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Power Unit Efficiency

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Photo by: www.kymillman.com/f1

Much has been made of the incredible efficiency of the current generation of hybrid power units used in Formula 1.  There has been some discussion in the comments of some of the recent articles here about how the efficiency figure was calculated.  Simplistically, this is just the maximum power delivered by the power unit divided by the maximum power available from the fuel used.

The technical regulations specify the fuel that is to be used:

19.1.1 The purpose of this Article is to ensure that the fuel used in Formula One is petrol as this term is generally understood.

19.1.2 The detailed requirements of this Article are intended to ensure the use of fuels that are composed of compounds normally found in commercial fuels and to prohibit the use of specific power-boosting chemical compounds.

While the regulations do not specify the maximum energy contained within the fuel, and I am sure that the individual fuel and lubricant suppliers will be working hard to formulate fuels that deliver that little bit extra performance, we can make an estimate based on the energy within the commercially available fuel that we put in our cars.  An internet search gives a range of values, these range from 36.4 – 49.6 MJ/kg of gasoline.  I am making an assumption that the fuel used in F1 will be at the top of this range (although this figure was for aviation fuel, which has an energy density greater than the fuels used for road vehicles).

The maximum flow rate of the fuel is limited by the regulations to 100 kg/hour, that is 0.027778 kg/second.  Multiplying this rate by the energy density gives the maximum power within the fuel as 1,377,778 Watts.  With 745.6999 Watts to a brake horsepower, that is 1847.63 bhp.

Mercedes has recently stated their intention of having 1000 bhp from their 2018 power unit, that would give them an efficiency of 54.12%.  The same article states that Mercedes’ first hybrid power unit achieved an efficiency of 44%, that would equate to a power output of 813 bhp.  A proportion of this maximum power is produced by the Motor Generator Unit – Kinetic (MGU-K), this is limited by the regulations to 120 kW (160.9 bhp).  This is using the stored energy recovered from braking from the MGU-K or from the exhaust energy recovered from the MGU-H.  Even during those portions of the lap when the stored energy is exhausted, the 2018 Mercedes will be producing 839 bhp, giving an efficiency of 45.41%, which is still 10% better than the 35% efficiency of the current non hybrid road cars.

With fossil fuels limited, the drive for efficiency will help the long term future of the sport.  While many countries have long term plans to eliminate petrol and diesel engines from their roads, hopefully racing will continue in some form to use fossil fuels if only for historic classes.  What do you think, is efficiency worth pursuing?  Let me know in the comments.

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A long time fan of Formula 1 and grass roots motorsport, I am interested in the engineering aspects not only of F1 but the 'men in sheds' who develop homemade specials to take on the products of the big racing car manufacturers.

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37 Comments on "Power Unit Efficiency"

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John The Race Fan (@JohnTheRaceFan)
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Ow! The maths!

If F1 chooses to remain the pinnacle of technology& motorsport, I can foresee a future where the cars are able to harvest enough energy to reduce fossil fuel usage to minimal amounts.

A Grand Prix in 10 liters of fuel? 5 liters? 1 liter?
The way hybrid and other alt-fuels are advancing, reduction in fossil fuel usage is here to stay.
And what better way to stay road relevant (even though there isn’t really a need) than to reduce fossil fuel consumption.
Dead dinosaurs saved.
Less carbon emissions spewed.
Et al.

Rapierman
Member
Rapierman

Yanno, with the phrase “commonly used fuel”, one could conceivably use a special mixture fuel and introduce it into the common market at the same time, thus circumventing the rule.

sunny stivala
Guest
sunny stivala

NC, What does “invalid security token” mean?. That is what I got when I posted.

Negative Camber
Admin

I’m working on a few of the niggles and Rapierman has been keeping me posted on issues that aren’t working quite right. The edit function is open for about 15 minutes after you post something. I got the “reply” function up and running. Let me know if there are other issues. the devil is always in the detail when rolling out a new website with new features. :)

sunnystivala
Guest
sunnystivala

Many thanks for your attention/response, really appreciate your efforts. Yes the “reply function” has been restored, but the “edit function” disappeared again. As I said, at least from this side it is not as easy as before to post, and there are some other things that needs attention, but a start is always a start and again your efforts and determination are greatly appreciated. Wishing you and all those at Parc Ferme as well as all those that follows as posters all the best and a happy new year.

sunny stivala
Guest
sunny stivala

Many countries have long term plans to eliminate petrol and diesel engines from their roads but hybrids are not in their plans to eliminate.

sunny stivala
Guest
sunny stivala

In 2016 it was declared that the PU has gained 109 BHP since 2014 and that it was approaching 1000 BHP at 50% efficiency. 1000 BHP minus 160 electrical HP means that the ICE was producing 840 BHP. it also means that in 2014 the ICE was producing 730 BHP when at 44% efficiency.

sunny stivala
Guest
sunny stivala

Fuel used in F1 have roughly 0.5% additives, and one will be amazed how big HP gains could be made with them.

sunny stivala
Guest
sunny stivala

Having had to post 4 times and short posts due to difficulties encountered when posting. This plus both reply and edit facilities does not function.

Rapierman
Member
Rapierman

Try it now.

sunny+stivala
Guest
sunny+stivala

Yes the reply facility is working and thanks for your prompt attention.
The edit facility is missing fro on this page.

sunnystivala
Guest
sunnystivala

Thanks again, the edit function is now up and working. but still not as normal as before to post.

photogcw
Guest
photogcw

No. All this expensive research and development belongs in the laboratory and test track, not on the race track.

Rapierman
Member
Rapierman

While the pursuit of efficiency is nice, I think we’ve reached the point of diminishing returns. Check back over the records and see how many teams have been able to stay under the limit as opposed to past years. If only a few can stay under, then can we say that it’s unfair because it “de-facto” favors one or just a small handful of team(s) over others?

sunnystivala
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sunnystivala

The pursuit of efficiency is something to be commanded. As with everything that is pursued the gains will always tends to diminish. As with every formula raced under, there will be those that does a better job then others. But, I for one don’t see the system as unfair for those that didn’t do as good a job as some others did, or that the system favored those that did a good job.

Dave
Guest
Dave

https://m.youtube.com/watch?v=mjCRUvX2D0E
Slip this one in the next time you talk about horse power

Keep up the good podcasts

sunnystivala
Guest
sunnystivala

One cannot talk about efficiency without talking about horse power/fuel.

Geek49203
Guest
Geek49203

The USA alone has enough reserves of natural gas to last for 400 years.

JakobusVdL
Guest
JakobusVdL

Eliminating carbon based fuels isn’t being done because they are running out, but because of the harm the byproducts are doing to the environment.
The evidence is sufficient to convince most of the worlds scuentists and decision makers,
https://climate.nasa.gov/evidence/

JakobusVdL
Guest
JakobusVdL
Happy New Year Dave, thanks for the really interesting article. It does seem that Mercedes, and the other p.u suppliers, are being a bit obscure with their claims around efficiency and power output. I’d always assumed the efficiency claims would have to relate to the peak output of the i.c.e / turbo / mgu-h, excluding any input from the energy store via the mgu-k, as that’s the maximum rate of converting input energy to output. But I guess ‘Greater than 50%’ sounds much more impressive than 45.41%. However as you note 45.41% is still 30% more efficient than most modern… Read more »
sunny+stivala
Guest
sunny+stivala

Overall efficiency is one thing and thermal efficiency is another, overall efficiency reached in F1 is much higher than the 50% thermal efficiency reached.
Yes there is technology transfer between F1 and road car engineering, example is “NANOSLIDE” technology used to coat cylinder bore surface. than there is indirect transfer, where F1 serves as a research laboratory for developing new solutions and showing the world what’s possible.

sunny+stivala
Guest
sunny+stivala

My calculations from what those that are directly involve said, so I call them my personal opinions and interpretations only.
Fuel used in formula 1 consists of the same components (compounds) that are found in commercial premium unleaded 98 RON.
At the permitted 100KG/H fuel flow rate there is a “POTENTIAL OUTPUT” OF 1240 kw of power.
“POWER UNIT” BHP output= 1000 BHP.
“POWER UNIT” BHP per litre= 625 BHP/L.
Overall “POWER UNIT” efficiency= 59%.
“ICE” BHP output= 840 BHP.
“ICE” BHP per litre= 525 BHP/L.
“ICE” THERMALL EFFICIENCY= 50%.

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