2014-2020 Formula One 1.6l V6 turbo engine formula

[langwadt]

5.10 Fuel systems :
5.10.3 Homologated sensors must be fitted which directly measure the pressure, the temperature and the flow of the fuel supplied to the injectors, these signals must be supplied to the FIA data logger.
5.10.5 Only one homologated FIA fuel flow sensor may be fitted to the car which must be placed wholly within the fuel tank.
5.10.6 Any device, system or procedure the purpose and/or effect of which is to increase the flow rate after the measurement point is prohibited.
so a different story seems to be emerging ?
eg any time the engine is doing 10500 rpm or more it can draw fuel at the maximum rate, but need not burn it at that rate
so some fuel can be briefly held back eg to allow the fuel burn rate to increase as rpm progress beyond 10500
even at max rpm going to a burn rate slightly beyond the maximun supply rate
(the mean fuel burn rate of the 10500+ time not exceeding the mandated fixed fuel supply rate for 10500+)
so the engine CAN be run with at a constant best mep, constant best mixture, and constant best efficiency as rpm rises and falls !
these rules make sense, presumably their apparent evolution is due to the influence of the engine manufacturers
how else could the engine be efficiently used with a pool of only 8 (overall) ratios to cover the whole season ?

IMO
for the above to be workable about !cc of fuel held back from injection for about 1 second would typically be sufficient

the injection rate, even from any 1 injector must be and will be much higher than the fuel supply rate
(the injection period will probably be less than 10 deg of crankshaft rotation, and cannot be more than about 60 deg)
clearly rule 5.10.3 devices are not defined as able to supervene the rule 5.10.5, the master measurement

the master measurement is of a (relatively steady) fuel rate at very small pressures in the tank
fuel is then compressed to 200-500 bar ! (heated/cooled) then drawn intermittently from the engines casting 'common rail' reservoir
necessarily the peak massflow will be higher than the fuel tank supply rate

any real-world system will have enough inherent 'mass/time compliance' to be useable as above, without any illegal devices
(due to interrmittency, compressibility, expansion, dissolved atmospheric or gases intentionally dissolved as fuel etc etc)
(and mechanical compliance)

it seems clear that rules intent was to allow operation as above, and the rules cannot prevent such operation anyway

the rules were intended to prevent the harvesting of significant fuel eg under braking and cornering
(when the engine could easily be run eg at 10500 rpm for this purpose)
the rules will prevent that

they were never intended to prevent the engines being run on the chosen mixture strength over the normal and necessary rpm range

Agreed there has to be some form of accumulation, with DI you can't run the injectors at 100%
Even if you could do 50% you'd have already cut the available fuel to half, rather wimpy for an F1 car

they are trying to come up with a measurable/enforceable way to limit max power to say 500hp and not make it an average so gets to be 0 hp when breaking and 1000hp when accelerating

[WhiteBlue]

If you look at this thing with a microscope you have a continuous or analogue flow at low pressure and a binary or digitised fuel flow (on and off) at high pressure caused by the injection pulsing. Lets look at a period of one second under full fuel flow of 27.8 g/s at 10,500 rpm on the low pressure side and have a look what we get on the high pressure side.

We have 175 turns of the crankshaft and 1050 single injection events during that period. Let us further assume that we have a total injection time of 100 micro seconds per injection event. That would bring us to a total of 105 ms of total injection time out of 1000 ms. Or with a bit of creative rounding we can say that the digitised fuel flow occupies 10% of the duration we are looking at.

In our example it would be legal to achieve a temporary average fuel flow of 278 g/s during one injection event because for the next 900 ms the flow would be zero. This would balance out the total fuel flow in the system to the 27.8 g/s that is specified by the regulation.

Lets now look at another situation that may occur under braking or during cornering. The engine would be running at 5,250 rpm. So there would be only 525 injection events during one second. And the engine would run under very lean regime to save fuel. Let us assume that we would operate at idle with very low or no boost and a very lean mixture so that the engine takes only 2,8 g/s or 10% of the fuel it uses in max power mode. This consumption would be massively under the allowed fuel flow which is fixed at 22.4 g/s below 8,333 rpm. In fact we would be having a surplus of 19.6 g/s against the allowed fuel flow.

It would be very tempting to keep the fuel pump running and fill an accumulator with the additional flow rate of 19.6 g/s. That fuel would become very handy when the engine exceeds 10,500 rpm for the next time. Ideally we would want to empty the accumulator then to keep the power rising with the rpm all the way to the 15,000 rpm legal rev limit. Unfortunately that would lift our flow rate in the high pressure system way over the limit of the average 27.8 g/s and we would end up being illegal.

This concludes my little investigation into the legality of fuel accumulation and flow rates in reality. The upshot is that you may exceed the legal flow rate locally during an injector pulse but you have to balance that out by sufficient time with zero injection to bring the over all fuel flow rate to a legal level. And the digitised fuel flow IMHO is no excuse for illegal means to increase the fuel flow by accumulation.

[Tommy Cookers]

The upshot is that you may exceed the legal flow rate locally during an injector pulse but you have to balance that out by sufficient time with zero injection to bring the over all fuel flow rate to a legal level. And the digitised fuel flow IMHO is no excuse for illegal means to increase the fuel flow by accumulation.

you now seem to be clear over something that was clear to others a while ago

that is the need for a time window over which the mean injected rate is to comply with the mandated delivery rate
this will be necessary to a determinantion of legality or illegality

if your position is that the compliance window is to be 1 cycle (2 engine revolutions) that seems unenforcable, and thereby unworkable (how can very accurate validation via 'rule 3' measurements be obtained every few milliseconds ?)
it also seems impossible and unreasonable (how could a '1 cycle compliant' system even fuel the engine properly ?)

a 1.5 second compliance window would allow the engine to race according to the spirit and intent of the rules at any track, surely ?
that is run at the chosen mixture strength and chosen boost over the rpm range normal with the mandated pool of ratios
a system clean of accumulation devices would be able to do this (allow 1-2 cc of fuel to be 'borrowed' for 1 second)


the real can of worms is qualifying ?

[autogyro]

It will all depend on where you apply the electric drive.

[Blanchimont]

I agree with your conclusion and the general calculations, but i think you got some numbers wrong.

At 10500 rpm there are 525 single injections per second because it's a 4-stroke engine.
The same at 5250 rpm, there are only 262,5 injections per second.

The fuel flow isn't fixed at 22,4 g/s under 8333 rpm, the regulations say
"5.1.5 Below 10500rpm the fuel mass flow must not exceed Q (kg/h) = 0.009 N(rpm)+ 5.5."
which would allow a flow rate of 14,65 g/s at 5250 rpm.

[pgfpro]

My math that I learned from EFI 101 University by Ben Strader goes like this.

10500 rpm these are crank revolutions per minute. It takes two crank revolutions to equal one engine cycle on a four stroke.

So 10500 rpm / 2 = 5250 cycles per minute

5250 cycles per minute / 60 minutes = 87.5 cycles per second

1 / 87.5 = 0.0114

0.0114 * 100 = 11.4286 milliseconds seconds max for one cycle. this would be like batch, bank, multi-point etc. fire injection time, the whole cycle, not DI or sequential

These below are the different flavors of time measurements for injectors
11.4286 = 11.4286 milliseconds: 10-3 = 1 millisecond ms 1/1000 second = 0.001 s
11.4286 = 11428.6 microseconds us: 10 -6 seconds
11.4286 = 1142.86 10 microseconds: 1/100000 second
11.4286 = 114.26 100 microseconds: 1/10000 second

From above you can figure out what the fuel amounts that will be flowed. I ran out of time and had to get on the road for work:(

[WhiteBlue]

I agree with your conclusion and the general calculations, but i think you got some numbers wrong.
At 10500 rpm there are 525 single injections per second because it's a 4-stroke engine.
The same at 5250 rpm, there are only 262,5 injections per second.

My bad, I forgot the four stroke effect. So we have indeed 525 injections per second at 10,500 rpm.

The fuel flow isn't fixed at 22,4 g/s under 8333 rpm, the regulations say
"5.1.5 Below 10500rpm the fuel mass flow must not exceed Q (kg/h) = 0.009 N(rpm)+ 5.5."
which would allow a flow rate of 14,65 g/s at 5250 rpm.

Right again. Somehow I had in in my head that there was a limit at 8,333 rpm. But it was a different rule. There used to be a rule - which is now abolished - that dealt with 80% of the fuel flow which would have been at 8,333. I had a faulty memory and your figure is absolutely right.

Nevertheless with these corrections we still get very similar numbers for the pulsating fuel flow. We have to apply a correction factor of two. So the injection pulses would only occur during 5% of the time. The residual 95% of the time the high pressure flow would be zero.

Using the same assumptions for idle we would have a surplus of 11.85 g/s which we could theoretically stash away in an accumulator. That would be a useful additional flow if we were allowed to use it. But my view about the legality is still the same.

Although during injection pulses your systems by far exceeds the legal fuel flow for some microseconds this flow is followed by a long interval of zero flow. During one injection event plus the pause interval you must not exceed the specified average flow rate. That is the correct interpretation of the rule. The fact that your injection pulse uses a higher flow rate will be tolerated by the rule as long as you bring the average down by a long enough interval of zero flow. The FiA requires the measurement of the fuel flow at every injector. So technically they have the means to integrate the fuel flow and determine the average. My view is that you will be in trouble if the integrating measurement shows you in violation. Other people may come to different conclusions but this is my view of how things will be according to the published rules.

[WhiteBlue]

It will all depend on where you apply the electric drive.

I disagree. The MGUs are well defined by the rules and their position and function in the system is known. I fail to see how their design would impact on the issue of fuel flow management. Perhaps you can elaborate a bit?

[WhiteBlue]

if your position is that the compliance window is to be 1 cycle (2 engine revolutions) that seems unenforcable, and thereby unworkable (how can very accurate validation via 'rule 3' measurements be obtained every few milliseconds ?)

We can expect the sampling intervals well below one ms. But that is not the real issue here. The main point is that the whole control system is under the direct control of the FiA. So any functionality or program to mess with the flow rates would have to be supplied by Microsoft/McLaren. They would not do such a thing. You can bet the farm that their program will be squeaky clean so that they can keep their profitable monopoly for many more years.

This argument applies to managing an illegal accumulator as well as to exploiting accumulating properties of the common fuel rail. And individual teams could not program such functions into the software. They simply do not have the access to the software at that level. You would have to load a manipulated source code which would be immediately discovered when the cars are scrutinized.

Just as a general remark: Could you explain in a straightforward way by calculation or detailed technical description how you would exploit a loop hole in the regulations to burn more fuel than allowed by the regulations?

There must be a a kind of activation by the engine control program or an automatic physical effect that would allow you to increase the burn rate. Please elaborate on that method if you have something in mind. I have problems to understand how you want to exploit something.

[pgfpro]

Do you guys think the drivers will be doing any "brake boosting" into the corners?
(brake boosting... applying the brakes while still keeping the throttle around 50%).

I do this on my turbo road car a lot. It helps with keeping the turbo spooled up on exit of the corners. I have the anti lag map active to the break light switch, then it enables the anti lag map, retards ignition to fire ATDC timing (lowering engine power) and dumps more fuel that's burned in the turbine.

Plus on the 2014 cars it could add more turbine speed/load to energize the MGUH while still within the under 5.1.5 10500 rpm rule. Plus it would add more power to the KERS

I ran this scenario on the 2014 cars and just keeping the fuel values the same as acceleration map it comes within the 5.1.5 10500 rpm rule. There's is even some room to grow here. So one could add some more fuel to the map. Of course not is much as what I'm dumping but enough that i would think it would help them?

[WhiteBlue]

I don't think that fuel dumping will be a particularly useful strategy with the 2014 turbo engines. They have the MGU-H to keep the turbo spooled up all the time and that will probably be a lot more fuel efficient and potentially also a lot more drivable in terms of engine responsiveness out of corners.

[dren]

Also, instead of directly waste gating the boost pressure when lifting off the throttle when braking, would it be possible to harness the energy through the MGU on the turbo? Then during acceleration, you would motor the turbo MGU.

[dren]

Also, instead of directly waste gating the boost pressure when lifting off the throttle when braking, would it be possible to harness the energy through the MGU on the turbo? Then during acceleration, you would motor the turbo MGU.

So you would just pass the compressed air from the compressor side through the engine when braking, without fuel/spark, and back through the turbine side. You would then use the turbo to generate. The initial compressed charge wouldn't be wasted, and then the engine would revert into just an ambient air pump until the throttle is pressed again.

Would it be more efficient to harness energy from the turbo generator or the one connected to the transmission?

[dren]

And one more question:

Would it be of benefit, or is it even legal, to cut two cylinders of fuel and spark after the 10500rpm? You continue to fuel 4 cyclinders, with higher fuel flow for the higher revs. You're stuck with the mechanical losses of the two extra cylinders.

Also, with note to the oil burning. Is there a way to still effectively seal the piston/cylinder while passing much more oil ? You could use the combustion pressure to force the rings outward, but it would be hard to still seal during the compression stroke.

[WhiteBlue]

Also, instead of directly waste gating the boost pressure when lifting off the throttle when braking, would it be possible to harness the energy through the MGU on the turbo? Then during acceleration, you would motor the turbo MGU.

That is a key capability of the hybrid electric turbo. You use any surplus turbine energy for electricity generation and use electricity to keep the turbo spooled up all the times.