<div style="font-size:10pt;font-family:arial,helvetica,sans-serif;color:black;"><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;" data-mce-style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;">If it helps, please find attached an Excel spreadsheet that calculates both the current compression ratio as well as the head volume needed to get the compression ratio you want.  Just put the dimensions in the yellow highlighted cells.  If running a pop up piston, you will need to determine the volume of the pup up above the normal piston crown surface.  The spreadsheet as attached has dimensions for a slightly modified TR4 with flat top pistons.  I hope this is self explanatory.</div><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;" data-mce-style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;"><br></div><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;" data-mce-style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;">Regards,</div><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;" data-mce-style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;"><br></div><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;" data-mce-style="font-family: arial,helvetica,sans-serif; font-size: 10pt; color: black;">Phil Gott<br><br><br>-----Original Message-----<br>From: Chuck Gee via Fot <fot@autox.team.net><br>To: Bob Bownes -Seiri <bownes@seiri.com><br>Cc: 'Friends of Triumph' Triumph <fot@autox.team.net><br>Sent: Mon, Dec 6, 2021 10:51 pm<br>Subject: Re: [Fot] Compression<br><br></div><div id="yiv0152095042"><div>Yes they will, but that isn’t really the problem.  The extra stroke of the TR6 motor makes building compression easy.  The 2L motor is a little more challenging because of the shorter stroke.  You just can’t shave enough off the head to get really high compression without getting into the water passages.  Pop ups are necessary to maximize compression.<br clear="none"><br clear="none"><div dir="ltr">Chuck</div><div dir="ltr"><div id="yiv0152095042yqtfd41027" class="yiv0152095042yqt5940126276"><br clear="none"><blockquote type="cite">On Dec 6, 2021, at 6:40 PM, Bob Bownes -Seiri via Fot <fot@autox.team.net> wrote:<br clear="none"><br clear="none"></blockquote></div></div><div id="yiv0152095042yqtfd13330" class="yiv0152095042yqt5940126276"><blockquote type="cite"><div dir="ltr"></div></blockquote></div></div><div id="yiv0152095042yqtfd97107" class="yiv0152095042yqt5940126276"><div><div dir="ltr"></div><div dir="ltr">Hmm,</div><div dir="ltr"><br clear="none"></div><div dir="ltr">Will a TR6 head fit? There is plenty of meat on those to get Ludicrous Compression. </div><div dir="ltr"><br clear="none"></div><div dir="ltr">Bob</div><div dir="ltr"><br clear="none"><blockquote type="cite">On Dec 6, 2021, at 20:58, Scott Janzen via Fot <fot@autox.team.net> wrote:<br clear="none"><br clear="none"></blockquote></div><blockquote type="cite"><div dir="ltr"></div></blockquote></div></div><div><div id="yiv0152095042yqtfd38264" class="yiv0152095042yqt5940126276">I’ve found the GT6 head has some thin spots and depending on the casting can’t take milling too much more than 11.5 to 1, maybe 12 if you get lucky with the right casting.  As to the lore that circle B heads are the best, I have not found that to be correct in this respect.  Seems like they are all over the map.<div class="yiv0152095042">The rest has to come from domed pistons, which I have not yet tried, so there’s probably some more HP to be found.  </div><div class="yiv0152095042">Before you mill a head, find a shop that can “xray” it for you to tell you how thick the metal is above the cooling passages.  When I had this done, they just marked the thickness directly on the head with a market.  If memory serves, one of the thinnest spots is not quite outside the fire ring on the head gasket near #1.  I had one fail there that got milled 50/thousandths too much.</div><div class="yiv0152095042"><br clear="none" class="yiv0152095042"></div><div class="yiv0152095042"><br clear="none" class="yiv0152095042"><div><br clear="none" class="yiv0152095042"><div class="yiv0152095042">On Dec 6, 2021, at 1:36 PM, McKearn McKearn via Fot <<a rel="nofollow noopener noreferrer" shape="rect" ymailto="mailto:fot@autox.team.net" target="_blank" href="mailto:fot@autox.team.net" class="yiv0152095042">fot@autox.team.net</a>> wrote:</div><br clear="none" class="yiv0152095042Apple-interchange-newline"><div class="yiv0152095042"><div dir="ltr" class="yiv0152095042">Now that we have the crank and rods figured out, how about we discuss making compression?<div class="yiv0152095042"> I know this can be a sore subject and everyone has an opinion as to how much is enough or too much so where do we start?</div><div class="yiv0152095042"> I have built a couple TR6 engines that were in the 13:1 range thanks to much head milling and pop up pistons. Will the 2.0 litre engine be the same ?</div><div class="yiv0152095042">                                      Thanks.  P.J.</div></div>
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