Re: piston choice

["James J." <m1garand@speakeasy.net>]

Craig,
   I have found that Hypereutectic pistons are quite cheap, if it is 
not a custom order.  They give you that extra bit of strength, and they 
don't expand, contract, and rock like forged ones do while they heat 
up.  Think of how long many cars go with their original cast OEM 
pistons.  10 years or more.  Usualy the piston is not what fails.  Most 
cars are sold long before the internal components suffer irreperable 
damage.  Usualy it is a bearing problem, and often that is to a gummed 
up oil system, not just material failure.  Also, we are putting these 
engines in cars that are only 60% of the weight of the OEM cars.  Take 
the T-5 transmission, for example.  It is rated for an engine producing 
no more than ~300 Ft-lbs (depending on the year).  But that rating is 
based on a 3600lb car.  They actualy can handle much more torque in a 
2100 lb car.
   So stock pistons are actualy a safe bet in our little cars, and 
hypereutectic ones are great insurance, and can handle mild boost or 
nitrous (key word: mild)  Forged are the strongest, cost twice as much, 
and will cost you torque on short drives because of all the blow-by 
before the piston fully expands (although some new alloys have a much 
lower Coefficient of Thermal Expansion).
   I'm using the Ford 255 pistons (+0.030) in my Rover 3.9 stroked 
engine, as per the LaGrou recipe.   I only bought cast ones because no 
one makes a stock hypereutectic replacment that isn't a custom order 
(key word: expensive).  But all the ones I've seen for Ford 302/351 and 
SBC Chevy are very reasonably priced.
Best of Luck.
JJJ


CraigFaubel@aol.com wrote:

>  I will be tearing down my (still unused) 302 again for rebalancing, and 
> while it's apart, I'm questioning my early choice of cast aluminum pistons.  The 
> car will see only a rare trip to a dragstrip just to see a timeslip, but it 
> seems like asking for trouble with the cheap pistons.  What thoughts or 
> predudices are out there regarding cast vs hypereutectic vs forged?
>  The +0.040" engine has Edelbrock RPM heads and cam, alum intake with Holley 
> 600 cfm, lots of port matching, block work, balancing (twice), align boring, 
> etc., etc.,T5, and low numeric ratio rear end.
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