[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