Some thoughts regarding the unpleasant tuning limits of the 997.2 & 991 PDK turbo cars:

It seems that most problems arise because of high torque, especially with the PDK (btw even though most folks say this and that part can only handle so and so much power, whereas it is actually torque).

Those engines should be capable of going to 8k rpm easily since piston velocity of 20 m/s (65 ft/s) occurs at 7700 rpm. 20 m/s (65 ft/s) used to be the limit for "old" engines but with nowadays metallurgic advances is quite a bit higher, e.g. 24 m/s in an M3 E90.

So why not make a tune that restricts boost mid-range so that torque never exceeds ~850 Nm (~630 ft lbf) and turns up boost at high rpms so that peak power is reached e.g. at 7500 rpm with 850 Nm/630 ft lbs which yields 900 bhp/ ~720 awhp?

It would probably require a larger compressor wheel (billet) or maybe larger turbos and additional fuel injection as well as bigger inlets and probably a ported head but that's not insurmountable.

Wouldn't need new rods though because they're mostly torque limited (rpm limited as well but not at 8 krpm, I think) and perhaps not an upgraded PDK.

>700 awhp would be all I and many others would need for a long time in a PDK car, I guess. But as of today there are only very expensive tuning programs available that put out much less power but unnecessarily high torque and, in turn, require replacement of all kinds of things like an upgraded PDK, rods etc.

Such a tune would be awesome also because it would essentially have the power characteristics of a huge *** n/a engine!

 

If the fuel system could handle it you could run the stock turbos to say 25 psi redline (7,200 rpm) and you'd make over 700 wheel on good gas (i.e. race gas or pump+meth). Problem is the stock fuel system doesn't flow well enough to handle that much power.

 

That's why I said upgraded fuel system. Like so for example:
http://www.porscheboost.com/content....-HPFP-software

Come on, the fuel system can't be a problem that can't be overcome. Much harder tasks have been challenged in the past and succeeded.

 

BBI has two DI motors that they built in early 2013 that have been awaiting an upgraded fuel system. BBI even built a PDK. But guess what...no fuel system. Too complicated apparently. Not just the hardware, but the software to make it work. Very competent shops have been trying but no luck so far. Maybe someone will crack it soon but for now nothing.

 

+1. The best minds in the US tuning world have been working on this issue but have not yet found a solution. It is extremely complicated and extremely expensive to do.

 

The 991 Turbo platform loves boost and will eat well at around 22-25 psi. I can confirm in my application the need for more fuel. On the dyno with big turbos We saw A/F soften around 650 WHP and immediately pulled out.

Apparently the only reliable workaround at the moment is to supplement with meth.

Torque and rpm limits are all tunable and should always remain in a safe zone rather than on edge for longevity of oem internals.

This is where it's important to have a good comfort level with a competent tuner.

 

Fek me you guys know what you're talking about!!!

But How and why do gtr tuners get so much Hp and torque out of their engines and fuel systems?? Are they not sustainable or lasting without engine rebuilds?

 

Wow, bummer 😕

 

The crazy numbers that you see from GTR tuners are with bigger turbo and often engine bills and fueling system upgrades. A full bolt on GTR with stock turbos/fueling/engine/transmission is not good for more than about 600 wheel horsepower. When I race them with my GIAC stage 2 + 991 TTS I beat them. But if they get a fueling system upgrade and can run E 85 then they are closer to 700 wheel horsepower and I can no longer beat them from a roll but I almost can from the big due to the incredible launch advantage of the 911 Turbo S. I have beaten a 900 hp GTR from in standing quarter-mile but only because of my huge launch advantage and he was pulling on me at the end but couldn't close the gap in time.

It's only with extra stuff like bigger turbos, fueling upgrades, engine builds and tranny upgrades that you see those killer 1000 bhp plus numbers.

If you're looking for a car with more than about 650 to 670 wheel horsepower (about at the fueling limit for the 991 Turbo) get a GTR. They have been modding them for many years and have done all the upgrades and the prices are not ridiculously high for 1000 bhp.

If you want to break the bank of course and have more than about 1000 bhp get a UGR Lambo or one of the really killer power GTR builds like a Switzer Goliath or Alpha 12 or up.

 

How about a stand alone engine management? Wouldn't circumvent the software problems?

 

http://www.evo.co.uk/porsche/911-tur...-detroit-debut

 

If the article's information is correct the improvements are nice but incremental rather than dramatic. The most interesting thing to me is the larger turbos on the Turbo S model. Wonder what tuners will be able to get out of them. Was disappointed that the power increase is only 20 hp. Not enough to run from a roll with the Ferrari 488