Forged pistons, silicon content and sidewall clearance

[Rick Frey]

At 08:21 AM 8/5/2003 -0500, Tait Parkin wrote:
>For my part I have run forged pistons in two different SR20s.  The first was
>an ill prepped, poorly build USDM SR20DE.  In this case the builder went
>with forged pistons from Probe and ran very loose piston-to-wall clearences,
>like ~6 thousands (if memory serves).  The engine rattled like a tine can
>until warm.  My latest engine was built by Sunbelt, who also used forged
>pistons, and the engine does not rattle at all, no rattling.  To date I have
>not gotten the build sheet, LOL, but I trust they knew what they were doing.
>I could probably get some info if anyone is interested, assuming I can get
>Jim on the phone.

I'd love to hear what piston to wall clearances are required to prevent
rattle and hear how close to the disaster side of that clearance limit
you're running at.

Were there any 'hi tech' coatings applied to the pistons in your sunbelt
engine?

If  your first engine rattle until warm, I assume there was significant
expansion of the piston.  The second set of pistons must be expanding a
similar amount.

TIA,

rick frey