lowest rpm where max fuel flow is available.

These engines are not conventional. Add in the effects of MGU-K and MGU-H in particular and I don't suppose it is clean cut.

The effects or otherwise of the ‘K’ and ‘H’ have nothing to do with this subject at hand. Yes these engines are not conventional but some facts cannot be stretched like a rubber band according to personal imaginations. The rules mandate a maximum fuel flow of 100kg/h @ 10500rpm, and it is at this maximum fuel flow and maximum RPM were each of the 31500 combustions per minute produced will peak their outputs. Each of these combustions will peak their outputs by using the 0.0528 grams of fuel permitted by the rules. Past that maximum RPM the number of combustions per minute increases, any additional increase in the number of combustions per minute will have to share the same 0.0528 grams of fuel permitted with the other 31500 combustions, this means less grams of fuel per combustion, les grams of fuel per combustion means each combustion is being weakened from the peak they had reached at the maximum permitted fuel flow. Each combustion of the best of these engines at its peak at the permitted maximum fuel flow/RPM, are bettering 0.0266 BHP per combustion, which means each cylinder is bettering 140 BHP at their highest possible racing mode.

[hollus]

Which would you prefer: optimized for max power with 1000 hp @ 10500 rpm with 980 @ 11000, 960 @ 11500 and 940 @ 12000 rpm (traditional route); or, optimized for area under the curve, 970 @ 10500 (less than otherwise possible), 980 @ 11000, 980 @ 11500, 970@ 12000?
The second one would be optimized for combustion at 11250 rpm, meaning you are never more than 750 rpm away from that, at the cost of less ideal combustion at 10500.

The numbers are completely made up, of course.

[hollus]

There ia also this from Cosworth plans for the 2014 formula, when they were naively planning to rev close to 15000. Max output was expected well above 10500rpm.

[henry]

Which would you prefer: optimized for max power with 1000 hp @ 10500 rpm with 980 @ 11000, 960 @ 11500 and 940 @ 12000 rpm (traditional route); or, optimized for area under the curve, 970 @ 10500 (less than otherwise possible), 980 @ 11000, 980 @ 11500, 970@ 12000?
The second one would be optimized for combustion at 11250 rpm, meaning you are never more than 750 rpm away from that, at the cost of less ideal combustion at 10500.

The numbers are completely made up, of course.

Made up but not far from the numbers I got from my analysis.

[gruntguru]

Suggesting that a particular formula car/one engine peak power was being produced at 11500 rpm means that car/engine maximum fuel flow has been shifted from the mandatory 10500 rpm to 11500 rpm.

Conventionally you would expect peak power to coincide with the lowest rpm where max fuel flow is available.

These engines are not conventional. Add in the effects of MGU-K and MGU-H in particular and I don't suppose it is clean cut.

The rules mandate a maximum fuel flow of 100kg/h @ 10500rpm, and it is at this maximum fuel flow and maximum RPM were each of the 31500 combustions per minute produced will peak their outputs. Each of these combustions will peak their outputs by using the 0.0528 grams of fuel permitted by the rules. Past that maximum RPM the number of combustions per minute increases, any additional increase in the number of combustions per minute will have to share the same 0.0528 grams of fuel permitted with the other 31500 combustions, this means less grams of fuel per combustion, less grams of fuel per combustion means each combustion is being weakened from the peak they had reached at the maximum permitted fuel flow.

The above is correct although you continuously specify 10,500 rpm as the point of maximum fuel flow which is not correct. Maximum fuel flow is available from 10,500 to 15,000 rpm.

The quote below is not correct.

Each combustion of the best of these engines at its peak at the permitted maximum fuel flow/RPM, are bettering 0.0266 BHP per combustion, which means each cylinder is bettering 140 BHP at their highest possible racing mode.

1. It is not correct to equate fuel-per-combustion event (fuel/CE) to power/CE. It should be energy/(CE).

2. Although the fuel/(CE) and energy/(CE) will reduce as rpm increases above 10,500, the power available is constant because there are more CE per unit time. (Power = energy per unit time).

3. (As I said previously) the only reason power reduces above 10,500 is increasing friction and other losses and this will be a gradual tapering of power.

4. It is relatively easy to shift the peak power rpm slightly (to say 11,000) by optimising various engine parameters for the higher rpm. Because of friction etc the peak power will be slightly less than it would be if optimised for 10,500. However the average power across the rpm range used will be higher if optimised for the higher rpm. I have created two power curves to illustrate the difference. Look at the operating range from 10,500 to 11,500 and decide which power curve you would prefer.

[saviour stivala]

“The rules mandate a maximum fuel flow of 100kg/h@10500rpm, and it is at this maximum flow and maximum RPM were each of the 31500 combustions per minute produced will peak their outputs. Each of these combustions will peak their outputs by using the 0.0528 grams of fuel permitted by the rules. Past that maximum RPM the number of combustions per minute increases, any additional increase in the number of combustions per minute will have to share the same 0.0528 grams of fuel permitted with the other 31500 combustions, this means less grams of fuel per combustion, less grams of fuel per combustion means each combustion is being weakened from the peak they have reached at the maximum permitted fuel flow”. (The above is correct) Thank you for confirming granguru. “you continuously specify 10500rpm as the point of maximum fuel flow which is not correct. Maximum fuel flow is available from 10500 to 15000rpm” Yes according to the rules 10500rpm is the point at which maximum fuel flow is reached. I never said that above 10500rpm maximum fuel flow is not available, what I was saying all along was that above 10500rpm a constant fuel flow will be weaker/will be less in volume for the needs of the increased number of combustions. And that is why past 10500rpm combustions will start to fall from their developed peak. Shifting the peak (maximum) power speed from 10500rpm upwards or downwards is not possible. Downwards because the maximum fuel flow is not there yet. And upwards because the extra number of combustions having to share the same amount of fuel will be weaker. There should be no doubt that above the maximum power speed of 10500rpm engine output will not increase simply because the extra fuel flow needed to sustain the extra number of combustions at their peak output at the higher RPM is simply not there. The racing engines being run/used at a higher RPM than their maximum power speed for upshifting, being they NA or forced induction, seems to have pushed some into a lot of imaginations, it has nothing to do with increasing the power output, this way of running/using the engines have been there forever. It is in itself an interesting subject.

[Tommy Cookers]

.... I was saying all along was that above 10500rpm a constant fuel flow will be weaker/will be less in volume for the needs of the increased number of combustions. And that is why past 10500rpm combustions will start to fall from their developed peak.
Shifting the peak (maximum) power speed from 10500rpm upwards or downwards is not possible. Downwards because the maximum fuel flow is not there yet. And upwards because the extra number of combustions having to share the same amount of fuel will be weaker. There should be no doubt that above the maximum power speed of 10500rpm engine output will not increase simply because the extra fuel flow needed to sustain the extra number of combustions at their peak output at the higher RPM is simply not there....

the statements above are wrong ....because 'combustions' won't as claimed 'fall from their developed peak' .....

if the claimed 'developed peak' has a lower AFR (though still lean of course) than optimal - it won't be the real 'peak'
eg if there's overall-efficiency optimal AFR used at some rpm over 10500 (say 11100) then the real 'peak' will be at 11100

optimal AFR has greatest efficiency - as there's more air the combustion gas is cooler so far less heat is taken to coolant
this is how the principle of heat dilution by high boost gives improved efficiency (and less heat is wasted in exhaust)
as less of the fuel's heat is dumped to atmosphere more is converted to work done on the pistons
going to greater AFR than optimal means efficiency falls again as combustion is inconsistent or incomplete

the unknown is how much they do as I suggest above
eg constant optimal AFR via eg 95 kg/hr at 10500 rising to 100 kg at 11100
(this doesn't prevent use of 100 kg/hr at 10500 rpm if/when desired)
and whether they do other things as I suggested in my previous post

[saviour stivala]

"constant optimal AFR via eg 95kg/h at 10500 rising to 100kg at 11100" means shifting the maximum fuel flow point up by 600 rpm and that will be in breach of the rules. But than, it looks like 'to hell with the rules' as long as some facts said by others are opposed just for the sake of opposing.

[hollus]

"5.1.4 Fuel mass flow must not exceed 100kg/h.
5.1.5 Below 10500rpm the fuel mass flow must not exceed Q (kg/h) = 0.009 N(rpm)+ 5.5."

That's what is in the rules. Of course one is allowed to use less than 100kg/h at 10500rpm and 100kg/h at 11100rpm.

[henry]

"constant optimal AFR via eg 95kg/h at 10500 rising to 100kg at 11100" means shifting the maximum fuel flow point up by 600 rpm and that will be in breach of the rules. But than, it looks like 'to hell with the rules' as long as some facts said by others are opposed just for the sake of opposing.

Nobody is opposing for opposing sake. They have a different view of how these engines are operated. The engines have some radical differences from any that have been used before and the specific controlling regulation, fuel flow rate is also novel. Why is it so difficult to acknowledge that their operation might be different from previous norms?

The views that are different from yours are supported by the regulations and by empirical evidence.

[saviour stivala]

"5.1.4 Fuel mass flow must not exceed 100kg/h.
5.1.5 Below 10500rpm the fuel mass flow must not exceed Q (kg/h) = 0.009 N(rpm)+ 5.5."

That's what is in the rules. Of course one is allowed to use less than 100kg/h at 10500rpm and 100kg/h at 11100rpm.

"95kgh at 10500 rising to 100kg at 11100" means shifting the maximum fuel flow point up by 600rpm".

[hollus]

Which contradicts neither 5.1.4 not 5.1.5.
The rules do not prevent you from using less than the legally available resources.

[63l8qrrfy6]

"5.1.4 Fuel mass flow must not exceed 100kg/h.
5.1.5 Below 10500rpm the fuel mass flow must not exceed Q (kg/h) = 0.009 N(rpm)+ 5.5."

That's what is in the rules. Of course one is allowed to use less than 100kg/h at 10500rpm and 100kg/h at 11100rpm.

"95kgh at 10500 rising to 100kg at 11100" means shifting the maximum fuel flow point up by 600rpm".

what is the problem with that ?