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According to the 156 Crosswagon and 156 Sportwagon Q4 brochures, the torque split is 58/42, the diffs can apportion up to 80% of the power to one axle using (mechanical) torsen diffs (although this is nothing to do with the cars age - electronically controlled torque apportioning has been available since the 80s). Acab fitted the Q4 drivetrain to a 1750 engine from the 159/Brera (the Giulietta/4C blocks wont fit), the rear suspension is different on Q4 156s and there are no lowering springs available you could get some custom made, most of your questions are already answered in the thread or the other threads about this.
Ok, thanks. I didn't see anything about changing the bias on the thread. Maybe I missed it? But so you're saying you could set it to up t0 80% to the rear? How does that work?
 

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Ok, thanks. I didn't see anything about changing the bias on the thread. Maybe I missed it? But so you're saying you could set it to up t0 80% to the rear? How does that work?
I didnt say YOU could change the bias, I said IT could apportion up to 80% of the torque to one axle - the Torsen diffs do the apportioning - if all grip was lost at both wheels at one end of the car, the system could channel 80% of the drive to the other end.
 

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I didnt say YOU could change the bias, I said IT could apportion up to 80% of the torque to one axle - the Torsen diffs do the apportioning - if all grip was lost at both wheels at one end of the car, the system could channel 80% of the drive to the other end.
Ok. Sorry for the confusion. So it's indeed a variable system, just not electronically controlled. Totally missed the mention of Torsen in your post.The standard split set to 58/42 but variable as need up to 80/20 either way. Got it.

Is there a way of changing the set split from 58/42 to 80/20 for example? This was more my question. :)
 

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Ok. Sorry for the confusion. So it's indeed a variable system, just not electronically controlled. Totally missed the mention of Torsen in your post.The standard split set to 58/42 but variable as need up to 80/20 either way. Got it.

Is there a way of changing the set split from 58/42 to 80/20 for example? This was more my question. :)
If its anything like a Q2 diff, then it will be done mechanically based on resistance (grip) of axles relative to one another. Torque is sent to the axle with most grip.
 

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If its anything like a Q2 diff, then it will be done mechanically based on resistance (grip) of axles relative to one another. Torque is sent to the axle with most grip.
Sure. But I'm thinking the torque split between front and rear could be changed or reset? Most likely by regearing? For example there are VWs with 95-5- front and rear split while BMWs can have 36/64 split. I think the BMW even uses the same Torsen III the Alfa uses. So it seems the torque split can be set. I'm thinking the center gearing would have to be changed?
 

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Yes its doable, but youd have quite a bit of power loss due to it being a car originally designed as front drive. I d find the other 3 Q4 threads and read them if I were you.

You could always make a rear mid engined 156, someone else has.
 

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Yes its doable, but youd have quite a bit of power loss de to it being a car originally designed as front drive. I d find the other 3 Q4 threads and read them if I were you.

You could always make a rear mid engined 156, someone else has.
Thanks. A rear mid engine 156 doesn't attract me as much. If I would do that I would probably try to do it with the 916. But the GT Q4 seems the simplest. :)

But do you think that a 80 or 75 rear bias would really affect power that much? It's only about 15-20% shift from original. And I guess one could always tune the engine and increase power.

And would I be looking at a custom gear or is there something I could get from other Torso versions?

I already located a crashed crosswagon. So if I can do this the way I want I will pull the trigger. ;)

I will try to find the 3 threads you speak of.
 

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You need to understand differentials.

https://www.mustang6g.com/forums/threads/torsen-differential-how-it-works-video.28064/

The center diff is a a torsen type diff, meaning it is a torque sensitive diff. Its set up is in the construction, there is no easy way to change its character.

A high bias 4wd system is built that way with viscous coupling. Medium levels of static bias or controlled bias are achieved by clutch based differentials.

You will have to replace the torsen system with one of the other systems , and that is not as easy as it sounds.

Power output of the engine has little to do with the usable power at the wheels if you mess up traction. Traction is achieved on the axle with the most effective weight. (mechanical, inertial weight shift and down force combined)

Having a lighter rear end with most of the power being sent that way, you will loose out on use able power.
 

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He could keep the rear torsen to apportion power between the 2 rear wheels, surely ?

But most rear drive cars have "light" rear ends compared to the front where the engine is and the Q4 has a slightly heavier rear end than the FWD versions cos of the rear diff.
 

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Well, after some reading in several threads here, never mind about making it more rear wheel biased. It seems even with 58-42 there would be some power struggle. So let's keep it simple and standard with 58-42. :)

Ok then. Busso is a no go and we need to keep it around the Crosswagon to keep it simple and financially worth it.

But it seems that it's only kind of worth it if you use the 1.75 TBi engine. The other 4 cylinders seem to be under powered for a Q4 with sport pretensions. But even the 1.75 TBi with 200bhp is a bit little, since it seems you must use the TBi from the 159 as the later Giulietta QV and 4C engines don't have the mounting points. But I guess you could just run more boost or do some mods to get the 240bhp from the Giulietta QV?

At 240bhp it could be worth it. But otherwise I fear it would be slower than the FWD 4 cylinder petrol cars.

Also, I took a look at used 1.75 TBi engines and they seem hard to find and expensive compared to other engines. Even some Bussos. :(

How much power are you getting from your 1.75 TBi Acab?
 

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Well, after some reading in several threads here, never mind about making it more rear wheel biased. It seems even with 58-42 there would be some power struggle. So let's keep it simple and standard with 58-42. :)

Ok then. Busso is a no go and we need to keep it around the Crosswagon to keep it simple and financially worth it.

But it seems that it's only kind of worth it if you use the 1.75 TBi engine. The other 4 cylinders seem to be under powered for a Q4 with sport pretensions. But even the 1.75 TBi with 200bhp is a bit little, since it seems you must use the TBi from the 159 as the later Giulietta QV and 4C engines don't have the mounting points. But I guess you could just run more boost or do some mods to get the 240bhp from the Giulietta QV?

At 240bhp it could be worth it. But otherwise I fear it would be slower than the FWD 4 cylinder petrol cars.

Also, I took a look at used 1.75 TBi engines and they seem hard to find and expensive compared to other engines. Even some Bussos. :(

How much power are you getting from your 1.75 TBi Acab?
Not sure what you mean by "power struggle" - the 58/42 set gives some oversteer. Front drive cars with stiff rear ends also oversteer BTW.

Bear in mind also that the 1.9 jtd16v that the Sportwagon Q4 and Ceosswagon Q4 used, can make 300 bhp + with a GTB2056v or a GTB2060 turbo, this also means 600 lbs/ft (450nm) + of torque.

Also the Q4 drivetrain can be fitted to 147s and GTs as well as 156s, although the prop would need to be shortened by 5cm on 147s.
 

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Not sure what you mean by "power struggle" - the 58/42 set gives some oversteer. Front drive cars with stiff rear ends also oversteer BTW.

Bear in mind also that the 1.9 jtd16v that the Sportwagon Q4 and Ceosswagon Q4 used, can make 300 bhp + with a GTB2056v or a GTB2060 turbo, this also means 450nm + of torque. Also the Q4 drivetrain can be fitted to 147s and GTs as well as 156s, although the prop would need to be shortened by 5cm on 147s.
Sorry for the confusion. By power struggle I mean the engine will be under powered for a Q4 as there is power loss even with a 58-42 split. A more rear biased split would make this problem even worse. At least with the stock engines. Hence why I said the 1.75 TBi is the best option.

I'm only interested in doing this with the GT and I don't want a diesel engine. So it's either the 1.75 TBi or the stock 1.8 TS or 2.0 JTS. But the 1.8 and 2.0 are both under powered for a Q4 with sports car pretensions IMO. This is what I meant.
 

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Sorry for the confusion. By power struggle I mean the engine will be under powered for a Q4 as there is power loss even with a 58-42 split. A more rear biased split would make this problem even worse. At least with the stock engines. Hence why I said the 1.75 TBi is the best option.

I'm only interested in doing this with the GT and I don't want a diesel engine. So it's either the 1.75 TBi or the stock 1.8 TS or 2.0 JTS. But the 1.8 and 2.0 are both under powered for a Q4 with sports car pretensions IMO. This is what I meant.
All 4wd cars will have some degree of power loss compared to 2wd, the Q4 also adds 150kg to the weight of the car.

Stlll theres not that much power loss, nothing some minor tuning cant overcome.
 

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All 4wd cars will have some degree of power loss compared to 2wd, the Q4 also adds 150kg to the weight of the car.

Stlll theres not that much power loss, nothing some minor tuning cant overcome.
Yes, sure. But trying to change the bias even more towards the rear, even if possible, would mean even more power loss.

Yes, I think the extra 150kg plus the power loss of the Q4 system would probably make the car slower than the FWD version, unless the engine power would be tuned up.

So in your opinion what would be the best or most efficient way of getting more power? 1.75 TBi? 1.8 or 2.0 tuned up? How much power can one expect from the 1.8 or 2.0, reliably? And what is "better" or easier and most reliable, turbo or supercharging?
 

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Thanks. I will look for it.

But so the 1.75 is indeed the best option? Tuning the 1.8 or 2.0 is not viable?
You can tune any engine and the 1.8 and 2.0 tune ok, not read much about tuning the 156 and GT only JTS, but there are a fair few threads about the 1.8 and 2.0 TS.

But the 1750 is a newer, better version of the 1.8/2.0 TS/JTS (theyre all, long with the JTDs, part of the same family of engines using the same basic block design) so more power is possible.
 

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You can tune any engine and the 1.8 and 2.0 tune ok, not read much about tuning the 156 and GT only JTS, but there are a fair few threads about the 1.8 and 2.0 TS.

But the 1750 is a newer, better version of the 1.8/2.0 TS/JTS (theyre all, long with the JTDs, part of the same family of engines using the same basic block design) so more power is possible.
Reason I ask is, the TBi seems hard to find and are expensive. So if similar power can be reliably had with one of the stock petrol GT engines for less money, that would probably be better.
 

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Reason I ask is, the TBi seems hard to find and are expensive. So if similar power can be reliably had with one of the stock petrol GT engines for less money, that would probably be better.
It would take a lot to get similar power from the older 1.8/2.0 TS or JTS.

Just keep an eye out for an original Giulietta with the iron blocked 1750TBi breaking on eBay.
 

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To get TBi power out of a TS motor, you will have to turbo the TS.

To boost the TBi more for more power is easier than to turbo the TS from scratch.

That said I managed to get 3.2 power from a stock internal 2.0TS with a turbo at 0.5bar boost. There is much more power available if one put in lower CR pistons and forged conrods and bump up the boost.
 
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