[WEC] Porsche Prototype Discussion

[Chuliandred]

Originally Posted by GTfour

Welcome to the worlds best motorsport forum Chuliandred. ;-)

Oh. Thank you. After a long time read only i thought it was time for me to step up

[porman]

Originally Posted by J Jay

"Mr Enzinger, tear down this wall!"


In other news, Timo Bernhard has a new helmet design for this race in memory of Stephan Bellof who died at the Spa 1000kms on September 1st, 1985.

(Picture from DSC)

I was very happy to hear this. A nice tribute to a great driver.

[Spyderman]

Is it me , or are the holes in the rear wheel covers different sizes on each car?

[chernaudi]

I believe that those holes are the rear brake ducts, and it does seem that different fairings can be fitted over them to increase/decrease the size of that inlet.

[Richard C]

Originally Posted by Spyderman

Is it me , or are the holes in the rear wheel covers different sizes on each car?

They do look progressively larger front to rear. Assuming the gray bar on the livery is located the same on each, you can also see the reduced white-space between the intake and the gray bar on each.

Wasn't there an earlier discussion about them having different sized covers/intakes? Are they running different ones to see which on generates the right amount of cooling for the rear brakes? (I assume those feed the rear brakes). You would assume that prior testing and track specific computer modeling would have already mostly figured that out.

Richard

[Spyderman]

The pitch of the cars also look different, especially between #17 and #19.

[CyberMotor]

Originally Posted by Spyderman

The pitch of the cars also look different, especially between #17 and #19.

Are they both on air jacks?

[Spyderman]

I don't think so.

[Deleted]

Brief interview with Nico
https://www.youtube.com/watch?v=Xq38Lx_fLLU

[J Jay]

Haha, time for Porsche!

Originally Posted by Racecar Engineering June 2015 Issue

- In 2014 the 919 ran at 900kg (30kg overweight). The increase was mostly due to the battery's weight.
- For this year the chassis is a one-piece monocoque as opposed to the two-piece bonded chassis of last year and the 2013 test mules. This has given the usual benefits of weight savings and improved rigidity.
- Following the change in chassis the front suspension has also been redesigned extensively, mainly to improve tyre performance over stint lengths.
- While Porsche are developing a FRIC system, there is not one installed on the 919. Instead they have a hydraulic & spring-based system that completely separates heave and roll motions.
- After the change in firing order to resolve the vibration issues, the ICE now has new conrods, pistons, cylinder heads, exhaust, turbo, crankshaft and crankdrive.
- Changes to the crank have increased the stroke by "a little bit" and reduced weight. The new pistons, conrods, heads have been designed to cope with the higher cylinder pressures being used this year.
- The new turbo was planned for 2014 but due to the general engine development it was held back until the start of this season, with the turbo using new turbine and compressor technology compared to last year.
- Because the ICE turbo has fixed geometry and the using the wastegate as as a pressure controlling device would waste energy, the exhaust energy recovery uses variable turbine geometry.
- Splitting the turbo and MGU-H (with a twin pipe exhaust) was done to allow the car to run in the case of a hybrid failure, as was the decision to still use a wastegate. While this is heavier, it also allows for individual tuning of the two systems.
- Although the battery in the 2015 car was scheduled to debut next year, after consideration post-Le Mans the development was pushed forward as the 2014 battery was considered insufficient. However the 2015 chassis had enough room to accommodate the 2014 battery if needed.
- Power density was the main concern for the new battery, with the new cells also bringing an expected weight and volume decrease. To cope with the increased power, the electronics have also been redesigned.
- Hitzinger admits that a car that can "just about" recover 8MJ at Le Mans would probably not be able to recover the maximum at other WEC races. 7MJ is given as the "break-even point" where any potential benefit at La Sarthe is outweighed by the drawbacks at other circuits.
- Porsche's tyre approach is described as more similar to Audi than Toyota's because of the energy recovery over a single axle as opposed to both.
- Sensitivity is the main improvement on the aerodynamics of the 919, with the 2015 car being less "peaky" and more predictable through a corner.
- The brake-by-wire system (new for 2015) is completely electronic compared to the previous hydraulic system. Where the old system compensated for the loss of feel, the new system gives no indication as to whether the KERS is on or off.

Nissan in March, Toyota in April, Porsche in May, only one left for RCE next month

[carbon_titanium]

"Changes to the crank have increased the stroke by "a little bit" and reduced weight. The new pistons, conrods, heads have been designed to cope with the higher cylinder pressures being used this year"

so the displacement this year is more than 2.0L?

[Bandicoot17]

Yes, but not by enough to warrant saying it's larger.

[seanyb505]

Even without knowing the exact measurement I'd wager displacement is not significantly larger, unless they found a way to use the same amount of fuel. 2.0L four cylinder doesn't have a ton of room such that increases in crank throw drastically alter the overall displacement. Increasing the stroke by 1/8" won't yield as much increase in overall size on a four cylinder than an eight or ten cylinder engine.

[J Jay]

That's what I took from it as well. I assume it's something like going from 1.98L to 2.0L, an increase that is so small that it still rounds to two litres.

[Spyderman]

I know it is just qualifying, but ...Congratulations Porsche. That was stunning!

[TF110]

Amazing times! Lets see how their race pace and tire wear hold up.

[Deleted]

Top speeds are funky considering aero, speeds will skyrocket at Mulsanne

#17 Porsche 319.5
#18 Porsche 317.6
#19 Porsche 317.6
#7 Audi 309.5
#8 Audi 309.5
#2 Toyota 298.3
#1 Toyota 294.3
#4 Kolles 294.3
#9 Audi 283.5

Interestingly enough all those except Kolles were in FP3, not Q, despite the better lap times. Maybe some changes between sessions

[MyNameIsNigel]

Originally Posted by Chiana

Top speeds are funky considering aero, speeds will skyrocket at Mulsanne

#17 Porsche 319.5
#18 Porsche 317.6
#19 Porsche 317.6
#7 Audi 309.5
#8 Audi 309.5
#2 Toyota 298.3
#1 Toyota 294.3
#4 Kolles 294.3
#9 Audi 283.5

Interestingly enough all those except Kolles were in FP3, not Q, despite the better lap times. Maybe some changes between sessions

Sort of demonstrates that top speed is not everything.

It will be hard to stop those three Porsche during the race. Hope the LM-spec Audi can give them a good and fair fight tomorrow.

[Chuliandred]

Originally Posted by Chiana

Top speeds are funky considering aero, speeds will skyrocket at Mulsanne

#17 Porsche 319.5
#18 Porsche 317.6
#19 Porsche 317.6
#7 Audi 309.5
#8 Audi 309.5
#2 Toyota 298.3
#1 Toyota 294.3
#4 Kolles 294.3
#9 Audi 283.5

Interestingly enough all those except Kolles were in FP3, not Q, despite the better lap times. Maybe some changes between sessions

That could also be explained by the slipstream they found in FP3 while they all searched clear laps in the quali session.

Neverthless, congratulations to Porsche. They improved quite well over the winter. Brother of an old friend (yeah I know...~~) works for Porsche and was reported with three non working days last month. Seems to pay off ^^

[Spyderman]

From Romain:http://www.endurance-info.com/fr/rom...es-ont-change/

[carbon_titanium]

Originally Posted by Chiana

Top speeds are funky considering aero, speeds will skyrocket at Mulsanne

#17 Porsche 319.5
#18 Porsche 317.6
#19 Porsche 317.6
#7 Audi 309.5
#8 Audi 309.5
#2 Toyota 298.3
#1 Toyota 294.3
#4 Kolles 294.3
#9 Audi 283.5

Interestingly enough all those except Kolles were in FP3, not Q, despite the better lap times. Maybe some changes between sessions

To me, these speed don't show the truth... to me 919 hits faster top speeds during the kammell straight but when the car goes through TS trap, car is slower because the hybrid boost was already gone

[Spyderman]

The boost affects acceleration: It gets to its top speed earlier and spends longer at that top speed. The ultimate speed will always be affected by areo and gearing.

[gustavobamba]

Originally Posted by Spyderman

The boost affects acceleration: It gets to its top speed earlier and spends longer at that top speed. The ultimate speed will always be affected by areo and gearing.

That´s the magic of have 8MJ… you achive your top speed sooner and stay there longer time… that´s awesome for lap time

[Spyderman]

Good race, but very disappointed.
Bring on Le Mans

[J Jay]

Originally Posted by Spyderman

Good race, but very disappointed.
Bring on Le Mans

Tyres, mate. For all that power the 919 has its tyres have to be able to put it down consistently well throughout the stints. There's also a knock-on effect on lateral grip which doesn't help in the corners.

We're at the point where Michelin make custom tyres for each factory so what else can be done to prolong the tyre life?