CorvAircraft> How can you tell the difference between cast andforged pistons?

[Clare Snyder]

Forged pistons are more dense, so if the design was the same the forged
would be heavier. However, forging allows a much more accurate form, so less
material CAN be used.

Generally speaking, the Hyper Eutectic pistons are usually the lightest
because the material is lighter than forged (very marginally) and the
manufacturing process is closer to forging in accuracy than normal cast
pistons.

I'm not saying the H.E. piston is the way to go, but many performance engine
builders do prefer them to forged pistons. 

> -----Original Message-----
> From: corvaircraft-bounces at mylist.net 
> [mailto:corvaircraft-bounces at mylist.net] On Behalf Of Daniel Weseman
> Sent: Wednesday, January 09, 2008 8:56 PM
> To: Corvair engines for homebuilt aircraft
> Subject: Re: CorvAircraft> How can you tell the difference 
> between cast andforged pistons?
> 
> Forged piston are somtimes  lighter since they are stronger?
> 
> Michael Amick <mkamick at bellsouth.net> wrote:  I assume (I 
> know I know ass u me) there should be a weight gain with the 
> Forged above the cast.
> My forged .60 overbores are 19.4 onces w/ pins each.
> 
> Michael Amick
> Nashville
> 
> 
> 
> Keith Rhea wrote:
> > I bought a converted 95 hp engine that had flown on a Piet for 200 
> > hours, was overhauled flew 8 more hours, lost RPM and 
> landed in a corn 
> > field. I bought the engine all torn down and all the parts, prop 
> > included. I have checked the crank and cyls and they are 
> standard. My 
> > problem is i can't determine if the pistons are cast or 
> forged. They 
> > an "F" beside the wrist pin and inside the piston is a "C" 
> with an n 
> > inside of it. I see what would be die marks for casting. 
> Then when i 
> > read about Clarks forged description and they state on page 22 that 
> > their sealed power forged pistons look like they have 
> casting marks on 
> > them. Other than the 601 cowl and spinner, I have 
> everything to make a 
> > flight worthy engine. And that won't be too far off. Maybe another 
> > month or so. Can anyone tell me for sure what these pistons are? I 
> > would hate to order a set from Clarks and find that's what 
> i already 
> > had.
> >
> > Thanks
> >
> >
> > Keith Rhea
> > N52VP
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