Don't forget and i'm not knocking you, it may sound simple but theres lots of little things to consider such as:
1. Where to put the radiator, can't be at the front as the water pipes would be 5" long the water pump could not cope
2. Engine loom how are you going to wire this into the cinq loom ?
3. Wheres the fuel tank/fuel lines going to go
4. Considered strengthening the chassis?? A massive V6 with all that power and weight might bend/ripple the chassis due to the rear floor section being cut out to house the engine
5. Rear suspension would need to be the front alfa struts to mount to the driveshafts, you would need to fabricate some turrets to mount the struts to the back of the cinq
6. Rear brake lines
7. Rear driveshafts from gearbox, they would need to be profesionally shortened/new ones manufactured, you can't cut them and weld them back up they would snap
8. Exhaust system, you would need to fabricate a custom exhaust system that provides enough backpressure, no backpressure on a NA car is bad news
9. Extend the original or have a bespoke gearlever made up
10. The alfa is rear wheel drive?!? How would you connect the rear wheels to the gearbox, if your thinking of using the original gearbox and connecting it to the reardiff with a shortened propshaft the engine would need to be where the driver sits leaving you on the bonnet!!!
I seriously considered doing a rear bike engine conversion on a cinq when i had my Sei and i saw one at the Autosport show last year with a bike engine in the back but i found out it would cost £££££££££££££'s, the autograss Sei was basically a spaceframe inside with the Sei shell bolted ontop.
You may of heard of Z Cars ??
They have created single and twin R1 engined minis this i've heard costs around £5000 to do, not cheap!!
If you do this it would be truly awesome but it would be a lenghtly and costly project.
Good luck to you
Did have a very modded Sei then a Impreza RB5, Err and now got a Honda Civic Type-R
