'94 5.0... are pistons forged or caste?

The hypers are supposed to be better for n/a applications because they don't 'expand' as much as a forged piston.

A buddy of mine was told me that the guy who invented hyper pistons intended them to be for boosted applications... FAIL

hyper-ew-tect-icks

I think that's how you say it. They can say all they want about what they're intended to be used for, but to me they're nothing but a crutch. Even if they're better for an NA engine, what if a year later i wanna run nitrous or a blower? They're not so much better that the high end automakers are using them, nor are the big racing leagues out there. You're not gonna find them in an F1 engine or in Top Fuel, so that to me says forged is best.

From Kevin Cameron, motorcycle guy:

"The piston is the busiest component of an engine. It travels the most distance at the highest speeds & rates of acceleration. It is subjected to the highest temperatures that an engine sees, in the most hostile environment imaginable. It has to transfer the highest pressures of combustion to the crankshaft to deliver the all-mighty "horsepower" to the ground. It has to seal the combustion gasses in the combustion chamber (for which it is the bottom portion of) and keep the oil from the crankcase out of the combustion chamber. It also controls the "squish" band to coerce the gasses to go where we ant them to, and stay out of where we don't.

Stock pistons are generally a cast part that is capable of enduring the environments originally intended by the OEM when designing such a part. In a lot of cases, the part is "over engineered" to be as reliable as possible for a road-going vehicle that has a warranty. This is to the advantage of the engine builder up, but only up to a point. Recently, for example, two of the riders I support had their bone-stock 2005 GSX-R1000s crack the pistons right across the crowns. This was due to Suzuki pushing for maximum performance from a stock part. Under normal street applications, these pistons would probably last the life of the rest of the bike. However, under racing conditions, where the piston is subjected to the maximum designed environment (or over)100% of the time...and the occasional hard downshift...the material fatigued and caused an engine failure.

For this reason, most race engine builders prefer to run a forged piston. Forging is a form of metal reshaping using a die in the rough shape you want and, under extreme pressure (hundreds of tons) forcing the material to take on a new shape. This forms a much tighter grain structure and pattern that ends with a much stronger part for the same given volume of material. In many cases, a forged racing piston can be made lighter at the same time as stronger because of its higher density. Also, forging alloys are usually of much higher quality materials, adding better durability there as well.

Tooling costs to make a forging die are very expensive. You need to stamp out thousands of parts to make your money back on a single tooling die. Therefore, making a die to the net shape is practically unheard of, and what you're left with is piston companies that have bulk forgings for a large variety of pistons that need to be custom machined to suit. But, when you're a small R&D shop such as G-Force, only looking to make 16 to 24 pistons at a time, the selection is very limited. You can either run what has already been produced, you can pay for a tooling die, or you can elect to have the parts 100% CNC machined from billet. This is definitely more expensive than a traditional forged piston because of the design and machine run times. But, it is far cheaper than paying for a tooling die.