Consolidated 991RS thread
02-20-2015, 07:15 PM
#4651
Yea I got that. Just thought I'd do some math for everyone...
02-20-2015, 07:17 PM
#4652
Sweet, the car has cupholders....I'm in. 
Why only 2 exterior colors? 
Why only 2 exterior colors?
02-20-2015, 07:19 PM
#4653
Rennlist Member
Pete, do you have any idea why the upcoming 991 RS engine will "only" produce 500 hp, the same as the 997 RS 4.0, even though the 991 RS engine is DFI?
02-20-2015, 07:30 PM
#4656
02-20-2015, 07:44 PM
#4657
))
02-20-2015, 07:50 PM
#4658
Technically it's a little harder to make power as the bore to stroke ratio gets worse. The 997 RS 4.0 has a 1.28:1 bore to stroke, the 991 RS has 1.25, so it's gone slightly in the wrong direction, and all else being equal would be expected to cut into power output slightly.
I don't believe that's the real reason, however, because I don't believe 500 hp is a technical limitation as such. If a higher power output was a priority they would have found a way.
Every one of Porsche's cars needs to fit into a "box" defined by market positioning, etc. These cars need to leave room for their successors to outperform them, they need to outperform the cars below them in terms of price but not embarrass cars above them, etc. The dimensions of this engine were defined around eight years ago- the 9A1 appeared in 2008 with this exact bore (102 mm, in the 3.8S) and stroke (81.5 mm, in the 3.6L)... but they've never put this bore and stroke together before. This combination sat on the shelf until now, waiting for this particular model which required this power output. If the product roadmap said they needed it sooner, say that the 991 GT3 needed more power to compete with its rivals, we would have seen it sooner.
Now it's quite possible that it would have been quite expensive to improve on 500 hp in this application, due to the bore/ stroke limitations and the fixed parts dimensions I mentioned. I also suspect that they took the opportunity to reduces stresses and improve reliability somewhat over the 997 RS 4.0- those lifters for example were highly stressed in the old engine and didn't last long if the car was used flat out, and I'll bet the new rocker lifters improved that issue without losing power. Thus overall I'd again say I'd take this new, presumably lighter and more reliable 4.0 over the Mezger all else being equal. But I'd bet a lot of money that they could have made more power and they chose not to. And I'd bet similar money that it's really making more than the 500 hp that it says on the tin- not sure if that's more or less than the old 4.0 though.
Long answer to a short question...
02-20-2015, 08:01 PM
#4660
02-20-2015, 08:21 PM
#4662
They say it has carbon front "wings" too, not sure what those would be other than fenders. In German "fenders" are Kotflügel, often shortened to flügel... which translates to wing, hence I've often seen fenders called wings.
02-20-2015, 09:31 PM
#4663
Rennlist Member
Hi Pete. I think the paragraph you are taking this from is all talking about the rear wing. The alloy wings are in black.
The differences between 991 GT3RS and GT3 have been highlighted in black through out the presentation. Many of the differences are trim, finishing, specification and materials changes.
The key differences appear to be Aero, Track, TYRE, Capacity and Output.
To be honest I was a bit disappointed to hear the engine does not rev to 9000 rpm. I know it is only a small thing but the 9000 rpm was a headliner for the 991 GT3 and it still wears this over the RS even if the later makes more power and is quicker. The thing that IM disappointed in is that the 458 Speciale can manage 9000 rpm with a larger capacity engine so I was expecting the 9000 rpm to be a NOT NEGOTIABLE part of the remit for the engine. I suspect the GT3 engine issue had a knock on effect to the max rpm for the RS. I have it on good information the fasteners form the RS were used in the replacement GT3 engines, so perhaps they were running to the edge of development here without total re design.
Otherwise the engine and gearbox seem to have no material details changes according to this slide over the 991 GT3.
Interestingly there is no mention of any mythical ram inducing 40 bhp Kawasaki vortex system operating in the rear fenders....
Standard colour choices are a little limiting. I can see many will have to pay extra for the Lava Orange with colour keyed rear cage (no doubt an exorbitant extra cost item!). Porsche are a bit cheeky.
In ROW trim the car will have cage, harness and plastic rear windows. It appears this spec was used to get the weight down to 1390/1400 kg. Hopefully a lower US price will reflect the missing parts.
Still an immensely exciting car and in the flesh it will look fantastic. Interestingly rear light apparently "tinted" along with front LED DRL if what I read is right so those will make a nice upgrade for 991 GT3 owners in time Im sure. The car sure is going to look great with all that extra detailing but hopefully not too busy....
02-20-2015, 09:51 PM
#4664
To be honest I was a bit disappointed to hear the engine does not rev to 9000 rpm. I know it is only a small thing but the 9000 rpm was a headliner for the 991 GT3 and it still wears this over the RS even if the later makes more power and is quicker. The thing that IM disappointed in is that the 458 Speciale can manage 9000 rpm with a larger capacity engine
02-20-2015, 10:11 PM
#4665
Rennlist Member
Pete, thanks for your thoughts on the RS hp output with the 4.0 DFI engine.
I agree that the simplest explanation is that Porsche is leaving room to be able make modest changes to the 991 4.0 engine, and then generate 525hp for the 991.2 RS.
Still it's disappointing that this brand new 991 RS will "officially" produce the exact same torque and hp as the old RS 4.0. Heck, even a small bump to 505-510hp would have been nice.
I'm not that tempted by the 991 RS, it's not that much of an improvement over the 991 GT3 for the relatively large price increase. Maybe I'll look at the 991.2 RS, if I feel that Porsche is really maximizing all their engineering in the engine, etc, of the 991.2 RS
I agree that the simplest explanation is that Porsche is leaving room to be able make modest changes to the 991 4.0 engine, and then generate 525hp for the 991.2 RS.
Still it's disappointing that this brand new 991 RS will "officially" produce the exact same torque and hp as the old RS 4.0. Heck, even a small bump to 505-510hp would have been nice.
I'm not that tempted by the 991 RS, it's not that much of an improvement over the 991 GT3 for the relatively large price increase. Maybe I'll look at the 991.2 RS, if I feel that Porsche is really maximizing all their engineering in the engine, etc, of the 991.2 RS
Last edited by Drifting; 02-20-2015 at 10:48 PM. Reason: .