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I'm sure this has been debated to death and I'm a defender of the M32 often , my own TBI is remapped to 240 without issue , however if your adding a K04 Turbo and re-mapping I'd imagine you'd be looking at getting up to 280 - 300...this would be the point I'd be nervous, I also think the Giulietta TBI has some small small changes to stock internals.
 

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Discussion Starter #3 (Edited)
GQV have lower compression (9.25 vs TBi 9.50). No idea why.
A stock VW 1.8T 150HP can be tuned to 260-300HP easy without changing any internals.
Can’t see why the 1750 Tbi should have issues going same route.
Bigger turbo, decat, ECU map and bingo.
I don’t care about the M32. It could hold unless car is hammered everday.
Anyway, new bearings fitted is an easy job.
Could also upgrade with new M32 endcase and 62 mm bearings. Not that costly.
 

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Discussion Starter #7
After reading some more on the subject, it seems like an overall bad idea to upgrade OEM turbo on the 159 TBI.
 

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The stock turbo of 159 models, or 1750 tbi 200hp version is a k03 turbo not the k04.

My next modification is put a k04 modified and remap it for around 330hp without meth.

if you check the Revlimit website you will see a Brera 1750tbi with stage3 and you can saw the modifications for achieve 350/360hp
 
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I think as long as the gearbox has been upgraded (F40?) the engine would be fine running a stock K04 turbo. I don't think I would want to push it any higher than that though, but happy to be proved wrong :)
 

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Discussion Starter #12
The M32 wont break down instantly just because a Giulietta QV turbo is installed (actually an upgraded/hybrid K03 turbo and not as such K04 turbo)
I know @acab is selling these "K04" turbos and apparently have it installed on his 159 TBi (or is it Brera)
But in the lack of his missing documentation, and reading some of Ian Lusso's 159 Tbi Turbo post gave me second thoughts, and until a full succesfull build is shown in details, I'll pass.
 
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The M32 wont break down instantly just because a Giulietta QV turbo is installed (actually an upgraded/hybrid K03 turbo and not as such K04 turbo)
I know @acab is selling these "K04" turbos and apparently have it installed on his 159 TBi (or is it Brera)
But in the lack of his missing documentation, and reading some of Ian Lusso's 159 Tbi Turbo post gave me second thoughts, and until a full succesfull build is shown in details, I'll pass.
I know it won't break down instantly but for a gearbox which is designed to take a max of 320nm of torque, it would wear very quickly if your engine is running 400+nm which is why I would rather start thinking about upgrading the gearbox first before chasing the big numbers.
 

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Discussion Starter #14
M32 Gearbox ? WG Motorworks

It is commonly thought that high torque output causes the bearings to fail on remapped cars etc. – but this simply is not the case. We have cars running 350-400lbft without issues, yet we can see low output engines (1.3 CDTI / 1.8 non-turbo etc) experience issues. It is true that the greater the power, the more heat will be generated, but a high percentage of the cars we repair are run-of-the-mill cars, which still run into gearbox issues. Essentially, doing long distances on the motorways, during which 95% of the time is spent in 6th Gear. Transfering the engines torque all the way down the input shaft, across to the 6th Gear (closest to the end on the output shaft), and then back down to the final drive put maximum load on this small top bearing.
That's some 470-540 Nm..
 

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Discussion Starter #20 (Edited)
That kind of power would be more than difficult to put on the ground on the heavy 159. A Quaife ATB would be neccessary, but still not enough to prevent massive wheelspin in the lower gears.
I had major issues on my car just with Novitec Poverjet 3 @lvl7 and full decat (HP/NM unknown)
It’s so much much better now with the Quife ATB installed, but not everyone wants to fork out 1200 Eur for this.

Personally I would never want more than 300 hp / 450 Nm out of the 159 tbi 1750 engine.
You can’t just compare with the power potential of the GQV 1750 engine with its lower compression, maybe different pistons, changed cam timing and who knows what.
Even the Guiletta Squadra Corse is below 300 hp - most likely the “safe” limit.
I always thought a bigger turbo would spool slower and give less torque at low rpm, something not fun in a heavy sedan. Also that kind of power could most likely put engine, gearbox, clutch and dual mass at risk.

Looking forward to your project and dyno results.
 
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