18 replies to this topic

[rodlamas]

A bit of some technical question...

1) Cars can use up to 110kg of fuel per race, but we constantly listen to drivers on the radio being told to save fuel, follow the dash, lift and coast etc. Has anyone any idea on how much fuel cars are using per race?

2) On a track like Monza or Vegas, where they run woth very little downforce (and therefore much less drag), is the mileage (km/kg) higher than on a track such as Barcelona where cars are fully loaded with DF/drag?

3) If you go for a lower downforce set-up will you be able to run less fuel on a race than a driver that has more downforce? If so, how much less, % talking?

[MikeTekRacing]

A bit of some technical question...

1) Cars can use up to 110kg of fuel per race, but we constantly listen to drivers on the radio being told to save fuel, follow the dash, lift and coast etc. Has anyone any idea on how much fuel cars are using per race?

2) On a track like Monza or Vegas, where they run woth very little downforce (and therefore much less drag), is the mileage (km/kg) higher than on a track such as Barcelona where cars are fully loaded with DF/drag?

3) If you go for a lower downforce set-up will you be able to run less fuel on a race than a driver that has more downforce? If so, how much less, % talking?

Good topic. When the limit was put, it was tracked for a while on graphics.

i think cars will always be on the limit as nobody wants to carry additional weight - so they plan on saving fuel if not VSC or SC happen. 

Fuel consumption is rising with drag, not downforce levels. Drag grows with speed, so Monza would have a HUGE fuel consumption while Monaco will have the lowest (even if Aero load is different).

yes, less wing helps on Monza with both fuel consumption and ERS management.

[EvilPhil II]

I guess ironically the more fuel they carry the less fuel efficient they become due to the weight they have to move around. 

[pdac]

They mandate so many things these days (now, even the number of pit stops), so I don't see why they don't mandate that every car must start with the same amount of fuel. They'd still, of course, try to burn it off as soon as possible, but it might make for some different strategies.

 

As to how much they are using per race, it probably depends on the track, the weather and whether they think the safety car will be deployed. But it's sure to be as little as they can get away with.

[EvilPhil II]

They did mandate that the cars had their starting fuel prior to q3 qualifying a few years ago. And then we had 15 minutes of cars running around in fuel burn mode before doing flying laps.

[Brod]

A bit of some technical question...

1) Cars can use up to 110kg of fuel per race, but we constantly listen to drivers on the radio being told to save fuel, follow the dash, lift and coast etc. Has anyone any idea on how much fuel cars are using per race?

2) On a track like Monza or Vegas, where they run woth very little downforce (and therefore much less drag), is the mileage (km/kg) higher than on a track such as Barcelona where cars are fully loaded with DF/drag?

3) If you go for a lower downforce set-up will you be able to run less fuel on a race than a driver that has more downforce? If so, how much less, % talking?

 

Interesting questions. But compared to the good old fuel meters days....I think pretty irrelevant. Someone might correct me but the fuel consumption of these engines was all over the place at the beginning of the hybrid era compared to today. 

 

Or compare it to the ruefuel-era....when tank sizes, consumption and strategy varied extremely. In 1999 Frentzen was able to win Magny Cours with 1 Stop...not every car would've been able to do it....5 years later there was Schumacher winning it with 4 stops. 

[MikeTekRacing]

 

Or compare it to the ruefuel-era....when tank sizes, consumption and strategy varied extremely. In 1999 Frentzen was able to win Magny Cours with 1 Stop...not every car would've been able to do it....5 years later there was Schumacher winning it with 4 stops. 

That was more on the impossibility of overtaking. 

the Ferrari had so much more pace they could win with any number of pitstops, but had to get free air. 
Similar as Hungaroring 1998 when they had to release Michael from behind DC.

 

Overtaking was next to impossible on some occasions, even with different fuel levels.

[ATM]

Yeahhhh, I remember that period, not a good time to watch F1 overtaking. It did give us the Hakkinen-Schumacher move on Zonta but even that was a "go big or go home" moment.

Now, regarding the Monaco vs Monza fuel consumption and by doing a (stupid) analogy with road cars...a road car consumes most when în the city, start-brake-start, when în lower gears etc (that would be Monaco). The fuel does go up when going flat out, like on a highway (Monza), but still less than a city run. My point is I still don't understand exactly why Monaco would burn less fuel (other than it's a shorter race distance anyway).

[SparkPlug86]

I wonder what the actual mpg figure of an F1 car is on average? 

[NewMrMe]

I think there are a few factors which mean comparisons between motorway and city road driving don't really hold up when comparing high and low speed circuits.

 

• Drag is proportional to the square of the speed. At high racing speeds a small increase in speed can mean a large increase in drag and therefore make a noticeable difference in fuel consumption.
• On high speed circuits such as Monza cars are still frequently varying their speed, slowing down for corners and accelerating out of them. The main reason why fuel consumption on motorways is better is because your speed is constant. Similarly Indycars get better fuel consumption on super speedways than other circuits.
• What really kills your fuel consumption when driving in town or cities are the times when you are stationary waiting at junctions or traffic lights. Racing cars rarely stop unless they are making a pit stop.

[pdac]

They did mandate that the cars had their starting fuel prior to q3 qualifying a few years ago. And then we had 15 minutes of cars running around in fuel burn mode before doing flying laps.

 

That was qualifying, not the race.

[rodlamas]

One extra thing to consider: cars cannot burn more than 100kgs/hr of fuel.

So on a straight line past 10,500rpm the faster you go (due to wings, DRS, hybrid, tow etc) the greater mileage you get.

[MikeTekRacing]

Yeahhhh, I remember that period, not a good time to watch F1 overtaking. It did give us the Hakkinen-Schumacher move on Zonta but even that was a "go big or go home" moment.

Now, regarding the Monaco vs Monza fuel consumption and by doing a (stupid) analogy with road cars...a road car consumes most when în the city, start-brake-start, when în lower gears etc (that would be Monaco). The fuel does go up when going flat out, like on a highway (Monza), but still less than a city run. My point is I still don't understand exactly why Monaco would burn less fuel (other than it's a shorter race distance anyway).

a car in the city idles - and that’s terrible efficiency. You don’t idle in monaco. You don’t start stop either:)
Monaco is just low average speed - less time spent on max throttle, a lot of lifting etc.

[GreenMachine]

Fuel consumption is rising with drag, not downforce levels. Drag grows with speed, so Monza would have a HUGE fuel consumption while Monaco will have the lowest (even if Aero load is different).
yes, less wing helps on Monza with both fuel consumption and ERS management.

Half right.

Fuel consumption rises with drag. Drag rises exponentially with speed - but F1 drag is fundamentally a derivative of the lift/drag ratio where lift is negative (ie downforce). IOW you don't get downforce for nothing, it creates drag.  FI drag is a function of drag from airfoils, which is readily calculable if you know the airfoils (we don't), plus the drag from the underbody.  I haven't seen any numbers for the latter, probably only known by the teams, and probably tightly held within them too.

 

Anecdotally, drivers' comments about the decelleration when lifting from high speed may be indicative, but that would be the sum of drag, compression braking, and MGU-K regen.

 

Probably should have asked the question in the Technical Forum.

[Henri Greuter]

Not a present day value but one of the past that truly shocked me when I read about it.

 

 

1988 Monaco.

 

EVERY turbo car was going to struggle with fuel to make it to the end on the maximum of 150 liters allowed.

The McLaren-Honda's started the race with 140 liters since they didn't need the fuel anymore on the permitted maximum boost.

[PayasYouRace]

Yeahhhh, I remember that period, not a good time to watch F1 overtaking. It did give us the Hakkinen-Schumacher move on Zonta but even that was a "go big or go home" moment.

Now, regarding the Monaco vs Monza fuel consumption and by doing a (stupid) analogy with road cars...a road car consumes most when în the city, start-brake-start, when în lower gears etc (that would be Monaco). The fuel does go up when going flat out, like on a highway (Monza), but still less than a city run. My point is I still don't understand exactly why Monaco would burn less fuel (other than it's a shorter race distance anyway).

When driving on the road in a city, your car is using lots more fuel for going very little distance. A excess of fuel is burned when travelling at very low speeds (or stopped) which is incredibly inefficient. With fuel economy there is a sweet spot of speed below and above which you’re being less efficient. Below because you’re burning too much fuel for the distance you actually travel, and above because you need more power to overcome drag. Racing at Monaco (at above typical motorway speeds) is well above that maximum range speed for the car. It’s actually in the “highway” side of that curve, just less so than at Monza.

Coupled to the fact that racing at Monza is still flat out and hard braking, not motorway cruising, means there’s no respite like you do on the motorway. Unless you’re in a very small engined car, you’re not flat out on the motorway.

[LegendInTheMaking]

Going back to the original question: the current F1 fuel is E10 petrol, which means it a mixture of 90% petrol and 10% ethanol. Petrol has a density of 720 kg/m^3 at 20 degrees c, whereas ethanol density is 789 kg/m^3. This makes an average of 727 kg/m^3. This means the 110kg allowed amount equals to about 151l of E10, even though this can vary with temperatures. According to this article, the fuel tanks used in practice are between 130-145l. As 1kg needs to be submitted to the FIA after the race, effectively 0.9% is not consumable. 

 

Building on the example of the Italian GP: 53 laps at Monza equals 306.7km, so including a lap to the grid, the formation lap and a lap after the race has finished, it adds up to about 325km. This means the fuel consumption needs to equal 145l * 99,1% / 325km to be compliant, or 130l * 99,1% / 325km with the smaller fuel tank. This gives a range of 40-44l/100km over the full distance. Or, for the non-metrics amongst us, that is about 5.9-5.4 MPG. Mind you, of the 325km covered, 306.7km was done at an average of over 246km/h by Lando Norris last year.  

 

By comparison: in the heyday of the turbo era, Alain Prost took almost 1:18 hour to finish 51 laps at Monza, equaling 295.8km of race distance and about 313km in total, with 220 liters of fuel. Here, the average race speed was 'only' 227km/h, with fuel consumption of 70l/100km or 3.3 MPG. As there were no strict fuel regulations in those days, the comparison is not a straightforward one though. 

 

So, even though there are obviously a lot of assumptions in play in the comparison above and there are different circumstances, an argument can be made for the relative efficiency of modern day F1 engines. 

 

There are a bunch of interesting articles about the subject of the efficiency compared to the output of modern day F1 engines:

Motorsport Magazine about the current engine formula.

F1 dictionary explaining fuel thermal efficiency.

Honda on their development journey from 2015 to 2021.

 

Edit: numbers correction. Thanks Henri Greuter!

Edited by LegendInTheMaking, Yesterday, 11:29.

[Wuzak]

Imagine them racing at Indy for a Grand Prix distance.

 

If an average speed of ~310kph can be acheived, the race will take 1 hour and the maximum fuel consumption would be 100kg (maximum fuel flow 100kg/hr).

[Henri Greuter]

Going back to the original question: the current F1 fuel is E10 petrol, which means it a mixture of 90% petrol and 10% ethanol. Petrol has a density of 720 kg/m^3 at 20 degrees c, whereas ethanol density is 789 kg/m^3. This makes an average of 753 kg/m^3. This means the 110kg allowed amount equals to about 146l of E10, even though this can vary with temperatures. According to this article, the fuel tanks used in practice are between 130-145l. As 1kg needs to be submitted to the FIA after the race, effectively 0.9% is not consumable. 

 

Building on the example of the Italian GP: 53 laps at Monza equals 306.7km, so including a lap to the grid, the formation lap and a lap after the race has finished, it adds up to about 325km. This means the fuel consumption needs to equal 145l * 99,1% / 325km to be compliant, or 130l * 99,1% / 325km with the smaller fuel tank. This gives a range of 40-44l/100km over the full distance. Or, for the non-metrics amongst us, that is about 5.9-5.4 MPG. Mind you, of the 325km covered, 306.7km was done at an average of over 246km/h by Lando Norris last year.  

 

By comparison: in the heyday of the turbo era, Alain Prost took almost 1:18 hour to finish 51 laps at Monza, equaling 295.8km of race distance and about 313km in total, with 220 liters of fuel. Here, the average race speed was 'only' 227km/h, with fuel consumption of 70l/100km or 3.3 MPG. As there were no strict fuel regulations in those days, the comparison is not a straightforward one though. 

 

So, even though there are obviously a lot of assumptions in play in the comparison above and there are different circumstances, an argument can be made for the relative efficiency of modern day F1 engines. 

 

There are a bunch of interesting articles about the subject of the efficiency compared to the output of modern day F1 engines:

Motorsport Magazine about the current engine formula.

F1 dictionary explaining fuel thermal efficiency.

Honda on their development journey from 2015 to 2021.

 

I think your calculation of 753 kg/m^3 is not correct.

That seems to be an average of both values on a  1:1 ratio.

 

But if I use the percentages you given I get a weight of 727 kg/m^3

But then I have not considered the fact that there is a chance that the volume is slightly less because of the smaller ethanol molecules hiding within the dead volume of the petrol molecules. The same effect you get when mixing given volumes of water and methanol together always ending up with a smaller volume than the two individual volumes added up.

Edited by Henri Greuter, Yesterday, 10:56.