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Location:
Brisbane
Registered:
May 2002
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2JZ TTC mod: thumbs up!
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Wed, 17 December 2003 12:58
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I decided to try the True Twin Conversion (TTC) on my Supra tonight. For those not familiar with the theory:
http://www.mkiv.com/techarticles/ttc/ttc.htm
Basically it disables the sequential system and makes the turbos spool up in parallel, just like the 1JZ. And what's the point of this you ask? Surely this will just make it more laggy without actually increasing power?
That's what I thought as well, but I've been having intermittent boost problems lately which I assumed was something screwing up with the sequential system, so I thought I'd give the TTC mod a go and see if it fixed the problem. It's piss-easy to do, basically there are two vac lines that need to be re-routed and that's it!
The first thing you notice is the exhaust is heaps louder; this is because the exhaust is fully opened up and isn't trying to squeeze through one tiny exhaust housing. The second thing you notice is the increased off-boost throttle response, no doubt due to the better flowing exhaust. The third thing you notice is no more boost below 2500rpm, but it is making 5psi before 3000rpm and full boost by 4000rpm. The best part about this is the way it smoothly and progressively builds power, without any of the crazy peaks and troughs introduced by the sequential fandanglery.
So is it worth doing? Well in my case yes. At the end of the day it's a 3 litre engine in a 1300kg car so the increased lag isn't a problem at all. The better throttle response is a real bonus and makes it easier to drive the car smoothly in traffic. And on the highway, absolute magic - if you're in the right gear full boost is available instantly, and it simply rockets away, no hiccups and no hesitation! Would it be worth doing in a Mk4? Not sure about that, the extra weight might make it a bit sluggish in some circumstances... then again you have a 6-speed box so it should be easier to keep it in the right gear at all times! I guess it would be a case of try it and see. If anyone would like to loan me a TT Mk4 for a few days I'd be happy to try it out... all in the name of science of course. 
I originally planned to try the TTC mod for a day or two and then change it back, but I think it will be staying this way from now on. Lag is cool! 
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Registered:
November 2002
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Re: 2JZ TTC mod: thumbs up!
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Wed, 17 December 2003 13:18
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Well done Norbie.
I had read somewhere that the TTC conversion that was done in a Mk4 did make it sluggish/laggy at low revs, but then you have another 300kg to get up and bogie with in one of those. In a Mk 3 it sounds like it is magic - great stuff !
Cheers,
Mitch.
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: 2JZ TTC mod: thumbs up!
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Wed, 17 December 2003 13:23
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or in a mk2 like norbie has
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Registered:
November 2002
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Re: 2JZ TTC mod: thumbs up!
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Wed, 17 December 2003 13:24
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Oops - yes sorry - he does - confused myself. 
Thanks.
Mitch.
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Location:
Melbourne
Registered:
May 2002
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Re: 2JZ TTC mod: thumbs up!
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Wed, 17 December 2003 13:47
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would not be a mod for a MkIII thats for shure 
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Location:
Gold Coast
Registered:
May 2002
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Re: 2JZ TTC mod: thumbs up!
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Thu, 18 December 2003 00:29
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Told you it would be better!! 
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Registered:
May 2002
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Re: 2JZ TTC mod: thumbs up!
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Fri, 19 December 2003 05:53
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Are you going to drill out the second turbo's wastegate to seperate the turbos?
Rather than use the second turbos wastegate as a control valve?
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Location:
Brisbane
Registered:
May 2002
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Re: 2JZ TTC mod: thumbs up!
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Fri, 19 December 2003 09:31
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Nah, can't be bothered. This seems to work ok for now.
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Location:
Brisbane
Registered:
November 2002
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Re: 2JZ TTC mod: thumbs up!
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Fri, 19 December 2003 22:44
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I won't comment too solidly until I see a dyno figure
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Location:
Brisbane
Registered:
May 2002
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Re: 2JZ TTC mod: thumbs up!
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Sat, 20 December 2003 08:20
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I never said it had any more power, did I?
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Registered:
August 2002
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Re: 2JZ TTC mod: thumbs up!
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Sun, 21 December 2003 10:14
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21st Century Performance By Julian Edgar.
Refer to page 184.
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