[AMC-list] 360 pistons

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

>I know a lot of you are looking for?cheap alternatives for 360s but one
thing to keep in mind is to build the low end torque most are looking for
out?of a 360, you need higher cylinder pressure.? The cheaper style cast or
>even hypereutectic pistons (hypereutectic pistons are just a?cast piston
with?a higher silicone content) are?them?vulnerable to breaking under these
conditions.? Now if?are looking for a low compression pistons?and a >cam
that?has doesn't create a of? pressure, you are ok but you are also not
going?to get a lot of power?out of it either.? There?are pistons out there
for?most of the AMC?Gen II and III engines in both cast and forged.? >Not
sure why there is a such a big fuss for a piston that is only slightly
better than a stock cast piston.? I am not saying?we shouldn't try to get
these, just that I don't see the huge need.? There are already a few brands
of >cast?pistons for the 360.? I?make?forged pistons for

>them so really both performance areas are fairly well covered.??

 

I'll have to disagree with ya on this one Nick. First there are different
"grades" of hyper pistons. You are right that hyper pistons are cast pistons
and as such are susceptible to the same limitations that stock cast are,
mostly RPM, HOWEVER they ARE better in several regards. First (and most
important IMHO) is the resistance to skirt galling. There are quite a few OE
Manuf that use Hyper pistons as an upgrade for their turbo motors so
(properly designed and used) they WILL stand up to heavy duty usage. 

I used to do a lot of circle track 2.6 Mitsubishi motors. These things have
a long stroke and are pretty hard on piston skirts, when I would disassemble
them for a "freshen up" the skirts looked pretty bad. One thing I noticed
was the Turbo version of these engines used a Hyper piston and the skirts
had VERY little wear. I couldn't use the turbo version in the circle track
motors because of the deep dish.

I found a manufacturer (now long gone unfortunately) who was making a Hyper
version of the piston which only had a very small dish which allowed use of
the early small chamber head without jacking the compression way up. I could
cut the top of the piston flat removing the dish and lightening the piston
as well. This proved to be the answer and we never had any piston "scuffing"
problems again.

It also makes the ring lands harder which helps prolong ring life. 

Adding Hyper alloy to a piston normally doesn't add a lot to the price.
Nowhere NEAR what forged one's cost.

Then you have the KB line. These are heat treated which does add to their
strength but also adds to the cost. I have used KB pistons with good success
in Toyota and Chebbys as long as they are operated within their limits. I
have even used them in race motors turning 6800 and not had any problems.

As long as you're turning LESS than 6,000 RPM (and most street AMC motors
especially with a hydraulic cam will not see more than 5800) you're BETTER
off with a hyper piston in a NON-POWER ADDED (nitrous or blown) engine!!

The reason for the "big fuss" is COST!!!!

A Hyper piston should come in at about HALF of what your forged pistons are
and would be a great alternate for motors built for the street.

Right now there is NO in between choice from cast stock to forged. That's a
BIG jump for most street engines. If Hypers could come in at $350 that would
save enough to cover the cost of a cam kit. 

 

As to WHY Silvolite refuses to offer them (even after TELLING me they might)
I don't know. That fellow TOLD me they would NOT have to make a new mold
(that was their excuse last year) and that "it doesn't look like it would
take much to make them" face to face. How can you possibly gauge sales on an
item you aren't making or even promoting??

I wish to hell I could come up with a piston company that would LISTEN to
their customers' requests instead of DICTATING to them. Far cry from the old
days when a rep would visit your shop every couple of months just to see how
things were going and to get feedback, and when you could CALL them and
actually get to TALK to an engineer.

Rant off,,,,,,

But HEY,,, that's just ME!!

Bruce Hevner 

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