[WEC] Porsche Prototype Discussion

[deggis]

Originally Posted by Spyderman

New Porsche video: http://www.youtube.com/watch?v=WQ2qznsYSmg

Onboard camera angle done right. Take note, ACO.

[gwyllion]

Porsche's report of the WEC prologue: http://www.endurance-info.com/en/355...n-paul-ricard/

Team principal Andreas Seidl: “The Prologue was an excellently run test by the WEC organisation and we were able to complete our programme. After concentrating on long distance racing during our private test, when we covered two six hour race distances, we have now also tested our qualifying performance. We made good progress in all areas – be it team-work, performance or reliability. But we know very well that we cannot catch up overnight with the advantage our competition has in terms of experience, and we have quite a lot of homework to do before the season’s opening race on 20th April in Silverstone.“

Alexander Hitzinger, Technical Director LMP1: “To decide on the best megajoule class requires a complex calculation. To put it simply, you can say we have designed our energy recovery systems as big and heavy as the overall car concept allowed. With the amount of energy we can recuperate this way, we fit well into the six megajoule class.“

[TF110]

"Tested qualifying"; Could explain those 1:41's!

[gwyllion]

"We designed a system to see what was possible and with that system it's not really possible to achieve 8MJ," explained Porsche LMP1 technical director Alex Hitzinger said. "That is why we have homologated the car at 6MJ."

Porsche has denied that this is a U-turn: a company spokesman insisted that it had only announced that it was its goal to run in the highest class.

source: http://www.autosport.com/news/report.php/id/113159

[CTD]

Interesting that Porsche has chosen to position the driver in the left side of the car, like Toyota, instead of the right as Audi, which is the most suited position for Le Mans.

[vincegail]

Originally Posted by CTD

Interesting that Porsche has chosen to position the driver in the left side of the car, like Toyota, instead of the right as Audi, which is the most suited position for Le Mans.

Depends. Probably they have a lot of weight of ERS stuff on the right hand of the car. Or chose to have easier pitstops this way.

[GT6]

I remember asking the Audi people on our pit visit a few years ago and they said they seat the driver on the side that suits the pit stop access

[Spyderman]

http://www.youtube.com/watch?v=vKQne...EI_V0DVXjXDALA

[GT6]

good little video and great to see mr attwood, a real hero of le mans

[Mike E]

Most race tracks run clockwise which is why 2 seater prototypes are usually right hand drive - the driver can jump out into the garage area rather than into pitlane traffic. However, on a clockwise track you spend more time turning right than left. In a cramped LMP1 cockpit, with the A pillar very close to the driver, visibility when turning right in a right hand drive car is not very good. IIRC this is why Toyota chose left hand drive for their current LMP1 series of cars. Maybe Porsche have had similar thoughts.

[JoestForEver]

I think it's pretty much like a habit they carry over since R8. As in the current pitstop rules, driver change is carried out during fueling. So it's not really helping making driver change faster as they are already than refueling.

[Spyderman]

I looked at the S3 times from the prologue. It looks like Porsche have some work to do for the twisty bits. I wonder if they tested the high/medium down-force package during their private test? I wonder if they have one available yet?

[CTD]

Originally Posted by Spyderman

I looked at the S3 times from the prologue. It looks like Porsche have some work to do for the twisty bits. I wonder if they tested the high/medium down-force package during their private test? I wonder if they have one available yet?

They would be one of the first "first-year" manufactures to have both LM and Sprint package ready before the first race.
Also given the rumors heard, I think Porsche is only focusing on doing a proper LM debut, and use the first races as another test session.

[Spyderman]

Agreed!

[Japanese Samurai]

Porsche 919 has twin third element?

[wdave0]

Originally Posted by JoestForEver

I think it's pretty much like a habit they carry over since R8. As in the current pitstop rules, driver change is carried out during fueling. So it's not really helping making driver change faster as they are already than refueling.

Driver on the left puts the fueller on the better side and away from the driver, the right side weight bias is taken care of by the ers, no longer the driver.

[jimclark]

Sprint, long distance; driver left, driver right for this reason or not.
I understand all the off season boredom/conjecture.
However....the real answer is aliens came down in UFOs and dictated what is to be to Porsche....

[CTD]

Originally Posted by jimclark

Sprint, long distance; driver left, driver right for this reason or not.
I understand all the off season boredom/conjecture.
However....the real answer is aliens came down in UFOs and dictated what is to be to Porsche....

Now your just being silly!

[GT6]

Originally Posted by jimclark

Sprint, long distance; driver left, driver right for this reason or not.
I understand all the off season boredom/conjecture.
However....the real answer is aliens came down in UFOs and dictated what is to be to Porsche....

i like your thinking

[MoMedic9019]

Originally Posted by Japanese Samurai

Porsche 919 has twin third element?

Interesting on the tea tray...Wonder how the split changes the flow.

[jimclark]

Originally Posted by CTD

Now your just being silly!

And I'm aLL THAT FAR OFF.....

[gwyllion]

The May 2014 edition of Racecar Engineering has an article on the 919: http://gb.zinio.com/reader.jsp?issn=0961-1096&o=ext&p=8

The following explanation is given why they went for coil springs:

The monocoque was finalized at the end of 2012 to meet with the company's schedule of rolling out the car in June, announced just before the Le Mans 24 hours. This meant that the front suspension concept was designed early, and the team opted for coil springs rather than the now-standard torsion bar layout in LMP1.

Porsche was extremely coy over its choice of layout, claiming that the kinematics, aerodynamics and stiffness caused them to go down this route. It is believed that the suspension is interlinked, not a major piece of news other than it was it was the link between front and back that was susceptible to the vibration caused by the engine difficulties in the early part of testing.

Alexander Hitzinger talks extensively about the engine vibration issue:

We had vibration issue caused by the engine configuration. We changed the engine configuration and reduced the vibration level a lot by changing the firing order. Changing the firing order means a new crankshaft and camshafts, and new calibration because of the gas exchange changes. It was a big thing. We discovered the problem at the rollout. For it was quite clear at the beginning that this was going to be a problem that would otherwise be very difficult to solve. I decided very quickly because it is such a big change that it takes a long time to implement it, but if you let it drag on before you try to solve it, you could be in trouble later on. We saw the problem, and we acted decisively.

The vibrations made it very difficult for the drivers to good feedback about the feeling of the car.

This is his explanation for the V4 configuration.

From a thermodynamic point of view, you want a certain ratio between air and volume in the combustion chamber and that leads you towards a smaller number of cylinders at a given capacity. With a four cylinder V configuration, you can nicely install it in the car as a structural component, so that leads you that solution.

[gwyllion]

Porsche has exclusive access to the A123 battery technology.

I think it was the smallest compromise to go with batteries. It is the best compromise between energy and power density. It gives you more flexibility in terms of strategy and A123 technology is in my opinion the best out there, and we are lucky to have them. We are exclusive in LMP1 and it is a very good thing for us. I think it is a lighter solution than the others. You size it according to how much power and energy you need, and how safe you want to be. You cannot compare like for like [with Audi and Toyota] because you don't know what the others have done. Our investigations concluded that this would be the lightest solution for our application and our assumptions.

A short explanation about the exhaust gas ERS:

It is another turbine which drives an electric generator, so as soon as there is more exhaust energy than required for the turbocharger, then the surplus exhaust gas flows through the additional turbine. It is nothing to do with anti-lag. Flowing electric energy from the exhaust energy recovery system to the front is possible, or direct it to the battery.

[Spyderman]

Thank you Mr G!

[GasperG]

Am I the only one who is surprised by the fact the Porsche chose li-ion batteries?

Their storage is build around something like this:
http://www.a123systems.com/products-...-core-pack.htm

This is the pack that gives the max power rating, that A123 cell give you per kg.

Here is the data sheet for the individual cells:
https://www.google.si/url?sa=t&rct=j...64125504,d.bGQ

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

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).

When they chose the li-ion over supercap, they had to chose the highest power rating cells (45 C), but that still meant the pack must be oversized on the capacity that the actually need (4,4 kWh for 200 kW).

Of course you can always tweak it to produce more power, but that means they can throw away a pack of batteries after every race. Even at the rated rating they will have to have a good thermal management to complete the 24h race.

Is there any data that I have missed?