2014-2020 Formula One 1.6l V6 turbo engine formula

[Tommy Cookers]

the area under the curve (over 10500 rpm) will suffer due to the fuel rate cap

accelerating quickly through the gears the rules would not appear to prevent fuel systems having a convenient dynamic characteristic
such that for the brief excursions significantly over 10500 the ideal AFR is maintained despite the fuel rate limit ex-tank
(if the injection pulse demanded is unchanged, only God would know if the actual fuel rate briefly exceeded the magic 100)
such limited use of iirc 3cc of fuel 'accumulated' at eg 10500 is apparently not intended to be prevented by the rules that were written
remember the fuel will compress by 4.3% at 500 bar
remember the thousands of hours of transient dynamometry

not so under steadier conditions, when apparently the AFR must fall or the boost must fall
fwiw I still think (after 4 years) the least depletion of 'area under the curve' will be by loading the turbine to raise the exhaust backpressure

laughably, the FIA fuel rate metering only claims to be 'accurate' to +- 0.5%
isn't this equivalent to eg Mr Usain Bolt having to run 100.5 m and an adjacent competitor having to run 99.5 m (or vice versa)


btw wuzak - you seem to be using HHV for your efficiency - but LHV is the standard for engine efficiency ?

[mrluke]

I would wager that combustion efficiency is not a monolith but is actually variable in the RPM range. A consequence of having fixed valve timing. It very well could be that the engine is efficient at over 50% over a certain rpm range, and pedal map condition but less efficient at others. Say between 7,500-8,800 rpm at almost full throttle the engine is actually 56% efficient, but only 47% from 9-10,500, and even less efficient at higher revs. In other words it's entirely possible that peak output actually happens slightly before 10,500rpm, the better engines have a wider plateau because of improved efficiency. This would go along with the assertion of certain people that the difference in peak power isn't tremendously great. Rather it's a matter of area under the curve.

The engineers can pretty much chose where to make peak power when designing the engine.

Why would they pick any point in the RPM range other than the one with the highest fuel flow and lowest frictional losses?

Thank you Wuzak for putting some numbers to it.

Here's a copy of the chart that Cosworth published back in 2013/2014 which is somewhat down on power compared to today's cars but serves to illustrate the link between power and fuel flow.

[r101]

laughably, the FIA fuel rate metering only claims to be 'accurate' to +- 0.5%
isn't this equivalent to eg Mr Usain Bolt having to run 100.5 m and an adjacent competitor having to run 99.5 m (or vice versa)

I am sure they are testing the flow on each FIA unit and using the better ones.

[godlameroso]

Well it's what they've discovered using ever larger compressors. Peak *torque occurs at slightly before peak fuel flow. The sweet spot between friction, combustion efficiency, and fuel flow *and compressor size for their given combustion technique is actually right before theoretical peak. Of course the power band is so broad that it's essentially flat over those two points.

Engineers can't set peak power where they want, it doesn't work that way, they may trim the power band in places to make power delivery better. Peak power depends on too many interconnected variables(even engine harmonics affects combustion) and improving it is still a process of trial and error.

[roon]

We should all remember that comparing torque between engines with completely different peak-power-rpm is utterly useless.

We might also remember that telling people what they're doing is useless, without saying why it is useless, can be quite useless. Can you expand upon your premise?

[godlameroso]

He means the power bands of the different power units are all different, not just among each other but depending on the pedal map and rpm, intake runner length etc.

https://youtu.be/6VoiD4PjK_o?t=53m21s

[PlatinumZealot]

thanks to mugh the boost is very flat. Normally volumetric efficiency will increase with rpms due to accoustics, but thanks to variable runners even at kid rpms the VE is quite good and possible level across the board. So torque is also very, very flat at maximum fuel flow. I expect a linear power increase with slight deviations only due to secondary effects.

The plus or minus 5% is not an issue. That number is simply the absolute accuracy of the meter off the shelf compared to some standard. It is not saying the meter readings are not repeatable. They are very repeatable.
What you would do is benchmark the meter for each car. So you know the error. So even if they are not the same absolute accuracy you still can normalize the readings for the different cars.

[gruntguru]

[/list]accelerating quickly through the gears the rules would not appear to prevent fuel systems having a convenient dynamic characteristic
such that for the brief excursions significantly over 10500 the ideal AFR is maintained despite the fuel rate limit ex-tank
(if the injection pulse demanded is unchanged, only God would know if the actual fuel rate briefly exceeded the magic 100)
such limited use of iirc 3cc of fuel 'accumulated' at eg 10500 is apparently not intended to be prevented by the rules that were written
remember the fuel will compress by 4.3% at 500 bar
remember the thousands of hours of transient dynamometry

Isn't this what the furore was all about last year? It is clear some teams were exploiting the rules, to accumulate fuel somewhere in the system between the fuel flow sensor and the injectors by altering the pressure in that portion of the system.

No doubt such exploitation is now much more difficult - courtesy of the subsequent regulation changes. (I believe fuel pressure is now monitored at various points in the system).

[gruntguru]

Engineers can't set peak power where they want,

Of course they can.

The broad process is not "trial and error" either. Simulation allows the engine to be largely optimised prior to final optimisation on the dyno. The key variables that will determine the rpm where peak efficiency (power) occurs include:
- compressor characteristic
- turbine characteristic
- intake and exhaust lengths and diameters
- combustion chamber shape
- pre-chamber volume
- pre-chamber nozzle size, number and design

[gruntguru]

We should all remember that comparing torque between engines with completely different peak-power-rpm is utterly useless.

We might also remember that telling people what they're doing is useless, without saying why it is useless, can be quite useless. Can you expand upon your premise?

Sorry but countless "power-torque" debates have done such topics to death. My point is - it is meaningless to compare the torque or the torque-rpm-bandwidth of two engines with different rpm characteristics eg:
Engine A develops 1000 hp at 17,000 rpm. Engine B develops 1000 hp at 10,000 rpm. The peak torque and the rpm at which it occurs will be massively different for these two engines, yet they will produce similar performance in a given car - all else being equal.

[gruntguru]

thanks to mugh the boost is very flat. Normally volumetric efficiency will increase with rpms due to accoustics, but thanks to variable runners even at kid rpms the VE is quite good and possible level across the board. So torque is also very, very flat at maximum fuel flow. I expect a linear power increase with slight deviations only due to secondary effects.

Unlike almost any other engine - airflow/VE characteristics have very little to do with the shape of the power and torque curves of these engines. All teams are given the same fuel-flow vs rpm characteristic to work with. The power at any rpm depends entirely on the BTE (brake thermal efficiency) at that rpm.

The engine design team can (for most of the useable rpm range) add whatever quantity of air they need to produce best BTE, simply by controlling the manifold pressure, charge air temperature and exhaust back pressure. (So - no, I don't expect the boost would be "very flat")

In broad terms the power will do what the fuel-flow does - increase linearly with rpm until 10,500 then stay constant from 10,500 to 15,000. In reality (because this would require constant BTE at all rpm which is impossible) the designer will aim for peak BTE at say 10,500 - 11,000 and BTE taper-off above and below the peak. Likewise power will "droop" somewhat below the ideal in red font above as rpm moves above or below the BTE peak.

[roon]

- all else being equal.

Except for gear ratios. We could use your 'Engine A' in a semi truck, with the right gearbox & ratios. Perhaps you're making a point about comparing variables in isolation, in which case I agree. Wasn't clear to me in your other post.

[wuzak]

In broad terms the power will do what the fuel-flow does - increase linearly with rpm until 10,500 then stay constant from 10,500 to 15,000. In reality (because this would require constant BTE at all rpm which is impossible) the designer will aim for peak BTE at say 10,500 - 11,000 and BTE taper-off above and below the peak. Likewise power will "droop" somewhat below the ideal in red font above as rpm moves above or below the BTE peak.

Basically what I said.

[wuzak]

btw wuzak - you seem to be using HHV for your efficiency - but LHV is the standard for engine efficiency ?

I used a number for illustrative purposes. As I did with the efficiency number.

It just so happens that they appear to be ballpark what the engines are doing.

[mrluke]

- all else being equal.

Except for gear ratios. We could use your 'Engine A' in a semi truck, with the right gearbox & ratios. Perhaps you're making a point about comparing variables in isolation, in which case I agree. Wasn't clear to me in your other post.

You could use both engines in a semi truck. The gearing will be set for each application to normalise the differences in engine torque and create and essentially equal force "at the wheels / to the road"

There are many examples of where this has been discussed ad nauseam on the forum so please search through the other topics.

Engineers can't set peak power where they want, it doesn't work that way, they may trim the power band in places to make power delivery better. Peak power depends on too many interconnected variables(even engine harmonics affects combustion) and improving it is still a process of trial and error.

They don't just throw a load of parts together and see how it works, every part of the engine is designed from scratch. So with that in mind you design each part to be working at its peak efficiency at a certain RPM, given you are at the design stage, you would select the RPM where the most power is available and design everything accordingly.