991 GT2...
07-01-2013, 11:22 PM
#61
Burning Brakes
If you dyno a "380 hp" 996 GT3 vs a "380 hp" X51 997 Carrera w/ powerkit you'll realize Porsche has been under-rating the GT3s for years. They are simply keeping the tradition.
Seems fairly clear that they have two options, increasing the RPM where peak power is made or stroking to increase displacement.
Keeping torque the same but moving peak power up by 500 rpm (from 8250 to 8750) would result in 30 additional hp. While it's not 100% clear they can do this it seems very likely: the new top end's reason for existence is an aggressive high rpm cam, and the bottom end is obviously capable based on the (relatively, vs audi, etc) low pistons speeds the car is running at 9000 rpm. Also keep in mind that removing the human from the equation has eliminated the headroom that was once needed to cover a missed shift, another reason pushing the RPMs up seems relatively straightforward. All this suggests that a 3.8L version could comfortably rev past 9000 rpm if needed, and a 9000-9250 rpm redline .1 RS with "500 hp" (really 525-530) primarily though a cam change would be my bet.
Alternatively stroking the motor, which I agree was part of the plan from the beginning, could deliver a similar increase by itself, or be combined with a shift up the RPM band to get more than 50 hp total (though the stroked motor would probably not be able to exceed 9000 rpm, one reason we may not see an increase in a .1 3.8 RS redline). Given the potential of the bottom and new top end I eventually expect to see a ~550 hp @ 8700 rpm 4 liter. The question is when we'll get to see that- I tend to agree that we might need to wait for a .2 RS.
My fear is that simply increasing the RPM on a 3.8 .1 RS will leave the large hole in torque on the lower end, making the motor significantly less suitable for pairing with a manual.
Seems fairly clear that they have two options, increasing the RPM where peak power is made or stroking to increase displacement.
Keeping torque the same but moving peak power up by 500 rpm (from 8250 to 8750) would result in 30 additional hp. While it's not 100% clear they can do this it seems very likely: the new top end's reason for existence is an aggressive high rpm cam, and the bottom end is obviously capable based on the (relatively, vs audi, etc) low pistons speeds the car is running at 9000 rpm. Also keep in mind that removing the human from the equation has eliminated the headroom that was once needed to cover a missed shift, another reason pushing the RPMs up seems relatively straightforward. All this suggests that a 3.8L version could comfortably rev past 9000 rpm if needed, and a 9000-9250 rpm redline .1 RS with "500 hp" (really 525-530) primarily though a cam change would be my bet.
Alternatively stroking the motor, which I agree was part of the plan from the beginning, could deliver a similar increase by itself, or be combined with a shift up the RPM band to get more than 50 hp total (though the stroked motor would probably not be able to exceed 9000 rpm, one reason we may not see an increase in a .1 3.8 RS redline). Given the potential of the bottom and new top end I eventually expect to see a ~550 hp @ 8700 rpm 4 liter. The question is when we'll get to see that- I tend to agree that we might need to wait for a .2 RS.
My fear is that simply increasing the RPM on a 3.8 .1 RS will leave the large hole in torque on the lower end, making the motor significantly less suitable for pairing with a manual.
My concern about pulling additional HP (500+) from the GT3RS 4.0 is that several friends who have been running those 500 HP Engines both in racing
and HPDE applications have required very early Engine rebuilds and several racing teams have returned to the more reliable, lower HP 3.8 Engine.
Never having Dynoed a GT3RS 4.0 Engine, admittedly the "500 HP" rating
may be understated, and the new 9A1 type Engine may be more reliable at
those high specific power outputs. Time will tell.
In any event, IMHO I believe our Porsches need more Torque therefore more displacement. For adding Torque, a longer stroke will help but at the expense of RPM capabilities. "There is no substitute for Cubic Inches" in normally aspirated Engines. Note that the new 6.2 Liter Corvette makes more Torque at idle than our 991 GT3 does at 6,250 RPM before making its Torque peak of 325 Ft. Lbs. Of course our 991 3.8 L Turbo S makes a very admirable 516 Ft. Lbs of Torque (553 Ft. Lbs for 10 Seconds) Presumably the GT2 with higher boost pressures will exceed even that admirable figure.
07-02-2013, 12:43 AM
#62
Rennlist Member
PDK won't improve driveline efficiency. Performance, yes. Rear wheel hp no.
Its claim to fame is to be able to fully take advantage of a motor that is, in essence, peaky. Like my motocross bikes from long ago, it's a transmission that allows you to stay 'on the pipe'. PDK is a bit of an equalizer wrt high tq (displacement) cars.
IMO.
Its claim to fame is to be able to fully take advantage of a motor that is, in essence, peaky. Like my motocross bikes from long ago, it's a transmission that allows you to stay 'on the pipe'. PDK is a bit of an equalizer wrt high tq (displacement) cars.
IMO.
Porsche flat six N/A engines have always been revvy not torquey. Porsche however have competition that is building engines that are both....
Since the 1999 996.1 GT3, horse power for the GT3 has risen 110 bhp over 14 years. That's an increase of 31%.
However torque has only risen 40 lbft. That's only 14%!
The closer you dwell on this dynamic the more you realize Porsche had to look at using a PDK-S box to get maximum effect from the new 991 GT3. I think they contemplated a manual before even the PDK but realized almost straight away that it just wasnt going to buy them the performance car they need of the next 3-4 years until the gen 2 cars are released. You have to remember too that have visibility into the full VAG product calender for the next 4-6 years so they know what their competition will be and what their market segment will need to stay ahead of the game in 12-24 months etc.
To be perfectly, openly honest, I believe what Porsche really need is an 8 cylinder engine in the back of the 911, much the same way RUF has done (that's just a beautiful light engine that revs high and has stonking torque). The GT3 needs 360-400 lbft torque to really be a bullet proof and practical performance machine for the next decade....
07-02-2013, 03:04 AM
#63
Race Director
Not an endorsement, but perhaps reality.......
07-02-2013, 05:02 AM
#64
Rennlist Member
I think you are perhaps right. The 991.2 GT3 (4.0L) may use displacement to address torque and keep the peak power headline moving along but the 992? GT3 is likely to use hub mounted motors and a lightweight KERs style recharging system to add 40lbft and 50 bhp to the car from 0 rpm. This will keep Porsche in the game. I think you are correct here and I am wrong - there will be no 8 cylinder Porsche. DC motors will take care of that!
Its interesting to note that the 4.0RS is 1365kg making 493 bhp and 339 lbft but is slower than the 991 GT3 by 2 seconds on the North Loop. This is a demonstration as to how the PDK is optomising the use of the new engine its advantage given in every other dimension (weight, power, torque) the 991 GT3 is down. It also means the engine and clutch probably are less stressed too....
07-02-2013, 07:32 AM
#65
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The video and pics show the new GT3RS test mule. They are using turbo tubs for extra wide body.
Id say the RS will be 500Hp, less weight thanks to maybe carbon front fenders/hood and pull tab door handles, more aero and wider tires.
It should be good for few seconds off the non RS 991GT3.
I cant see them building a GT2.... Afterall, it would be a 2wd 991TTS with a tune and 991GT3RS aero with maybe carbon front fenders/hood..... i suppose it would be faster then 991GT3RS, but would there be a market and would it take away from GT3RS market?
Id say the RS will be 500Hp, less weight thanks to maybe carbon front fenders/hood and pull tab door handles, more aero and wider tires.
It should be good for few seconds off the non RS 991GT3.
I cant see them building a GT2.... Afterall, it would be a 2wd 991TTS with a tune and 991GT3RS aero with maybe carbon front fenders/hood..... i suppose it would be faster then 991GT3RS, but would there be a market and would it take away from GT3RS market?
07-02-2013, 09:09 AM
#66
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Its interesting to note that the 4.0RS is 1365kg making 493 bhp and 339 lbft but is slower than the 991 GT3 by 2 seconds on the North Loop. This is a demonstration as to how the PDK is optomising the use of the new engine its advantage given in every other dimension (weight, power, torque) the 991 GT3 is down. It also means the engine and clutch probably are less stressed too....
I agree that CAFE standards mean hybrid drivetrains are in the 911's and ultimately GT3's future.
I think the PDK decision was as much about cost as performance - cost drove not developing a one-off application to fit the Mezger and cost drove not offering a manual on the 991 GT3.
07-02-2013, 09:34 AM
#67
Nordschleife Master
The closer you dwell on this dynamic the more you realize Porsche had to look at using a PDK-S box to get maximum effect from the new 991 GT3. I think they contemplated a manual before even the PDK but realized almost straight away that it just wasnt going to buy them the performance car they need of the next 3-4 years until the gen 2 cars are released.
Since you're famous for your predictions,here's mine : once Porsche has gone down the PDK path with their most focused car,my prediction is that by next generation (992 or whatever will be called) or possible even starting with the 991.2 cars,even a plain old Jane Carrera will be PDK only!
07-02-2013, 12:26 PM
#68
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I think you're attributing too much to the PDK in terms of Ring times. The 991 Cup is lapping Silverstone 2sec faster than the 997 Cup and it uses the same motor and transmission (in theory there's a slight gain on downshifts due to the paddles on the wheel vs the sequential stalk but it's fractions of a second - no doubt easier but only marginally faster for the skilled driver), which means it's primarily down to chassis changes and larger rubber. See here for firsthand report: https://rennlist.com/forums/porsche-...ne-report.html
I agree that CAFE standards mean hybrid drivetrains are in the 911's and ultimately GT3's future.
I think the PDK decision was as much about cost as performance - cost drove not developing a one-off application to fit the Mezger and cost drove not offering a manual on the 991 GT3.
I agree that CAFE standards mean hybrid drivetrains are in the 911's and ultimately GT3's future.
I think the PDK decision was as much about cost as performance - cost drove not developing a one-off application to fit the Mezger and cost drove not offering a manual on the 991 GT3.
The performance bump in the hands of a pro come mostly from enhanced grip and more zoot. IMO. For the rest of us it's grip, zoot and PDK.
07-02-2013, 12:47 PM
#69
Burning Brakes
+1 on this...
Porsche flat six N/A engines have always been revvy not torquey. Porsche however have competition that is building engines that are both....
Since the 1999 996.1 GT3, horse power for the GT3 has risen 110 bhp over 14 years. That's an increase of 31%.
However torque has only risen 40 lbft. That's only 14%!
The closer you dwell on this dynamic the more you realize Porsche had to look at using a PDK-S box to get maximum effect from the new 991 GT3. I think they contemplated a manual before even the PDK but realized almost straight away that it just wasnt going to buy them the performance car they need of the next 3-4 years until the gen 2 cars are released. You have to remember too that have visibility into the full VAG product calender for the next 4-6 years so they know what their competition will be and what their market segment will need to stay ahead of the game in 12-24 months etc.
To be perfectly, openly honest, I believe what Porsche really need is an 8 cylinder engine in the back of the 911, much the same way RUF has done (that's just a beautiful light engine that revs high and has stonking torque). The GT3 needs 360-400 lbft torque to really be a bullet proof and practical performance machine for the next decade....
Porsche flat six N/A engines have always been revvy not torquey. Porsche however have competition that is building engines that are both....
Since the 1999 996.1 GT3, horse power for the GT3 has risen 110 bhp over 14 years. That's an increase of 31%.
However torque has only risen 40 lbft. That's only 14%!
The closer you dwell on this dynamic the more you realize Porsche had to look at using a PDK-S box to get maximum effect from the new 991 GT3. I think they contemplated a manual before even the PDK but realized almost straight away that it just wasnt going to buy them the performance car they need of the next 3-4 years until the gen 2 cars are released. You have to remember too that have visibility into the full VAG product calender for the next 4-6 years so they know what their competition will be and what their market segment will need to stay ahead of the game in 12-24 months etc.
To be perfectly, openly honest, I believe what Porsche really need is an 8 cylinder engine in the back of the 911, much the same way RUF has done (that's just a beautiful light engine that revs high and has stonking torque). The GT3 needs 360-400 lbft torque to really be a bullet proof and practical performance machine for the next decade....
There comes a point where hanging a bigger, longer, heavier, more powerful engine out the *** end of a 2WD car just doesn’t make sense, and I think we’re getting very close to that point. PDK-S, RWS, advanced TC algorithms, etc. may allow Porsche to squeeze a few more years out of the 911 platform as a top tier car to match the best of the competition, but I’m afraid its days in that role are numbered. It pains me to say that, because I’m a huge fan of the 911 and have been for a long time.
As mentioned in the other post, electric motors and big flywheels are another way to add a temporary burst of power and torque without having to cram a bigger motor into the back of the 911, but the competition can also play that game with products that have bigger engines and better layouts as a starting point.
07-02-2013, 12:57 PM
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There comes a point where hanging a bigger, longer, heavier, more powerful engine out the *** end of a 2WD car just doesn’t make sense, and I think we’re getting very close to that point. PDK-S, RWS, advanced TC algorithms, etc. may allow Porsche to squeeze a few more years out of the 911 platform as a top tier car to match the best of the competition, but I’m afraid its days in that role are numbered. It pains me to say that, because I’m a huge fan of the 911 and have been for a long time.
- IIRC, the vette motor is actually light yet is a tq monster.
07-02-2013, 01:43 PM
#71
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The formula used by the competition has been fairly straightforward: (1) More cylinders/displacement/power/torque, and (2) Conventional mid-engine, or front/mid-engine layout. IMO, what Porsche needs is the 960, with a 600+ HP V8 planted between the driver and the rear wheels.
There comes a point where hanging a bigger, longer, heavier, more powerful engine out the *** end of a 2WD car just doesn’t make sense, and I think we’re getting very close to that point. PDK-S, RWS, advanced TC algorithms, etc. may allow Porsche to squeeze a few more years out of the 911 platform as a top tier car to match the best of the competition, but I’m afraid its days in that role are numbered. It pains me to say that, because I’m a huge fan of the 911 and have been for a long time.
As mentioned in the other post, electric motors and big flywheels are another way to add a temporary burst of power and torque without having to cram a bigger motor into the back of the 911, but the competition can also play that game with products that have bigger engines and better layouts as a starting point.
There comes a point where hanging a bigger, longer, heavier, more powerful engine out the *** end of a 2WD car just doesn’t make sense, and I think we’re getting very close to that point. PDK-S, RWS, advanced TC algorithms, etc. may allow Porsche to squeeze a few more years out of the 911 platform as a top tier car to match the best of the competition, but I’m afraid its days in that role are numbered. It pains me to say that, because I’m a huge fan of the 911 and have been for a long time.
As mentioned in the other post, electric motors and big flywheels are another way to add a temporary burst of power and torque without having to cram a bigger motor into the back of the 911, but the competition can also play that game with products that have bigger engines and better layouts as a starting point.
07-03-2013, 12:33 AM
#72
Rennlist Member
You keep insisting with this idea ad nauseam and defending Porsche's decision like you're their top lawyer. As long as you'll continue beating the dead horse I'll continue to say that they should've offered a choice in terms of transmission. No reasonable person would say that PDK isn't the better transmission but some of us don't care about lap times. And no,Porsche wouldn't have been losing money because their production cost would've been higher to build the car with both transmissions!
Since you're famous for your predictions,here's mine : once Porsche has gone down the PDK path with their most focused car,my prediction is that by next generation (992 or whatever will be called) or possible even starting with the 991.2 cars,even a plain old Jane Carrera will be PDK only!
Since you're famous for your predictions,here's mine : once Porsche has gone down the PDK path with their most focused car,my prediction is that by next generation (992 or whatever will be called) or possible even starting with the 991.2 cars,even a plain old Jane Carrera will be PDK only!
Sorry for beating a dead horse. What Im trying to do is put the choice of PDK-S only into some sort of real world context. Im trying to see it through PAGs eyes to determine what may have been the tipping point for the decision. I dont believe cost was the primary motivator. PAG could increase the new GT3 price another 10 or 20K and they will still sell all they make as compared to other similar performance vehicles on the market (excluding Nissan GTR) its a relative bargain.
Yes predictions are all we can make right now. Last week on the other thread I said we would receive two reviews in the next week or two and one would be from a USA journalist/publication. That one arrived Monday morning by way of the Edmunds review. Maybe it was a lucky guess!
Im relatively bypartisan when considering the new GT3 but firmly confident it will be an eye opener for many. I have a great "organic" MT 911 which I plan to keep. For me the GT3 is exciting because of it revolutionary approach to the GT theme. It really does promise to be something different from the RS & GT3 Ive owned before. I guess it provides a nice alternative to my rather raw air cooled car...
07-03-2013, 01:02 AM
#73
Burning Brakes
Porsche has looked awful at times this season in GrandAm. They got a major BOP concession in the last round – no restrictor plate whatsoever – and managed to finish third, but they don’t have a win this season. Magnus is leading by virtue of consistency, not outright speed.
I don’t doubt there will still be a 911 five or even ten years from now; I just don’t think it’ll be the flagship model that competes at the top level of production car motorsports. As with all predictions, only time will tell.
