Honda Power Unit Hardware & Software

[Paul]

I picked two random accelerations of McLaren and Mercedes to compare how low their revs drop on upshifts:





The lowest I see for McLaren is 106XX rpm compared to 104XX rpm for Mercedes. Not a huge difference, but something to think about...

[tok-tokkie]

The amount of kinetic energy is half of the mass of the car x the square of the speed change. How far the car travels is not part of the equation.

Yes but the share allowed to be taken up is 160kW, which isn't nearly the available amount. So the distance (well: time) most definitely is part of that equation.

Quite right. I overlooked that. Thanks.

[Muulka]

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.

Surely the engines being more drivable would serve to decrease the partial throttle time; with a drivable engine you can minimise it.

And I never said that partial throttle wasn't a significant fuel burn, just that the overriding driver of fuel economy is time down the straights.

That Honda run their engine with less than 100 kg/hr over 10.5k rpm is extremely surprising to me. Surely the most LT-efficient way to save fuel is just lift and coast, rather than ruining the entirety of the straight...

[henry]

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, to 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.

Mercedes do drop below 10500, at least on a qualification lap. If you watch the qualification lap from Abu Dhabi you will see the upshift at about 11800 to 10300. This different from earlier in the year when it was 12000 to 10500. They have steadily lowered the upshift RPM over the course of the formula, in the first year it was nearer 12600.

Also if you watch Laps you will see Mercedes spend a lot of time away from the peak RPM and "peak" power, around 40% of the lap at Spain for instance. There is lots of part throttle, low RPM, running in this formula, and hence lots of opportunity to be more efficient.

[Craigy]

Mercedes do drop below 10500, at least on a qualification lap. If you watch the qualification lap from Abu Dhabi you will see the upshift at about 11800 to 10300. This different from earlier in the year when it was 12000 to 10500. They have steadily lowered the upshift RPM over the course of the formula, in the first year it was nearer 12600.

Also if you watch Laps you will see Mercedes spend a lot of time away from the peak RPM and "peak" power, around 40% of the lap at Spain for instance. There is lots of part throttle, low RPM, running in this formula, and hence lots of opportunity to be more efficient.

This is team/gearbox/gearing dependent. The Mercedes factory team usually shift up at 11800rpm, and have been doing so practically all season in 2016. With the same engine, the Force India quite often changes up at 12700rpm.

The Force India and Honda engines are the ones from the grid that I've noticed changing up at the highest RPM - usually between 12500 and 12900. The Mercedes (factory) is the lowest I've noticed.

All of this is from the onboard footage.

[mclaren111]

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.

That's why Senna is so highly rated !!! Absolute Genius !!!

[Andres125sx]

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.

4cm? Wow they could have substitude it with a switch

4cm and noticeable lag, I can´t understand how did they do it to control the most powerful engines in F1 history, wich such a sort pedal travel, and that lag.

I guess that´s what Wazari meant, with the MP4-4 they didn´t use partial throttle (generally speaking) because of the turbo lag so they had to wait until the car was straight, and hit the throttle switch, while today the absence of lag means they can play with the throttle a lot more, wich means using partial throttle extensively

[AnthonyG]

Perhaps they only use that much travel to control the start. I think my road car doesn't even have 11cm pedal travel.

[Craigy]

4cm? Wow they could have substitude it with a switch

4cm and noticeable lag, I can´t understand how did they do it to control the most powerful engines in F1 history, wich such a sort pedal travel, and that lag.

I guess that´s what Wazari meant, with the MP4-4 they didn´t use partial throttle (generally speaking) because of the turbo lag so they had to wait until the car was straight, and hit the throttle switch, while today the absence of lag means they can play with the throttle a lot more, wich means using partial throttle extensively

Senna's approach to the throttle was typically 100% on or 100% off.
When he wanted partial throttle, he'd bang on and off full throttle repeatedly.
It's a technique he had ever since his karting days.

100% throttle on a car with traction control isn't the same as 100% torque to the wheels at all times, and for at least part of his career he was in a McLaren with good TC.

[godlameroso]

11.5cm becomes more than simple throttle control. That's about as much travel as your average Honda clutch pedal has. Most road cars have a pedal stroke around 7 to 9 cm, then again most people's throttle control is accelerate, accelerate angry and floor it. It's said good race car drivers have as many as 10 different conscious levels of throttle control. Then with the MGU-K and H to provide "torque fill" maybe they need such a long pedal stroke to fit all the different pedal maps.

[Andres125sx]

That´s a good point, how did they do it to control the car when in traction limited phase in 1st, 2nd and 3rd gears?

And under the rain?



Was TC allowed in 85-90 era?

[godlameroso]

4cm isn't that low, is about how much it takes for you to pivot on your heel from ~80 degrees vertical to ~45 degrees, that's about go kart throttle travel. 11.5cm means you have to physically move your leg.

[Postmoe]

Could this level of pedal travel be also related to fuel consumption management?

[bauc]

Could this level of pedal travel be also related to fuel consumption management?

Or poor drivability?

[Postmoe]

Could this level of pedal travel be also related to fuel consumption management?

Or poor drivability?

For example.

It could be another way of managing those issues without doing it fully on the mapping side. Easier rev management, easier tyre management an even the possibility of asking for a precise percentage of throttle applied in certain circumstances, turns, straights. I understand the frustration of old school drivers: even if it's beautiful and demands skills, it's what I do on my commutes to avoid excessive wear and radars.