Forged pistons

mike kojima
Tue, 5 Aug 2003 16:26:23 -0500

Coatings work and for internal coating Swain's work
the best.  Nissan motorsports used swain's stuff
extensivly on the IRL motors with good results.  Other
brands of coatings didnt work so well.

I use swain stuff on my motors. The trouble that some
people may have is due to them not getting the piston
to wall clearance right, the trick is to set
clearances and machine the block before coating. The
coatings will reduce your clearances 0.001-0.0007 or
so but thats ok. The coating will burnish in quickly
and not cause skuffing or anything.

Swain coating on a high silicon forged piston with
proper clearances will be as quiet as stock even when
stone cold.

I don't particularly like swains white lighting
coating on thin wall tubular headers, it tends to
flake off due to the differing expansion rates between
the coating and the header tube but it works well on
cast or weld-el thickwall turbo manifolds.

Of the thermal barrier coatings it does work the best
though.  I measured only about 350 degrees manifold
surface temp on a turbo motor on the dyno which is
pretty amazing.

The swain gold coat has the third gold color layer
change color which is often mistaken for it coming
off.  It actualy cures in the first few minutes of
engine operation and changes color.

On my turbo Z I used gold coat and closed up my
uncoated forged piston to wall clearances to about
0.0025 and after coating the clearance is about
0.0012-0.0015.  This engine is absolutly silent.