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Discussion Starter · #1 ·
My current spec :-

97' 9000 2.3 (manual)
T25 Turbo
Abbott Ecu
3" downpipe - abbott system - custom back box
Water/Methanol Injection
Heater plate removed
Coolant throttle bypass
No catalyst
Abbott intake pipe, Abbott induction kit
Abbott uprated wastegate actuator

Rolling roaded 2 weeks ago, 267bhp and 321lb/ft

I have today been offered a reconditioned TD04 from a 9000 Aero.

Is it worthwhile making this upgrade ? or should I be looking at maybe a T25 Hybrid ?

Will my newly fitted actuator function with the TD04 turbo ?

I am also lead to believe that the ECU will be fine with this turbo.

I guess what I am basically asking, will fitting the TD04 and running at the same boost levels (approx 18psi) as the T25 give me more power ?
 

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It might well do (Bill J's Aero produced 300 BHP on the rolling road), but I'm certain you'll have more lag on every throttle application and the TD04 will not produce as much boost at low rpms as your current unit. I'd say the T25 is by far the more drivable unit - I had it on my '90 Carly. Every turbo is a compromise between the bottom and top end of the rev' range.
 

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It might be kinder to the gearbox, though. If that amount of torque is kicking in lower down the rev range that with an Aero, it's new gearbox and driveshaft time just around the corner.
 

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If one looks at the compressor maps of the two turbos, I think they'll find that the TD04 pumps more air per 20k rpm than does the T25. Both the turbine and compressor are larger on the TD04, but the mass of the turbine is less than the T25. What does this mean? Well, the moment of inertia is proportional to the mass, but it's also proportional to the square of the radius. I'd suspect that the larger physical size of the turbine and compressor gives the TD04 a higher moment of inertia. But, it doesn't have to be turning as fast to provide the same volume of air. Yes, I'd wager the TD04 will spin-up at a slower rate. But, in effect, it'll provide boost just as fast, if not faster than the T25. I've owned both and I can honestly say that TD04 boosted as well as the T25 at low rpms and there was no contest at high rpms - 1.2 bar of boost above 5500 rpms. My advice: go for the TD04 - the engineers at Saab knew something when they added this to the Aero. The only turbo I'd use to upgrade the TD04 would be a GT-R series from Garrett - something like a GT2871R.
 

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that gt 2871r is an extremely interesting proposition
small turbine for fast spool and big compressor for 400 hp mmmm nice
and only 1200 bucks
 

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Discussion Starter · #6 ·
I was thinking of heading towards 350bhp as an ultimate total, not looking to be as extreme as Ylee (although it is tempting)
nor was I looking to invest 1200 in a turbo
as I know that SWMBO would freak over that credit card transaction !
 

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And, if exchange rates keep going in your favour (it's now at $1.87/1£), a 6 or 7% increase of your currency would bring it down to 600 quid - this is contrary to what many had predicted back in the fall. Anyway, I agree w/you, Ylee - I wouldn't mind having one of those Garretts - they're very stealthy, in that they're much smaller than the GT30's or 35's.
 
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