156 2.5 ph2 manifold and 3.2 ph3 manifolds - Alfa Romeo Forum
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(Post Link) post #1 of 9 Old 11-07-12 Thread Starter
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156 2.5 ph2 manifold and 3.2 ph3 manifolds

Hi

Are the manifolds for the 156 2.5 liter the same diameter as the 3.2 liter (GTA) diameter ?
Are they a straight swap ?

The ph2 do not have cats in them, so thinking it may improve performance...
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It's a common upgrade and I am pretty sure they would fit. You would need different pipes to link up the 2.5 headers to the GTA cats but you can get these now quite easily.

There is power to be gained but you get more noise and vibration. It isn't for everyone.
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Quote:
Originally Posted by cannotstop View Post
Hi

Are the manifolds for the 156 2.5 liter the same diameter as the 3.2 liter (GTA) diameter ?
Are they a straight swap ?

The ph2 do not have cats in them, so thinking it may improve performance...
As said its a common mod, search in gta lounge.

With 2,5 v6 manifolds there is one extra issue, the rear bank doesnt have the lambda sensor plug and this needs to be drilld and welded on. Thats why 3,0 v6 cf2 manifolds are more popular, but also much harder to get and more expensive.
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I see.
But, apart from the sensor plug, is it a straight swap ?
Or would I need new down pipes ?

Would it be possible to weld the sensor plug from another manifold of the same type ?
(ie: are all of the lambda senders the same, and can I steal one from say, a twin spark manifold ?)

Last edited by cannotstop; 11-07-12 at 18:32.
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Quote:
Originally Posted by cannotstop View Post
I see.
But, apart from the sensor plug, is it a straight swap ?
Or would I need new down pipes ?

Would it be possible to weld the sensor plug from another manifold of the same type ?
(ie: are all of the lambda senders the same, and can I steal one from say, a twin spark manifold ?)
In every case you need modified or custom made downpipes. All CFII manifolds have 2 bolt flange and CF3 have 3 bolt flange. the angles are also different. So you need manifolds and downpipes for a swap.

Any welder can make a lambda socket, just drills a hole in the manifold, welds a piece of suitable size metal and cuts a thread for lambda. Little bit of cleaning of the edges and its done in 10 min. TS lambdas will have the same thread I think. If you dont know any welder shop that could modify the manifolds for you and want a "finished " item, search for gtv 3,0 V6 manifolds.

147GTA,Grigio Metallico,Imola leather,3.75l conversion,ported heads,F575 TB,Carbon plenum,Stainless manifolds,EQ pipes,Supersprint silenced cat back,18" GT multispokes,KW V3,Galfer 6pot 355mm,Brembo sport rear

147 1.6TS, Nerro,Beige Interior,Galfer Extreme Brake kit,2,0TS intake manifold,Custom ex. manifold,200CPI cat,Supersprint silenced center + OO backbox,GTA spoiler,GTA side skirts,GTA headlights,Blaupunkt LA MP74 + Focal + MacAudio + Dynamat + HERZ subwoofer
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You need to adjust the oil-cooler & PS pipes a bit too when fitting CF2 manifolds, plus its not an easy job to fit them. You need to take the engine out or grow extra elbows and knuckles.
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Quote:
Originally Posted by Pud237 View Post
You need to adjust the oil-cooler & PS pipes a bit too when fitting CF2 manifolds, plus its not an easy job to fit them. You need to take the engine out or grow extra elbows and knuckles.
I see
When its about removing the engine, I think I will wait a bit. Will get the suspension sorted first.

Thanks for the replies, thread kept.

Last edited by cannotstop; 13-07-12 at 11:01.
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It is possible to do it with the engine in the car, but it is very difficult. I think it is easier to take out the engine, or at least take it off the mounts so you can move it forward a bit.
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Unless you cut the manifold into pieces I can not see how you will get the rear one out without at least tilting the motor forward.
So in short it is a lot of work and probably best to do with a clutch change or something.
We normally attempt combining it with a clutch and cam belt service in which case we just remove the complete motor gearbox assembly and do everything next to the car.
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