Racecar Engineering – September 2019

14 http://www.racecar-engineering.com SEPTEMBER 2019

GTE – PORSCHE 911 RSR

theengineandoffersupmoreaerofreedom,

particularlyundertherearofthecar,whichnow

hasspacefora moreefficientdiffuser.

‘Wetooksidepipesfortworeasons,’explains

Zurlinden.‘Oneis thetorqueanddriveability,

andthesecondis theweightandpackaging.

Theexhaustis asshortaspossible,andit

benefitsaerotoo.Theexhaustflowontheside

is moreadequateaerodynamicallythanatthe

rear.It is stillthebestsoundingGTEcar[andwill

remainsoas]it is a normallyaspiratedcar.’

Pittheyounger

Therehasalsobeenaerodevelopmentatthe

frontofthecar,andoveralldownforcehasbeen

improved.Allthis,coupledwitha development

programmewithtyresupplierMichelin,means

thattyrewearshouldbesignificantlyimproved.

WiththeWECgoingbacktoseparatingout

refuellingandtyrechangesduringthepitstop

sequence,thiscouldprovetobea significant

advantageinthelonger-distanceraces.

Theenginesizehasincreasedandat

4.194-litreit is nowthelargestenginefittedtoa

911.Thishashelpedtoimprovethedriveability

andtheteamsaysthatit hasalsoimproved

thereliability.Fuelconsumptionis alsoa little

better than the old car, but with the balance

of performance system that does not make a

big impact on the performance and was not

a primary target. That said, in the sprint races

in the States fuel consumption can make a

difference to the overall race result.

‘This is more than an evolution, I would call

this a brand new engine,’ says Zurlinden. ‘The

torque curve is more flat, which [makes] the

driveability better, this was the target. We see

with the customers this was an important point,

to make it easier to drive, and this was also the

point with the aero, to make it easier to set-up.’

Porsche has also improved the gearbox,

which is now lighter and more rigid than

its predecessor, while offering drivers faster

gearshift times, the company tells us.

The primary focus for the car was to improve

the driveability, with a view to competing on the

various different race circuits around the world.

The US tracks are typically low abrasion, while

the WEC typically operates on Grade 1 circuits

with higher abrasion and more grip. Porsche

struggled on some circuits more than others,

and so the team worked on improving the

operating window. ‘Now it is more predictable,’

says Zurlinden. ‘Before, you had a sweet spot to

find, but this [new car] is really easy to set up.

The suspension has changed. It is an evolution

of the previous concept and some parts are

even the same. We got the feedback from the

customer teams, and from the works teams, and

90 per cent of the points that they requested

are now in the car. We worked together with

customer drivers, teams, mechanics and

engineers as well as the works teams. Since we

have the GTE car running in customer hands^

we have learned a lot, also about reliability and

how to use things, how people see it, and this

is an important step for all of us.’

Racing ahead

While this might be the last of the 991s, it

may also be the last of a generation of GTE

cars, depending on what happens to the top

class in the WEC and what the manufacturers

commit to. There are rumours that Porsche

may compete in the hypercar category itself,

against Aston Martin and Toyota, but with no

final regulations in place no one can plan that

far ahead. For now, Porsche is happy to have

produced its new Le Mans challenger, and to

have places to race it. Now it just hopes it will

be as successful as its predecessor.

‘We had the feedback from customer teams and from the works teams

and 90 per cent of the points that they requested are now in the car’

The car is expected to be easier on its tyres, which could prove to be a significant factor in longer WEC races now that refuelling and tyre pit stop rules for GTE have been changed