AAN & ABY specific differences

[Error404]

I've had a bit of a search and picked up a few bits of info.

Basically i'm considering the AAN route to a 20v turbo converson on my CQ mainly due to cost and availability of the engine and 6 spd gearbox. I wanted an AAN / ABY as opposed to the 3B for the individual coil set-up.
I wanted to use an ABY loom idealy though, for easy of fitment into the coupe without chopping it about.
Is the block and head the same beween them, except the early AAN with the hall sensor in the 7A / 3B dizzy location?
I assume i'll need to find 3B / ABY intake manifold and pipeworker, IC & crossmember & downpipe - do the AAN and ABY share the same sensors and engine management since the ECUs are similar?
What are the main differences between the engines that might make this conversion tricky?

cheers for any advice
Alex

[urquattro-island]

yup

you can switch them in between, the main differences are what youve allready mentioned, Im, pipework, ic and so on, the sensors used are mostly the same, some wires may be longer due to the bigger engine bay.

[Error404]

Thanks!
This is good news - i can probably find the intake, pipework, IC etc etc pretty easily & cheaply from some folk who've upgraded.
Any usefull info anyone has would be greatfully received

[S2central.net]

Yes - electrically the ABY and AAN are the same... Although as pointed out the wiring looms are different as location of some sensors is slightly different and the fusebox is of course very different. If using AAN engine to transplant into a 3B Coupe then you are best with an ABY loom. The ABY loom will expect the hall sensor for the camshaft position to be under the cam pulley - this is not the case on the early AAN engines. I can dig up the breakpoint in the AAN engine numbers for that if it helps.

The AAN has different inlet manifold of course and it has a viscous fan pulley that won't work on the Coupe. Pretty sure you'll need bracketry from ABY to mount things like aircon, alternator and hydraulic pump to the AAN in a COupe...

Water rail is different too, but the block and head are essentially the same so anything from ABY can be bolted on ...

[UrS4boy]

... I can dig up the breakpoint in the AAN engine numbers for that if it helps....

I would certainly be interested in such data, especially if you can correlate the data to the build date of the car the engine went it to (which might be tough, I know).

[S2central.net]

According to illustration 905-20 for an MY92 A100Q the hall sender on the head comes into effect from 4A-N-100-001

But dammit I have seen the engine number for this crossover somewhere else... Looking now.

[Error404]

Thanks Paul. Sounds fairly straight forward, just a few extra bits to source.
I guess it will depend what comes up in the way of breakable condiotion cars when the time comes

[Rusty]

RE2500 has just transplanted an ABY from an avan into a CQ, doesn't directly answer your question but he might have soem pearls of wisdom HTH

[Error404]

yeah i was following with interest.
My issue is going to be finding a suitable ABY to break for the parts - they get snapped up quickly and fetch good money as breakers... whereas a scruffy URS4 or URS6 can be had for little over £1k, providing the engine and gearbox on the cheap once a few bits are sold off, and also likely to have had less abuse.
I'm planning on rebuilding the engine anyway to refresh it, possibly with stronger rods and bottom end balance with a port & polish to make it future proof (depending on budgetary limits)

[S2central.net]

Good idea 404 - try and get a late AAN though - should have stronger (RS2 spec) bottom end bearings and the CMP in the right place.

[20vQC]

Hey mate! well, let's say the NM and the 7A are the same engines but only with a 300cc of difference between one and another. Sensors are the same everywhere. Since I have my AAN running... the use of the main sensors VR sensor and RPM sensor...these last two are located on the fly) are exactly the same, the vems has no problems recognizing if it's the NM's or the AAN's. Place the AAN, with the 7A cams, the distributor (with the 3b rotor tip) is a nice way to go...!!! I wanted to go that way but... somebody convinced me to VEMS the AAN hehe. If you have an ABY donor car, will resolve EVERYTHING! hey if you know of another S2 style front bumper...PM me pleaseeee!!! hehehe For any questions about palcing the rad with the aan's IM... let me know!

[20vQC]

Paul... since which year exist that "late AAN"???? what is the CMP???

[S2central.net]

CMP = Camshaft Position Sensor

When I say 'late AAN' I mean the ones with CMP at the camshaft pulley (like ABY and RS2)... The early AAN has CMP inside dissy housing.
Break point was approx Jan/Feb 1992 - I can't find the engine number for this change - but I have seen the info somewhere

[20vQC]

I haven't understand the difference mate... On my aan, the CMP was behind the cam pulley, the pulley had a housing with a 18mm window that was the signal for the sensor. But the guy who sold me the engine told that was from a 95' UrS4

[spink]

this is what an early AAN has for a cam sensor