Fuel Limit Changes

[Scootin159]

Originally the fuel limit was 100kg/hr maximum flow and 100kg/race total. They then raised the per-race limit to 105kg, and now 110kg. There's been much speculation that this is all for naught, as there are only one or two races per season where the entire 105kg/race was being used - it was almost always better to just run lighter and plan on saving fuel at some point in the race.

My question is - could this maximum fuel capacity per race be used as a way to circumvent the 100kg/hr flow rate limit? In particular, would it be possible to implement an accumulator of some sort after the fuel flow meter, but before the injectors, allowing you to "save" some fuel during off-throttle times to "spend" during full-throttle times?

Thinking of the same idea, but in a different way, could you have the "accumulator" above be in the battery instead of the fuel rail? The idea being that under "low torque demand" you still burn fuel in the engine, but limit power unit output torque to the driver-demanded level by harvesting in the MGU-K? This way you can generate during part or off throttle operation more aggressively than allowed by braking alone, and using the reserve to have more electric power on the straights. Running the engine at 100% during part-throttle operation would also have the added benefit of increasing exhaust gasses, helping spool the turbo (saving the electrical power used in the MGU-H for this purpose).

[henry]

Accumulators are banned.

They already use the MGU-K in the way you describe. Pretty much all the time in qualifying, when there is no limit on the quantity of fuel burned, and likely in extremis in the race, preparing for overtake or defence.

[MrPotatoHead]

The only reason the max fuel load isn't used most of the time is because of the fuel flow limit.

[Scootin159]

.... and they just announced they're dropping the fuel flow limit for 2019. This to me is a much bigger change, and could mean a big increase in HP, especially for qualifying where total fuel consumption is all but meaningless.

[1158]

They are increasing the total fuel limit. I have not seen anything about changing the instantaneous limit. There is no way that would happen. The PUs would need to be redesigned if it happened.

[MrPotatoHead]

.... and they just announced they're dropping the fuel flow limit for 2019. This to me is a much bigger change, and could mean a big increase in HP, especially for qualifying where total fuel consumption is all but meaningless.

I have also seen no mention of this.

[AJI]

.... and they just announced they're dropping the fuel flow limit for 2019. This to me is a much bigger change, and could mean a big increase in HP, especially for qualifying where total fuel consumption is all but meaningless.

I have also seen no mention of this.

Neither have I. Probably because it makes absolutely no sense.

What also makes no sense is the 110kg of fuel. The can currently do it with 105 or much less.
If they said every car MUST start the race with 110kg of fuel then that would be interesting...

[FightingHellPhish]

.... and they just announced they're dropping the fuel flow limit for 2019. This to me is a much bigger change, and could mean a big increase in HP, especially for qualifying where total fuel consumption is all but meaningless.

I have also seen no mention of this.

Neither have I. Probably because it makes absolutely no sense.

What also makes no sense is the 110kg of fuel. The can currently do it with 105 or much less.
If they said every car MUST start the race with 110kg of fuel then that would be interesting...

They want to drop the fuel flow limit for 2021

[AJI]

They want to drop the fuel flow limit for 2021

You mean drop as in no fuel flow limit, or drop as in lower?

[bill shoe]

If they said every car MUST start the race with 110kg of fuel then that would be interesting...

Yea, during the first lap cars would burn off fuel (a.k.a. weight) as quickly as possible. They'd be on the 100 kg/hr flow limit continuously until they burned off enough fuel. Actually they probably already have a "reduce fuel weight ASAP" mode to deal with unexpected safety cars late in the race.

[AJI]

[quote="bill shoe" post_id=758920 time=1524014861 user_id=6694]
[quote=AJI post_id=758889 time=1523998890 user_id=34938]
If they said every car MUST start the race with 110kg of fuel then that would be interesting...[/quote]
Yea, during the first lap cars would burn off fuel (a.k.a. weight) as quickly as possible. They'd be on the 100 kg/hr flow limit continuously until they burned off enough fuel. Actually they probably already have a "reduce fuel weight ASAP" mode to deal with unexpected safety cars late in the race.
[/quote]

It was said here somewhere (maybe the Honda PU thread) that in one race last year the Mercs started with ~90kgs vs Honda's ~105. That's a hell of an advantage, so I'd say Mercedes use a very economical fuel strategy and if there's a safety car they motor against the K right up to the 2MJ limit (or more sneakily back through the H to the ERS "honda style") and run the H in high recovery mode.
If they had to start the race with 110kg of fuel there'd be a lot more of that.
It fits in with Liberty's strategy of trying to even out the field. With the driver minimum weight set at 80kgs and the car minumum at... whatever it is now less 80kgs.., and all cars starting with the same amount of fuel, they've removed the unknown of the starting weight.

[mclaren111]

This will change nothing.

They still have only three PU's for the year !!

[henry]

The only reason the max fuel load isn't used most of the time is because of the fuel flow limit.

How do you arrive at this assertion?

Looking at China. From last year’s qualifying lap it’s about 60% Max torque demand and 15% zero ( harder to measure but a ballpark) in a 90 minute race that would be 90kg at 100 kg/hr leaving 15kg for the 25% part throttle, which doesn’t seem enough.

Perhaps another reason for not needing the full quantity is the tyres. Running max available power would likely reduce their life unacceptably so they don’t run up to the flow limits or approach the max load.

An increase to 110 kg may change things at one or 2 circuits but in general if they want to encourage pit stops by having limited durability tyres then teams will always short fill as much as possible.

[johnny comelately]

????

[MrPotatoHead]

The only reason the max fuel load isn't used most of the time is because of the fuel flow limit.

How do you arrive at this assertion?

Looking at China. From last year’s qualifying lap it’s about 60% Max torque demand and 15% zero ( harder to measure but a ballpark) in a 90 minute race that would be 90kg at 100 kg/hr leaving 15kg for the 25% part throttle, which doesn’t seem enough.

Perhaps another reason for not needing the full quantity is the tyres. Running max available power would likely reduce their life unacceptably so they don’t run up to the flow limits or approach the max load.

An increase to 110 kg may change things at one or 2 circuits but in general if they want to encourage pit stops by having limited durability tyres then teams will always short fill as much as possible.

If there was no fuel flow limit they would rev the engines higher, make more power and use a lot more fuel.
That is why I make that comment.