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3.0 or 3.2 V6?

26K views 166 replies 24 participants last post by  maly85 
#1 ·
I have a 156 2.5 V6 which is due a Cambelt change next year. I am looking at getting either a 3.0 or 3.2 fitted instead. My 2.5 is absolutely lovely and very well cared for but I would like a little more power.
So cost aside, what are your opinions on either choice? I've heard the 3.0 is a better engine and a bit more reliable but there must be merits to the 3.2 because they are now found in most modern V6 Alfas.
Fuel consumption is not really a factor. I drive a V6 because I love the sound of the busso engine. I will feed it as much petrol as it needs! I just want to make an informed decision on the best engine to go for. Your opinions and experiences are much appreciated.
 
#5 ·
Well the 3.2 is in essence just a longer stroked 3.0 motor, BUT it has a more aggressive inlet cam (lets call it GTA1 spec). The throttle body, intake manifold, inlet runners, exhaust cam, bore, etc are all the same.

A shorter stroke means the piston speed is a bit lower, thus the engine is a bit happier to rev (but we are talking about 6mm over 72mm (8.3% more) so there is very little in that. The cam and software gives the biggest edge for the 3.2.

In my 156 SW (still 2.5 ECU) I have a 3.0 engine with GTA1 spec inlet AND exhaust cams and decat, free flow exhaust that make 156 GTA type power. So my advice is take the specific engine you trust the seller best for having looked after the engine
 
#6 ·
Get the 3.0. The 3.2 has manifold cats fitted which casues the engine to run hot and can cause cyldinder head/valve seat issues.

I am not saying there is anything particularly wrong with the 3.2 but for the least aggro go 3.0. If you went with a 3.2 I would replace the head gaskets and re-grind the valves before fitting.
 
#11 ·
if you can find a CF2 3.2 then go for it...thing is it will likely be a few quid, thing is is those manifold cats in the CF3 increase the back pressure which is one of the reasons CF3 3.2's are more prone to HG failure than any other permutation of the V6. the 20 extra ponies,longer stroke more aggresive mapping all result in an engine running much closer to the limits than a CF2 3.0.

added to which the 3.0 are a bit more common having been used in the GTV and the 166..so you are looking at 3 figures for a good 3.0 and 4 figures for a les reliable 3.2.

I know which i would buy!!

when considering changing my Derv for a V6 recently I looked at the GTV ahead of the GT simply because of the 3.0 V6 instead of the 3.2 in the GT, this was after a spate ( 3 or 4 cars o the forum) of 3.2's needing top end rebuilds at lower mileages, one at 50k!

I am not saying the 3.0 doesn't suffer as well but I have not heard of one yet., seeing as its a more common engine than the 3.2 it says a lot IMO.
 
#23 ·
With regard to my con rods, yes. If I could fit a Busso into my 159 Q4, 2,5, 3.0 or 3.2 I would. The 3.2 Busso with 240 horses would do me not least because I don't believe the Q4 makes 260 PS - 254 BHP? If I could, I think it would be the ultimate Modern Alfa - albeit with a 30 year plus engine.
The more I look at my wrecked 3.2 G.M. engine, the more angry I become. But I still believe it is essentially a good engine and a way around it's problems can be found. But how many of us will commit to the outlay?
I think it deserves it, not least because unwittingly Alfa built a better package than they realized. If they had and got the engine right, it should have been rolling out at £40K.
 
#35 ·
Like all projects it depends on your budget. As this guy has a road car; swapping cams is a wast of time.
If it was my money i would go with a simple swap and use the 3l.
Giving a reasonable amount of extra tourque. If you also use pre cat manifolds, the results are even better by some margin, you will also benefit
from better mpg (Compared with cat equipped manifolds that is).
Most road going cars spend the vast majority of their time under 4000rpm


Regards Martin
 
#36 ·
I've got a 156 3.0 with JK 10mm cams and it is fast above 4K. It's not got the lower end grunt of my mom's GTA though. The GTA has a more linear pull all the way till the rev limit. I suspect with JK's cams there is less dynamic compression and with ony 10:1 static compression, the performance in the low revs like below 3000 rpm isn't as good as a stock 3.0 would be. But above 4K, it pulls REALLY hard even without a remap.

I have been attending to the 156 for now, but am going to finish up my 75 3.2 with JK cams. This one has shaved heads as well, so it should be a pretty fast car.

To the OP, the 3.0 is the best bang for the buck. If you plan on adding cams, maybe consult your mechanic if you can shave the heads a little to increase your static compression. Even for a road car I beat the hell out of the my 156, 7K rpm every 5 minutes. Can't help myself. The 75 3.2 is my race car.
 
#38 ·
Wow, what a weird thread! This has popped up in the digest so expect a few puzzled comments...

Leaving aside the peculiar bits in this thread, you're better off getting a 3.0. The 3.2 is a lovely, lovely engine but by the time you've done all the work you'd need to do (upgraded suspension and brakes all round, q2, ecu / loom, whatever you choose to do manfold / exhaust-wise, etc) it'd have been far cheaper to get a decent GT / GTA and have done with it.

There are still some CF2 3.0 v6s around so that'd be the one to go for if you've got an earlier CF2 156, though they are likely to be higher mileage than the CF3s. But if yours is a CF3 156 you might as well go for the 3.0 CF3 and stick a pair of Wizard manifolds on it

Whatever you do it's not going to be a cheap conversion though, certainly way more expensive (and probably time-consuming) than getting a cambelt change. Best bet is to read some of the conversion threads on here to see how much work is involved, and then decide if your enthusiasm / wallet stretches that far.
 
#43 ·
Wow! Can't thank you all enough! There are some excellent opinions out there!
I currently have a CF3 2.5V6 so I will go for the CF3 3.0V6 after considering everything. Although I do take on the point that (to some extent) I do know the history and reliability of my current engine. It is now approaching 100k miles and is still going strong (it must be one of those lucky Alfas built on a Monday!).
 
#45 ·
3.2's are £2k + and for that reason alone I would not be putting one in a non gta 156 daily driver as it just doesn't make sense. You might as well buy a GTA or a 3.2GT straight off.

Both obviously great engines but I wouldn't be paying £1500 extra for another 27bhp when the 3.0 will already be a big improvement in power over the 2.5.
 
#68 ·
Sizewell and Chris 155, if you want to come out down the pub, I will buy the drinks all night....

I have a Cf2 3.0 166 and also a 156 GTA.

They both are due timing belts in the spring. This thread has got me thinking about camshafts for the 166....what would GTA cams do for the 3.0 166 (this car has a quaiffe diff and uprated suspension already)? on the other hand what would Colombo and Bariani cams do???

GTA cams I can see as any garage with GTA camlocks could do the timing belt in the future... what happens with timing Colombo and Bariani cams?

Oh, my 166 is fast approaching 160,000 miles...all is running well as far as I can tell, should I leave it well alone except changing the belts...?
 
#70 · (Edited)
#75 ·
edit: i had the window open so long i didnt se all new posts :)

yep setting the timing for performance cams is interesting job. I have a video (it's in Slovenian language sorry) where i show how to check if max lift is at desired point (107degrees for ahm) You go 5 degrees over and under and the gauge has to be at the same number, then you know that the middle is 107 exactly.
More about this in my old thread: http://www.alfaowner.com/Forum/motoring-images/137704-my-gran-turismo-veloce-6c-11.html

and a video i mentioned before:
 
#79 ·
edit: i had the window open so long i didnt se all new posts :)

yep setting the timing for performance cams is interesting job. I have a video (it's in Slovenian language sorry) where i show how to check if max lift is at desired point (107degrees for ahm) You go 5 degrees over and under and the gauge has to be at the same number, then you know that the middle is 107 exactly.
More about this in my old thread: http://www.alfaowner.com/Forum/motoring-images/137704-my-gran-turismo-veloce-6c-11.html

and a video i mentioned before: https://www.youtube.com/watch?v=CttJWduxRbU
Great Alan. I used to do this with my old Twin Cams. Happy Days!:beer:
 
#96 ·
Quote from maxwell "I can't believe you said that! There is only so much you can take off the back face. If you do, then you risk the possibility of stuffing a valve into the piston crown".

The major thing that C&B have discovered is from the listed data: More total lift on the In than the Ex. (which has been done many times before) BUT! then combined it with longer Ex duration than the In. AND THEN!!!!! Gave the Ex more lift at TDC than the In.
Have a look at any Piper, Kent or Cat cams offerings and you`ll see what C&B have done. Truly quite incredible.
 
#111 ·
Not wishing to enter the debate further, other than say, it is here for the benefit of "Someone" who understands how to interpret "Cam Profiles". And the Fact that they be appropriate, as I have a Q4. Also, unless you are in a position to qualify what you say about the G.M. engine that Alfa Adopted, you shouldn't go along with the misconceptions others have about it. It has It's problems. But they are not unsurmountable. And in my opinion, it is fundamentally a good engine. But of course you wouldn't know that, would you? Given you don't own one. I think you and many others may be in for a surprise just how good it could be. But even if I am wrong, at least I will understand the reasons why. As opposed to those who never know the reasons why anything is right or wrong.

This is not applicable to everyone on this thread, but someone said, "There is so much crap on this thread, I don't know where to begin" - his words, not exactly verbatim. My response, "Then Don't". My thoughts at the time - "Take your petty egotistical clap trap somewhere else and leave people alone. "Hoisted by his own Petard".

"I't better to keep ones' mouth shut and be thought a fool, than to open it and confirm the suspicion".

I'm out now!
 
#109 · (Edited)
Alan,

Did you remap with your AHM cams or did you use MS3? My idle is **** because there is no one worth a cow's turd here who can remap it. It has JK 10mm cams, just like Sabertooth's cams.

Anyway here is my 156 3.0 with ELFP and Bollente rear muffler (Japan, like Unicorse, Array, MEXC-S)

 
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