Martin said:
If your going to do the V8 conversion you may as go all the way and get a 351W EFI, standard diff will be alright (XF is the same one as in XDs and XEs) T-5 wont be strong enough but a 4 speed single rail would be ok though.
I looked at this before deciding not to go 351 for a number of reasons:
1) engineer said no because 351 perceived power output too high for conversion recommendations - I argued that XD / XE had 351, he said yes, but issue was 351 efi standard power output was much higher than the old smog carbie 5.8's in xd & xe - in other words he said not to attract too much scrutiny, and go the 5.0 - seeing he was doing the conversion, who was I to argue, I wanted it passed.....interestigly enough the roller cam 5.0 HO mustang motor standard power output was line ball with an XD / XE 351anyway, which is why 5.0 was passed.......
2) he said also that if I was serious about displacement, after it was passed, put in a 347 stroker kit and no - one will be the wiser
(wink wink)
3) I know its a small reason, but the thrify1 is one inch wider, about an inch taller and a bit heavier - performance parts are also slightly harder to get than the five o's .
4) go to your newsagents and get 5.0 MUSTANG magazine (american), read about the endless possibilities with the 5.0..........
5) The only difference between 6 and V8 t5's is first gear ratio. Structurally, they are all the same. I have an engineers letter from borg warner confiming this. No argument that T5's are not the worlds strongest boxes, but having 5 overdrive makes up for this, unless you plan on dragging the car everyday....
5 overdrive has allowed me to run 4.11 gears while still getting good top end speed as well. The mods Ive done to the 5.0 give me 220kw, and the 6 t5 originally out of the XF has not complained, even though ive had a few episodes with the enemy (HSV). The 4.11 gears also compensate for the "deficient" first gear ratio in the 6 T5.