Honda Power Unit Hardware & Software

[turbof1]

No we are looking both at power per kg of fuel. You are simply starting from a different variable. Nowhere did I state teams run less then 100kg/hr above 10.500 rpm (I even think that would be an infraction of the technical rules and could result in DSQ). What I do state is that teams do not run 10.500 rpm or above constantly. Not possible with corners.

It would not be an infraction to the rules(as they are written) to run below max fuel above 10.5K rpm, it would just be incredibly silly.

That's not what he meant. The issue is that you can only have 100kg of fuel for the entire race. On average you are not running 100kg/h during the race, but more like 66kg/h. So peak power is not the issue when it comes down to the fuel efficiency, but rather a "too thirsty" engine (or insufficient energy recovery systems).

In the above, I wasn't sure if you meant that they ran 66kg/hr at full throttle above 10.5k rpm, because when I said they don't, you didn't reply to that, but then somebody else claimed that they run below max fuel rate above 10.5K rpm.

I think that could have been worded slighlty better at my part. The average flow would be around 66kg/h across a race that runs 90 minutes. I did not make any comments on rpm.

Also, you are referring to Jozeki:

Probably something that is confusing you is the fact that full throttle doesn't mean that 100 kg/h of fuel are used by the engine over 10.5k rpm, all the manufacturers are well below the maximum fuel flow permitted in the race most of the time.

My interpretation of this is that you are bound to run below 10.5k rpm (and thus below 100kg/h) at moments during the race, like accelerating out of corners. I don't think he meant to say that you'd run less than 100kg/h above 10.5k rpm.

And yes, there are races where literally nobody tops up to 100kg of fuel. However, there are also races where they all fully top up to it. Canada is one of them. However for simplicity sake, let's assume 100kg is used during each race. It leaves out guessing for which track which amount of fuel is being carried.

[hurril]

In the above, I wasn't sure if you meant that they ran 66kg/hr at full throttle above 10.5k rpm, because when I said they don't, you didn't reply to that, but then somebody else claimed that they run below max fuel rate above 10.5K rpm.

The average consumption comes out as 66kg/h.

Not if they use way less than the full 100kg per race which Merc usually does, we've seen them win races using less than 75kg.

Right but this exchange seems to have started with you implying that you cannot have good peak power but bad fuel efficiency. If only 59% of a given track runs at full throttle, then clearly 31% of it does something else. It's not like they just coast that part.

[godlameroso]

If fuel rate is limited to 100kg/hr at 10,500rpm, then any rpm above that will not make more power, rpms below 10,500 rpm use less fuel than 100kg/hr. If you need to rev to 12,500 rpm to get the MGU-H to make enough electrical power, then you'll be less efficient than if you only need to rev to 11,300 rpm, because when you switch gears you'll be above 10,500 rpm and at full fuel flow, whereas other manufacturers will go under the 100kg/hr limit, hence higher efficiency.

Think of it in terms of power band, and not so much in terms of peak power. Honda's interpretation ended with a peaky not so flexible engine, and they tried their best to make it work. They should be commended for the amount they were able to develop the power unit, but it was a limited concept that reached it's limit.

[ENGINE TUNER]

Right but this exchange seems to have started with you implying that you cannot have good peak power but bad fuel efficiency. If only 59% of a given track runs at full throttle, then clearly 31% of it does something else. It's not like they just coast that part.

Not exactly, I'm saying they have bad fuel efficiency BECAUSE they have poor "peak" power.

That 31% is coasting, braking, and part throttle, obviously, and the fuel used during that time is negligible.

[ENGINE TUNER]

If fuel rate is limited to 100kg/hr at 10,500rpm, then any rpm above that will not make more power, rpms below 10,500 rpm use less fuel than 100kg/hr. If you need to rev to 12,500 rpm to get the MGU-H to make enough electrical power, then you'll be less efficient than if you only need to rev to 11,300 rpm, because when you switch gears you'll be above 10,500 rpm and at full fuel flow, whereas other manufacturers will go under the 100kg/hr limit, hence higher efficiency.

Think of it in terms of power band, and not so much in terms of peak power. Honda's interpretation ended with a peaky not so flexible engine, and they tried their best to make it work. They should be commended for the amount they were able to develop the power unit, but it was a limited concept that reached it's limit.

We don't get a lot of McLHonda on boards, but they do not allow the ICE below 10.5K on the straights, even during the upshifts, none of the PU's do, we know that as a fact. And yes I do think of the power band that is why I put "peak" in quotations. These PU's are run in a very narrow power band.

[Muulka]

The average consumption comes out as 66kg/h.

Not if they use way less than the full 100kg per race which Merc usually does, we've seen them win races using less than 75kg.

Right but this exchange seems to have started with you implying that you cannot have good peak power but bad fuel efficiency. If only 59% of a given track runs at full throttle, then clearly 31% of it does something else. It's not like they just coast that part.

The amount of fuel burned while braking is effectively nil and partial throttle will burn a negligible amount of fuel. Just in terms of the ICE, more power IS more fuel efficiency. They are inextricably linked because of the flow limit. More power makes you spend less time on WOT down the straight, so you burn more fuel. I'm sure there are clever things they can do to burn extra fuel to generate energy, but those things will be very much second order.

[hurril]

Right but this exchange seems to have started with you implying that you cannot have good peak power but bad fuel efficiency. If only 59% of a given track runs at full throttle, then clearly 31% of it does something else. It's not like they just coast that part.

Not exactly, I'm saying they have bad fuel efficiency BECAUSE they have poor "peak" power.

That 31% is coasting, braking, and part throttle, obviously, and the fuel used during that time is negligible.

Yes and you have a good point there. I just don't think that is the whole story. One engine can produce power that is consistently above another engine's, on the same RPM and using the same amount of fuel, but with a peak that is only slightly higher. The area under the graph could still be considerably larger, thereby providing more drive for less fuel.

[hurril]

Not if they use way less than the full 100kg per race which Merc usually does, we've seen them win races using less than 75kg.

Right but this exchange seems to have started with you implying that you cannot have good peak power but bad fuel efficiency. If only 59% of a given track runs at full throttle, then clearly 31% of it does something else. It's not like they just coast that part.

The amount of fuel burned while braking is effectively nil and partial throttle will burn a negligible amount of fuel. Just in terms of the ICE, more power IS more fuel efficiency. They are inextricably linked because of the flow limit. More power makes you spend less time on WOT down the straight, so you burn more fuel. I'm sure there are clever things they can do to burn extra fuel to generate energy, but those things will be very much second order.

I get this. But more power and more peak power is not the same thing.

[Wazari]

Hamilton finished Canada GP in 1:31:05.3 or 91.09 minutes x .59(59% full throttle) x 1.667kg/min(=100kg/hr)=89.57kg of fuel.(approximately, without accounting for partial throttle, formation lap, pit stops, yellow flags, etc)

Good example, I think the 59% is a little low, so you believe that the rest of the 41% race can be run on 10 kilos of fuel? There is fuel being consumed at zero throttle, it is not zero consumption. Even at idle which is quite high, there is constant fuel flowing. However using your formula, 91.09 mins x .65 (I believe more realistic) x 1.667 = 98.7 Kg.

I really can't disclose exact numbers but the 100 kg weight limit is much more of a factor in race strategy than the fuel flow limit and yes there are settings where WOT is less than 100 kg/hr.

Food for thought. Gas pedal travel on the MP4-31 is 11.5 cm; MP4-4 was 4 cm.

[godlameroso]

I was under the impression that to balance the KERS harvesting a little fuel is used here and there under braking.

[gruntguru]

Food for thought. Gas pedal travel on the MP4-31 is 11.5 cm; MP4-4 was 4 cm.

Very interesting. Everyone here should think about that and what it actually means.

[Abarth]

The amount of fuel burned while braking is effectively nil and partial throttle will burn a negligible amount of fuel. Just in terms of the ICE, more power IS more fuel efficiency. They are inextricably linked because of the flow limit. More power makes you spend less time on WOT down the straight, so you burn more fuel. I'm sure there are clever things they can do to burn extra fuel to generate energy, but those things will be very much second order.

While I agree with most of your post, I don't think partial throttle is negligible. These engines, unlike those in the 80ies, are much more driveable, and partial throttle surely has a higher share than at that time. Partial throttle in corners and early acceleration in grip limited situations are rather frequent situations, judging from some recent onboard recordings.

And this

Gas pedal travel on the MP4-31 is 11.5 cm; MP4-4 was 4 cm

is a clear hint that modulating power is important, else they would not install something which isn't really great ergonomically, especially in a tight race car cockpit.

[Abarth]

Food for thought. Gas pedal travel on the MP4-31 is 11.5 cm; MP4-4 was 4 cm.

Very interesting. Everyone here should think about that and what it actually means.

Agree.

And in combination with the regulations

5.5 Power unit torque demand :
5.5.1 The only means by which the driver may control acceleration torque to the driven wheels is via a single chassis mounted foot (accelerator) pedal.
5.5.2 Designs which allow specific points along the accelerator pedal travel range to be identified by the driver or assist him to hold a position are not permitted.
2016 F1 Technical Regulations 24/90 30 September 2015
© 2015 Fédération Internationale de l’Automobile
5.5.3 The accelerator pedal shaping map in the ECU may only be linked to the type of the tyres fitted to the car : one map for use with dry-weather tyres and one map for use with intermediate or wet-weather tyres.
5.5.4 At any given engine speed the driver torque demand map must be monotonically increasing for an increase in accelerator pedal position.
5.5.5 At any given accelerator pedal position and above 4,000rpm, the driver torque demand map must not have a gradient of less than – (minus) 0.045Nm/rpm.

it is very clear that they need the driver to input his torque demand with a pretty high "resolution" to exactly discriminate different pedal positions. Which would be more difficult for the driver when having only a small pedal travel.
I too am a bit surprised, but managing partial throttle situations without wasting energy because of a too rough feedback input (the driver being part of the control loop) seems really of relevant importance (surely also for tyre management).

[Abarth]

Food for thought. Gas pedal travel on the MP4-31 is 11.5 cm; MP4-4 was 4 cm.

Very interesting. Everyone here should think about that and what it actually means.

Agree.

And in combination with the regulations

5.5 Power unit torque demand :
5.5.1 The only means by which the driver may control acceleration torque to the driven wheels is via a single chassis mounted foot (accelerator) pedal.
5.5.2 Designs which allow specific points along the accelerator pedal travel range to be identified by the driver or assist him to hold a position are not permitted.
5.5.3 The accelerator pedal shaping map in the ECU may only be linked to the type of the tyres fitted to the car : one map for use with dry-weather tyres and one map for use with intermediate or wet-weather tyres.
5.5.4 At any given engine speed the driver torque demand map must be monotonically increasing for an increase in accelerator pedal position.
5.5.5 At any given accelerator pedal position and above 4,000rpm, the driver torque demand map must not have a gradient of less than – (minus) 0.045Nm/rpm.

it is very clear that they need the driver to input his torque demand with a pretty high "resolution" to exactly discriminate different pedal positions. Which would be more difficult for the driver when having only a small pedal travel.
I too am a bit surprised, but managing partial throttle situations without wasting energy because of a too rough feedback input (the driver being part of the control loop) seems really of relevant importance (surely also for tyre management).

[Brian Coat]

Abarth: I agree, plus traction management of course

... and is a 5.5.2-beater possible with long pedal travel?