forged or hyper (anyone tell by the way they look?)

[Flaming87lx]

I just took the heads off my car and I wonder how you can tell the difference between a cast or forged piston. I cleaned the top of the piston off and no numbers or letters on it. I can see what looks to be machine marks on top of the piston (you know how when you cut something on a lathe, the circular lines it leaves). I googled flat top ford pistons and they look exactly like the KB w/2valve relief and the SRP w/2 valve relief. I've never compared a cast and a forged piston side by side and looked closely to the finishes. I can take some pics if that helps. I don't want to take the pistons out to see, as I'm just changing heads and intake right now. I would like to know for future reference in case I spray it. Thanks Troy

[PaulFiveOh]

Is it a 302?

If so, what year is the engine originally?

[Rick93coupe]

You can use hyper pistons if thats what they are, they're just not as forgiving. Keep a safe tune in it and let it fly.

[Flaming87lx]

It's a 302, I don't know the year. The motor is a non roller, but has the HO firing order, so apparently it has a cam for a windsor in it. The pistons are definetly aftermarket. I was told the motor was a 306 originally built from a 82 gt motor.

[Rich]

Generally, you can look at the underside of the piston. A cast piston will have casting flash lines and forged piston will look smooth.

[Flaming87lx]

Thanks Rich. Do you know if a cast piston is machined on top. The top of these pistons looks like they have been machined (the reliefs and the whole top area). I don't have anyway to look at the bottoms right now. Thanks again

[Rich]

Even cast pistons are machined, so looking at the top won't tell you much. I have two short blocks in the garage(one forged, one hyper), I will try and take a pic of the underside of them and see if it can point out the difference.