[WEC] Porsche Prototype Discussion

[chernaudi]

Audi have used a lithium ion batter as the main power source for their LMP1 cars since 2009 if I remember correctly. That decision was driven by weight/packaging and power density, much like the use of LED and Laserlight systems.

Not exactly new technology even for LMP1 cars, and most hybrid road cars use them extensively as well, and also the Tesla Roadster.

[gwyllion]

Originally Posted by GasperG

What is the electric motor power? Should be at least 200 kW, or not?

According to http://www.porsche.com/usa/eventsand...turesandspecs/ the front MGU produces over 250 hp (= 184 kW).

Originally Posted by GasperG

For 200 kW, the individual cells only (without the housing, BMS, inverter, cooling) would weight 74 kg, that is a lot. And the whole capacity of the pack would be around 4,4 kWh (15 MJ).

That means you are using 2.7 kW/kg as power density. As explained in this post, A123 has developed battery technical for F1 that achieves a much higher power density.

Specifically, Mercedes-Benz HPE commissioned A123 to develop a cell with a power density of about 9,300 watts-per-kilogram (W/kg) while maintaining an energy density of 44 watt-hours-per-kilogram (Wh/kg). The increased power capability would enable Mercedes-Benz HPE to deploy fewer battery cells in its KERS design to maximize performance while minimizing weight.

However, A123’s cells could only produce about 4,300 W/kg, so to meet the KERS specifications and amplify rate capabilities, A123 modified several aspects of its existing cell design. This included increasing thermal, electrical and ionic conductivity within the electrode stack and terminal hardware. The resulting cell met the power density and energy density requirements for the Mercedes-Benz HPE KERS. But just six months before the first race of the 2009 F1 season, Mercedes-Benz HPE made changes to the design of its KERS that would require A123 to engineer a completely new battery cell.

“The motor in our F1 engine ran at a higher voltage than the KERS battery pack, so in our initial design, we implemented a DC-to-DC converter to boost the voltage of the battery pack. However, we determined that this was unnecessarily complex and we should be able to run the motor directly from the voltage produced by the battery pack,” said Cowell. “Our new concept required a battery with lower capacity, and we would simply deploy more of them in series. We needed a complete redesign to meet the new capacity and system voltage parameters, all while making sure the increased number of cells did not significantly add to the weight of the car.”

The initial cells that A123 provided to Mercedes-Benz HPE met the original KERS criteria, but they were optimized for a lower voltage. Working closely with Mercedes-Benz HPE to understand the new KERS system, A123 designed, developed and manufactured a completely new battery, delivering it to Mercedes-Benz HPE well ahead of the first race of the F1 season. For its new design, A123 decreased the mass of its existing cell by about 48 percent while increasing the rate capability by about 14 percent. This enabled the KERS system to operate at the desired voltage while providing Mercedes-Benz HPE with increased power density capabilities— the new cells were capable of producing more than 20,000 W/kg for pulses lasting for multiple seconds and more than 40,000 W/kg for millisecond pulse applications. The new batteries also decreased the weight of the KERS system to about 26kg, which is believed to be lighter than competing KERS designs.

source: http://info.a123systems.com/customer...mance-engines/

With those specs the battery will only weigh 184 kW / 9.3 kW/kg = 20 kg and have a capacity of 44 Wh/kg * 20 kg = 880 Wh = 3.2 MJ.

[GasperG]

Thanks, great achievement by the A123, I found the original source of this:
http://www.google.si/url?sa=t&rct=j&...ErvSQTwoMEtHSQ

[gwyllion]

If you fill in some fake info, you could also download it from my link

Or http://www.a123systems.com/baef9f26-...f/download.htm

[Richard C]

Originally Posted by gwyllion

The May 2014 edition of Racecar Engineering has an article on the 919:

Thanks for the RE article info and highlighted quotes.

I had been adamant on Mulsannes Corner's FB page weeks ago that the 919 would NOT be using coil springs given that most everyone today uses torsion springs. That the renderings that they showed hid the real suspension setup. So I will eat my words on that one.

I was somewhat right in that they didn't show all of the details in the renderings. I just knew the suspension had to be linked at least left to right on the front which is not shown. They didn't even include roll bars let alone third spring!

Your quote from the RE article doesn't outright say they would prefer torsion, but it heavily hints that because they froze the suspension design early, it was a case of not having time to do a torsion design. I understand the idea around freezing the design early, but I would have thought that they would have settled on a basic architecture (pushrod, torsion, interlinked) and then performed the basic engineering work. You can always continue to polish the design, slight geometry changes here and there, etc. At some point you freeze the basic design and hard points so the tub can be built. But I can't see them starting coil and then thinking they would switch to torsion later? I still find it all a bit odd.

Otherwise I think everyone was spot on regarding why a V4 instead of an I4. More compact and easier to use as a structural member.

Richard

[porman]

Are you going to COTA?

[TF110]

Originally Posted by gwyllion

According to http://www.porsche.com/usa/eventsand...turesandspecs/ the front MGU produces over 250 hp (= 184 kW).

That means you are using 2.7 kW/kg as power density. As explained in this post, A123 has developed battery technical for F1 that achieves a much higher power density.
source: http://info.a123systems.com/customer...mance-engines/

With those specs the battery will only weigh 184 kW / 9.3 kW/kg = 20 kg and have a capacity of 44 Wh/kg * 20 kg = 880 Wh = 3.2 MJ.

Pretty good weight for those batteries. Wonder what the total weight for their kers system will be.

[Spyderman]

Originally Posted by Richard Casto

Thanks for the RE article info and highlighted quotes.

I had been adamant on Mulsannes Corner's FB page weeks ago that the 919 would NOT be using coil springs given that most everyone today uses torsion springs. That the renderings that they showed hid the real suspension setup. So I will eat my words on that one.

I was somewhat right in that they didn't show all of the details in the renderings. I just knew the suspension had to be linked at least left to right on the front which is not shown. They didn't even include roll bars let alone third spring!

Your quote from the RE article doesn't outright say they would prefer torsion, but it heavily hints that because they froze the suspension design early, it was a case of not having time to do a torsion design. I understand the idea around freezing the design early, but I would have thought that they would have settled on a basic architecture (pushrod, torsion, interlinked) and then performed the basic engineering work. You can always continue to polish the design, slight geometry changes here and there, etc. At some point you freeze the basic design and hard points so the tub can be built. But I can't see them starting coil and then thinking they would switch to torsion later? I still find it all a bit odd.

Otherwise I think everyone was spot on regarding why a V4 instead of an I4. More compact and easier to use as a structural member.

Richard

Remember that there will be an almost new 2015 car.

[Japanese Samurai]

1250bhp!!!
https://twitter.com/F1Photographer/s...79757459296256

[vincegail]

But as always, no mention of how long those 1250 bhp are available. But we all know, the more horsies a car has, the shorter the time is they can use it.

[GasperG]

Isn't electric motor rated only at 250 HP? Is that 2.0 Turbo producing 1000 HP alone?

I think all those numbers are irrelevant when you add fuel flow restriction. If the BSFC numbers circling around here are true, then we can calculate:

Petrol: 89,000 g/h / 220 g/kw*h = 404 kW
Diesel: 80,200 g/h / 195 g/kw*h = 411 kW

The engines are therefore restricted to around 550 HP, they are all a bit oversized to produce better fuel economy.

[MyNameIsNigel]

Originally Posted by Japanese Samurai

1250bhp!!!
https://twitter.com/F1Photographer/s...79757459296256

Originally Posted by vincegail

But as always, no mention of how long those 1250 bhp are available. But we all know, the more horsies a car has, the shorter the time is they can use it.

I doubt this figure has any truth to it. The ICE alone is supposed to develop a peak power output of the order of 400 kW (as mentioned by GasperG), i.e. approx. 535 BHP (Porsche indicate an ICE power of more than 500 BHP). The MGU is reported by Porsche to have a power of 250 BHP (source: Porsche 919 Hybrid specs). That at best leads to a combined power output of less than 800 BHP.

[PorscheFanNo1]

Probably just a way to respond to Toyotas 1000hp claim. As you say, no one can know for certain just how much power these cars will have, and how much they could have, had they not been running the fuel flow restrictor. Just PR BS

[Spyderman]

Originally Posted by MyNameIsNigel

I doubt this figure has any truth to it. The ICE alone is supposed to develop a peak power output of the order of 400 kW (as mentioned by GasperG), i.e. approx. 535 BHP (Porsche indicate an ICE power of more than 500 BHP). The MGU is reported by Porsche to have a power of 250 BHP (source: Porsche 919 Hybrid specs). That at best leads to a combined power output of less than 800 BHP.

To be fair, Porsche report the MGU to have > 250HP
They use the > sign for the engine output, the MGU and the top speed.
However, this is not to say that the 1,250hp is reality.

[nkoske]

Originally Posted by Japanese Samurai

1250bhp!!!
https://twitter.com/F1Photographer/s...79757459296256

Because Anthony Davidson knows all things Porsche? Again how does a quote from someone not in the program mean really anything?

Why doesn't he tell us how much power is available in the Toyota? Something I'm sure he's more familiar with?

[TF110]

1250hp? Maybe with 8mj and a bigger output electric motor at full power, but Im guessing 850hp is much more likely.

[deggis]

Ricard video:

https://www.youtube.com/watch?v=9zyf2W1aOWs

[GT6]

For those in the UK Mobile 1 the grid featured a piece on porsches return to lmp1, will be repeated on channel 4 plus 1 at 7.30, first feature.
Be warned there are some unforgivable comments from both Mr Webber and a certain ex friend of sportscar racing about the feeder series being more important.

[deggis]

^ http://www.grid1.tv/motorsport/artic...1-2014-preview

[Spyderman]

Nice interview from Neel Jani: http://www.speedchills.com/home/spee...es-of-a-legend

[vincegail]

Porsche doing a 24 Hours of Le Mans exhibit at their museum. Free entrance during the 24 Hours of Le Mans. (not going then...)

Not nice. I hoped they would bring some old Le Mans stuff to the village during race week, but apparently they keep it at home...

http://www.petrolicious.com/new-24-h...-is-a-must-see

[GT6]

Originally Posted by vincegail

Porsche doing a 24 Hours of Le Mans exhibit at their museum. Free entrance during the 24 Hours of Le Mans. (not going then...)

Not nice. I hoped they would bring some old Le Mans stuff to the village during race week, but apparently they keep it at home...

http://www.petrolicious.com/new-24-h...-is-a-must-see

Who ever thought of that at porsche is obviously not really thinking about it unless they are also showing full live coverage of the race for those fans unable to travel to France and those staff stuck in Germany.

[Dead-Eye]

Originally Posted by GT6

Who ever thought of that at porsche is obviously not really thinking about it unless they are also showing full live coverage of the race for those fans unable to travel to France and those staff stuck in Germany.

They are:

Visitors will be able to watch the long-distance race on multiple screens in and around the museum.

[GT6]

That makes sense

[Simmi]

It should pull in a few locals but you wouldn't travel there especially - certainly not when you could actually go to the race. I think there will still be quite a few historic Porsches knocking around at Le Mans.