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The mkiv Supra Owners Club

one for the techies...True Twin Conversion, new method


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There is (was?) an article on MKIV.COM about a true TT conversion, rather than playing with pipes it was controlled by a dash switch connected to the ECU. It seemed pretty simple and only had one big caveat. Don't switch when there is ANY pressure in the system as it will blow the pressure tank.

 

I asked around and nobody here had tried it or could see any advantage to it. I think it allows the first turbo to use full boost, rather than peaking at 10PSI (or whatever it is)

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Theres an article on the New Zealand site which I've paraphrased below. Now I don't know whether this effect quoted was a one off or would be applicable to all vehicles, but it may help out.

 

Quote

What happens if you do this? When I tried it on my Japanese spec mkiv TT 6 speed, the results were not good. There was no boost below 3000rpm and it got to about 12lb by 4000rpm and max boost by 5000rpm. This resulted in extremely poor low down torque (felt like an NA 2.0L) and was a much harder car to drive quickly around town. When I tried it at the drag strip it was also not very good. Unless I changed the gears at the redline, it would bog down and I would get a slow high 13 second pass. Changing at the redline dropped this to a best of 13.5sec, which is still slower then it should do with 227kw at the wheels. I have changed the turbos back to sequential and am really enjoying the huge low down torque this gives.

Unquote

 

http://mkiv.supras.org.nz/techo.htm#TTC

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simon, that was done using the mkiv.com method. this way is a little different.

 

ive been seriously thinking about ditching the seq setup and going true parallel. im sure, with a good amount of off boost ignition timing, this would produce more area under the power curve and give a more usable mid range.

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Looks theoretically possible, I'm not sure what benefits it will give though, and how much the ECU will wig out over making 1.3 bar of boost at 3000 rpm in 6th, but looks worth a try if anyone is interested.

 

-Ian

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Auto

 

In TTT I like the increased low revs exhaust note:innocent:

 

When I'm out playing and in Manu mode its great once your moving ........ cos its always above 3k then anyway and its a nice smooth powerband ... good for gettin the arse out controllably.

 

I switch between the two all the time ...... lately just using seq when at lights etc

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just tried it in a manual. 'kin 'el its loud a bit too loud for me, totaly changes the exhaust note, it sounds like a spitfire. +ve boost before 3k, full just after. very smooth. needs remapping to take full advantage.

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Originally posted by eyefi

just tried it in a manual. 'kin 'el its loud a bit too loud for me, totaly changes the exhaust note, it sounds like a spitfire. +ve boost before 3k, full just after. very smooth. needs remapping to take full advantage.

 

Louder you say? Be back in a minute! :flame Dev

 

Actually I'll give it a go some other day when I've more time, I'm just curious.

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Sounds VERY interesting....

 

I'd try it, but, ANY chance it's gonna strain/blow me engine:eek: ?

 

and, what IS the 'switch' version ? ? that sounds better...

 

I presume the 'ultimate' boost is still the same ? or are the turbos

actually 'working' differently ?

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Originally posted by Steve W

Sounds VERY interesting....

 

I'd try it, but, ANY chance it's gonna strain/blow me engine:eek: ?

 

and, what IS the 'switch' version ? ? that sounds better...

 

I presume the 'ultimate' boost is still the same ? or are the turbos

actually 'working' differently ?

 

MUCH less chance of blowing No2 Turbo.

John:flame Dev

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