What is a 996TT?

[RobM77]

Apologies for what may seem like a daft post, but what is a 996TT? Everyone keeps on about them and I'm confused! Google doesn't come up with anything. I've never heard the term in the motoring press.

[zcacogp]

I believe it is a 911 (996 model, so the first of the water cooled ones), with Twin Turbos.

So a late 1990's 911 Turbo.

(Am I right? Someone who knows more will be along soon!)


Oli.

[Fidgits]

almost right.

996 started in 97/98, Turbo wasnt released until 2000


but yes, 996TT is the 996 Turbo, with the 3.6 twin turbo engine.

[RobM77]

aha, so this is just another term for what Porsche, and all the motoring press, refer to as the "996 Turbo"? I presume that the 'TT' stands for twin turbo, which I guess all 996 Turbos were?

[Fidgits]

yup.

the 993 was also twin turbo IIRC..

[RobM77]

thanks guys I can now read this forum without being constantly confused!

[DirkDiggler]

whilst we're on the subject of 996TT, does anyone know how the turbos spool up? ie, are they identical and both spool up at a certain revs, or is one smaller and spools up earlier than the other?

trying to get an idea of the power delivery

cheers


Rich.

[USS Bozeman]

Identical and both spool up at the same time / same pressure I think (hence the massive shove in the back !)

[zcacogp]

I stand corrected on the 996TT - thanks Fidgits.

Fidgits said:

yup.

the 993 was also twin turbo IIRC..

There I learn something new as well - I thought that 993 were single turbos.

(Note to OP - this guy knows more than me!)


Oli.

[anonymous-user]

Think the last single Turbo was the 964. Usually referred to as a Turbo 2 just to add more confusion! 993 was definitely twin turbo.

[OrangeBob55]

USS Bozeman said:

Identical and both spool up at the same time / same pressure I think (hence the massive shove in the back !)

Indeed, the two turbo's are identical, one for each bank (each side of the engine).

[DirkDiggler]

thanks people

[pikey]

Whilst we're here, why twin turbos instead of a single?

Pikey (completely lacking in all turbo knowledge)

[RobM77]

USS Bozeman said:

Identical and both spool up at the same time / same pressure I think (hence the massive shove in the back !)

Is there much of a jump? I've never been a fan of turbocharging as I've always found it frustrating how the torque curve isn't smooth. I remember trying in vain to lap an M400 at Bedford Autodrome, and around two of the bends the revs were at just the right point for the turbos to suddenly spool up just after turn in...

[964RS]

RobM77 said:

USS Bozeman said:

Identical and both spool up at the same time / same pressure I think (hence the massive shove in the back !)

Is there much of a jump? I've never been a fan of turbocharging as I've always found it frustrating how the torque curve isn't smooth. I remember trying in vain to lap an M400 at Bedford Autodrome, and around two of the bends the revs were at just the right point for the turbos to suddenly spool up just after turn in...

Its incredibly progressive...you only get a thump in the back if you floor it...then the power delivery is pretty impressive as the horizon gets ever closer!

Never really a jump....just light speed on tap

[LanCat]

pikey said:

Whilst we're here, why twin turbos instead of a single?

Pikey (completely lacking in all turbo knowledge)

Wild guess, two smaller ones spin up quicker than one large one hence less lag.

[RobM77]

964RS said:

RobM77 said:

USS Bozeman said:

Identical and both spool up at the same time / same pressure I think (hence the massive shove in the back !)

Is there much of a jump? I've never been a fan of turbocharging as I've always found it frustrating how the torque curve isn't smooth. I remember trying in vain to lap an M400 at Bedford Autodrome, and around two of the bends the revs were at just the right point for the turbos to suddenly spool up just after turn in...

Its incredibly progressive...you only get a thump in the back if you floor it...then the power delivery is pretty impressive as the horizon gets ever closer!

Never really a jump....just light speed on tap

Sounds nice, I'll get saving!

[anonymous-user]

LanCat said:

pikey said:

Whilst we're here, why twin turbos instead of a single?

Pikey (completely lacking in all turbo knowledge)

Wild guess, two smaller ones spin up quicker than one large one hence less lag.

yep (and probably better packaging and heat dissipation in 911)

a better solution would be 2 big turbos though

Edited by fbrs on Wednesday 19th September 11:31

[Fidgits]

fbrs said:

LanCat said:

pikey said:

Whilst we're here, why twin turbos instead of a single?

Pikey (completely lacking in all turbo knowledge)

Wild guess, two smaller ones spin up quicker than one large one hence less lag.

yep (and probably better packaging and heat dissipation in 911)

a better solution would be 2 big turbos though

Edited by fbrs on Wednesday 19th September 11:31

I would imagine with the flat-6 configuration - its more efficient to have a small one on either bank, rather than the piping from both to a single turbo, back to each bank.

From what ive heard, the orignal turbos used to suffer a lot of lag - probably due to this - whereas the twin configuration will have shorter piping, helping, and smaller turbos, therefore much less lag..

[anonymous-user]

Fidgits said:

fbrs said:

LanCat said:

pikey said:

Whilst we're here, why twin turbos instead of a single?

Pikey (completely lacking in all turbo knowledge)

Wild guess, two smaller ones spin up quicker than one large one hence less lag.

yep (and probably better packaging and heat dissipation in 911)

a better solution would be 2 big turbos though

Edited by fbrs on Wednesday 19th September 11:31

I would imagine with the flat-6 configuration - its more efficient to have a small one on either bank, rather than the piping from both to a single turbo, back to each bank.

From what ive heard, the orignal turbos used to suffer a lot of lag - probably due to this - whereas the twin configuration will have shorter piping, helping, and smaller turbos, therefore much less lag..

and in fairness to the older cars a decade of r&d!