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I've been thinking if it would be possible to optimize an engine for less than 100 kg/h fuel flow and still achieve faster lap times.

The thinking is that the loss in power would be partially offset by:

1. Potentially higher thermal efficiency.
An engine optimized for lower peak fuel flow could achieve MBT at maximum allowed CR easier (assuming current engines are not there yet).
Lower combustion chamber thermal loading could allow more liberties in terms of compression ring height, thermal barrier coatings etc.
Assuming the engine would operate at the same lambda as a 100 kg/h engine the air flow requirements would be smaller, more potential for less aggressive valve timing or smaller, lighter valves which would translate into lower pneumatic pressure requirements and hence lower losses in the valvetrain. Smaller valve lift could potentially mean a cleaner piston crown.
Fired FMEP would be lower.
Main and big end bearings as well as piston pins would be less loaded meaning that diameters can be reduced lowering frictional losses even further. Actually this argument can be made for pretty much any lubricated joint that is loaded in some form by the firing loads.
Lower fluid flow rates and volumes.

2. Improved engine packaging.
Such an engine would allow for a smaller bore pitch and other architectural changes (main bearing support, gear train width, etc) that have the potential to reduce the engine volume overall. Of course the minimum PU weight limit would still have to be met but there is potential for aero benefits still.

3. Lower cooling requirements and smaller engine air intake.
All heat rejections would reduce in line with the reduction in fuel flow (or even more if I we consider the potential for higher thermal efficiency). This would mean that charge air cooler, water and oil radiators can all be smaller.

4. Lower starting fuel mass.
Self-explanatory

As an example let's consider assume that a 100 kg/h engine makes 800 hp. Maybe a 90 kg/h would not be the full 10% down on power - let's say it only makes 736 hp. Could a car lacking 64 hp make up for the power deficit by starting with a much lower fuel load, smaller radiators and air intake and better engine packaging ?

Does anyone have an inkling of how sensitive the lap time is to car weight and radiator size compare to engine power ?
Also, are chassis bits allowed to intrude into the FIA defined engine box ?

Largely pointless within the current regulations. The minimum weight requirement of the cars pretty much negates any advantage you could get from running less fuel.

Minimum weight is for the car without any fuel right?

But putting that weight where you want it is better than having it sloshing around high up in a fuel tank.

Swapping fuel weight for ballast is a tiny gain, but they're in to tiny gains these days.

Odd question, but must the engines be 1.6L? Could they drop to 1.55L if they wanted to?

Can't be smaller.

due to cost savings, most engine format is regulated. Else, a company like Daimler could just test anything from a one cylinder 1.0. to a V12 with different size bores per cylinder, etc etc.

from the top of my head it must be a 90degree V6, with one turbo and a set bore and stroke. Exhausts must be on the outside and max 4 valves. Minimal weight for each component, list of banned materials and even a minimum hight for the CoG.

What is not forbidden I think is cylinder cutting or skipping injections. But given the formula is aimed at pure efficiency and therefor the goal is to burn every drop of fuel at a downstroke, the aim would be to have the chambers as large and going as slow as possible.

having the same speed with less fuel could be achieved only by rule changes. For the PU, lower the min RPM (so they can burn even more efficient and less friction loss) or change the aerodynamic rules so downforce van be achieved more efficient (a F1 car is as draggy as a truck).

Mudflap wrote: ↑

19 Feb 2020, 01:34

Minimum weight is for the car without any fuel right?

Including fuel I believe

Maplesoup wrote: ↑

19 Feb 2020, 03:05

Mudflap wrote: ↑

19 Feb 2020, 01:34

Minimum weight is for the car without any fuel right?

Including fuel I believe

I think it's dry weight, or they would all fail post race weight checks.

Maplesoup wrote: ↑

19 Feb 2020, 03:05

Mudflap wrote: ↑

19 Feb 2020, 01:34

Minimum weight is for the car without any fuel right?

Including fuel I believe

Without fuel. Therefore most races cars don’t take the full 110 kg on board at the start.

The weight regulations is the problem.

If the wieght was free and the engine was free. We wouldsee classic Prosche 911 turbo GT2 versus prosche GT3 RS philosphies.
Heavy turbo engine with gobs of toque versus light weight engine free revving spirit.

I always thought a 3.0l V10 with 600kg weight without driver with curent aero regs would be way faster than waht we have now. That balance between parts sizes, weight, power and laptime is so profound.

The advantages from lower overall car weights would net be there on saturday or at the end of the race, so it loses some value.

5 years ago I made a very simple F1 sensitivity model with Optimum Lap. Veeeeeeeery simplified!
viewtopic.php?p=564563#p564563

hollus wrote: ↑

21 Mar 2015, 13:36

To give a view on the relative influence of the different parameters on lap time, this brutally simplified car, in its average simplified lap around an average simplified track...

...to improve lap time by 1 second must either:

a) Shed 14.3% of its drag (without downforce loss)
b) Improve downforce by 6.0% (without a drag penalty)
c) Gain 69.7HP (everywhere, no consideration electric power at the beginning of the straights)
d) Shed 33.6kg of weight (or fuel)

That gives you ballpark figures for what you need to gain to recover those 64HP. All parameters behaved in a rather linear way, so you can combine small gains in different aspects just by adding the proportional gains.

hollus wrote: ↑

21 Mar 2015, 13:36

To give a view on the relative influence of the different parameters on lap time, this brutally simplified car, in its average simplified lap around an average simplified track...

...to improve lap time by 1 second must either:

a) Shed 14.3% of its drag (without downforce loss)
b) Improve downforce by 6.0% (without a drag penalty)
c) Gain 69.7HP (everywhere, no consideration electric power at the beginning of the straights)
d) Shed 33.6kg of weight (or fuel)

. . or approximately:

a) 14%
b) 6%
c) 10%
d) 5%

Zynerji wrote: ↑

19 Feb 2020, 03:08

Maplesoup wrote: ↑

19 Feb 2020, 03:05

Mudflap wrote: ↑

19 Feb 2020, 01:34

Minimum weight is for the car without any fuel right?

Including fuel I believe

I think it's dry weight, or they would all fail post race weight checks.

All teams announce the amount of fuel they intend to use for the race when weighed they weigh the car then drain the fuel and weigh it again.

But I stand corrected the weight limit includes the driver but not the fuel

hollus wrote: ↑

19 Feb 2020, 09:26

The advantages from lower overall car weights would net be there on saturday or at the end of the race, so it loses some value.

5 years ago I made a very simple F1 sensitivity model with Optimum Lap. Veeeeeeeery simplified!
viewtopic.php?p=564563#p564563

hollus wrote: ↑

21 Mar 2015, 13:36

To give a view on the relative influence of the different parameters on lap time, this brutally simplified car, in its average simplified lap around an average simplified track...

...to improve lap time by 1 second must either:

a) Shed 14.3% of its drag (without downforce loss)
b) Improve downforce by 6.0% (without a drag penalty)
c) Gain 69.7HP (everywhere, no consideration electric power at the beginning of the straights)
d) Shed 33.6kg of weight (or fuel)

That gives you ballpark figures for what you need to gain to recover those 64HP. All parameters behaved in a rather linear way, so you can combine small gains in different aspects just by adding the proportional gains.

Thanks hollus.
I think what I really need is change in drag as a function of heat rejection.

I suppose the CFD boys could work out the numbers assuming that radiator face area is proportional to heat rejection?

Any idea if someone has done this already ?

I would expect that drag from radiators to be a tiny portion of overall drag in which case it is still better to target peak output.

The weight sensitivity still looks reasonable, I think drivers were quoting 0.3 tenths per 10 kg fuel during the first week of testing.