{"id":17613,"date":"2015-09-01T14:14:47","date_gmt":"2015-09-01T19:14:47","guid":{"rendered":"http:\/\/caddyinfo.com\/wordpress\/?p=17613"},"modified":"2015-09-01T20:40:39","modified_gmt":"2015-09-02T01:40:39","slug":"cadillac-northstar-lh2-4-6l-v8-vvt-tuning-hptuners-motorama","status":"publish","type":"post","link":"http:\/\/www.caddyinfo.com\/wordpress\/cadillac-northstar-lh2-4-6l-v8-vvt-tuning-hptuners-motorama\/","title":{"rendered":"Cadillac Northstar LH2 4.6L V8 VVT Tuning #hptuners #Motorama"},"content":{"rendered":"<p>The LH2 V8 added variable valve timing (VVT) based on the Premium V6 schema of the same time.\u00a0 Interestingly, the LH2 and the LC3 use the same base cam timing, which reinforces how much the LC3 Supercharged V8 in my STS-V is a supercharged 4.4L LH2.\u00a0 It may also give us some insights into how the LH2 VVT is programmed vs the <a href=\"http:\/\/caddyinfo.com\/wordpress\/vvt-tuning-for-the-cadillac-sts-v-lc3-v8\/\">LC3 VVT<\/a>.<\/p>\n<p>Here in Plano, Texas we stay in the High BARO table, so we&#8217;ll be looking there.\u00a0 The same principles should apply in other barometer ranges.<\/p>\n<p>Here is the OEM calibration for the intake and exhaust cams at high baro.\u00a0 During WOT my LH2 operated around .57 g\/cyl airmass so I have blue-lighted the .56-.60 areas: [click to zoom in, back to return]<\/p>\n<p><a href=\"http:\/\/caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/lh2-vvt-intake-and-exhaust-cams.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-large wp-image-17615\" src=\"http:\/\/caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/lh2-vvt-intake-and-exhaust-cams-1024x633.png\" alt=\"lh2 vvt intake and exhaust cams\" width=\"584\" height=\"361\" srcset=\"http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/lh2-vvt-intake-and-exhaust-cams-1024x633.png 1024w, http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/lh2-vvt-intake-and-exhaust-cams-500x309.png 500w, http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/lh2-vvt-intake-and-exhaust-cams-485x300.png 485w, http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/lh2-vvt-intake-and-exhaust-cams.png 1263w\" sizes=\"auto, (max-width: 584px) 100vw, 584px\" \/><\/a><\/p>\n<p>What we see is that the intake cam goes from 16-19 degrees at 4400 rpm down to 2 degrees at 6800 rpm.\u00a0 The exhaust cam goes from 3-6 degrees at 4400 rpm to 4-5 degrees at 6800 rpm.<\/p>\n<p>The values for the intake cam should be degrees of advance, and the values for the exhaust cam degrees of retard. \u00a0 For the LH2 it appears 0 degrees of either are Top Dead Center (TDC) [ref: Helms manual pg 9-340]. \u00a0 If that is the case, as the engine moves to high RPM the intake cam gets less advanced (retards), and the exhaust cam gets more retard (retards).<\/p>\n<p><a href=\"http:\/\/caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/camactuatoroperation.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-17626\" src=\"http:\/\/caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/camactuatoroperation.gif\" alt=\"camactuatoroperation\" width=\"568\" height=\"160\" \/><\/a><\/p>\n<p>Simple cam tuning rules for Naturally Aspirated engines like my LH2: <a title=\"HpTuners Forum\" href=\"http:\/\/www.hptuners.com\/forum\/showthread.php?35092-Basic-VVT-Tuning-info\" target=\"_blank\">[ref]<\/a><\/p>\n<ul>\n<li>Advancing both cams =&gt; more low-RPM power, less high-RPM power<\/li>\n<li>Retarding both cams =&gt; more high-RPM power, less low-RPM power<\/li>\n<li>Less overlap =&gt; more low-RPM power, less high-RPM power<\/li>\n<li>More overlap =&gt; more high-RPM power, less low-RPM power<\/li>\n<\/ul>\n<p>So as the engine moves to higher RPM we want to see both cams retarding, and that is what we appear to see.\u00a0 We would also like to see more overlap, and that is not what we see &#8212; the net change between the two cams appears to introduce more overlap not less.<\/p>\n<p>I am interested in the changes over cylinder air mass within the table.\u00a0 At lower cylinder airmass the changes have the same basic shape, but to different degrees.<\/p>\n<p><a href=\"http:\/\/caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/LH2-Intake-Cam-Graph.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-large wp-image-17617\" src=\"http:\/\/caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/LH2-Intake-Cam-Graph-1024x659.png\" alt=\"LH2 Intake Cam Graph\" width=\"584\" height=\"376\" srcset=\"http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/LH2-Intake-Cam-Graph-1024x659.png 1024w, http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/LH2-Intake-Cam-Graph-500x322.png 500w, http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/LH2-Intake-Cam-Graph-466x300.png 466w, http:\/\/www.caddyinfo.com\/wordpress\/wp-content\/uploads\/2015\/09\/LH2-Intake-Cam-Graph.png 1224w\" sizes=\"auto, (max-width: 584px) 100vw, 584px\" \/><\/a><\/p>\n<p>This graph shows the degrees of intake cam (left axis) vs rpm (bottom axis) at various gram\/cyl air pressures.\u00a0 The top two lines are our lines of interest, which seems odd, but because the graph maxes out at that point every other range over-writes the top line.<\/p>\n<p>I think our first step will be to begin logging the intake and exhaust cam positions in order to verify that there are not other tables having an impact on these values.<\/p>\n<p>What do you see in the data?\u00a0 How would you tune these values for low-end torque and high end power?<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The LH2 V8 added variable valve timing (VVT) based on the Premium V6 schema of the same time.\u00a0 Interestingly, the LH2 and the LC3 use the same base cam timing, which reinforces how much the LC3 Supercharged V8 in my &hellip; <a href=\"http:\/\/www.caddyinfo.com\/wordpress\/cadillac-northstar-lh2-4-6l-v8-vvt-tuning-hptuners-motorama\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[310,779,6,523,299,300],"tags":[],"class_list":["post-17613","post","type-post","status-publish","format-standard","hentry","category-cadillac-engines","category-hp-tuners","category-site-info-news","category-sts-v-cadillac-models","category-xlr-cadillac-models","category-xlr-cadillac-models-2"],"_links":{"self":[{"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/posts\/17613","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/comments?post=17613"}],"version-history":[{"count":7,"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/posts\/17613\/revisions"}],"predecessor-version":[{"id":17628,"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/posts\/17613\/revisions\/17628"}],"wp:attachment":[{"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/media?parent=17613"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/categories?post=17613"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.caddyinfo.com\/wordpress\/wp-json\/wp\/v2\/tags?post=17613"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}