Curious to know how much horsepower a 53-56 frame can hold in its original flex frame style

I would like to do a 4 link in rear and ifs up front so would do some boxing up then but I would like to run it with a engine tranny first for a while before spending that much more money

Engine is a 408W with about 450-500HP

 

I'd say your chances are 50/50 that you'll break something. I have a friend that has a hefty sbc in his 54 w/ stock drivetrain and although he hasn't broken the frame he has busted other suspension parts.

 

How much traction are you going to have and how hard are you going to pound it?

 

Hi have a 51 with a 390PI @ about 400hp. The frame being semi boxed seems to be holding it just fine.

But, I've snapped an aftermarket tube under type motor mount, and beaten the stock spring on the passenger side to death.

If you box the frame from front to cab and have a good set of solid motor mounts built for it that are integrated with your IFS you shouldn't have any problems.

If you get a Mustang II IFS be sure you get at least 425# springs or higher.

Also, be sure, since you won't be using a stock transmission, that when you replace the transmission cross member, you box two feet front and back of that and have a strong new crossmember made.