Hi All,
Keith Said:
" The edges of the pistons are going to have Huge quanity's of material...
so
I just don't think that's a factor... Having the wrong compression ration
on the other hand can be ugly..."
I totally agree.
Pison Crown thickness is different to piston shoulder (outside diameter)
thickness on a dished piston.
i.e. a picture paints a thousand words - so here is an attempt at an asci
art example of a dished piston...
____ ____
l \ / l
l \_________________________/ l
l l
l l
^
l _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ l crown thickness ^
l l
l l
=============================== top ring
l l
i.e on a dished piston, - "machining the top of the piston" - actually means
"machining the outside 'shoulder' of the piston - as Keith rightly said -
and it only affects the compression ratio and piston/ head clearance. It
generally has NO effect on piston strength
I just checked the depth of the dish in an old piston from a 100/4 engine in
the garage - with a RULER - it was nearly 3/8in deep (.375 in) ..... so
machining the shoulder by .030 will not affect the strength of the
piston..... Check you own pistons more scientifically before
proceeding......
It is clearly different on a flat top piston, where machining the piston
crown = changing the thickness of the piston crown = reducing the strength
of the crown of the piston itself
Hope this helps..
Chris
----- Original Message -----
From: "Keith Turk" <kturk@ala.net>
To: "Dave & Marlene" <rusd@velocitus.net>; "Roland Wilhelmy"
<rwil@sbcglobal.net>
Cc: <healeys@autox.team.net>
Sent: Monday, June 14, 2004 10:04 AM
Subject: Re: how much can you take off the top of a piston?
> Dave... I really liked your .055 piston to head clearance as a minimum
> number...
>
> and I agree on your minimum thickness... thou I wouldn't change anything
if
> it had more... I like around 200 on a forged piston as well.... ( keep in
> mind that I do brutal things to pistons )
>
> I think the real key to this equation is to come up with the compression
> ratio of choice and work backwards from there...
>
> The edges of the pistons are going to have Huge quanity's of material...
so
> I just don't think that's a factor... Having the wrong compression ration
> on the other hand can be ugly...
>
> Keith Turk
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