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--></style></head><body lang=EN-US link=blue vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>Interesting discussion and I would agree on point. What would interesting to know is how the HP change was measured; chassis dyno or engine dyno?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Ken </p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">Mail</a> for Windows</p><p class=MsoNormal><o:p> </o:p></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:fot@autox.team.net">Lorne Fritz via Fot</a><br><b>Sent: </b>Friday, January 12, 2024 7:13 AM<br><b>To: </b><a href="mailto:tr4racing@googlemail.com">tr4racing@googlemail.com</a><br><b>Cc: </b><a href="mailto:fot@autox.team.net">fot@autox.team.net</a>; <a href="mailto:fubog1@aol.com">fubog1</a><br><b>Subject: </b>Re: [Fot] Piston to head clearance</p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Good point. </p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Thu, Jan 11, 2024 at 6:45 PM <<a href="mailto:tr4racing@googlemail.com">tr4racing@googlemail.com</a>> wrote:</p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>That is one thing to consider.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>When is turbulence supporting and when is turbulence overdone and disturbing.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>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.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>That’s why we had the best power with 0.047” gap.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Cheers</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Chris</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><div><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0in 0in 0in;border-color:currentcolor currentcolor'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span lang=DE>From:</span></b><span lang=DE> Fot <<a href="mailto:fot-bounces@autox.team.net" target="_blank">fot-bounces@autox.team.net</a>> <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 <<a href="mailto:lorne.fritz@gmail.com" target="_blank">lorne.fritz@gmail.com</a>>; Steven Belfer <<a href="mailto:steve@artwithcars.com" target="_blank">steve@artwithcars.com</a>><br><b>Cc:</b> <a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a><br><b>Subject:</b> Re: [Fot] Piston to head clearance</span></p></div></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>Steve nailed it, both on the ##s, & the importance of it.</span></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>It depends on what rods & crank, piston to wall clearance & what RPM, but for most applications that's right in the ballpark.</span></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='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</span></p></div><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='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 & head to maximize the squish effect, which creates turbulence, which assists in good combustion...</span></p></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:12.0pt;font-family:"Arial",sans-serif'> </span></p></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>Glen Efinger.</span></p></div></div></div></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:12.0pt;font-family:"Arial",sans-serif'> </span></p></div></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:12.0pt;font-family:"Arial",sans-serif'> </span></p></div></div><div id="m_986188904719810780ydpeb00682yahoo_quoted_5223032547"><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>On Thursday, January 11, 2024 at 01:00:50 PM EST, Steven Belfer via Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>> wrote: </span></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> </span></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> </span></p></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>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’ve been running .032 and it’s working out great<br>~Steve<br><br><br>> On Jan 11, 2024, at 9:13 AM, Lorne Fritz via Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>> wrote:<br>> <br>> </span><span style='font-size:10.0pt;font-family:"Tahoma",sans-serif;color:#26282A'></span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><br>> 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<br>> _______________________________________________<br>> <a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a><br>> <br>> <a href="http://www.fot-racing.com" target="_blank">http://www.fot-racing.com</a><br>> <br>> Donate: <a href="http://www.team.net/donate.html" target="_blank">http://www.team.net/donate.html</a><br>> Archive: <a href="http://autox.team.net/archive" target="_blank">http://autox.team.net/archive</a> <a href="http://www.team.net/pipermail/fot" target="_blank">http://www.team.net/pipermail/fot</a><br>> Unsubscribe/Manage: <a href="http://autox.team.net/mailman/options/fot/steve@artwithcars.com" target="_blank">http://autox.team.net/mailman/options/fot/steve@artwithcars.com</a></span></p></div></div></div></div></div></div></div></blockquote></div><p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt;margin-left:4.8pt'><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><br>> <br>> <br>_______________________________________________<br><a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a><br><br><a href="http://www.fot-racing.com" target="_blank">http://www.fot-racing.com</a><br><br>Donate: <a href="http://www.team.net/donate.html" target="_blank">http://www.team.net/donate.html</a><br>Archive: <a href="http://autox.team.net/archive" target="_blank">http://autox.team.net/archive</a> <a href="http://www.team.net/pipermail/fot" target="_blank">http://www.team.net/pipermail/fot</a><br>Unsubscribe/Manage: <a href="http://autox.team.net/mailman/options/fot/fubog1@aol.com" target="_blank">http://autox.team.net/mailman/options/fot/fubog1@aol.com</a></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>