I was wondering about how much hp an fd rear can take. I know there are some guys on here who are running around 700-800hp in their cars and was also wondering if they used the stock axles.rear end or did they swap to a ford 8.8/9 rear or the like. Any help appreciated. Thanks!

 

Rears aren't necessarily limited by horsepower. Torque is what hurts the rear.

That said, it also depends on your application. Since you're talking about high horsepower cars, I'll assume you want to drag race. The stock differential has been known to grenade on hard launches at near stock power levels.

If you're road racing or not launching hard, the stock rear should hold a lot of power.

Most high HP guys are running either a Ford Cobra rear or a Kaaz rear.

 

Kaaz 1.5 is the way to go

 

i have seen them blow at 330whp while preloading....with a diff brace