The German manufacturer has revealed that it is working on a new crankshaft for the 4.6-litre, twin-turbo LMDh engine developed out of the normally-aspirated units used in the RS Spyder LMP2 and the 918 Spyder plug-in hybrid road car.
Urs Kuratle, head of the LMDh project at Porsche, explained that the marque was now waiting on approval from the sanctioning bodies of the World Endurance Championship and the IMSA SportsCar Championship before setting out a timeline for racing the updated engine.
“The last discussion point with IMSA and the Automobile Club de l’Ouest [which jointly runs the WEC with the FIA] is whether we can introduce it in 2024 and not the following season,” said Kuratle.
“If the answer is no, we are not running it, and [if the answer is yes] we are not sure when we are running it for the first time.
“As we all know, changes like crankshafts have a massive lead time that takes months to get these things on the cars, and we must have the first pieces to do endurance testing.
“Definitely we will not run it at any race before Le Mans; if we introduce it in Le Mans we are not sure yet – we simply don’t know.”
Kuratle pointed out that only one homologation is allowed in LMDh, which means the engine would have to be introduced across all the 963s, both the factory Penske and customer cars, racing in WEC and IMSA at the same time.
That could mean as many as six cars at Le Mans on 15/16 June and then four more at the Watkins Glen 6 Hours IMSA round two weeks later.
“If you introduce something new, it has to be on all the cars,” he said. “And if they are bigger parts, you run into supply chain issues.”
Porsche has not revealed the exact reasons behind the planned engine updates, but it suffered with vibration issues with the flat-plane crank V8 over the course of the maiden season, which had a negative effect on reliability.
It is not clear if the revisions will be as significant as on the 919 Hybrid LMP1 early in its development: Porsche opted on a redesign involving a change in the firing order of its two-litre V4 after the first proper circuit test of the car in the summer of 2013.
Porsche has also not said if the engine change would count as one of the five performance developments, so-called ‘evo jokers’, allowed over the lifecycle of both LMDh and Le Mans Hypercar prototypes.
Revisions aimed at safety and reliability are free, but manufacturers must still apply to the rule makers for permission to make the changes and then update the homologation.
The evo joker system, which was aligned for LMDh and LMH last year, effectively involves a process of negotiation, which explains Kuratle’s comments about the approval process with the ACO/FIA and IMSA.
The four 963s running at the Daytona 24 Hours IMSA season-opener, which kicks off this weekend with the pre-event Roar test, are largely unchanged from last year: Porsche has said that it has not invoked any jokers in the developments.
“It’s a number of small points: it’s things like different sensors or different layouts of cables,” explained Kuratle.
“There will be nothing visual on the car, so you won’t notice anything different on the outside shell of the car, so the aerodynamics look the same.
“It’s just a number of details, sometimes a material change where it used to be aluminium and, for reliability reasons, we changed to steel.
“They are minor details and it’s a relatively small list.”
Kuratle confirmed that the cars were running in updated specification at the official IMSA sanction test at Daytona at the beginning of December.
