159 3.2 Q4 Manual - Anyone Changed Diff Ratio?

[Darryl]

A few years ago I didn't buy a 159 Q4 manual and bought a subi liberty 3.0 with a 6 speed that has reasonably close ratios - in particular in/around the speed range one might actually consider using in this country and in any country on some twisty bits. I've started looking at something to replace the subi and the 'ol 159 has depreciated a bit - so it is tempting to buy one. However I can't quite come to grips with the (imho completely inappropriate for oz) choice of ratios that give you max speed in gears of

55
106
157
205
254
291

the subi gets (at same RPMs - not sure what redline in each is but pretty similar)

59
91
122
160
222
285

Now, it may be that the GM donk has a big fat torque curve, the subi only really comes on cam when the variable cam profile thing (whatever subi call theirs) kicks in but taking a 159 for a test drive through some twisty bits up a hill I can't find a gear that "works" to overtake something slow when I can see past it. I suspect much the same will apply for getting past a row of caravans on a trip up the Bruce...

A bit of googling shows you can get a 13/57 final drive:

http://www.bacciromano.com/?p=prodotti&l=eng&cat1=24&cat2=39&mar=3

which would give

49
94
140
182
225
259

which looks a lot more usable, at some possible loss of some highway cruise in 6th fuel economy - though tbh I'm not sure it would make much difference to that...

Anyway - anyone done this? Any other sources for a different diff ratio? Or should I just suck it up and enjoy the lazy drive (and probably just buy an auto - gasp!).

[oz3litre]

Better still, get one of the 1750 TBI models or a 2.4 JTDM and avoid the American style Holden engine. We bought a 2.4 ti wagon and love it. I couldn't bring myself to buy an Alfa with a Holden motor. A lazy American engine is just wrong in an Alfa in my opinion.

[Craig_m67]

Is it really a lazy American donk?

I understand the emotive arguments but has anybody done (or is there) a comparison between the relative outputs etc. of both 3.2 (JTS vs GTA)

The 159/Brera/spider are really heavy cars, I suspect the Busso would struggle in them too.

Ti Sportwagons are getting into retail therapy money now.  I'm 90% sold on another JTD however part of me would love the Q4 and I wonder just how 'bad' the JTS engine is

[Darryl]

Ok - given the effort involved I think changing diff ratio on mums taxi may be a bit off the deep end - I think I'm recovered from the rush of blood...

Re picking a different 159 variant I'm not trying to convert anyone - and tbh I'm not a huge fan of the GM V6 (based on driving it, rather than on some "american donk" bias) but otoh it's not actually a bad thing. The 159 is heavy - but that set of ratios makes it feel heavier than it needs to with the 3.2 in it. I thought I'd actually like the JTD given the torque but after driving a few I didn't - not so much the engine as the overall feel/dynamics of the car. Maybe if they had brought the Q4 JTD over here I'd feel differently? I can't really imagine I'd like a fwd 1750 either, though it being lighter than the diesel would help.

re hp figures - the 3.2 JTS on paper has it over the busso - peak power of 191kW at 6200 rpm and 322Nm at 3800 rpm vs 184kW at 6200 and 300 Nm at 4800 for the busso. I think the criticism stems more from the broad torque curve + heavy car making it feel the engine isn't "doing anything" above 4000 rpm or so than any real lack of power.

Anyone (Craig?) who does want a JTD Ti wagon could do worse than the one on carsales at Oxley that I had a look at btw...

[oz3litre]

I had the use of a Q4 Brera Spider for four days back in 2007 so I do know what they are like. It just wasn't my cup of tea compared to the Busso engined 75 I was driving at the time. I really like the 2.4 JTDM in our Sportwagon though. It has loads of grunt and is amazingly quick off the line. The six speed Aisin auto is fantastic and perfectly matched to the engine. I never thought I would say this about a diesel but I like the sound of it. It has character. My wife loves it. She does 70 kilometres a day, so a V6 would be out of the question fuel consumption wise. With my GT 3.2 and the 159 we feel we have two great cars to drive.

[[MotoPete]]

A lazy American engine is just wrong in an Alfa in my opinion.

Actually the 3.2 and 3.6 litre Alloytec variants of GM's HFV6 engine family were designed and manufactured in Australia.

Whilst not wholly Italian (Alfa Romeo did actually have substantial input into the final product as they only acquired the engine's core design from Holden), one thing I will say for Holden engines is that they are reliable. I've owned a number of Holden products over the years, and must admit that even when the darn things were near on falling apart they always kept on going.

For those considering the 3.2 litre motor, I would highly recommend you look at replacing the exhaust system, which courtesy of Alfa Romeo comes from the factory with no less than 4 catalytic converters and 3 mufflers.

Sure, doing so won't come cheap, but I can assure you that the performance between the two is like night and day.