russbert
Pooh-Bah
Reged: 07/02/02
Posts: 2005
Loc: Cincinnati, OH
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In reading about the Variable Turbine Geometry (VTG) used in the new TT ... could it be used in a 996 TT or not? Even if it fits / works, would you want to use it? What would be the benefits or drawbacks?
The reason I ask is the various debates time-to-time re: K16's vs K24's and hybrids, etc. Or is it just too early to tell?
Would someone care to enlighten me (or at least try).  Thanks.
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Russ
04 TT GR / Blk
03 C4S MB / GG (was his; was hers; gone)
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Grant
Carpal \'Tunnel
Reged: 06/27/02
Posts: 4750
Loc: Denver, CO USA
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VTG is a big improvement (less lag and better boost at all rev ranges), but it is thoroughly integrated into an electronic network of controllers and the engine's brain. It acts like the best combo of small turbos (fast spooling) and big turbos (flows alot of air - big boost levels at high revs). It would be impossible or very difficult to retrofit, due to the electronic systems to control the vanes.
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73 Carrera RS 2.7 Carbon Fiber replica (240hp & 1,890 lbs)
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Dock (Atlanta)
F6B00ST
Reged: 07/01/02
Posts: 9871
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Russ - The only real advantage the VTG turbo brings to the table is it's ability to produce better power lower in the rpm range. The 997 Turbo will make max torque (457 lb-ft) at just below 2000 rpm. That sounds great, but when you put that in a 1st gear pull situation it might not be such a good thing. Why? Because the 997 Turbo has the same overall gearing in 1st that the 996 Turbo does, and as you well know, 1st gear is as about as short as is practical to use.
Anything above about 3000 rpm, the k24 and after market turbos (with ECU upgrades) will produce much more power than the current 997 Turbo's VTG's will.
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2002 Turbo
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Grant
Carpal \'Tunnel
Reged: 06/27/02
Posts: 4750
Loc: Denver, CO USA
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Doc - If you made the same type of ECU mods (same boost levels, etc.) to the 997TT as the ones you propose to the 996TT, don't you think the advantage would fall to the 997TT?
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73 Carrera RS 2.7 Carbon Fiber replica (240hp & 1,890 lbs)
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russbert
Pooh-Bah
Reged: 07/02/02
Posts: 2005
Loc: Cincinnati, OH
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Grant & Dock,
Thanks for the information; I "assumed" it wouldn't work but I'd rather hear from the experts.
So now I'd love to hear a discussion on the hybrids ... which ones to use, when and why?
Which turbos do you all have? Future plans?
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Russ
04 TT GR / Blk
03 C4S MB / GG (was his; was hers; gone)
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Dock (Atlanta)
F6B00ST
Reged: 07/01/02
Posts: 9871
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Quote:
If you made the same type of ECU mods (same boost levels, etc.) to the 997TT as the ones you propose to the 996TT, don't you think the advantage would fall to the 997TT?
Not with the rpm's at or above ~3000. Once the VTG turbos are up to speed in the power band, they flow about the same as a k24 turbo. They can not match the flow (once on speed) of a hybrid that's larger than a k24.
The real advantage of the VTG is in the low rpm range.
The real disadvantage of the VTG is when some of the vanes get stuck open or closed.
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2002 Turbo
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Grant
Carpal \'Tunnel
Reged: 06/27/02
Posts: 4750
Loc: Denver, CO USA
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I assumed that the turbos in the 997TT were sized for big flow. Maybe they'll wait for the Turbo S or GT2 to do that. The whole point of VTG is that you shouldn't have nearly the same compromise with turbo choice as you do without it. With a big turbo and VTG, you should be able to make big power without giving up too much low-end...
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73 Carrera RS 2.7 Carbon Fiber replica (240hp & 1,890 lbs)
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JKern
newbie
Reged: 07/01/02
Posts: 69
Loc: Joliet, IL
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Just switched out my K16's for 24's. Turbo lag is not an issue. Courage to hold the throttle down is the issue.........
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Dock (Atlanta)
F6B00ST
Reged: 07/01/02
Posts: 9871
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Have you upgraded your ECU?
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2002 Turbo
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russbert
Pooh-Bah
Reged: 07/02/02
Posts: 2005
Loc: Cincinnati, OH
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Sorry I didn't reply sooner; I've been very sick the last several days.
Can you tell me more re: K24's? Where did you get them? Your impressions of them vs the K16's? I always assumed there would be more lag given the larger size. Thanks.
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Russ
04 TT GR / Blk
03 C4S MB / GG (was his; was hers; gone)
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DUANE
enthusiast
Reged: 06/29/02
Posts: 291
Loc: Miami
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Test
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2002 TT X50
www.986host.com/gallery/DUANEB
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Ed NY
Moderator
Reged: 06/30/02
Posts: 3119
Loc: Westchester, New York
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Dock:
What ECU upgrade would you recommend with the K24 turbos but without having to upgrade the clutch?
Also, having test driven a 997S and enjoying the sport chrono acceleration settings, would you know if is it possible to program the e-gas response of the 996?
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Ed, 2010 6-Spd Turbo Cab
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Dock (Atlanta)
F6B00ST
Reged: 07/01/02
Posts: 9871
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I'd recommend the GIAC Stage 2, through either ImagineAuto, or EVO. The throttle response is improved a bit with this ECU upgrade. Of course a LWFW would also provide an immediate, and bigger improvement.
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2002 Turbo
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Ed NY
Moderator
Reged: 06/30/02
Posts: 3119
Loc: Westchester, New York
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Thanks, Dock. LWFW?
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Ed, 2010 6-Spd Turbo Cab
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Dock (Atlanta)
F6B00ST
Reged: 07/01/02
Posts: 9871
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Light weight fly wheel
It's noisy, but it's great!
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2002 Turbo
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Ed NY
Moderator
Reged: 06/30/02
Posts: 3119
Loc: Westchester, New York
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Quote:
Light weight fly wheel
 I thought you were suggesting "Launch When F____ing Ready" LWFR as a remedy for the E-gas lag! LOL
Thanks,
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Ed, 2010 6-Spd Turbo Cab
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