991.2 first-hand impressions and test drives
12-27-2015, 01:48 PM
#106
Rennlist Member
Not wanting to start a debate on Power vs Torque, but that graph shows exactly why the new engines can feel a little "boring" going through the rev range.
Assume for a second that it actually is the torque pushing the car forward (torque on the crankshaft through the gearbox out to the wheelhubs and then times the lever which is the wheel radii gives force pushing the car forward)
From 1750 rpm you have a completely flat torque curve which means the force pushing the car forward (hence acceleration) is constant as the revs rise. What you feel in the seat is actually a gradually declining acceleration since that constant force works against wind and rolling resistance and wind resistance increases with speed => acceleration feels "linear" or maybe even tapering off slightly.
Look at the old engines torque curve and you'll realize that the climbing torque gives more and more force to overcome the increasing wind and rolling resistance and this is what gives a feeling of getting more acceleration as you rev it through the range. You are "rewarded" for revving the engine!
The new engine torque curve has the same shape as a modern diesel engine, it only revs a bit longer, but the characteristics are the same. Feels strong but not very "rewarding". At any point along the curve you can shift to a higher gear and as long as you end up above "the knee" at 1750rpm the acceleration will be more or less the same. Only benefit will be the eventual aural experience at higher revs.
I have no problem with modern diesels and gasoline engines with these type of torque curves. As daily drivers/highway cruising they offer very good driveability and possibility to increase speed without having to shift down. But for an "enthusiast car" I want my car to be more "alive" than that and then nothing can match an NA-engine.
As a side note, the reason for creating the shape of these torque curves is (again) CO2/fuel cunsumption. With a very high torque low in the rev range you can shift to higher gear sooner in the test cycle and the engine efficiency will be higher for a number of reasons (larger throttle opening => less pumping losses, lower revs => lower parasitic and friction losses. Etc) This is also the explanation for the irritatingly long final gears all cars get nowadays... Get the revs down in the test cycle...
Assume for a second that it actually is the torque pushing the car forward (torque on the crankshaft through the gearbox out to the wheelhubs and then times the lever which is the wheel radii gives force pushing the car forward)
From 1750 rpm you have a completely flat torque curve which means the force pushing the car forward (hence acceleration) is constant as the revs rise. What you feel in the seat is actually a gradually declining acceleration since that constant force works against wind and rolling resistance and wind resistance increases with speed => acceleration feels "linear" or maybe even tapering off slightly.
Look at the old engines torque curve and you'll realize that the climbing torque gives more and more force to overcome the increasing wind and rolling resistance and this is what gives a feeling of getting more acceleration as you rev it through the range. You are "rewarded" for revving the engine!
The new engine torque curve has the same shape as a modern diesel engine, it only revs a bit longer, but the characteristics are the same. Feels strong but not very "rewarding". At any point along the curve you can shift to a higher gear and as long as you end up above "the knee" at 1750rpm the acceleration will be more or less the same. Only benefit will be the eventual aural experience at higher revs.
I have no problem with modern diesels and gasoline engines with these type of torque curves. As daily drivers/highway cruising they offer very good driveability and possibility to increase speed without having to shift down. But for an "enthusiast car" I want my car to be more "alive" than that and then nothing can match an NA-engine.
As a side note, the reason for creating the shape of these torque curves is (again) CO2/fuel cunsumption. With a very high torque low in the rev range you can shift to higher gear sooner in the test cycle and the engine efficiency will be higher for a number of reasons (larger throttle opening => less pumping losses, lower revs => lower parasitic and friction losses. Etc) This is also the explanation for the irritatingly long final gears all cars get nowadays... Get the revs down in the test cycle...
Everyone has to potentially learn this lesson at their own speed, you just can't tell 'em. You won't *need* or over time *want* to drive the car hard due to that torque curve - in fact you can't on the street - it will be too fast. Then the question for some becomes - well, it's still not as comfortable as a bimmer so why not get a bigger more comfy "sports" car... and you find you're shopping M5s cause everyone needs 550+ turbo hp on the street.
Buy one though, try it out...I predict many of you will be back looking for a non-turbo. I paid my dues to go that route too.
Long live the NA engine in a 911! I hope Porsche keeps making those in their GTs so I can buy a new one at some point.
12-27-2015, 02:43 PM
#107
Burning Brakes
I can only relate to the motorcycle world. A 600cc four cylinder bike makes low torque so you have to rev it high to get it to go. I rode a friend's at the track and you keep in the 12K-15K range. Yikes! Terrible for street riding. Much better is a 1000 sport bike. Decent torque combine with high horsepower and a high redline means a bike that can go almost 100mph in 1st gear. Crazy. I had one for awhile. Compare that to my current bike which is a 1300cc v-twin which makes a lot of torque above 3K rpm and also makes good hp. Not much need to shift and a handful of throttle will get you over the speed limit very very fast. Total overkill for the street, and this is my favorite street bike of all those I have owned. Maybe the na 911 would sort of compare to the 1000cc four-let it rev and you are rewarded with a rush of big hp. The new turbo would compare to my current bike. Lot's of torque everywhere but also builds to high hp. I love to blast out of a corner riding that huge torque curve as the traction control keeps the wheel spin under control and the anti-wheelie keeps the bike from flipping over. Intoxicating. So I have ridden and owned bikes with all sorts of power curves and I really like torque! So I can imagine driving the new turbo C2s and having the car just pull like crazy as the acceleration builds-similar to my bike. Can't wait!
12-27-2015, 02:53 PM
#108
Burning Brakes
I don't know a lot about cars but since 1983 I have owned seven new Porsches. Every new car was better than the one it replaced. I now have a 991.2S on order and I am very confident it will be better than the 13 991S Cab it is replacing.
For years I have been reading from the doubters that the new model will destroy Porsche. Facts have not been with the heretics. At first it was air cooled vs Liquid cooled. Then it was the 996 was too big. Then it was DFI will be problematic. Then the PDK was for people who can't drive. All this progress has proven the doubters WRONG.
If you want a car that can compete with the best, R&D is key, otherwise you will be left in the dust. The 991.2 will be the best Porsche ever built. But this won't last. The next generation will be even better and the doubters will forecast the end again. A generation from now all these cars will be electric. What will they say then????
There will always be people who won't accept change and then there are the Steve Jobs of the world who believe we can always make it better.
For years I have been reading from the doubters that the new model will destroy Porsche. Facts have not been with the heretics. At first it was air cooled vs Liquid cooled. Then it was the 996 was too big. Then it was DFI will be problematic. Then the PDK was for people who can't drive. All this progress has proven the doubters WRONG.
If you want a car that can compete with the best, R&D is key, otherwise you will be left in the dust. The 991.2 will be the best Porsche ever built. But this won't last. The next generation will be even better and the doubters will forecast the end again. A generation from now all these cars will be electric. What will they say then????
There will always be people who won't accept change and then there are the Steve Jobs of the world who believe we can always make it better.
12-27-2015, 03:30 PM
#109
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To the average 911 buyer, the complaint about the engine basically sounds like this: "it accelerates too fast...I don't like it when it goes so fast so quickly". From many reviews it's also said that the steering is much better than the 991.1, but I think the hardcore 991.1 ppl here are too caught up with the engine to even notice.
12-27-2015, 04:06 PM
#110
Rennlist Member
The reality is that there are good engines and bad engines on both sides of the NA vs Turbo fence. I have owned a collection of both. Some were good, some were not so good. I am not pathologically against one or the other. I just like good engines be they NA or Turbo, and the 991.2 is a good one. So I do not need to "learn" about turbo engines having lived on and off with them for over 20 years. Btw, worst turbo engine I ever drove was a Saab.
And I wouldn't characterize the 9A2 engine as being like a Diesel engine only just revving a bit longer. The 9A2 engine rev limit is only marginaily below the 9A1! And it is still developing more HP at its rev limit of 7500 than the 9A1.
So please, drive the damn thing before you all dis it. I have and it has it's good points and it bad points, just like the current 991.1. If you still hate it after that, then fine...but be balanced with the criticism.
And I wouldn't characterize the 9A2 engine as being like a Diesel engine only just revving a bit longer. The 9A2 engine rev limit is only marginaily below the 9A1! And it is still developing more HP at its rev limit of 7500 than the 9A1.
So please, drive the damn thing before you all dis it. I have and it has it's good points and it bad points, just like the current 991.1. If you still hate it after that, then fine...but be balanced with the criticism.
12-27-2015, 10:13 PM
#111
RL Community Team
Rennlist Member
Rennlist Member
Even though I was disappointed with some elements of the car, I kind of feel like I have to defend it considering how much negativity it is getting.
As I have reported earlier, it seems that I got some quite different impressions from the car. Just goes to show you that one mans meat is another mans poison.
I felt that the power build up was indeed linear which made chasing the higher RPMs worthwhile. Just look at the power curve of the 991.1 vs 991.2. They are very similar. Main differences being that the 991.2 just develops more HP earlier and peaks earlier, but is still developing more hp than the 991.1 at its peak.
It's possible that some drivers are feeling the drastically different torque curve and confusing it with power.
Like others, my biggest disappointment was the sound. But it is not synthesized. Yes, it now has two sound symposers but this is just piping natural sound into the cabin like the 991.1 did with one symposer. But now it's a more muffled induction noise due to the turbos.
Overall, even with all the changes, it's still the best sports car out there. At the price point, what else are you to buy.
As I have reported earlier, it seems that I got some quite different impressions from the car. Just goes to show you that one mans meat is another mans poison.
I felt that the power build up was indeed linear which made chasing the higher RPMs worthwhile. Just look at the power curve of the 991.1 vs 991.2. They are very similar. Main differences being that the 991.2 just develops more HP earlier and peaks earlier, but is still developing more hp than the 991.1 at its peak.
It's possible that some drivers are feeling the drastically different torque curve and confusing it with power.
Like others, my biggest disappointment was the sound. But it is not synthesized. Yes, it now has two sound symposers but this is just piping natural sound into the cabin like the 991.1 did with one symposer. But now it's a more muffled induction noise due to the turbos.
Overall, even with all the changes, it's still the best sports car out there. At the price point, what else are you to buy.
Not wanting to start a debate on Power vs Torque, but that graph shows exactly why the new engines can feel a little "boring" going through the rev range.
Assume for a second that it actually is the torque pushing the car forward (torque on the crankshaft through the gearbox out to the wheelhubs and then times the lever which is the wheel radii gives force pushing the car forward)
From 1750 rpm you have a completely flat torque curve which means the force pushing the car forward (hence acceleration) is constant as the revs rise. What you feel in the seat is actually a gradually declining acceleration since that constant force works against wind and rolling resistance and wind resistance increases with speed => acceleration feels "linear" or maybe even tapering off slightly.
Look at the old engines torque curve and you'll realize that the climbing torque gives more and more force to overcome the increasing wind and rolling resistance and this is what gives a feeling of getting more acceleration as you rev it through the range. You are "rewarded" for revving the engine!
The new engine torque curve has the same shape as a modern diesel engine, it only revs a bit longer, but the characteristics are the same. Feels strong but not very "rewarding". At any point along the curve you can shift to a higher gear and as long as you end up above "the knee" at 1750rpm the acceleration will be more or less the same. Only benefit will be the eventual aural experience at higher revs.
I have no problem with modern diesels and gasoline engines with these type of torque curves. As daily drivers/highway cruising they offer very good driveability and possibility to increase speed without having to shift down. But for an "enthusiast car" I want my car to be more "alive" than that and then nothing can match an NA-engine.
As a side note, the reason for creating the shape of these torque curves is (again) CO2/fuel cunsumption. With a very high torque low in the rev range you can shift to higher gear sooner in the test cycle and the engine efficiency will be higher for a number of reasons (larger throttle opening => less pumping losses, lower revs => lower parasitic and friction losses. Etc) This is also the explanation for the irritatingly long final gears all cars get nowadays... Get the revs down in the test cycle...
Assume for a second that it actually is the torque pushing the car forward (torque on the crankshaft through the gearbox out to the wheelhubs and then times the lever which is the wheel radii gives force pushing the car forward)
From 1750 rpm you have a completely flat torque curve which means the force pushing the car forward (hence acceleration) is constant as the revs rise. What you feel in the seat is actually a gradually declining acceleration since that constant force works against wind and rolling resistance and wind resistance increases with speed => acceleration feels "linear" or maybe even tapering off slightly.
Look at the old engines torque curve and you'll realize that the climbing torque gives more and more force to overcome the increasing wind and rolling resistance and this is what gives a feeling of getting more acceleration as you rev it through the range. You are "rewarded" for revving the engine!
The new engine torque curve has the same shape as a modern diesel engine, it only revs a bit longer, but the characteristics are the same. Feels strong but not very "rewarding". At any point along the curve you can shift to a higher gear and as long as you end up above "the knee" at 1750rpm the acceleration will be more or less the same. Only benefit will be the eventual aural experience at higher revs.
I have no problem with modern diesels and gasoline engines with these type of torque curves. As daily drivers/highway cruising they offer very good driveability and possibility to increase speed without having to shift down. But for an "enthusiast car" I want my car to be more "alive" than that and then nothing can match an NA-engine.
As a side note, the reason for creating the shape of these torque curves is (again) CO2/fuel cunsumption. With a very high torque low in the rev range you can shift to higher gear sooner in the test cycle and the engine efficiency will be higher for a number of reasons (larger throttle opening => less pumping losses, lower revs => lower parasitic and friction losses. Etc) This is also the explanation for the irritatingly long final gears all cars get nowadays... Get the revs down in the test cycle...
The torque curve on the 991.2 is simply higher.
12-28-2015, 01:26 AM
#114
Banned
12-28-2015, 04:59 AM
#115
Burning Brakes
Thread Starter
I can only relate to the motorcycle world. A 600cc four cylinder bike makes low torque so you have to rev it high to get it to go. I rode a friend's at the track and you keep in the 12K-15K range. Yikes! Terrible for street riding. Much better is a 1000 sport bike. Decent torque combine with high horsepower and a high redline means a bike that can go almost 100mph in 1st gear. Crazy. I had one for awhile. Compare that to my current bike which is a 1300cc v-twin which makes a lot of torque above 3K rpm and also makes good hp. Not much need to shift and a handful of throttle will get you over the speed limit very very fast. Total overkill for the street, and this is my favorite street bike of all those I have owned. Maybe the na 911 would sort of compare to the 1000cc four-let it rev and you are rewarded with a rush of big hp. The new turbo would compare to my current bike. Lot's of torque everywhere but also builds to high hp. I love to blast out of a corner riding that huge torque curve as the traction control keeps the wheel spin under control and the anti-wheelie keeps the bike from flipping over. Intoxicating. So I have ridden and owned bikes with all sorts of power curves and I really like torque! So I can imagine driving the new turbo C2s and having the car just pull like crazy as the acceleration builds-similar to my bike. Can't wait!
Not that I necessarily want the same thing out of a car engine, though, or want two vehicles that do similar things, but was interesting to read someone who sounds like their experience on two wheels was the same as mine.
12-28-2015, 09:36 AM
#116
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12-28-2015, 03:23 PM
#117
As stg says, I'll reserve my opinions until I actually drive it, BUT I'm lookin forward to it. Like all the motorcycle analogies, I've had crotch rockets and big twin Harleys, but the vrod engine seemed to be best of both worlds - not a peaky high rpm screamer and not a big block low end torque monster, but good enough low end to ride in normal traffic and revvy enough to wind out on back roads. Thinking the 991.2 might be same way.
As to 996 comparisons, wasn't the LOOKS of that car that killed it? I know the engine had IMS issues, but the turbo was Mezger engine and its values are half the 997. From what I've read, the 997 shares the chassis, but the return to the traditional look and the non-ford explorer looking interior is what keeps its values up? So how can the 991.2 be the 996 bc of a turbo engine? Confusing.
Any of Yall read the motor trend with the new NSX (same issue as Miami blue 991.2) - yikes! High revving NA power plants are fading in the rear view, for you fans of such, I don't know where you will go in the future except for used market.
As to 996 comparisons, wasn't the LOOKS of that car that killed it? I know the engine had IMS issues, but the turbo was Mezger engine and its values are half the 997. From what I've read, the 997 shares the chassis, but the return to the traditional look and the non-ford explorer looking interior is what keeps its values up? So how can the 991.2 be the 996 bc of a turbo engine? Confusing.
Any of Yall read the motor trend with the new NSX (same issue as Miami blue 991.2) - yikes! High revving NA power plants are fading in the rear view, for you fans of such, I don't know where you will go in the future except for used market.
12-28-2015, 04:02 PM
#118
Race Director
lol, now you guys are complaining it has too much torque? I swear you lot must be the type that drive around town at 6000rpm. I always thought that was because you thought you looked cool, but I guess its because you like to actually have some torque available. Interesting.
Btw, STG, can you please give us your opinion of the turbo 991.2? I'm not sure we know what your standpoint on the new car is
Btw, STG, can you please give us your opinion of the turbo 991.2? I'm not sure we know what your standpoint on the new car is
12-28-2015, 04:21 PM
#119
Race Director
Originally Posted by Quadcammer
Btw, STG, can you please give us your opinion of the turbo 991.2? I'm not sure we know what your standpoint on the new car is
What they mean to anyone, it's a personal call. One good thing about the USA, we have choices.
12-28-2015, 05:42 PM
#120
Instructor
Look at the old engines torque curve and you'll realize that the climbing torque gives more and more force to overcome the increasing wind and rolling resistance and this is what gives a feeling of getting more acceleration as you rev it through the range. You are "rewarded" for revving the engine!
The new engine torque curve has the same shape as a modern diesel engine, it only revs a bit longer, but the characteristics are the same. Feels strong but not very "rewarding". At any point along the curve you can shift to a higher gear and as long as you end up above "the knee" at 1750rpm the acceleration will be more or less the same. Only benefit will be the eventual aural experience at higher revs.
The new engine torque curve has the same shape as a modern diesel engine, it only revs a bit longer, but the characteristics are the same. Feels strong but not very "rewarding". At any point along the curve you can shift to a higher gear and as long as you end up above "the knee" at 1750rpm the acceleration will be more or less the same. Only benefit will be the eventual aural experience at higher revs.