Blago

Hey guys, what's up? There's probably people on here who already know all this but I decided to post it anyway in case anyone is considering doing this swap.

So I picked up a '93 Audi 90 Quattro 5spd with a bad engine (low compression) and decided to replace the engine. The engine that I got is from a '96 A4 automatic. Basically, everything is different between the two engines and has to be swapped over from the AAH to the AFC A4 engine. Intake manifold, exhaust manifolds, coolant pipes, brackets etc all have to be swapped. The metal duct going into the thermostat has to swapped and the timing belt has to be adjusted. The idle pulley's are different (the A4 had a mechanical fan on it) But that's not a problem cause you don't need the idler, just remove it and use an A4 serpentine belt.

Now because the engine came from an automatic car, there was a spigot bearing inserted into the crankshaft with the flexplate sitting on the bearing. This bearing has to be removed in order to bolt up the manual flywheel onto the crankshaft. There are a few different methods of removing it (google spigot bearing removal) but I just grinded it off and chiseled it out.

The over swap is pretty straight forward if you are mechanically inclined and have done work like this before. Obviously it takes more time and is more complicated because of the differences between the two engines, but it's definitely doable.

The other thing that's doable is a 30v swap, don't let anyone tell you that it's impossible. If I were to ever do this again, that's the way I would go. The only pain about the 30v swap (besides the wiring issues) is the exhaust manifolds. The exhaust manifolds on the A4 point straight back, whereas the ones on the 90 curve downwards. In order to make the 30v a straight bolt in, you would have to obtain the exhaust manifolds from the 30v engine that came in the C4 Audi A6, which was only sold in europe.

maineman

Thanks for sharing.

onfir3

So you think a 97 or 98 A4 engine would drop in if you carried over the wiring harness from the A4? That would be something for sure. I really doubt it would run on stock 12v electronics unless you can find someone to burn a chip for you which would probably be a bit silly in the end. Really interesting stuff though, well done on the engine swap.

Blago

The '97 A4 came with the 12v motor. The '98 A4 came with the 30v motor. To swap the 30v motor in, you need the complete engine i.e. with the intake manifold and all of the associated sensors, the 30v engine harness and the 30v ecu. You cannot use the 12v electronics, the 30v has variable valve timing. The 30v will bolt in using the stock Audi 90 motor mounts and motor mount brackets. But the problem is with the exhaust manifolds. The stock exhaust manifolds on the 30v A4 motor point straight back, in which case in the Audi 90, they point straight into the tie rods. You need exhaust manifolds which curve downwards just before the tie rods. So you either make custom manifolds or you source out exhaust manifolds from the European C4 Audi A6 with the 30v motor.

onfir3

Make it sound so easy. Might be worth it to just not get a Cab at that point, but its hard finding cheaper audi Verts. I'm thinking it wouldn't be as hard as I make it out to be though, I'm sure the general routing of the wiring harness is the same so you could just replicate everything in that resepects. I'm guessing most don't attempt it because the I5 20v is more so the "enthusiast" motor of the audi crowd, along with the 1.8ts. +

Blago

Well with the turbo motors you can get more power out of them in the long run. The thought process is that if you're going to swap the engine, you might as well go turbo. Both engines, the I5 and 1.8T, will bolt up to the stock transmission, but you can't use the stock engine mounts. With the 30v motor you can.

SC_09iduA

VERY interesting...can you post photos when you're ready?! I'd like to see how everything fit and a brief write-up on how the power difference would be noticed. Great work!

Blago

Was your post referred to me? My swap has been done for weeks now. There is no power difference since it's a 2.8L 12v motor, the same motor as the one that came out of the car. The only difference is that the newer motor came from an A4 and not from another Audi 90.

Also, the engine bay visually looks the same, the only differences are that the A4 motor has black, plastic valve covers whereas the Audi 90 motor had silver, aluminum valve covers. And that I am running an A4 serpentine belt with the A4 belt tensioner.

SC_09iduA

Ooohhh, I understand then. Well kudos to your swap. I was thinking you went with the 30v but after re-reading more I notice you kept the 12v and updated the belt system. Is the only difference the serpetine belt system & sensors; is the A4's intake manifold composite and not aluminum? Sorry for the rash of noob questions...seems like a descent swp though as they're more available then low-mileage 90 motors...

Blago

The intake manifolds are the same but the manifold on the A4 engine has a different throttle body and different sensors on the back, so I just took the whole manifold off and put on the Audi 90 one. And ya, A4 12v motors are more readily accessible and are on lower mileage, it's just more work to swap one in.