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

[Dr. Acula]

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.

I recommend to have a closer look to one rule hollus has posted.

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

Well, we know that at 10500rpm they're allowed to reach 100kg/h flow rate. But how much fuelflow are they allowed to have at 5250rpm? Obvious isn't it...50kg...well, no!


but


So if they would go for the biggest bang per cycle, 10500rpm wouldn't even be that great.

[saviour stivala]

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

Those the rules allow you to shift the maximum fuel flow point up by 600rpm?

[saviour stivala]

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.

I recommend to have a closer look to one rule hollus has posted.

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

Well, we know that at 10500rpm they're allowed to reach 100kg/h flow rate. But how much fuelflow are they allowed to have at 5250rpm? Obvious isn't it...50kg...well, no!


but


So if they would go for the biggest bang per cycle, 10500rpm wouldn't even be that great.

Would the 'bang' be bigger/biggest at 11100rpm were the maximum fuel flow is being suggested that it will be shifted?

[Jolle]

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.

I recommend to have a closer look to one rule hollus has posted.

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

Well, we know that at 10500rpm they're allowed to reach 100kg/h flow rate. But how much fuelflow are they allowed to have at 5250rpm? Obvious isn't it...50kg...well, no!


but


So if they would go for the biggest bang per cycle, 10500rpm wouldn't even be that great.

Would the 'bang' be bigger/biggest at 11100rpm were the maximum fuel flow is being suggested that it will be shifted?

There is a big flaw in the theory that they wouldn't use 100kg/h fuel at 10.500 rpm to have the optimum power at 11.000. If they wanted to have their max power half way in the power band they use, they would let the rmp drop to 9.700 rpm or something and have max power at 10.500, where the natural highest efficiency of power is. They don't do this, so they have their peak at 10.500.

[Dr. Acula]

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

Those the rules allow you to shift the maximum fuel flow point up by 600rpm?

Yes they do. They always have. The rules really just say 2 things. Don't use more than 100kg/h. At lower than 10500rpm you can calculate the maximum allowed fuelflow with this lovely formula. Q (kg/h) = 0.009 N(rpm)+ 5.5.

Would the 'bang' be bigger/biggest at 11100rpm were the maximum fuel flow is being suggested that it will be shifted?

No, but that doesn't matter. Higher rpm will potentially give you a higher power output in the end. Basically with the rules as they are, you would have the most fuel per cycle available at very low rpm, basically at idle. But no team drives around with their engine at 4-6rpm because it makes no sense. Power of an engine/motor is the result of torque and rpm...or angular velocity if you wanna use SI units. So to make a lot of power you need a torque engine which revs quite high.
Potentially they win more power reving a good amount above 10500rpm than they lose through the torque lose when they go beyond the point when the max fuel limit is reached.

[roon]

Small displacement SI TC motorsports engines tend to spin around 8k - 12k rpm, across various series and eras. One exception being WRC which operate around 6k rpm. F1 and many others have found some sort of happy medium here between cylinder pressure, aspiration type, piston geometry, and engine speed.

[Tommy Cookers]

There is a big flaw in the theory that they wouldn't use 100kg/h fuel at 10.500 rpm to have the optimum power at 11.000. If they wanted to have their max power half way in the power band they use, they would let the rmp drop to 9.700 rpm or something and have max power at 10.500, where the natural highest efficiency of power is. They don't do this, so they have their peak at 10.500.

well what's wrong with the above is that they can never use more than 95 kg/hr at 9700

my way allows 95 kg/hr or anything up to 100 kg/hr at 10500
the best of both worlds

you could have CVT emulation with negligible losses and run a constant 10500
negligible losses as the CVT is the minor torque path in parallel with the existing gearbox

[saviour stivala]

"Potentially they win more power reving a good amount above 10500 rpm" They must be all fools not utilizing the maximum of 15000rpm allowed by the rules.

[Jolle]

There is a big flaw in the theory that they wouldn't use 100kg/h fuel at 10.500 rpm to have the optimum power at 11.000. If they wanted to have their max power half way in the power band they use, they would let the rmp drop to 9.700 rpm or something and have max power at 10.500, where the natural highest efficiency of power is. They don't do this, so they have their peak at 10.500.

well what's wrong with the above is that they can never use more than 95 kg/hr at 9700

my way allows 95 kg/hr or anything up to 100 kg/hr at 10500
the best of both worlds

you could have CVT emulation with negligible losses and run a constant 10500
negligible losses as the CVT is the minor torque path in parallel with the existing gearbox

With the current rules, if they wish to use only 95kg/h, they would do that at the lowest rpm possible because that gives the most power because of the less friction and is the most efficient. If they want 95 instead of 100 kg/h during a part of the race, they would just shift a fraction earlier. That way you get the most bang from your fuel. Lower fuel flow at 10.500 rpm is a pure waste of energy.

[gruntguru]

"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".

There you go again. There is no "maximum fuel flow point". Maximum fuel flow is a range from 10,500 to 15,000.

[gruntguru]

“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”.

Here is the flaw in your logic.

Consider a rpm range from 10,500 - 15,000 with constant fuel flow rate at any rpm in this range. For now lets neglect friction and other losses.
- Yes, individual combustion events are most energetic at 10,500.
- Yes, if you increase rpm by 10%, each combustion event will be 10% weaker.
- No, The power will not reduce by 10% due to the weaker combustion events - the TORQUE will reduce by 10%.
- Power = Torque x speed. The torque has reduced by 10% and the speed has increased by 10%. The power is the same.

In reality the power does reduce somewhat (less than 10%) due to losses but it is easy to optimise other factors to move the BEST EFFICIENCY point (same as the maximum power point) to a higher speed - say 11,000 or 11,500. These factors could include valve timing, valve sizes, port sizes, combustion chamber shape etc etc. Reducing fuel flow at particular speeds (completely legal) could shape the power curve but is not realistic for any modes other than fuel conservation.

[Tommy Cookers]

With the current rules, if they wish to use only 95kg/h, they would do that at the lowest rpm possible because that gives the most power because of the less friction and is the most efficient. If they want 95 instead of 100 kg/h during a part of the race, they would just shift a fraction earlier. That way you get the most bang from your fuel. Lower fuel flow at 10.500 rpm is a pure waste of energy.

you write as if efficiency was determined (in a given engine) only by friction
efficiency is determined by AFR more than by friction

because with these engines friction is unusually small
and indicated thermal efficiency is unusually large - and varies strongly with AFR eg going from 10500 to 12000 etc peak
because 15% change in air mass causes a disproportionately greater change in heat taken by coolant
far greater than the change in friction over that rpm range

ok AFR can be kept constant over 10500 to 12000 but exhaust pressure would be dropped disproportionately

[Jolle]

I think the more interesting question is what they do with air flow. Does the turbo speed stay the same from 10.500 forward, keeping the air/fuel mix level and have a drop in pressure in the cylinder or do they have a leaner fuel/air mixture with the rising of the revs (or both of course)

[Jolle]

With the current rules, if they wish to use only 95kg/h, they would do that at the lowest rpm possible because that gives the most power because of the less friction and is the most efficient. If they want 95 instead of 100 kg/h during a part of the race, they would just shift a fraction earlier. That way you get the most bang from your fuel. Lower fuel flow at 10.500 rpm is a pure waste of energy.

you write as if efficiency was determined (in a given engine) only by friction
efficiency is determined by AFR more than by friction

with these engines friction is unusually small
but indicated thermal efficiency is unusually large - and varies strongly with AFR eg going from 10500 to 12000 etc peak

could be, but for some reason all three of the original engine manufacturers where very clear to what rpm the engines shifted back to at 2014, 10500 rpm, the same revs where max fuel flow was beginning.

[Singabule]

In reality, driver prefer flat torque curve in corner exit, hence below 10K rpm the manufacturer would design the engine with flat torque but not flat power, however in straight flat power is preferable than flat torque. In connection to efficiency, lower RPM would be better than higher one, the main problem if the engine could withstand the heat and pressure in lower RPM (knock included), and more strurdy engine lead to heavier and bulkier one. Not to mention the Turbo and MGUH design and recovery, there is no straightforward answer of this. 2016 and 2017 honda engine as the best example when the manufacturer switch focus from driveability (high rpm) to efficiency (low RPM) , and it is troublesome and RA17 cant withstand the working conditions (even worse since the long shaft MGUH bend). Remember when Honda and Renault engine lose its conrod