If you have an easy option for a 3L, go for it. I’m personally not so keen on the converted 164 engine install but if it’s an original transaxle car 3L, then totally do it. The costs of overhaul are the same and it’s a significant power upgrade.

 

The power increase more than makes up for the slight loss of edginess and pitch, and also to note that different exhaust systems produce quite different results. The factory OEM, well broken in sounds great on the 2.5. The 3.0 engine still sounds amazing. The usable power increase between stock-to-stock feels much more significant than the numbers would suggest and even a slightly modified 3.0 goes on from there. My old Italian mechanic, Carlo Durante at Alfa of Tacoma (RIP) and builder of many Alfa and exotic engines preferred the 2.5 for sound and balance. He felt there was a very small difference in the balance of the engine no matter how carefully he built the 3.0. Of course he sensed things that I would never detect. His GTV6 and Milano kept their 2.5 motors, liking that engine more than many/most exotic powerplants (and he drove all of them). So you can’t go wrong.

 

Interesting to read! Thanks! I'm not sure how much I would like the power benefit if it loses some of the "balance" or tone it has now. Even though I know the gtv6 is not fast by any means, revving the engine up and timing the shifts is so engaging that it feels fast and always puts a smile on the face. A little more speed of course wont hurt as while I'm doing all of this any modern day car driving next to me would wonder "what's with the smile when he's driving that slow". Anyhow I guess it is just a little more power would kick out the rear end a bit more easy as well. But the balance in the 2.5 is certainly something special. Pros and cons...

 

I would go for the 3.0 as well. It's not so much the greater horsepower as a GTV6 will be slow with either engine compared to modern cars, but the torque curve make the 3.0 easier to drive in everyday traffic.

 

If you choose to go with the 3.0 liter conversion do the round toothed timing belt mod as well. Alfa actually sells the parts to do the 3.0 liter engines (the right hand head is different on the Milano and later 3.0 liters than the 2.5s) so you can get the necessary sprockets and pulleys straight from the OEM. If you convert the 2.5 you'll have to get the kit from Chris Snowden Racing (CSR, alfettagtv6.co.uk) and it runs about 860 pound sterling = $1,122.91 at current rate of exchange

 

That's a good one Tom! I look into that. Thanks for the response

 

Hi all,

I know this is a topic that has been discussed here and there, but I'd still love to get some more thoughts on this matter. I own a US '86 GTV6 and live in the Netherlands. I absolutely love the sound of my GTV6 cat still in place, mid muffler and Ansa rear.

I'm planning to do an engine overhaul after this season and got the opportunity from my mechanic to put in a 3.0 liter. I wouldn't mind a little more power but just trying to judge from videos it does seem that the sound is quite different, lower and not as revvy.

Can anyone chime in that did the swap and noticed that the sound changed? I'd love to hear your thoughts.

Best,

Maarten.

I have the same exhaust set up as you but with a 3 liter conversion. There is a slight change in the exhaust note from comparing it to the 2.5 stock engine, but you have to listen carefully.

 

I see! Is there anything you miss from the 2.5?

 

On the balance thing, that is a comment from a one-in-a-million genius, a 1960’s F1 mechanic that sensed things that “regular” great mechanics and drivers will never feel or sense. My brother has a 2.5 Milano with a Carlo-built stock component engine. It spins magically, essentially balanced/blueprinted in the right places, by a world class engine builder.

 

Thanks Peter, do you know what he changed on the 2.5 to get some increase of power?

 

Though I have never owned a 2.5, I've owned four three liter cars. For the two valve? The ultimate sound is the 3.0l in combination with headers with a Stebro exhaust. Imho

 

This is a good point; much depends on what sort of exhaust you're able to run. For example, if you need to run cat's then you're behind the 8 ball on sound already. Running a non-cat system with some of those after-market 3-into-1 headers and a nice open resonator at the rear can sound awesome on a GTV6, every bit as good on a 3.0 as on a 2.5.

You say your car is a US market one with cat still in place. But do you need to run that in the Netherlands? When I put a 3.0 into my '85 GTV6 in Australia I sourced the engine from the US but used the original injection, which for pre-'86 cars in Australia meant no cat and no oxygen sensor. I actually used the 2.5 ECU which despite protestations is exactly the same Bosch part as the early euro 3.0 cars. I used some locally made 3-into-1 headers with the factory pipes through to the rear axle - but without the flexible parts - and a simple resonator at the rear (which my memory tells me was a generic truck part). The setup worked really well, the HP was exactly the same as a factory 3.0 75, it sounded great, and was not expensive.

 

Hi All, thought I would give everyone an update on 2.5 vs 3.0

I will probably do a separate post on this as well where I'll keep everyone updated on the built.

2.5 was leaking more and more oil during my Schotland NC 500 tour. After going back to the garage where I purchased my GTV6 it was diagnosed there was a leaking crack shaft ring and pretty much all the other gaskets had to be done.

I was still a bit on the fence whether I would either do just the gaskets in the hope the rest was good, do a rebuild of the 2.5, or go ahead with the 3.0. Like many of you, my mechanics advised to go with the 3.0 liter since if you would ever do it, it was pretty much now. They had a few laying around so we could find a good candidate.

3.0 with verde pistons from a 75 (or Milano in US). The heads are from the mechanic himself from way back when and have larger air intake pistons which supposedly is good for better airflow and a few horses.

I have the option to work in the garage myself in my spare time to clean up the engine bay and retouch some sections that can use some sanding and a bit of paint to prevent from rust. If someone reading this is thinking of pulling the engine, try to put some time in and effort in the places you're not able to reach with the engine in (photo 8&9). These spots are particularly prone to collecting debris and water but are really hard to reach while the engine is in.

I'll keep people posted on this project. If there are any questions let me know! I'm really curious to see how this turns out. Thanks for all the feedback.

 

So... Yesterday I wrapped up the 3.0 swap. My god... What a difference. It is simply put a different car with a different character. I can't fully open it up yet but the difference in torque and even sound (removed cat) is huge. Very happy I did the swap. Not the round toothed timing belt option but I did put the Centerline Staybelt as the timing belt tensioner (quite overpriced I think)....
I can't wait to open it up and see what it does above 4k rpm.

If anyone wants to read about the details of the build I'll be posting more info and pictures here;

GTV6 3.0 build

After weighing the pro's and cons for a long time I decided to convert my 2.5 to 3.0. Writing this mainly to help out people that are thinking about a conversion as well. I knew the day was coming to go over the engine and had the opportunity from my mechanic to put in a 3 liter so I started...

www.alfabb.com

 

So... Yesterday I wrapped up the 3.0 swap. My god... What a difference. It is simply put a different car with a different character. I can't fully open it up yet but the difference in torque and even sound (removed cat) is huge. Very happy I did the swap. Not the round toothed timing belt option but I did put the Centerline Staybelt as the timing belt tensioner (quite overpriced I think)....
I can't wait to open it up and see what it does above 4k rpm.

If anyone wants to read about the details of the build I'll be posting more info and pictures here;

GTV6 3.0 build

After weighing the pro's and cons for a long time I decided to convert my 2.5 to 3.0. Writing this mainly to help out people that are thinking about a conversion as well. I knew the day was coming to go over the engine and had the opportunity from my mechanic to put in a 3 liter so I started...

www.alfabb.com

I'm curious, what did you use for the FI, the 2.5 GTV-6 system or the Milano's, and did you swap the ECU?

 

I miss A of T too. Lino and Carlo.
Lino in front, Carlo with the cars in back, and always like walking in a wonderful hot rod exotic car shop. Ferrari and Alfas. It was fun just to stand there and admire the cars.

 

I miss A of T too. Lino and Carlo.
Lino in front, Carlo with the cars in back, and always like walking in a wonderful hot rod exotic car shop. Ferrari and Alfas. It was fun just to stand there and admire the cars.

Yes for sure. I grew up in Tacoma, Lino sold me my first and second Alfas. They became good friends and I think about them often as I get in my GTV6, which sat in the basement there for twenty years before I acquired and got her running again. Carlo sold me the crate 3.0 that he had been hoarding for 20+ years. That was the last time I saw him (and Lino) in the fall of 2019 before his passing from COVID.

ps - Carlo wasn’t a purist he modified a lot of cars including 3.0 swaps but he liked the 2.5 more than the 3.0, he thought the 2.5 had optimal balance. My brother has his black 2.5 Milano that Carlo built for himself. Have to admit that is a wonderful motor. Who knows what tricks he did to make so incredibly smooth and free-revving. For any motor there is a difference between a custom-built engine from a expert on that particular motor versus what even highly-skilled home mechanics can do.

 

I was driving up to Seattle one day (don't live there anymore) and I saw Lino driving that Milano north up I5. I know the one you are talking about. Yes, they had a basement full of interesting things.

 

Unfortunately this post takes a turn fort the worse. After 370 (great) miles, starting the car and driving slowly for the first 500 meters of my night drive the engine stalled. Car doesn't start anymore although putting the car into first gear makes the car do a hick-up and makes the car move (I did this ones). After inspection the timing belt is now extremely loose...

Any ideas what might be going on anyone? Hope the engine is not bust 😅

 

Unfortunately this post takes a turn fort the worse. After 370 (great) miles, starting the car and driving slowly for the first 500 meters of my night drive the engine stalled. Car doesn't start anymore although putting the car into first gear makes the car do a hick-up and makes the car move (I did this ones). After inspection the timing belt is now extremely loose...

Any ideas what might be going on anyone? Hope the engine is not bust [emoji28]

I would also like to see what happened to the Staybelt. I have one on my GTV6, over 3000 miles and a few years with no issues yet.

Sent from my GM1917 using Tapatalk

 

This unfortunately does not sound good if the timing belt is loose enough to jump a tooth or a few. Did the mechanic build the engine or did you assemble? If mechanic assembled I would call them and not touch it. If you assembled can you rotate by hand? Did the tensioner come loose? If you can’t rotate the engine (plugs out) easily and the belt is loose, 😞. Then next step would be to take off the heads and see how much damage if valves collided with pistons. Good luck.

 

Ok so not good is right! Pistons hit the valves... Not sure yet which ones but my mechanic said it was not good. The cause... Freaking Centerline STAYBELT breaking of internally. All I can say is: STAY AWAY FROM STAYBELT!!! If manufacturing is that shaky on such a crucial item developed specifically to prevent from beltjump, you missed the point as a manufacturer. Will contact centerline about this. Gosh how ironic being too careful bites me right in the...

 

That’s hugely disappointing to have that part fail. Good luck with the inspection.

 

Can you take a picture of the broken Staybelt?

 

soon!

 

The car is at the garage at the moment getting some new heads, tensioner and belt. My mechanic told me that the staybelt has to deal with a constant load and thus the metal bolt that is in the center gets tired and can snap off. I don't quite understand yet... Is it possible this was installed the wrong way? I'll get pictures when I'll pick up the car and the broken tensioner.

 

Can you post a photo when you get it back. Many thanks.

 

What is Centerline saying? There are lots of these in use today. If this is a common failure I don't think they would be selling them anymore.

 

I've e-mailed them today. I'll get back with their response

 

So I finally have the car back and it is clear what happened with Centerline's Staybelt. It turns out this is simply an assembly fault from Centerline. My mechanic explained it to me as followed:

Ok so here it is.

Stay away from STAYBELT.

The part basically consists of a large shaft that holds the rotating mechanism. The rotating mechanism consists of two brass bushings that shouldn't be touching as that would allow the main assembly to rotate freely. If they DO touch they won't turn and the tension of your belt comes on the main shaft which will then break off due to metal failure (see black metal residue). Which is what happened...

When you order this part from Centerline you get it pre-assembled. I really don't understand how their quality control department messed this up.

For all of you thinking of getting a STAYBELT for your GTV6, STAY THE HELL AWAY!!

I'll come with an update after I get a reaction from Centerline.

 

NO COMMENT about CENTERLINE'S Quality Control? department.
WHY DOESN'T EVERYONE USE THE FACTORY REPLACEMENT UNIT? I've had three of them on my GTV-6, my wife's Milano and on our 164L and I've NEVER had a minutes trouble with any of them. They solve the oil leaks and they work with the temperature changes. And, my wife can attest I'm willing to bounce my GTV-6 off the rev limiter when I'm in a hurry. Why does everyone want to reinvent the wheel?

 

Centerline EZEL HOOFD

 

when you change the engine to 3.0 from 2.5, you need to put the ecu and the air floe meter of 3.0 engine?

 

Screw a 3 liter swap. Didn't change the ECU. Read below for update. In short. **** that. Keep it original.

 

when you change to 3.0 liter from 2.5 is needed also to change the ECU and the air flow meter of 3.0 liter engine?

 

Ouch... This thread needs a little update. Correction big update! Got the car out of winter storage beginning of April. Drove it easy for let's say 40 minutes. Not above 4k RPM first corner consciously revving it above 4k let's say up to 5. and the engine completely blew up. Stuck like nothings else. Brought it back to my garage. The guy that build it got fired for unexplained reasons. I'm lucky in that I had the deal that if anything happened the first 1500k I wouldn't have any costs but man what a bummer!

Theres' a guy somewhere in his 70s that's always running small errands around the garage and is the general good coffee hang and laugh. When I started this journey and doubted the 2.5 vs 3... he told me against everyone else at the garage. YOU HAVE TO KEEP A CAR ORIGINAL. How do his words stick to this day. First thing I told him when he actually tagged along to pick up the car. Gosh... I should've listened to you haha.

It was a fun journey. I mean... 3 liter, sounds more than 2.5... although I really enjoyed powering out of every **** corner with the 3 I don't think I every got more joy, really. In the end this swap costed me a lot of time (I helped on cleaning and so and so and so.).

My first plan was always... head gaskets, which is a pretty significant job on a GTV6 but if you're in this scenario and someone tells you you just might as well put a 3 liter in for "a bit" (1500€) more money, don't do it.

3 liter, yes more torque but who gives a ****... the 2.5 sounds incredible and if you want to be faster than a GTV6, why not buy a VW caddy.

 

Hi MHDB,

Any updates on your car?

 

Hi Redmist,

Definitely there's an update. It is unclear why the engine failed but it was totally thrashed. I don't know the reason but here are a few things that sum up my particular situation in a Nutshell:

-First 3L build was done with a head that had bigger valves.
-Block Bottom was from a 164 with QV pistons I believe
-Lightened flywheel and made a fitting plate since the crank has a bit shorter measurement on the crank when you use a 164 block.
-Used Centerline's special mechanical spanner which unfortunately failed and ran the heads into soup. Joe from Centerline is still investigating with his manufacturer what was the cause.

-Second build was done with 3L normal 75 heads.
-Failed after 40 min drive after 4 months of storage.

Right now the 2.5 is getting new gaskets and goes in this weekend. Got rid of the lightened flywheel as well.
Right now my intention is to keep this car as original as possible.

Even though the guy that build the engine has a lot of experience with these engines I think there's very little room for error. Maybe the oil passages on the crank were not cleaned enough? Maybe some torque specs were off? Maybe when the intake plenum and manifolds were not cleaned diligently enough after sandblasting? Who will tell...

I just think that when an engine is build up there is very little room for error and your in for a nightmare if the slightest error is made.

Maybe literally fishing good working 3 liter from a 75 and dropping it in directly would work but why go with all that hassle. I also think the fun factor of a 3 Liter is entirely overrated. You can haul *** just as quickly with a 2.5 if you know how to smash it into a corner and stay off the brakes