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Re: [Fot] Piston to head clearance

To: "'fubog1'" <fubog1@aol.com>, "'Lorne Fritz'" <lorne.fritz@gmail.com>, "'Steven Belfer'" <steve@artwithcars.com>
Subject: Re: [Fot] Piston to head clearance
From: Chris Marx via Fot <fot@autox.team.net>
Date: Fri, 12 Jan 2024 00:45:52 +0100
Cc: fot@autox.team.net
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <CAH7tdL-g4s_GaDi2fX_gzfy2_wEY=+2LPYuB_ER2OQ9iKLCzaA@mail.gmail.com> <1E67C861-5F29-47D4-A2F1-C8AC3A6B9462@artwithcars.com> <1581877613.388538.1704999660473@mail.yahoo.com>
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That is one thing to consider.

When is turbulence supporting and when is turbulence overdone and =
disturbing.

=20

I could imagine to force too much turbulence with a very small squish =
gap the flame front expansion is compromised, thus slows down, and =
lowers the hp output.

That=E2=80=99s why we had the best power with 0.047=E2=80=9D gap.

=20

Cheers

Chris

=20

=20

From: Fot <fot-bounces@autox.team.net> On Behalf Of fubog1 via Fot
Sent: Thursday, January 11, 2024 8:01 PM
To: Lorne Fritz <lorne.fritz@gmail.com>; Steven Belfer =
<steve@artwithcars.com>
Cc: fot@autox.team.net
Subject: Re: [Fot] Piston to head clearance

=20

Steve nailed it, both on the ##s, & the importance of it.

It depends on what rods & crank, piston to wall clearance & what RPM, =
but for most applications that's right in the ballpark.

I've run as little as oops not enough ie .025 or less, .028 minimum (you =
won't get any carbon deposit on the squish area), but to play it safe =
nowadays I use .030-.032

Also on these engines it's not only a CR related issue, the squish is =
very critical, you want to minimize the clearance between piston top & =
head to maximize the squish effect, which creates turbulence, which =
assists in good combustion...

=20

Glen Efinger.

=20

=20

On Thursday, January 11, 2024 at 01:00:50 PM EST, Steven Belfer via Fot =

=20

=20

You want as little as necessary because this is where your high CR comes =
from.  The thickness of the head gasket is the major part of P to H =
clearance.  I ran .026 P to H clearance at Cal Speedway and the piston =
kissed the head and I spun a bearing.  My machine shop guy likes .040 =
for safety but I=E2=80=99ve been running .032 and it=E2=80=99s working =
out great
~Steve


> On Jan 11, 2024, at 9:13=E2=80=AFAM, Lorne Fritz via Fot =
>=20
> =EF=BB=BF
> Hi.  In the past I have had pistons hit the head and leave a =
mark(TR3/4).  What piston to head clearance are most of you running? =
Thanks in advance,  Lorne
> _______________________________________________
>=20
> http://www.fot-racing.com
>=20
> Donate: http://www.team.net/donate.html
> Archive: http://autox.team.net/archive =
http://www.team.net/pipermail/fot
> Unsubscribe/Manage: =
http://autox.team.net/mailman/options/fot/steve@artwithcars.com


>=20
>=20
_______________________________________________

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vlink=3Dpurple style=3D'word-wrap:break-word'><div =
class=3DWordSection1><p class=3DMsoNormal>That is one thing to =
consider.<o:p></o:p></p><p class=3DMsoNormal>When is turbulence =
supporting and when is turbulence overdone and =
disturbing.<o:p></o:p></p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><p =
class=3DMsoNormal>I could imagine to force too much turbulence with a =
very small squish gap the flame front expansion is compromised, thus =
slows down, and lowers the hp output.<o:p></o:p></p><p =
class=3DMsoNormal>That=E2=80=99s why we had the best power with =
0.047=E2=80=9D gap.<o:p></o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p =
class=3DMsoNormal>Cheers<o:p></o:p></p><p =
class=3DMsoNormal>Chris<o:p></o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><div><div =
style=3D'border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm =
0cm 0cm'><p class=3DMsoNormal><b><span lang=3DDE>From:</span></b><span =
lang=3DDE> Fot &lt;fot-bounces@autox.team.net&gt; <b>On Behalf Of =
</b>fubog1 via Fot<br><b>Sent:</b> Thursday, January 11, 2024 8:01 =
PM<br><b>To:</b> Lorne Fritz &lt;lorne.fritz@gmail.com&gt;; Steven =
Belfer &lt;steve@artwithcars.com&gt;<br><b>Cc:</b> =
fot@autox.team.net<br><b>Subject:</b> Re: [Fot] Piston to head =
clearance<o:p></o:p></span></p></div></div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><div><div><p =
class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'>Steve nailed =
it, both on the ##s, &amp; the importance of =
it.<o:p></o:p></span></p></div><div><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'>It depends on =
what rods &amp; crank, piston to wall clearance &amp; what RPM, but for =
most applications that's right in the =
ballpark.<o:p></o:p></span></p></div><div><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'>I've run as =
little as oops not enough ie .025 or less, .028 minimum (you won't get =
any carbon deposit on the squish area), but to play it safe nowadays I =
use .030-.032<o:p></o:p></span></p></div><div><div><div><p =
class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'>Also on these =
engines it's not only a CR related issue, the squish is very critical, =
you want to minimize the clearance between piston top &amp; head to =
maximize the squish effect, which creates turbulence, which assists in =
good combustion...<o:p></o:p></span></p></div><div><div><p =
class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'><o:p>&nbsp;</o:=
p></span></p></div><div><div><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'>Glen =
Efinger.<o:p></o:p></span></p></div></div></div></div><div><p =
class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'><o:p>&nbsp;</o:=
p></span></p></div></div><div><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Arial",sans-serif'><o:p>&nbsp;</o:=
p></span></p></div></div><div =
id=3D"ydpeb00682yahoo_quoted_5223032547"><div><div><p =
class=3DMsoNormal><span =
style=3D'font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282=
A'>On Thursday, January 11, 2024 at 01:00:50 PM EST, Steven Belfer via =
Fot &lt;<a href=3D"mailto:fot@autox.team.net";>fot@autox.team.net</a>&gt; =
wrote: <o:p></o:p></span></p></div><div><p class=3DMsoNormal><span =
style=3D'font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282=
A'><o:p>&nbsp;</o:p></span></p></div><div><p class=3DMsoNormal><span =
style=3D'font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282=
A'><o:p>&nbsp;</o:p></span></p></div><div><div><p =
class=3DMsoNormal><span =
style=3D'font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282=
A'>You want as little as necessary because this is where your high CR =
comes from.&nbsp; The thickness of the head gasket is the major part of =
P to H clearance.&nbsp; I ran .026 P to H clearance at Cal Speedway and =
the piston kissed the head and I spun a bearing.&nbsp; My machine shop =
guy likes .040 for safety but I=E2=80=99ve been running .032 and =
it=E2=80=99s working out great<br>~Steve<br><br><br>&gt; On Jan 11, =
2024, at 9:13=E2=80=AFAM, Lorne Fritz via Fot &lt;<a =
href=3D"mailto:fot@autox.team.net"; =
target=3D"_blank">fot@autox.team.net</a>&gt; wrote:<br>&gt; <br>&gt; =
</span><span =
style=3D'font-size:10.0pt;font-family:"Tahoma",sans-serif;color:#26282A'>=
=EF=BB=BF</span><span =
style=3D'font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282=
A'><br>&gt; Hi.&nbsp; In the past I have had pistons hit the head and =
leave a mark(TR3/4).&nbsp; What piston to head clearance are most of you =
running? Thanks in advance,&nbsp; Lorne<br>&gt; =
_______________________________________________<br>&gt; <a =
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