<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0cm;
margin-right:0cm;
margin-bottom:0cm;
margin-left:36.0pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
p.ydp3da3111dyiv6692933316msonormal, li.ydp3da3111dyiv6692933316msonormal, div.ydp3da3111dyiv6692933316msonormal
{mso-style-name:ydp3da3111dyiv6692933316msonormal;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.E-MailFormatvorlage20
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;
mso-ligatures:none;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 2.0cm 70.85pt;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:671180042;
mso-list-type:hybrid;
mso-list-template-ids:-994781364 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l0:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level2
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level3
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level4
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level5
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level6
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level7
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level8
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level9
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
ol
{margin-bottom:0cm;}
ul
{margin-bottom:0cm;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>The measurements were made on a rolling road….BUT on the rolling road at the Nurburging.<o:p></o:p></p><p class=MsoNormal>This dyno was in charge to measure the balance of performance power of the race cars under controlled regulations.<o:p></o:p></p><p class=MsoNormal>This dyno was equipped with a custom made software to be most exact. You can say the reference dyno.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Why did we get a little gain?<o:p></o:p></p><p class=MsoNormal>My GUESS - Two things come into play:<o:p></o:p></p><ol style='margin-top:0cm' start=1 type=1><li class=MsoListParagraph style='margin-left:0cm;mso-list:l0 level1 lfo1'>Turbulence – turbulence is good to the point when it gets so strong that it blows the flame out or it pushes against the flame front and hinder it<o:p></o:p></li><li class=MsoListParagraph style='margin-left:0cm;mso-list:l0 level1 lfo1'>Mathematical….assuming that you can make the gap zero between piston and head. The TR’s do have a chamber half the size of the piston surface. If you get the gap down to zero the pressure of the combustion forces on half of the piston deck: Force = pressure x area. If the area is half the size, the force is half as strong. Certainly this is only true on TDC as soon the piston moves downwards the full area of the piston deck comes in to play again.<o:p></o:p></li></ol><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I guess, these little things might make this little gain happen.<o:p></o:p></p><p class=MsoNormal>But, I’m not an engine developer, I only make some thoughts about it…maybe not true and the result is just luck.<o:p></o:p></p><p class=MsoNormal>On the other hand…..my car has many wins with standard crank and standard valve sizes. Does perform quite nice and seem to hold together.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Cheers<o:p></o:p></p><p class=MsoNormal>Chris<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=DE>From:</span></b><span lang=DE> fubog1 <fubog1@aol.com> <br><b>Sent:</b> Friday, January 12, 2024 5:30 PM<br><b>To:</b> Lorne Fritz <lorne.fritz@gmail.com>; tr4racing@googlemail.com; Ken Knight <kknight@klaenv.com><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=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>I'm still burning up (precious) brain cells on this, yes interesting, but that's one of my questions also, exactly how was the reported gain established?<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>I've always gone with the theory that more is better when it comes to turbulence, which requires minimal squish clearance.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>I would imagine that chamber & piston top configuration, ie flat-tops or a lump on top, may be part of the equation as well...<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>Yes compelling discussion!<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>Glen Efinger<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'><o:p> </o:p></span></p></div></div><div id="ydp3da3111dyahoo_quoted_5967812695"><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>On Friday, January 12, 2024 at 10:57:08 AM EST, Ken Knight <<a href="mailto:kknight@klaenv.com">kknight@klaenv.com</a>> wrote: <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p> </o:p></span></p></div><div><div id=ydp3da3111dyiv6692933316><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>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?<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>Ken <o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986" target="_blank">Mail</a> for Windows<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><div id=ydp3da3111dyiv6692933316yqt61391><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:currentcolor currentcolor'><p class=ydp3da3111dyiv6692933316msonormal><b><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>From: </span></b><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><a href="mailto:fot@autox.team.net" target="_blank">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" target="_blank">tr4racing@googlemail.com</a><br><b>Cc: </b><a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>; <a href="mailto:fubog1@aol.com" target="_blank">fubog1</a><br><b>Subject: </b>Re: [Fot] Piston to head clearance<o:p></o:p></span></p></div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>Good point. <o:p></o:p></span></p></div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>On Thu, Jan 11, 2024 at 6:45 PM <<a href="mailto:tr4racing@googlemail.com" target="_blank">tr4racing@googlemail.com</a>> wrote:<o:p></o:p></span></p></div><blockquote style='border:none;border-left:solid windowtext 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt;border-color:currentcolor currentcolor currentcolor rgb(204, 204, 204)'><div><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>That is one thing to consider.<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>When is turbulence supporting and when is turbulence overdone and disturbing.<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>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></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>That’s why we had the best power with 0.047” gap.<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>Cheers<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>Chris<o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><div><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0cm 0cm 0cm;border-color:currentcolor'><p class=ydp3da3111dyiv6692933316msonormal><b><span lang=DE style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'>From:</span></b><span lang=DE style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> 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><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div></div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'>Steve nailed it, both on the ##s, & the importance of it.</span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'>It depends on what rods & crank, piston to wall clearance & what RPM, but for most applications that's right in the ballpark.</span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'>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><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'>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><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'> </span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'>Glen Efinger.</span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div></div></div></div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'> </span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div></div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:#26282A'> </span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div></div><div id="ydp3da3111dyiv6692933316m_986188904719810780ydpeb00682yahoo_quoted_5223032547"><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Arial",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><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#26282A'> </span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#26282A'> </span><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><div><div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Arial",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:"Arial",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><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div></div></div></div></div></div></div></blockquote></div><p class=ydp3da3111dyiv6692933316msonormal style='mso-margin-top-alt:5.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:4.8pt'><span style='font-size:10.0pt;font-family:"Arial",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><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'><o:p></o:p></span></p></div><p class=ydp3da3111dyiv6692933316msonormal><span style='font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282A'> <o:p></o:p></span></p></div></div></div></div></div></div></div></body></html>