not on an 86, you will need to flycut the pistons as 86's had no valve reliefs

 

i am pretty sure that they only used the e6 heads in 86.

 

no the whole e6 engine was used after 86 and the 87-92 mustangs are rated higher but are the same engine and are rated differenlty

 

when people say e6 engine they usualy refer to the heads though.. not the whole engine.. the 86 was the only year for the e6 heads.. after that you got e7 heads.. not much better then the e6's.. but still better... and the 86 engine also had flat top pistons wich make it really difficult to swap heads or the cam on without doing modifacations to the pistons by fly cutting them.

 

e6 is just the casting number of the heads but is used to describe the engine, the e6 motors are used in the non ho versions of the 5.0 after 86 and have different heads, pistons, cam, intake was slightly different between e6 and e7 motors as well as the e6 throttle bodies are 58mm while the e7 is 60mm