I can't help you with any specifics on the BFM. There is a guy swapping one into an Audi on Motorgeek.com. It looks like he tested his engine outside the car.
Clipped from his thread:
Here's his build:
4.2l BFM help -- now build thread :: motorgeek.com
He hasn't posted to his thread lately, but he recently uploaded to YouTube. If I were working on a BFM swap, I'd try contacting him thru YouTube or his build thread.
Here's his YouTube:
https://www.youtube.com/channel/UCQs9VViKhACy98rhDoIUP-w
From what I have read, it looks like the BFM will present some challenges, but should be a good engine if you work it out.
That's all I have for you today.
