Consolidated 991RS thread
01-30-2015, 02:31 AM
#3827
Racer
01-30-2015, 07:06 AM
#3829
01-30-2015, 08:53 AM
#3830
Race Director
News!
http://www.worldcarfans.com/11501298...-live-streamed
Wrong RS sorry! Maybe easier to come by??
http://www.worldcarfans.com/11501298...-live-streamed
Wrong RS sorry! Maybe easier to come by??
01-30-2015, 11:38 AM
#3832
We are getting off topic , but I didn't start it so - the Ford RS looks nice , but I'm pinning all my hopes on the VW Golf R400 - good chance we'll see it here in the States . Might end up being a limited run car with fewer made than the GT3 RS ?
01-31-2015, 02:46 AM
#3835
I just noticed something interesting. I'd always expected the 991 RS 4.0 to be bored to 4.0L. It was just pointed out, however, that Porsche has a 81.5mm crank on the shelf from the 2010 9A1 base Carrera. And while it's not currently in use it's known to fit into the GT3's 9A1 block.
If one used that crank's 81.5 mm stroke in the 991 GT3, you'd get 4 Liters displacement. That would be an ideal number for homologation, as current GTE class rules state <4L. And the exactness of the displacement numbers sound too ideal to be chance to me, as Porsche likes round displacement numbers for race engines to maximize displacement for the classes, for example:
996 GT3: 100.0 x 76.4 = 3.600
997 GT3: 102.7 x 76.4 = 3.800
997 RS 4.0: 102.7 x 80.44 = 4.000
Note one dimension was always shared with the predecessor for parts commonality, while the other was always adjusted to get exactly the target displacement.
That 81.5 mm crank doesn't make a round displacement with any existing 9A1 bore (97, 89mm) etc... except the 102mm bore it's never been used with, that of the current GT3:
991 GT3: 102 x 77.5 = 3.800
991 RS?: 102 x 81.5 = 4.000
Seems like that was planned to me, and we know the crank fits the block. My bet? The 991 GT3 RS will get a 102mm bore and an 81.5mm stroke for 4.00 liters. This will make it difficult to maintain the current 9000 rpm redline, but I suspect they will pull it off.
Just thought I'd throw that out there...
If one used that crank's 81.5 mm stroke in the 991 GT3, you'd get 4 Liters displacement. That would be an ideal number for homologation, as current GTE class rules state <4L. And the exactness of the displacement numbers sound too ideal to be chance to me, as Porsche likes round displacement numbers for race engines to maximize displacement for the classes, for example:
996 GT3: 100.0 x 76.4 = 3.600
997 GT3: 102.7 x 76.4 = 3.800
997 RS 4.0: 102.7 x 80.44 = 4.000
Note one dimension was always shared with the predecessor for parts commonality, while the other was always adjusted to get exactly the target displacement.
That 81.5 mm crank doesn't make a round displacement with any existing 9A1 bore (97, 89mm) etc... except the 102mm bore it's never been used with, that of the current GT3:
991 GT3: 102 x 77.5 = 3.800
991 RS?: 102 x 81.5 = 4.000
Seems like that was planned to me, and we know the crank fits the block. My bet? The 991 GT3 RS will get a 102mm bore and an 81.5mm stroke for 4.00 liters. This will make it difficult to maintain the current 9000 rpm redline, but I suspect they will pull it off.
Just thought I'd throw that out there...
01-31-2015, 04:16 AM
#3836
I just noticed something interesting. I'd always expected the 991 RS 4.0 to be bored to 4.0L. It was just pointed out, however, that Porsche has a 81.5mm crank on the shelf from the 2010 9A1 base Carrera. And while it's not currently in use it's known to fit into the GT3's 9A1 block. If one used that crank's 81.5 mm stroke in the 991 GT3, you'd get 4 Liters displacement. That would be an ideal number for homologation, as current GTE class rules state <4L. And the exactness of the displacement numbers sound too ideal to be chance to me, as Porsche likes round displacement numbers for race engines to maximize displacement for the classes, for example: 996 GT3: 100.0 x 76.4 = 3.600 997 GT3: 102.7 x 76.4 = 3.800 997 RS 4.0: 102.7 x 80.44 = 4.000 Note one dimension was always shared with the predecessor for parts commonality, while the other was always adjusted to get exactly the target displacement. That 81.5 mm crank doesn't make a round displacement with any existing 9A1 bore (97, 89mm) etc... except the 102mm bore it's never been used with, that of the current GT3: 991 GT3: 102 x 77.5 = 3.800 991 RS?: 102 x 81.5 = 4.000 Seems like that was planned to me, and we know the crank fits the block. My bet? The 991 GT3 RS will get a 102mm bore and an 81.5mm stroke for 4.00 liters. This will make it difficult to maintain the current 9000 rpm redline, but I suspect they will pull it off. Just thought I'd throw that out there...
01-31-2015, 04:45 AM
#3839
01-31-2015, 05:45 AM
#3840