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Discussion Starter · #1 ·
Right - i have not got too much info as i did not bother measuring up the turbo when it was off the car (duh), and in the meantime I also changed the manifold. Yet to drive the car with the new mani, which might spool the turbo a bit sooner.

What i would like to know though is the following :

Currently the turbo used to come onto full boost (about 16 PSI / 1.1Bar ) at around 4200 RPM and started building boost noticably at around 3600 RPM.

The engine is stock apart from a forged bottom, and ported head. I would like to have the turbo to come on full boost earlier - and obviously with a set of nice Tomei Poncams i could possibly also achieve this to some extent. But I am thinking more in terms of changing the Turbine AR, and hopefully being able to 'move' the whole boost map downwards on the RPM range.

Redline on the motor is at 7300, and This does not leave me witha lot of RPMs in boost.. The car pulls really hard on the higher RPMs but it is not very awesome to drive in town ...

So my question is - what AR housing would you recommend on changing to, as it currently has a T61R on it, with a 70AR compressor, and a .69 AR turbine housing. I could measure the inducer / exducer - but need to remove the turbo from the car again in order to do that (which I really would like to avoid for the time being)

Any suggestions are welcome..
 

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The simple answer is smaller the better for quicker spool, but reduced top end... if you could modify a VNT turbo you could get the bost of both worlds... but no one's done this on an RB, have they?

What about M27 A/R 48 comp Cover machined for your comp wheel with a .63 turbine housing with a garrett - 34 Actuator? will give very good and quick spool, but will drop off around the 5500 - 5800 mark.
 

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People will be thinking, wow they are small housings, but you want a spool monster with no lag.... two of these will give you that lol
 

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Discussion Starter · #4 · (Edited)
Niz406 - thanks. I possibly need to include a few more details - apologies for their omission.

I would prefer to keep as much of the current turbo as possible, and am also running a External WG on a S-tec Tubular manifold. Also - it is running a big single. Changing back to twins is prolly going to solve my lag issue - but at insane cost...

This is on a GTR - so drop off at 5500 - 5800 is not ideal ... I ideally want something that will come in nice and responsive, be on full boost (1.2 Bar) at around 3600 and hold boost to redline (7300 currently - usually at 7800). I mean ... I don't like revving the nuts of the car just to remain in Boost....

Oh... and I prolly need to look into getting a decent electronic boost controller and do away with the bleed-off valve tipe (manual) I got now.
 

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ah ok sorry chap,

I didn't realise, thought it was stock twin setup - because I read the entire post properly Honest lol

I would say to improve low end, just change the exhaust housing to .63 or if you want ultimate spool .58 but remember there will be loss top end, but if you don't drive it in the higher ranges all that much its not a problem, I do however think that the .58 will be a bit of a choker what with the limiter being all the way up and beyond 7k rpm

As for bleed valve..... errrrrr I would get a good actuator set at 0.9 bar with a good EBC.
 

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Discussion Starter · #6 ·
Hey Niz406

I was thinking of a .63 AR turbine side as well - but they seem to all be T3 bolt-pattern. I have a T4 Flange and T4 turbine housing on now... so ... As far as i can see (from what i have been able to dig up over the course of today) all i can do is either get a .58 (which will choke the high RPM performance, unless i change the Exhaust wheel trim - which i prefer not to do) since the only other size is a .69 for a T4 bolt pattern flange. :(

Or i need to spend a ton of money and get cams and a EBC ... lol

Or am I missing something ?
 

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Your be amazed the difference the cams and more importantly the EBC will make a massive difference, get them on and I rink your be a happy bunny.
 

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Hey Niz406

I was thinking of a .63 AR turbine side as well - but they seem to all be T3 bolt-pattern. I have a T4 Flange and T4 turbine housing on now... so ... As far as i can see (from what i have been able to dig up over the course of today) all i can do is either get a .58 (which will choke the high RPM performance, unless i change the Exhaust wheel trim - which i prefer not to do) since the only other size is a .69 for a T4 bolt pattern flange. :(

Or i need to spend a ton of money and get cams and a EBC ... lol

Or am I missing something ?
Simple fix....... .63 housing with T4 - T3 adapter :)

eBay Link

If you are worried about it cracking, there are stainless steel ones around. You would also need to have your dump pipe extended to accomodate.

But will be cheaper this way than manifold etc.
 
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