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Discussion Starter #1
Hi guys!

I have the possibility of purchasing a low mileage 156 2.5 v6 with a busted cambelt (actually it was the tensioner) and a few bent valves.

I am facing two options here and I'd like your opinion:
a) fix this engine;
b) swap it for a 3.0.

In terms of cost, my mechanic tells me he does the same price for both jobs, so that will not be a decisive factor.

What would you guys do?
What are the advantages (if any) of the engine swap?
What are the advantages of keeping the original low mileage engine (rebuilt of course)?
What is the fuel consumption of the 3 litre conversion vs the 2.5 litre engine?

Thanks in advance for your input guys! :)

Bern
 

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I'd have the bigger 3.0 in straight away.
Fuel consumption will be a bit more especially if matted to the 2.5 gearbox as its a bit shorter. But we are only talking 1-2mpg at the most really.

Obviously if you start booting it everywhere its going to cost you in fuel.

But the difference in 2.5 3.0 and 3.2 is pretty much negligible.
 

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Discussion Starter #3
Thanks scottyf!

What about the strain on the diff? I think I read somewhere in here that one of the hassles of swapping for a 3.0 is the strain that the extra "torques" are going to put on the original 2.5 differential.
Any comments on this, guys? Or should I be ok for a while, bearing in mind I'm on probation, hence will not be able to rev the crap out of it until year end... :(
 

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Diffs only explode when booting it being far too agressive whilst doing a tight turn. That's when all the strain is kicked thriugh the diff.

Or if one wheel loses grip and spins and you keep booting it to death.

But treat the diff eith mechanical sympathy. Sending the torque to both wheels and they should be fine.

Once an lsd is in though you won't need to worry.

Whilst the engine's out might be worth doing. But its an expensive part.
 

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I would go for the 3 litre. I've had two 3 litre converted 156s (1 x saloon, 1 x SW) and they are great fun. I've also had a couple of 2.5s and while they are incredibly smooth and sound the nicest, I get a bit frustrated by the lack of low down torque.
 

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It's a tough choice, I have a 2.5 156, a 3.0 GTV and a 156 3.2 GTA. The 'nicest' to drive as a daily driver and all rounder is the 2.5, as Pud said, "super smooth" and imo great and the sharpest throttle response. But if it's grunt your after..........
 

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I also think the 2.5 has the nicest tune out the Busso's two.
But that maybe because it wants to rev up quicker.

But that's always going to be the way with a short stroke.
 

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I have a 3:0 GTV and a 2.5 156. I have always thought that the 156 was thirsty for the performance that it delivers . You have to work it significantly harder to make it go well. It lacks low down torque. I would go for the 3.0 every time . I don't think that it will drink that much more and you will get more smiles to the mile.
 

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Both my 3 litres were about the same on fuel as my 2.5s. In fact I found the 2.5s I had were no better on fuel even compared to my GTA.
 

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They are all a bit pants on fuel. Especially when you compare them to similar sized engines from other brands.
But generally they are all noted to be around the same.

They guzzle fuel. But they are fun!
 

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Discussion Starter #12
Well thanks guys! ;)

I think I'll go for the 3.0 then and keep the 2.5 to try to repair it. After all it only has about 80,000 km... :)

You mentioned the gearbox... What would I gain if I'd swap it for a 166 gearbox?
 

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Don't bother changing the gearbox, keep your original if its OK. Sell the 166 gearbox and use the money for a Quaife diff :)
 

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I think I'll go for the 3.0 then and keep the 2.5 to try to repair it
Good idea, you have more to gain after a 3.0, and f you rebuild the 2.5 one you gonna have a spare :thumbup:
Like Dan said, you should consider buying a quaife diff, or a Q2. It gonna improve the handling a lot.
 

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Discussion Starter #15
Little update here... :wink_org:

So I followed your advice and got myself an even lower mileage 3.0 engine from an auto-gearbox 166 with only 58 thousand kms!!! :biglaugh:

The low down torque is awesome!!! :thumbup:
On a 60 kms country side road trip I did with the family (car fully loaded) I did it in 5th and 6th gear at legal speeds (with the occasional mild acceleration...).

The car is wonderful and the engine choice is great! I really don't know why Alfa didn't put the 3.0 engine in the first place!

Well, just wanted to thank you guys for the advice! :beer:

And here's how it looks:
i-PBbNxZn-L.jpg
 

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I've done a few 3.0 conversions too, in fact we have a 3.0 in the garage that's waiting to go into one of our 156's. It's well worth it - much better performance and the low end torque means you don't have to work the engine anywhere as near as hard to, um, "make progress" the net result is better MPG in my experience.
 

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Glad you decided to fix it and fit the larger engine. I hope its everything you wanted.
I can imagine with the auto box it makes a huge difference.
 
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