• Hello there guest and Welcome to Fox Body Mustangs forum, This forum is intended to be used by enthusiasts of the Fox body Ford Mustangs (1979-1993)!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Explorer 5.0 question


New Member
Okay so I have an explorer 5.0 with the GT40P heads. My plan was to pop the heads off and swap them over to a fox body 5.0. I got the gt40 heads off and noticed that they're valve reliefs on the pistons. Was this common on the explorer engines? I remember reading somewhere that the explorer/mountaineer 5.0s didn't have them. I also read that the pistons aren't good for boosted applications. I'm wondering now because this explorer 5.0 only has about 60k miles on it. If it turns out it has the forged pistons, I'd want to toss the heads back on and run it.


New Member
My '99 Explorer 5.0 had 4 valve relief Hyperuetetic pistons. You don't haven factory forged pistons in that motor. I'd replace with forged units if you're going to use boost or nitrous, which is what I'm doing.