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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Mostly agreed.

After the want for power, turbo lag has probably sold more add on parts than anything for a CIS turbo.

When many of the writers were first talking up the 993TT back in 95 or so they almost alwas talked up TT's as haveing a response advantage... That was mostly the truth per what was available and reliable enough for a production car.

After all, the 993 was on the drawing board some 18 years ago. Also back then probably the only turbo mfg Porsche probably felt comfortable with for duty on there air cooled motors was KKK.

Flat 6 lends its self very well to a twin turbo lay out (look at the HE's of a TT compaired to the 3.6T's). Then there was the big success of the RUF Yellow Bird and all stars lined up for a TT. The market wanted it and it was a better set up.

On a side note, I belive if twin plugs were a clear advantage for an EFI Turbo of Porsche design, Porsche and RUF would have included it. It probably would not have added to direct labor and materal costs on there $100k+ car more than about $250.

One another side note, Porsche pretty much deemed the base 993 & 996 turbos (K16?) as limited to about 400hp before there effecency was starting to be questioned. Of cource tuners were happy to push them well beond that.

From my limited study it seems motor lay out and the design enviornment tends to be more the deciding factor these days as long as cost not an issue. A V6 or flat 6 is going to usally get a TT set up, a straight 4 or straight 6 a single turbo, a V8 twin turbos... Then there will be those companies that see a marketing advantage to a given lay out.

These days differance in performance between a single turbo and a twin turbo has more narrowed. Things like ball bearing center section; lighter impellers from different casting tech, materials, & machining; varable vein; and other tech improvements are part of this.

There can be single's that out performs TT's and there will alwas be TT's that out perform singles. I just do not see such a significant differance as there once was. Depending on the HP goal. Of course, there are those single turbo drag cars that sport single turbos making 1000 HP a such.

There is probably more of a differance with picking the right single or twin turbo to fit the application and or getting the tuning right when it comes to performance.

Not an expert, I could be off base, this is just my humble thoughts to date.

Last edited by 911st; 12-22-2009 at 04:11 PM..
Old 12-22-2009, 04:04 PM
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