718 Spyder Engine Crazy
11-23-2017, 08:48 PM
#61
Three Wheelin'
Not quite. Stroking the 3.8 is Porsche’s only practical option, and stroking results in a disproportionate increase in torque if you do nothing else. Top end flow hasn’t increased due to restriction through the valves, manifold, etc, so the higher rpms get throttled by trying to suck air through the same diameter draw straw, while the mid-range has no flow restriction and actually energizes resonant intake runners sooner and better. On a 997.2 GT3 to 4.0 this results in something around a 40 lbs ft bump in the mid-range if you don’t do something about it. Porsche’s own 997 RS 4.0 used not only a different cam but a different intake (with massive diameter runners) to counteract that bump in torque. If you don’t the result is a falling torque curve as you approach redline rather than a rising one, very different sensations. The GT group specifically tries to avoid this with their normally aspirated engines, and I’ll contend that they focus as much on the shape of the power curve as much as the absolute power itself.
11-24-2017, 01:46 AM
#62
By that logic the new 991.2 base Carrera (370 hp) should be quicker to 60 and through the 1/4 than the outgoing 991.1 GTS (435 hp), yes? Same 65 hp gap, torque advantage, etc. But the GTS is significantly faster to both figures...?
Again: right concept with torque, wrong conclusion. The Carrera GTS isn’t quicker than the GT3, etc, and more importantly Porsche insures the pecking order is maintained, so if it was in danger of being slower than the Cayman GTS they’d simply turn one of a dozen ***** to make it quicker.
It goes back to “value based pricing”. I’ve been asked to update this old thread, but it will give you an idea:
https://rennlist.com/forums/991-gt3-...tatistics.html
And of course this is exactly what makes the Spyder such a deal as a drivers car. On the performance scale it’s not hugely impressive vs it’s peers, but on an experience scale it’s way up there. A 4.0 liter torque monster of an engine that doesn’t need to pull to redline every gear to make speed would largely ruin that imho, one reason I’m quite sure they won’t do it.
Again: right concept with torque, wrong conclusion. The Carrera GTS isn’t quicker than the GT3, etc, and more importantly Porsche insures the pecking order is maintained, so if it was in danger of being slower than the Cayman GTS they’d simply turn one of a dozen ***** to make it quicker.
It goes back to “value based pricing”. I’ve been asked to update this old thread, but it will give you an idea:
https://rennlist.com/forums/991-gt3-...tatistics.html
And of course this is exactly what makes the Spyder such a deal as a drivers car. On the performance scale it’s not hugely impressive vs it’s peers, but on an experience scale it’s way up there. A 4.0 liter torque monster of an engine that doesn’t need to pull to redline every gear to make speed would largely ruin that imho, one reason I’m quite sure they won’t do it.
If you want rpm the GT3 engine has it and they can detune it to 430ps with slight changes. It will make more sense if they ustilise the same engine (in different tunes) across the GT platforms. A racing breed engine for GT cars!
In addition the 991.1 GTS (430hp) is not significantly faster than the 991.2 base (370 p) base. There are slight weight advantage to the GTS and GT3 as well.
Manuel vs manual (no launch control)
991.2 Base 0-100km/h (4.6s) 1430kg (DIN)
991.1 GTS 0-100km/h (4.3s) 1395kg (?)
PDK vs PDK
991.2 GTS 0-100km/h (3.7s) 1470kg (DIN)
0-160km/h (7.9s)
991.2 GT3 0-100km/h (3.4s) 1430kg (DIN)
0-160km/h (7.3s)
The above NA engines are 3.8 and 4.0 not 3.55. So you can't assume the result will be the same with 430ps from a 3.55L as torque is lower. With 981 Spyder/GT4 gearing +3.55 430ps engine a 718GTS could very well accelerate faster in the first 2 gears. That's why it is more realistic to have a bigger engine in the upcoming Spyder/GT4.
Your value based pricing is a hypnosis that seems to match previous data but in no way it is an official value positioning strategy from Porsche or that you can guarantee its validity on going.
11-24-2017, 03:33 AM
#63
Rennlist Member
9A2. Related, obviously, but enough differences that cross-generation compatibility is tricky- they would need to make many new parts with the associated testing and software to re-create the normally aspirated 3.8. All doable and it would make for a better, lighter engine in the end, but it would cost. With the 9A1 it would have been plug and play from the in-production parts kit...
It seems unrealistic to expect 9000 RPM GT3 engines to show up in these cars, just because of how much more expensive they must be to build. I agree with everyone who says "Shut up and take my money!", but if I had to gamble, my money would be on an NA version of the 3.8L engine in the 991.2 TT.
Edit: by the way, here's where I got the impression that the 991.2TT is not, in fact, using the 9A2:
https://www.total911.com/new-porsche...urbo-hits-200/
Obviously that was an early article, but it did quote August Achleitner more or less directly. In this case, then a "de-turbocharged" version of the 991.2TT engine would be similar to the 3.8L 9A1 they used in the previous generation...
Last edited by Noah Fect; 11-24-2017 at 03:50 AM.
11-24-2017, 03:42 AM
#64
Loads of interesting information here, particularly re the 4.0 and torque curves (thanks Petevb). It’s something I have in the back of my mind for my 991.1 one day, but don’t like the sound of a fade to redline!
11-24-2017, 10:31 AM
#65
Porsche long ago divorced what something costs from what you pay. Instead you pay based purely on how badly you want it, ie how much you will pay. Apparently Porsche customers value performance quite a lot, because they are willing to pay tens of thousands more for the exact same engine with slightly more power unlocked (base Carrera vs Carrera S, Cayenne GTS, etc). Meanwhile as you see from the image a few posts up until recently the base Boxster and Carrera S shared over 95% of their engine parts. In fact it would have been cheaper for Porsche to simply make them all 3.8s, but they didn’t. Why? Think about it, I’m sure you can come up with some reasons...
If your argument in the end is that you’d like a faster car for less money then best of luck. Chevy is happy to sell you something. However once you get past the game of Top Trumps you’ll likely find that all of the cars we’re discussing are hugely quick, and extra outright speed doesn’t by itself add much to the driving experience. Things like snapping through the gears, noise, shape of the power curve and throttle response are all more important in my mind that a tenth plus or minus. And chassis adjustability- the last Spyder was the most under-tired car Porsche made. That’s the stuff that made the Spyder great, and Porsche might give us more of it. More sheer speed for no more money... not so much.
Last edited by Petevb; 11-24-2017 at 06:01 PM.
11-24-2017, 10:43 AM
#67
Rennlist Member
Thread Starter
De-tuning doesn’t really work that way. Sure you can electronically prevent the throttle from going full open, etc, but the resulting low effective compression isn’t good for anything, and you’re still left with all the drawbacks of the more powerful engine. The manual GT3 is rated at 13 miles per gallon city when driven “normally”. Porsche is necessarily very sensitive to corporate fuel economy due to regulations. They couldn’t afford to keep that engine if they are not using its power potential.
Thanks for making my point. As for not re-gearing, you don’t need to worry about Porsche releasing a car with a 94 mph 2nd gear (what would result if they didn’t change ratios). They will re-gear, and that’s kinda the point actually. The biggest issue I (and others) had with they Spyder and my GT4 was the tall gearing. That gearing existed to keep those cars slower than more expensive Carreras to 60, but it meant you were less able to enjoy shifting. By keeping torque reasonable you’re able to drop 2nd gear back to ~72 mph where it should be and still not threaten the Carrera GTS, which is probably the new “cannot exceed”.
Lol. Is it that hard to connect the dots? This is a company that that charged over $1k colored seatbelts in the 918. How much do you think it cost them to order those belts in a different color?
Porsche long ago divorced what something costs from what you pay. Instead you pay based purely on how badly you want it, ie how much you will pay. Apparently Porsche customers value performance quite a lot, because they are willing to pay tens of thousands more for the exact same engine with slightly more power unlocked (base Carrera vs Carrera S, Cayenne GTS, etc). Meanwhile as you see from the image a few posts up until recently the base Boxster and Carrera S shared over 95% of their engine parts. In fact it would have been cheaper for Porsche to simply make them all 3.8s, but they didn’t. Why? Think about it, I’m sure you can come up with some reasons...
If your argument in the end is that you’d like a faster car for less money then best of luck. Chevy is happy to sell you something. However once you get past the game of Top Trumps you’ll likely find that all of the cars we’re discussing are hugely quick, and extra outright speed doesn’t by itself add much to the driving experience. Things like snapping through the gears, noise, shape of the power curve and throttle response are all more important in my mind that a tenth plus or minus. And chassis adjustability- the last Spyder was the most under-tired car Porsche made. That’s the stuff that made the Spyder great, and Porsche might give us more of it. More sheer speed for no more money... not so much.
Thanks for making my point. As for not re-gearing, you don’t need to worry about Porsche releasing a car with a 94 mph 2nd gear (what would result if they didn’t change ratios). They will re-gear, and that’s kinda the point actually. The biggest issue I (and others) had with they Spyder and my GT4 was the tall gearing. That gearing existed to keep those cars slower than more expensive Carreras to 60, but it meant you were less able to enjoy shifting. By keeping torque reasonable you’re able to drop 2nd gear back to ~72 mph where it should be and still not threaten the Carrera GTS, which is probably the new “cannot exceed”.
Lol. Is it that hard to connect the dots? This is a company that that charged over $1k colored seatbelts in the 918. How much do you think it cost them to order those belts in a different color?
Porsche long ago divorced what something costs from what you pay. Instead you pay based purely on how badly you want it, ie how much you will pay. Apparently Porsche customers value performance quite a lot, because they are willing to pay tens of thousands more for the exact same engine with slightly more power unlocked (base Carrera vs Carrera S, Cayenne GTS, etc). Meanwhile as you see from the image a few posts up until recently the base Boxster and Carrera S shared over 95% of their engine parts. In fact it would have been cheaper for Porsche to simply make them all 3.8s, but they didn’t. Why? Think about it, I’m sure you can come up with some reasons...
If your argument in the end is that you’d like a faster car for less money then best of luck. Chevy is happy to sell you something. However once you get past the game of Top Trumps you’ll likely find that all of the cars we’re discussing are hugely quick, and extra outright speed doesn’t by itself add much to the driving experience. Things like snapping through the gears, noise, shape of the power curve and throttle response are all more important in my mind that a tenth plus or minus. And chassis adjustability- the last Spyder was the most under-tired car Porsche made. That’s the stuff that made the Spyder great, and Porsche might give us more of it. More sheer speed for no more money... not so much.
Thanks for chiming in Pete! Never thought of the 981 Spyder as being Porsche's most "under-tired" car. I remember you said it was a Porsche street rod when it first came out. Great insight as usual.
11-24-2017, 10:53 AM
#68
Sure, but I guess what I'm asking is, since they do have a 3.8L version of the 9A2 that's currently used only in the 991.2 TT, why not just remove the turbos from that engine and use it in the new Spyder and GT4?
It seems unrealistic to expect 9000 RPM GT3 engines to show up in these cars, just because of how much more expensive they must be to build. I agree with everyone who says "Shut up and take my money!", but if I had to gamble, my money would be on an NA version of the 3.8L engine in the 991.2 TT.
It seems unrealistic to expect 9000 RPM GT3 engines to show up in these cars, just because of how much more expensive they must be to build. I agree with everyone who says "Shut up and take my money!", but if I had to gamble, my money would be on an NA version of the 3.8L engine in the 991.2 TT.
They would need to modify the intake manifold if they wanted to use the X51 kit in the new version (the current one is too tall for the engine bay without spacing the engine down). If Weissach is in charge of the engine development I would expect them to do something like that, as they have no experience with the GT3 engines. If the engine is being viewed as a Motorsports product on the other hand then they’d really want to make it a derivative of what they already know and have developed. It was hugely difficult to bring the 9A1 up to Motorsports standards originally- engine recalls, obviously, but also years on the dyno trying to get the Cup to work, etc. I would hope they take the GT4/ Clubsport seriously enough to give it a Motorsports durable engine. Costs could be mitigated by targeted parts changes (a shorter stroke crank could allow for steel instead of Ti rods, for example). In the end the big savings would be avoiding development rather than the parts themselves...
11-24-2017, 11:10 AM
#69
Rennlist Member
Thread Starter
The First top is genius IMHO. I really applaud the company taking a chance on an idiosyncratic soft top. I found the roof fascinating when it first came out and I could not imagine that spyder otherwise. Can we put that one to rest finally. The olde TOP IS COOL!
11-24-2017, 11:22 AM
#70
Rennlist Member
Thread Starter
Autocar in UK, normally reliable, have just reported the 4.0 https://www.autocar.co.uk/car-news/n...1-gt3-flat-six
4.0
Removable top
Manual and DPK
NO RADIO or AC
SIGN ME UP GEORGE Gobrial!
This would be my dream car! I'm going for radio and ac delete next time. Please Porsche make this happen if you are reading!
11-24-2017, 12:34 PM
#72
Nordschleife Master
Crossing my fingers and very excited after reading this article fro AutocarUK
4.0
Removable top
Manual and DPK
NO RADIO or AC
SIGN ME UP GEORGE Gobrial!
This would be my dream car! I'm going for radio and ac delete next time. Please Porsche make this happen if you are reading!
4.0
Removable top
Manual and DPK
NO RADIO or AC
SIGN ME UP GEORGE Gobrial!
This would be my dream car! I'm going for radio and ac delete next time. Please Porsche make this happen if you are reading!
Also the 981 Spyder roof will more than likely be carried over to the 982... It was the same for the base, S, GTS 982... exact same as the 981... also the rear trunk hatch is carried over from the 981 for that exact same reason.
So far, no PDKs have been photographed for the Spyder and GT4’s... doesn’t mean they won’t come later.
Most are discrediting the latest round of articles based on the fact they all have no source for their info. Most are claiming clickbaiting.
Fact is there is a long time before Debut... GTS hasn’t even had its show debut yet.
One thing is for sure, its going to be a looooooooong year with lots of speculation and arguing.
Last edited by n4v4nod; 11-24-2017 at 01:22 PM.
11-24-2017, 01:17 PM
#73
So if you COULD care less, it means you care? So you don't want a proper engine in the new spyder/gt4? Or did you mean you "COULDN'T" care less?
11-24-2017, 01:21 PM
#74
I think we are all just speculating. Why would Porsche throw a 4.0L 400-425HP N/A six cylinder engine into a Boxster? It would destroy 911 sales, IMO. If, however, they did just that, a reasonably equipped 718 Spyder would run at least $125K. For that kind of money, personally, I'd buy a Carrera S. Let's wait and see until Porsche announces how the car will be configured.
11-24-2017, 06:19 PM
#75
So why not a naturally aspirated version of their current 3.0L Carrera engine? Hot rodded of course. Heads, cam, pistons, tuning. Maybe a bump in displacement? All of the basic hardware is already there and you wouldn't be stepping on the toes of your sacred GT3 or dragging your outdated stuff out of the attic.
