Considering New Boxster as only car - 4Cyl Refresh Options?
Discussion
Mario149 said:
No, you've said it yourself, it needs a different gearing not more torque. ~270lbft is plenty to be getting on with in a car that weighs ~£1,350kg wet, it's just spoiled by long gearing whereby 2nd and third gears go to 84mph and ~115mph instead of something vaguely sensible like 70mph and 95mph respectively
Agree that would make a significant difference. That said, there is a bit of a hole in the torque curve between 2500 and 4000 rpm that rather exacerbates the issue and which the 991 Carrera doesn't suffer from. 
bcr5784 said:
Mario149 said:
No, you've said it yourself, it needs a different gearing not more torque. ~270lbft is plenty to be getting on with in a car that weighs ~£1,350kg wet, it's just spoiled by long gearing whereby 2nd and third gears go to 84mph and ~115mph instead of something vaguely sensible like 70mph and 95mph respectively
Agree that would make a significant difference. That said, there is a bit of a hole in the torque curve between 2500 and 4000 rpm that rather exacerbates the issue and which the 991 Carrera doesn't suffer from. Mario149 said:
That'll be a tuning thing to ensure the Carrera at least nominally stays ahead on performance. Porsche cold tweak the torque line to look like a heartbeat if they wanted to, they just don't. They artificially limit the engine so it is positioned correctly within their line-up and meets vacuous emissions regs
Porsche doubtless restrict the maximum power for that reason, but I'm not sure it's the reason for the trough. Usually such peaks and troughs occur as a result of resonance within the intake and exhaust systems (as well as the big peak caused by the variable valve timing). Some manufacturers introduce valves to vary the effective length of the intake or exhaust to smooth out the torque curve. The packaging on the 981 is much tighter than the 911 and that may restrict their freedom to do that, or configure the airbox quite as they might like. bcr5784 said:
Porsche doubtless restrict the maximum power for that reason, but I'm not sure it's the reason for the trough. Usually such peaks and troughs occur as a result of resonance within the intake and exhaust systems (as well as the big peak caused by the variable valve timing). Some manufacturers introduce valves to vary the effective length of the intake or exhaust to smooth out the torque curve. The packaging on the 981 is much tighter than the 911 and that may restrict their freedom to do that, or configure the airbox quite as they might like.
There's a shop in Germany (Ehresmann Automotive) that remaps the 981 3.4 using the 991 C2 software. The result is a smooth torque curve (no flat spot) and the same power output as the 991 engine. It's all about the ECU.
EricE said:
There's a shop in Germany (Ehresmann Automotive) that remaps the 981 3.4 using the 991 C2 software. The result is a smooth torque curve (no flat spot) and the same power output as the 991 engine.
It's all about the ECU.
Sounds interesting - do you have a link, I can't find anything except their fitment of the 3.8 unit in a Boxster. If it is as simple as that I'm surprized more people aren't doing it.It's all about the ECU.
bcr5784 said:
Sounds interesting - do you have a link, I can't find anything except their fitment of the 3.8 unit in a Boxster. If it is as simple as that I'm surprized more people aren't doing it.
http://www.pistonheads.com/gassing/topic.asp?t=149...
EricE said:
The simple remap (the 350hp version) has almost exactly the same hole in the power curve as the standard car. They don't show the torque curve, but since power flattens in the 2500-4000range, especially between 3200 and 3600 almost exactly as the standard car the torque must fall off. (a flat torque curve gives a straight line rising power curve - power increasing at the same rate as the revs Power = 2 x pi x revs x torque /33000 where torque is in ft lb and power is horsepower) .There are plenty of other simple remaps which all claim 340 hp - the same as the GTS, but I can't find any with torque curves. Every torque curve I've found for the 981 - 2.7, 3.4 or 3.8 shows a dip in midrange torque. (and even the 987 too)
While I take much of what Porsche says about why the Cayman might produce less power than a 911 with a large pinch of salt, I suspect there is a genuine technical reason why there is this dip, and it's not a marketing one (no-one is going to buy or not buy a Cayman on the basis of this dip - 99.99% of buyers will be unaware of it)
Edited by bcr5784 on Sunday 14th June 12:15
EricE said:
There's a shop in Germany (Ehresmann Automotive) that remaps the 981 3.4 using the 991 C2 software.
A BGTS with a C2 map on it and a 10% shorter final drive would be a wonderful thing, it'd pull like a Spyder/GT4. It'd work especially well with PDK as you'd still have 7th for cruisingmollytherocker said:
Porsche have just won Le Mans in a 4 cylinder turbo hybrid. Finished 2nd too.
Theres no going back now.
The Porsche PR department sighed a breath of relief after that win.Theres no going back now.
People complain about a 2L turbo 4 cylinder 981.2? "But we won Le Mans with that technology."
People complain about a hybrid 911? "But we won Le Mans with that technology."
etc...
however I'm pretty sure the 919 uses a hydraulic steering rack.
anonymous said:
[redacted]
The relevance to engine choice is the biggest stretch. Anyone who cares and thinks enough to want a 6 cylinder isn't going to read anything at all into the use of 4 cyl engines in Le Mans.Nobody is going to say 'I did really want a flat 6, but if it's good enough for Le Mans, it's good enough for me!'
anonymous said:
[redacted]
The relevance to engine choice is the biggest stretch. Anyone who cares and thinks enough to want a 6 cylinder isn't going to read anything at all into the use of 4 cyl engines in Le Mans.Nobody is going to say 'I did really want a flat 6, but if it's good enough for Le Mans, it's good enough for me!'
mollytherocker said:
Its hard to imagine the 4 cylinder motor being anything more than a crushing disappointment.
But it depends what you want. I am sure that the average new Boxster buyer will be fine with it.
Haven't read the whole thraed but didn't a 4 cylinder motor just win Le Mans?But it depends what you want. I am sure that the average new Boxster buyer will be fine with it.
ORD said:
The relevance to engine choice is the biggest stretch. Anyone who cares and thinks enough to want a 6 cylinder isn't going to read anything at all into the use of 4 cyl engines in Le Mans.
Nobody is going to say 'I did really want a flat 6, but if it's good enough for Le Mans, it's good enough for me!'
So why are Porsche building them then? Not just for fun but, presumably, marketing and to demonstarte that downsizing and hybrid tech actually works.Nobody is going to say 'I did really want a flat 6, but if it's good enough for Le Mans, it's good enough for me!'
The bit I don't get is the move from 6 to 4. Sure, reduce the capacity and add a turbo. Can't quite see how a 2.0 4 cylinder turbo produces less emissions than a 2.0 6 cylinder turbo though. AMG seem to have managed by downsizing the V8 and adding turbos - 'M' cars are 6 cylinder turbos now, so why do Porsche see a need to go to just 4? Seems that the brand will lose a key part of its character, and potentially will also lose a good number of enthusiast buyers.
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