Macca

This is the precise point where the needle max's out at 06s and 3.30s of the EVO video.

Like all the other videos I review that needle never comes anywhere near the solid red bar indicating 8800.

Unless someone can prove me wrong it appears there is a 8600 rpm soft limiter in place for auto and sport auto in the RS?

Thats would explain the dashes for the red.

It would be really good if someone can find a video in PDK manual of the car reaching 8800 - I think i saw one in my travels but Im in Vanuatu and bandwidth is an issue (slow satellite connection).

P.S. The early Porsche 991 GT3RS videos show the 9000 rpm tacho originally intended for the car before the GT3 engine issue. I dont think they are accurate to the production car as footage was made before headline RPM revision and shift software change.

P.P.S. If Porsche has done this its for a very valid reason. The 9000 rpm headline of the GT3 may be a glory point and definitely something nice but perhaps Porsche have some strong reservations about their design in these reaches?

karimgt3

I remember i heard that the 9000rpm is not needed for the RS as the torque dies towards the end.

Yes it was 9000rpm before they decided to lower it,, so it is capable of revving that high, so don't feel bad when cutting off at 8800 in manual mode

Kobalt

Could be marketing, maybe they save 9000 rpm for the 991.2 GT3 RS...

Macca

That is not correct. The torque dies in the 6000 range long before peak rpm and the power also ends well before peak rpm in both cars.

I can 100% confirm form factory source the engine was designed to headline at 9000 rpm. Infact the early Porsche marketing release footage shows this fact. The redline was revised after the engine fire issue with the GT3. The GT3 now has some RS hardware (fastener, valve spings) that were not originally meant for it but were substituted with the engine revision after the recall. the only significant difference between the engines after the revision as I understand it apart form the obvious bore related components (piston, cylinder, cams) is the crank as I understand it.

There is definately something going on here. The headline rpm is 8800 we understand that but the red dashes at 100 rpm increments indicate something else is happening and the lack of evidence of shifts beyond 8600 on the track and other journo full throttle in all gears in sport auto have me wondering thats all....either that or Ive missed something?

Anyone telling you engine was designed to soft or hard limit at 8600/800 is not telling full truth. The revision maybe but not the original engine.

Exhibit 1 is the original tacho with 9000 rpm. This was in production trim at the time Im told. This 991 RS video was made a year before release but leaked to market after the 991 GT3RS was revealed at Geneva. Someone in PAG marketing probably lost their job on this!

Exhibit 2 is a video filmed before Geneva revealed probably Nov 2014. It shows 8800 hard limit but not the red dashed at the time. Its probably a prototype tacho. maybe they were playing with a soft limiter here?

All video available on the net (and there are a couple showing the full 9000 tacho on the RS including one with a GT4 video inter spliced that came out from PAG after Geneva 2015)

<3mph

It's also rather odd that the red dashes start after 8400 rpm. Why do the dashes begin after 8400, as opposed to 8600 for example? Is there any significance to 8400 rpm?

Macca

If you go to minute 10 of this 1080 video it shows a fully finished 991 GT3RS. I mean look at that detail. Keep an eye on that tacho. Its the car that was used back in early 2014 for making the video where the backlit tacho above with the 9000 limit. You will clearly see the red starts at 9000 rpm.

Im emailing one of the few PAG people I can get info from on this. They will not tell me why this happened because thats a "secret" as I have found but they will tell me if there is a soft limiter in place. At this stage until someone can find evidence this is not the case I suggest the 991 Gt3RS shifts to 8600 in sport auto and 8800 in manual?

Macca

10.23 above video...

NateOZ

I've not seen it either and there is no data out on the GT3 R red line which according to PAG is using a substantially identical engine as the RS. All the more reason to sell my GT3 for me, PAG has clearly reduced rpm limits and it worries me longterm - wouldn't want to own one past warranty.

911dev

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Macca

Nate. From what you've said their aint much chance you will own it long enough to be beyond warranty in any case ;-)

I suspect the jury isn't out yet on the GT3/RS engine. This is a relatively young engine in the greater scheme of things. Remember the two Mezger engine fires during the 2015 Le Mans? Shows even after many years and factory support/ownership teams still things can go wrong...

Macca

What your saying is correct. The speed is the same. However we are suggesting the RS engine does not go beyond 8600 most of the time due to a soft limiter. This may have indeed been built into the re design to increase service life of the engine even though the crank has been upgraded and we are told the rods, fasteners etc are all "military grade".

My concern is the valve train. This is not to do with fasteners/rod bolts, cranks and rods etc. This is a pure function of revolutions. New rocker fingers, lifters, springs and cams, oil channels and windage, valves and valve guides are the items of importance here and their wear will accelerate exponentially with a lift from 8600 rpm to 9000 rpm regardless of the capacity of the engine.

This is not particularly exotic tech, 9000 rpm is done at Ferrari every day, however their engines are more stressed than Porsche GT engines typically and require more maintenance over similar intervals. maybe thats what 991 GT3 owners in 4-5 years time will have to learn to accept. Higher top end engine wear.

My personal belief is we wont see PAG revisit the 9000 rpm limit with another GT engine for at least a generation and by then Im sure force induction or Hybrid/Kers tech will be knocking on the door so engine speeds beyond this may not be needed.

The 991 GT3 3.8L was an ambitious project which ended up costing PAG significantly in money and reputation. The 4.0RS engine has a more conservative performance envelop as a result. The engines are now basically identical. The crank is quoted as a key difference. Id be curious once the PET comes out what teh detail changes are. Id be curious is there any additional oil galleries or channels in the head or rockers to aid lubrication etc

NateOZ

I probably won't have the 3 still, but I will have 3 9a1s in my garage at the end of the year. I've been dealing with some OEM part problems and see some posts on here from GT3 having the same issue. There is a recall from the part supplier for their own branded ones, but not one with Porsche. I think we are still in very early days on the 9a1s and I'm glad they reassessed it on the RS.

Macca

Nate. What part specifically are you referring to? Brembo? Bosch?

NateOZ

Bosch coils, they don't seem to be up to the heat in my experience. I don't have a definitive reason if it is pot luck of the parts or if they have too low of a heat tolerance in the 9a1. I have had six new ones put in my car and will do at least 5 hours of testing on Friday. It isn't a major issue, but I feel like I'm doing the testing for Porsche...

Mine is in a dedicated track car so things will break etc, but there is a thread on here of people having the same problems in their GT3s.

Loess

I guess I'm not very surprised or concerned that Porsche has lowered the max engine speed in the RS due to the piston size/velocity. I don't think engine speed or piston velocity are as important as is the piston weight and kinetic energy. The GT3 has a much larger piston size and cylinder volume than most. If they were running an 8 cylinder engine it would be 5L and you don't see a lot of 5 litre motors running 9000 rpm. Ferrari's 458 was 0.563 and is down to 0.488 now with the new turbo engine. Maybe Porsche should call it the RS 666 (or maybe better to round up to RS 667) and it would overshadow the engine speed issue. Ferrari likes lots of small pistons (3 litre V12) and Porsche likes tractor engines? (I thought that was Lamborghini?). A little tongue in cheek.