Power=economy?

[mertol]

I was thinking about why would a more powerful engine consume more fuel when they are all restricted to 100kg/hour. And I came to the conclusion that it doesn't it is actually more economic too here is why:
-The powerful engine is faster on the straights so it spends less percentage of the time at full throttle.
-The powerful engine reaches higher top speeds which means it has longer gears which means it works at lower rpm overall.
What do you think?

[hollus]

Kind of in the right track, IMO, although I don't think the gearing will be a big difference between teams this year.

Once we are at it, can we put to bed the concenpt that a less draggy car (likely to also produce less downforce) is using less fuel?
This year all cars will have the same amount of fuel available while at full throttle. This can be the fuel flow limit, or in cases where the total fuel becomes the lmit, a self imposed limit of, say, 95Kg/h. And you will use that much fuel for however many seconds you are at full throttle, no matter your power or drag levels.
Ironically, the fastest car might also have the largest amount of fuel available, as its race has less seconds in it.

Second order effects to be cosidered, though:

A car with more downforce spends a bit more time in the straights than in the corners compared to other cars, accelerates a bit earlier and brakes a bit later, so, yes, there is a bit of extra fuel consumption there, but it is more a consequence of the downforce than of the assocaited drag.

While changing your drag won't save you much fuel, a car that is down in power will optimize its lap time with a slightly lower downforce/drag level. But notice that lower power is the cause and lower drag the effect, and not the other way around. (unless I got this backwards).

[turbof1]

Kind of in the right track, IMO, although I don't think the gearing will be a big difference between teams this year.

Once we are at it, can we put to bed the concenpt that a less draggy car (likely to also produce less downforce) is using less fuel?
This year all cars will have the same amount of fuel available while at full throttle. This can be the fuel flow limit, or in cases where the total fuel becomes the lmit, a self imposed limit of, say, 95Kg/h. And you will use that much fuel for however many seconds you are at full throttle, no matter your power or drag levels.
Ironically, the fastest car might also have the largest amount of fuel available, as its race has less seconds in it.

Second order effects to be cosidered, though:

A car with more downforce spends a bit more time in the straights than in the corners compared to other cars, accelerates a bit earlier and brakes a bit later, so, yes, there is a bit of extra fuel consumption there, but it is more a consequence of the downforce than of the assocaited drag.

While changing your drag won't save you much fuel, a car that is down in power will optimize its lap time with a slightly lower downforce/drag level. But notice that lower power is the cause and lower drag the effect, and not the other way around. (unless I got this backwards).

Downforce and drag are a bit too simplified there imo. Take 2 cars with the same drag but one has more downforce (so also a better L/D). If the higher downforce one races to its limits it'll consume more fuel then the first car, but if it laps around the same time as the the first car, it consumes less.

Take also note that during the race the fuel consumption rate is averagely lower. A race that takes 90 minutes means an average rate of 66kg/h. So it isn't only about efficiency on the 100kg/h line, but also below that. I'm assuming efficiency isn't linear for all fuel rates.

[hollus]

Take 2 cars with the same drag but one has more downforce (so also a better L/D). If the higher downforce one races to its limits it'll consume more fuel then the first car...

But would it really? That high downforce car, driving to its limits, would also drive to a lower lap time. With higher corner exit speeds it might well end up spending less total time in the straight and less time at full throttle. Where is the extra fuel consumption going to come from?

[turbof1]

Take 2 cars with the same drag but one has more downforce (so also a better L/D). If the higher downforce one races to its limits it'll consume more fuel then the first car...

But would it really? That high downforce car, driving to its limits, would also drive to a lower lap time. With higher corner exit speeds it might well end up spending less total time in the straight and less time at full throttle. Where is the extra fuel consumption going to come from?

Simple: you can can apply throttle earlier when coming out of the corner because you have more grip AND you can brake later, because you have more aerodynamic braking (not the same as drag!) and can carry more speed into the corner entry. In order words you are x% more on throttle during the lap. Since drag remains the same, you'll be achieving a higher top speed (because you can accelerate earlier out of the corner before the straight and have to brake later).

I believe you are missing something when just looking at the laptime. A laptime isn't solely influenced by being on throttle, but also being on the brakes and not on throttle. It's more about the percentage you are on throttle. Spending in relative terms x% amount of fuel more during a lap will not bring down the lap with the same x%. The latter will always be less then x!

[Dragonfly]

I think you are drifting away from the original question which, if I understand it correctly, is about the engine and the delivered power under a fuel consumption cap. If there are two engines consuming the maximum allowed fuel but one delivers more power then it appears that the more powerful one can accomplish some fuel saving.
But I think this should be referred to the power unit as a whole as they are now. Up to this year there were two ways to more power - increased fuel consumption and increased engine efficiency, or both. In a fuel flow limited formula only the efficiency route is left while ERS system brings some totally new aspects with its capabilities to utilize dissipated power in the most efficient way.
So if we leave aside drag and downforce, etc. assuming they are equal, it seems so that a more powerful PU can actually save fuel especially during periods when less or equal power is required to preserve an achieved gap.

[Robbobnob]

To answer the question we must first understand it.
Lets define the terms; Economy, can be defined as: the careful management of available resources.

When applied to an internal combustion engine, the available resource is the fuel. With a controlled maximum fuel rate, the available energy into the system is the same for any engine.

Efficiency, when used in Thermodynamics refers to the ratio of 'output vs the required input'. Therefore, when the maximum input is dictated, the engine with the highest output would in simplified terms be the most efficient.

Economy would be used to describe the achievement of a goal when compared to the resources. Is the goal to achieved the highest relative power output, then the Engine with the highest power output would intern also have the highest fuel economy, in terms of power for a set resource. If the goal was to achieve the furthermost distance travelled per the available resources, then the highest specific output would be counter productive to that argument and a more efficient engine mode when comparing internal losses vs external output would be preferred to achieve a good economy.

Economy in a Formula 1 sense is related to completing a set distance in the least amount of time. For a restricted fuel flow, the car which achieves the distance in the least time, within the constraint of the maximum fuel usage will be the most economic.

The energy recovery aspect will complicate manner when discussing this more, as there will be efficiencies in the energy recovery and conversion into electrical power, then inversely from electrical power through to mechanical power. As the energy is recovered through quite different mechanical systems and not based on a fundamental thermodynamic cycle, such as the Carnot, comparing relative performances in terms of fuel efficieny might not be the most consistent measure due to the relative influence each driver will have on the economy.

[Dragonfly]

Yes. I agree that "economy" is too moot a term.
ICE efficiency and all aspects of the new PU were discussed a lot in the new engines thread which grew so large that is now difficult to grasp.
I think the initial question here was provoked by the claims that Mercedes engine deliver more power in comparison with the rest. And it's interesting to me if that is the case will they put less fuel and gain wight advantage or use more downforce (and respectively drag) while using the same amount of fuel and gain in lap times through higher corner speeds and/or better acceleration.
I think once the season is on those questions will start getting their answers on race by race basis. Not much of the old strategies as we know can be applied to the new format.

[Per]

Take 2 cars with the same drag but one has more downforce (so also a better L/D). If the higher downforce one races to its limits it'll consume more fuel then the first car...

But would it really? That high downforce car, driving to its limits, would also drive to a lower lap time. With higher corner exit speeds it might well end up spending less total time in the straight and less time at full throttle. Where is the extra fuel consumption going to come from?

Simple: you can can apply throttle earlier when coming out of the corner because you have more grip AND you can brake later, because you have more aerodynamic braking (not the same as drag!) and can carry more speed into the corner entry. In order words you are x% more on throttle during the lap. Since drag remains the same, you'll be achieving a higher top speed (because you can accelerate earlier out of the corner before the straight and have to brake later).

I believe you are missing something when just looking at the laptime. A laptime isn't solely influenced by being on throttle, but also being on the brakes and not on throttle. It's more about the percentage you are on throttle. Spending in relative terms x% amount of fuel more during a lap will not bring down the lap with the same x%. The latter will always be less then x!

Less than x, but still greater than zero. What you are neglecting is the crucial fact that all the things you are saying (particularly greater cornering speed) also lead to faster speed on the straight, so less time spent on the straight. At a constant fuel flow in kg/h this will lead to less fuel used to complete the straight. This is basic physics.

In conclusion, if you take identical cars but one has higher downforce (for the same drag), the one with higher downforce will consume less fuel per lap and have a faster lap time.

The topic starter is right in his thinking, although it is of course a simplified version of reality. For example, they might be racing on 95 kg/h to stay under 100 kg total consumption, and one engine might suffer a bit more from that than the other. But I expect these effects to be smaller than the outright difference of performance/efficiency there will be when all engines are running at 100 kg/h.

[WhiteBlue]

Power in the new formula comes from efficiency. Efficiency can be increased in many disciplines. You can reduce friction, reduce thermal losses, have more efficient and leaner combustion, you can recover more heat energy, more kinetic energy, loose less energy in conversions like energy storage and utilize more of the stored energy than your next best competitor. So there are many ways to generate more power and they all are governed by particular efficiency fields. The only thing that is tactical and does not involve engineering for efficiency is the decison when to expend more fuel than your average fuel curve and when to save it back in a race. That is pure tactical capability of the team and not in the hands of the engineers who designed the car and the power unit.

[Ciro Pabón]

Oh, sure. If you extrapolate this thread assumption we can quickly conclude that an infinite power engine would have zero fuel usage, while a zero power engine would have infinite fuel consumption.

Simple: with infinite power, you could accelerate instantaneously and would arrive in zero time, having thus zero drag and zero rolling resistance.

Your speed would be infinite meaning that you wouldn't have any losses in acceleration: as the air surrounding the car will not be aware of the presence of the vehicle (it would spend zero time crossing the air volume over the track) you could affirm with confidence that drag would be zero.

It would be as if the car never passed through the atmosphere.

Of course, cornering would be a bit of an issue, but let's not become party poopers, will ya?

On the other hand, any engine delivering zero power would spend an infinite amount of gas, no matter how tiny its fuel usage, because you would be trying to arrive (but not succeeding, of course) in an infinite time.

In conclusion, small cars with small engines are killing the environment

That's why I drive a Hummer (well, my second car is a Cadillac Escalade, but I'm thinking of selling it and buying two Hummers: you can never save enough fuel these days).

Final consideration: everybody knows that hypermilers get their extraordinary fuel mileages by accelerating harder than the regular driver.

So, my recommendation for cars that are running low on fuel towards the end of the race is to push the throttle harder.

Jokes aside, everything being the same in terms of the car, the generation of power is directly proportional to the amount of fuel spent, dear friends.

[riff_raff]

Oh, sure. If you extrapolate this thread assumption we can quickly conclude that an infinite power engine would have zero fuel usage, while a zero power engine would have infinite fuel consumption.

Simple: with infinite power, you could accelerate instantaneously and would arrive in zero time, having thus zero drag and zero rolling resistance.

Your speed would be infinite meaning that you wouldn't have any losses in acceleration: as the air surrounding the car will not be aware of the presence of the vehicle (it would spend zero time crossing the air volume over the track) you could affirm with confidence that drag would be zero.

It would be as if the car never passed through the atmosphere.

Of course, cornering would be a bit of an issue, but let's not become party poopers, will ya?

On the other hand, any engine delivering zero power would spend an infinite amount of gas, no matter how tiny its fuel usage, because you would be trying to arrive (but not succeeding, of course) in an infinite time.

In conclusion, small cars with small engines are killing the environment

That's why I drive a Hummer (well, my second car is a Cadillac Escalade, but I'm thinking of selling it and buying two Hummers: you can never save enough fuel these days).

Final consideration: everybody knows that hypermilers get their extraordinary fuel mileages by accelerating harder than the regular driver.

So, my recommendation for cars that are running low on fuel towards the end of the race is to push the throttle harder.

Jokes aside, everything being the same in terms of the car, the generation of power is directly proportional to the amount of fuel spent, dear friends.

Ciro, you sure opened a can of worms with that comment, and I'll argue with you just for fun.

Since there is a limited amount of fuel carried by the car, and that fuel mass has a theoretical limit of energy it can produce via combustion, the amount of power the engine can produce is also limited. In theory, an engine producing infinite power would need to combust some fuel, since a system with zero energy input will always have zero net output. On the other hand, an engine could conceivably combust fuel without producing any net output, which would result in an infinite BSFC rate.

[andylaurence]

What's important here is that fuel flow is limited by time, but the race (and lap) are measured in distance. A lap time of 90 seconds allows 2.5kg of fuel to be spent, utilising the whole 100kg/hr. Reduce that lap time to 89 seconds and only 2.47kg of fuel is available. However, given the limit on the entire race of 100kg, a 90 minute race gives 66.7kg/hr, whilst a 100 minute race gives just 60kg/hr, yet both result in 33kg/100km for a nominal 300km race distance.

[Sebp]

I hadn't thought about it like that. It's pretty stupid in a way to have a fuel flow per hour limit. In the end every team has to make 100 kg last the race. Why limit the flow rate between start and finish when everybody's average consumption has to be the same anyway? Am I missing something?

[joseff]

What's important here is that fuel flow is limited by time, but the race (and lap) are measured in distance. A lap time of 90 seconds allows 2.5kg of fuel to be spent, utilising the whole 100kg/hr. Reduce that lap time to 89 seconds and only 2.47kg of fuel is available. However, given the limit on the entire race of 100kg, a 90 minute race gives 66.7kg/hr, whilst a 100 minute race gives just 60kg/hr, yet both result in 33kg/100km for a nominal 300km race distance.

5.1.4 Fuel mass flow must not exceed 100kg/h

What it actually means is, the peak rate of fuel flow must not exceed 100kg/hr. Not the average consumption over an hour.

Further:

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

Thus defining a max flow ceiling with a slope between 0 to 10500rpm, which then plateaus all the way to 15000.