Alfa 90 V6 - 12 vs 24v

[elbee]

Hello!

Need help to decide my Novanta's future. It's completely original and rust free 84 2.5 QO, almost everything works, but form very beginning I have had problems with engine, first original 2.5 unit boiled and made bad noises, that was replaced with donor unit, the same story, makes pressure in cooling system, temperature goes up... And it feels like not enough power for real driving pleasure.

I'm very tempted putting a 24v 3.0 unit from Alfa 164 instead of old 12v, but feel like ruining a classic value with that move. What are your opinion? Is it acceptable to change old daddy busso to newer unit from ethical and historical point of view? I hope you understand my fears So keep it with stock 2.5 or change it to 3.0 24v?

This is my Novanta

[Zaagauto]

Hi elbee,

we were discussing the exact same issue here:
http://www.alfaclub.eu/forum/viewtopic. ... 752#750752

Don't put a 24V in a 90 2.5 with stock driveline.... go for the 3.0 12V.

Yes, the 24V outperforms the 12 V but only over 4000 RPM. Below that, the 12V has better torque and HP. With the (very) long end drive of the 90 2.5 gearbox and diff, you will only have a slight torque advantage at speeds of over 170 km/h in 5th gear. Below that, the 12V is quicker.

So from a performance point of view, you have to ask yourself the question how much time you spend at over 4000 rpm and how much fun you want below 4000 rpm. Only you can answer that question for yourself.

You can easily compare the torque and HP curves of the various engines here:
http://www.squadra-tuning.nl/autos/categorie/55.html

As long as the conversion is semi plug&play (which I believe a 3.0 12V is), you won't ruin the classic value at all as it can easily be reversed and will not leave any damage to the car by doing so. Besides that, you are already running the car with a non-original engine...

P.S.
Why don't you try to find the source of the problem with your current engine? Sounds like a blown headgasket which is easier to fix than transplanting an engine....

[yuri 75 V6]

Personally, I have no qualms from an ethical standpoint, but I agree with Zaagauto that a 12v engine is a much better mate for the Alfa DeDion cars than the 24v engine for the same reasons.

[frankalfa]

..... I agree with Zaagauto that a 12v engine is a much better mate for the Alfa DeDion cars than the 24v engine for the same reasons.

I second that, a 24v engine in an transaxle Alfa is not such a good idea (beside the point of downrating the value of a classic car by modifying engine wiring and moving up the complete pedalbox for instance)
As written by Zaagauto, the 24v feels lazy under 4K rpm, you're just kind of waiting for the power to kick in...

Are you sure the rest of the cooling system is 100%? I think it is at least remarkable that 2 different engines in the same car give up with the same kind of problems...

If all other cooling components are ok, simply upgrade to 3.0 12v.

Best regards,fRank

[giuliettaevo]

The 24v QV engine from the 164 would be my choice ... The torque is only a little bit lower under 3000rpm and above that point it just starts making more and more power. But a shorter gearing is definetely nicer, the car is more eager that way.

Originality is not my thing but the 3.0 12v can keep the original look for 98%. The 24v will look different but if done neatly and with an adapted 12v original intake it won't catch the attention immediately.

The 3.0 12v 164 QV engine with 200bhp would also be a nice choice if you can find one.

I would always go for an engine with the Motronic management, like the last 75 QV had or a converted 164 engine. Runs better and gives better mileage as the old Jetronic in my eyes.

[elbee]

Thank you for answers, will keep standard 2.5 engine, process already started!



Next problem - fuel tank. It looks exactly the same as in 75TS, located under the car and leaks when full Two years ago had the same problem with 75 and found out that no one offers new replacement tanks. Are there any news? How do you solve this problem in the Netherlands? Maybe someone selling good rust free tank?

[giuliettaevo]

Good rustfree examples are getting hard to find.

I believe the tank is the same as the one from the 4 cilinder 75 models, that would help in finding a decent one...

You could ask Richard from Alfanord, www.alfanord.nl , he probably has a good 75 one for you...

And offcourse you could always get the original tank welded, just amke sure that the guy who's doing the welding knows his stuff.

[frankalfa]

Good rustfree examples are getting hard to find.

I believe the tank is the same as the one from the 4 cilinder 75 models, that would help in finding a decent one...

You could ask Richard from Alfanord, www.alfanord.nl , he probably has a good 75 one for you...

And offcourse you could always get the original tank welded, just amke sure that the guy who's doing the welding knows his stuff.

Indeed the 90 v6 fuel tank is similar to the 75 (4-cilinder) type. New tanks are very hard to find, asking Alfanord for a good used one is a good idea.

Best regards,fRank