Alfa 90 - Not Another 3.0L Conversion!

[Beatle]

OK, so I've read a bit and searched a bit.  I have The Guide, http://alfagtv6.com/msdocs/3L_update_Conversion.doc  but still have some questions.

Basically, what is the quickest/easiest/cheapest route to dropping a 164 (auto) 3L 12V engine into an Alfa 90?:
     -Use the 164 fuel management (Motronic?) or swap all the L-Jet from the 2.5?
     -Why don't people use the 164 inlet runners?  Clearance problems?  Other problems?
     -AFM/Induction?
I assume bonnet clearance is less of a problem on the 90/75 than the GTV6.

[Duk]

Go the Motronic!
The Jetronic is just so damn old and not a match for the 3 litre.
So get the wiring loom, AFM and make sure the crank angle sensor is on the engine!
But remember that the donor car is obviously different in size and layout to the recipient, so be prepared to lengthen or shorten wires.

I really think that the flywheel will be the biggest drama for you. You'll need the (I think it's 4mm) spacer so the 2.5 flywheel is located correctly on the 164 3 litre crankshaft. On top of that, the 2.5 flywheel won't really be balanced to suit the 3 litre. How you'd go about replicating the the 164's flex plate and probably torque converter's balance............ Maybe have a yarn to Scott Venables.

[Sheldon McIntosh]

Basically, what is the quickest/easiest/cheapest route to dropping a 164 (auto) 3L 12V engine into an Alfa 90?:
     -Use the 164 fuel management (Motronic?) or swap all the L-Jet from the 2.5?

Quickest/easiest/cheapest is to keep the L-jet.  I did it this way, purely because I'm not much of a mechanic so I wanted to make the job as easy as possible.  The result was that the extra torque was amazing, but on the track when you're constantly at high revs the engine definitely feels like it's not breathing as well as it should at the top end.  To be fair that is probably due more to the design of the inlet system rather than the L-Jet itself.  It's still a lot stronger than the 2.5 up high in the rev range, but with such a strong mid-range it feels like there should be more up top.  On the road it would rarely be a problem (for me, I don't often go over 5000 on the road).

If I was going to do it again on a track car, I would definitely keep the Motronic.  On a road car, I'd think hard about it, but probably keep the L-Jet.  Motronic is a lot more work, for little extra gain (on the road).  To be honest, for the work involved I'd rather put my time and effort towards a megasquirt anyway.

     -Why don't people use the 164 inlet runners?  Clearance problems?  Other problems?

Have another look at the 164 inlet system.  If you use the 164 runners the intake to the plenum is pretty close to the firewall of the 90/75/GTV6, so you either have to make up a 180 degree adapter with a very tight circumference, or modify the plenum itself; both have been done, but it's a bit of work.

I assume bonnet clearance is less of a problem on the 90/75 than the GTV6.

I don't think so, it's still pretty tight in there.   Maybe a smidge more room.  Why, what are you planning on doing?

[Beatle]

I'm 'planning' on blowing up the 2.5........      I have a sneaking suspicion the engine has an oil-to-coolant leak as there is a little slime on the inside of the bottle, though the coolant itself looks OK (as does oil).

I'm just getting an idea of what an engine swap might entail in case the opportunity presents itself.  If I'm replacing the engine anyway, it doesn't seem like a lot more work to fit a three litre, and 2.5s are mostly all high KM these days.  Stock 3L would be easier than rebuilding and modifying a 2.5.

Something I hadn't considered though, is that 3.0 is 20% capacity increase.  I think NSW only allows a 15% capacity increase without an engineering cert. 

[Sheldon McIntosh]

So don't forget to also up your cooling capacity by 20% as well then.

Grind off the '3.0' on the back of the block, keep the L-Jet, and no-one will ever know......

[Beatle]

Won't the engine number give it away?  Remember we have annual roadworthies in NSW so I'd have to report the engine # change first time around.   After the initial notification ongoing roadworthies wouldn't be an issue.  I guess it depends how 'smart' the RTA database is.

[Sheldon McIntosh]

Ah well, sucks to be you then.

[shiny_car]

Ah well, sucks to be you then.

In VIC, the registration papers need to show that the VIN and engine numbers match. Engines can be changed but AFAIK do need an engineering certificate to fascilitate updating the registration, and presumably requires a formal VicRoads inspection.

Unregistered track cars are different, of course.

[aggie57]

Hi Paul - have done or been involved in a couple of these.  My first was in 1996 and I had to figure it all out 'cause almost nobody had done one before.

If you're doing a 12-valve 3.0 then like Sheldon says the quickest/easiest/cheapest approach is to bolt all the 2.5 bits on to the 3.0 core.  The L-J is fine for everyday use, and even some track work if you want, and despite what some of the Alfa parts books tell you my research at the time said that the very early 3.0 engines used exactly the same parts as the 2.5 engines.  Same ECU, same flow meter, same stacks, same everything.

If you want to go the next stage then personally I wouldn't bother with the 12-valve engine at all; I'd go straight to a 24-valve, plonk on a decent ECU (have played with Autronic but appreciate that there are others) and get some custom pipes made up for it.  Drive one of these and you'll never ever want to go back to a 12-valve.  Dollar per thrill it's a bargain, and if you are handy with spanners as you are its amazing how much of the conversion you can do yourself.

[VeeSix]

There is no doubt that the 24 valve is the fastest engine, owned them all, but its power is up in the rev range and i have found it higher maintance and less reliable than the 12 valves going on the stock management systems, for flat out fast the 24 valve is the best but for everyday driving i think you can not beat the 2.5 or 3.0 12 valve, good all round power in the rev range, easiest to stick with the L-Jet if you are converting a early 90 or 75 but there is no doubt the Motronic is just a more realiable system, the L-Jet seems more finicky to me where as Motronic seems more refined, i have found L-Jet will let you down more than Motronic although they are both good systems