do stock 5.0's have forged pistons or not?

notch88

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Oct 3, 2005
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ok ive always been told and read that certain years of the 5.0's such as like 89-92 came with stock trw forged pistons out of the factory now is this true or not i just bought a bone stock 91 gt roller motor im fixing to put in my 90 notch and i thought it would have the trw forged pistons outta the factory but my buddy was telling me none of the 5.0's had stock forged pistons he says they were all hyperetic ??
can someone fill me in the truth im kinda confused here.
thanks,
Tyler
 
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Starting in late '92 is when the switch to hypereutectic pistons was reportedly made. Before that, aero foxes had forged slugs.

The old quick and dirty visual test is if the motor has the original and unmolested oil pan, if it is grey in color, that suggests forged slugs. If the pan is black, that suggests hypers.



Good luck.
 
notch88 said:
ok ive always been told and read that certain years of the 5.0's such as like 89-92 came with stock trw forged pistons out of the factory now is this true or not i just bought a bone stock 91 gt roller motor im fixing to put in my 90 notch and i thought it would have the trw forged pistons outta the factory but my buddy was telling me none of the 5.0's had stock forged pistons he says they were all hyperetic ??
can someone fill me in the truth im kinda confused here.
thanks,
Tyler


i think only 88's came with forged, all the others are hyperetic
 
notch88 said:
so my motor would have the forged pistons then right?

If the motor is a 91`5.0L,GT motor the pistons are forged.The only way they wouldn`t be is if someone maybe rebuilt the motor somewhere along the line and threw in cast pistons,or if someone pulled a scam and sold you a 5.0L base engine with a 5.0L HO intake bolted on it.:shrug:.
Did you see the car it came out of?
If it`s an original 91`5.0L,GT motor the pistons are forged.

The engine ID decal is probably long gone.
 
No motor with over 250 ft/lbs. of torque can have forged pistons. Becuase of the ludacris amount of pressures exerted by the 5.0L motors, you can actually squeeze out the piston fluid (aluminum oxide) from the tops of the pistons. This fluid then causes the air / fuel mixture to lean out and utimately leads to blown motors. Again, this is when you use forged pistons on the 5.0L's. The best way around this is to use the stronger (but more brittle) Hyperutectic pistons that are cheaper and easier to produce. Since they are more brittle there is no piston fluid that can be extracted during hard acceleration runs in the Mustang which means that you won't blow up your car.... Of course if you believe this, than I am going back to Hawaii!

www.mustanggt.org will tell you everything you need to know.
 
HISSIN50 said:
Starting in late '92 is when the switch to hypereutectic pistons was reportedly made. Before that, aero foxes had forged slugs.

The old quick and dirty visual test is if the motor has the original and unmolested oil pan, if it is grey in color, that suggests forged slugs. If the pan is black, that suggests hypers.



Good luck.
times 2
 
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ditto,the reason that ford went to the hypers in 93 was because of complaints of piston slap,the blocks were also
made with an unusually high nickel content which was supposed to reduce bore wear and taper.
 
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frcefedlx said:
My 93 has a gray oil pan(It was built in September of 92)

HISSIN is right on with what he said, the color of the pan is not completely foolproof, but is a general rule of thumb. You could have a freak of nature 93 that used an engine that came out of back stock or if you are not the original owner the engine may have been swapped out before you got it. Hot Rod Magazine has a good article where they had a 5.0 on the dyno and it had those weak Hypers in it and the piston shattered like glass, the were pieces of it everywhere!
 
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I believe the reason Ford went to Hyper. pistons was because the Hyper. pistons have a higher Silicon content and do not expand/contract as much as Forged Pistons. thus allowing for tighter ring tollerances and less blowby.

But you get the drawback... They suck.
 
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onefstsnake said:
I believe the reason Ford went to Hyper. pistons was because the Hyper. pistons have a higher Silicon content and do not expand/contract as much as Forged Pistons. thus allowing for tighter ring tollerances and less blowby.

But you get the drawback... They suck.

Plus with any Company they are looking to cut costs at any possible time. Hypers are dirt Cheap, Forged are expensive, the been counters see dollar signs and say put the cheapest thing in the engine you can find.
 
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onefstsnake said:
I believe the reason Ford went to Hyper. pistons was because the Hyper. pistons have a higher Silicon content and do not expand/contract as much as Forged Pistons. thus allowing for tighter ring tollerances and less blowby.

But you get the drawback... They suck.

In the Hot Rod Article they said another one of the downsides of the Hypers is if the bore tolerance is too tight the piston will just stick and the connecting Rod will just rip the bottom of the piston right off.
 
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Shakerhood said:
In the Hot Rod Article they said another one of the downsides of the Hypers is if the bore tolerance is too tight the piston will just stick and the connecting Rod will just rip the bottom of the piston right off.

Lovely. :rolleyes:

Cant wait to build a new motor... Maybe in a few years.