Cheers zetec, must be doing something right if a fordster approves!
Marc, it's a "fairly" simple operation mechanically, there are very few custom parts needed, most of it is off the shelf vag stuff. Quick run down
The engine mounts on the new and old engines bolt on and are in the same location so mounts off the mk2 engine will bolt to the 20v engine, engine then drops into the bay in the same place as original.
Clutch and flywheel have been replaced for a single mass item. Standard golf g60 parts have been used.
Gearbox is an o2a from a vr6 mk3 golf gti. Sadly these are cable shift and hydraulic clutch. The same vr6 donated its cable shift set up ( tiny but of fabrication needed). I converted the box to cable clutch using seat Ibiza parts.
Drive drive shafts - 2 main options but shaft choice affects hub and therefore brake choice . Standard mk2 golf items fit but then you have to try and find a big brake kit to suite. I opted to run mk3 vr6 brakes allowing me to use vr6 hubs and shafts too. These are slightly longer than mk2 so I also needed to use vr6 bottom arms and anti roll bar but these are direct fit to the mk2 ( when combined with the other vr6 parts fitted).
Only issue we encountered is the wider track meant the mk2 track rods were too short. Mk3 ones were needed but they don't fit mk2 rack. I could have fitted mk3 rack but they are pas and I really want this car to still feel like a mk2 so that was out of the question. We tried loads of stuff and were about to custom make (cut and shut) but a mate just happened to have a mk 3 and mk4 track rod end in his garage. Mk4 are identical to mk3 but about 20mm longer, which is absolutely perfect. Problem solved.
Rear brakes were simply a case of swapping the discs to vr6 items to get 5 stud all round.
So in terms of where the wheels sit, they are about an inch further out than before but that was from my choice of fitting the mk3 parts rather than directly because of the engine I used.
Exhaust and intercooler were custom items but luckily I just happened to be on eBay as someone was breaking a mk2 with the same conversion so picked them up cheaply.
This particular engine has the fly by wire accelerator pedal so we needed to fabricate a mount for that.
The standard master cylinder is mm's away from the cam belt cover, plus they are a bit weedy so we have fitted a seat Ibiza Cupra item. It's much shorter but fatter so works much better and gives enough clearance. On he subject we had to move the battery a bit and shift the header tank to the opposite side of the engine bay.
The wiring was a challenge. There is a golf legend known on the Internet as rubjonny , he knows pretty much everything and was worth his weight in gold. He has online instructions showing how to splice various looms into various fuze boxes. It's last literally a case of "take the orange plug and the white plug, this goes there, that goes there and bin the rest" there were however a few errors which took a while to sort through.
Ecu is the standard one for the engine. The immobiliser is linked to the original key and also the clocks from the donor key. Most people fit the mk4 clocks and sometimes the whole dash but this toe would ruin the car. I had my mate Gareth at http://www.map-tech.co.uk
remove the immobiliser . It was also he who did the wiring. Once the car is back on the road he will be custom mapping it to suite the mods.
I think that covers it. Only custom parts were the pedal mount, a bit of faffing for the gear lever, intercooler, exhaust and the wiring. Not too bad really.
As a side note this was a budget conversion. The idea was to do the conversion for £1000. I stopped counting at 1600 lol