{"id":1403,"date":"2017-07-05T15:46:40","date_gmt":"2017-07-05T23:46:40","guid":{"rendered":"https:\/\/stratifiedauto.com\/blog\/?p=1403"},"modified":"2017-07-05T16:22:44","modified_gmt":"2017-07-06T00:22:44","slug":"does-a-leaner-air-fuel-ratio-result-in-more-power-on-the-mk7-gti","status":"publish","type":"post","link":"https:\/\/www.stratifiedauto.com\/blog\/does-a-leaner-air-fuel-ratio-result-in-more-power-on-the-mk7-gti\/","title":{"rendered":"Does a leaner Air-Fuel Ratio result in more power on the MK7 GTI?"},"content":{"rendered":"<iframe src=\"http:\/\/www.facebook.com\/plugins\/like.php?href=https:\/\/www.stratifiedauto.com\/blog\/does-a-leaner-air-fuel-ratio-result-in-more-power-on-the-mk7-gti\/&amp;layout=standard&amp;show_faces=1&amp;width=450&amp;action=like&amp;colorscheme=light&amp;font=\" scrolling=\"no\" frameborder=\"0\" style=\"border:none; overflow:hidden; width:450px; height:25px\"><\/iframe><div class=\"\" data-block=\"true\" data-editor=\"2vlui\" data-offset-key=\"duq0k-0-0\">\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><span data-offset-key=\"duq0k-0-0\"><span data-text=\"true\">Calibrating an engine\u00a0revolves around solid data analysis and testing of any hypotheses. In the case of the MK7 GTI,\u00a0the OEM ECU calibration commands a relatively lean air-fuel ratio (AFR) target during wide open throttle operation<\/span><\/span><span data-offset-key=\"duq0k-0-0\"><span data-text=\"true\">. For the majority of a pull, unless one of the temperature failsafe thresholds are triggered, the ECU will command a 14.7 AFR tapering to mid 13s by redline.<\/span><\/span><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><a href=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-OEM-air-fuel-ratios.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1405\" src=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-OEM-air-fuel-ratios-300x248.jpg\" alt=\"vw-gti-mk7-oem-air-fuel-ratios\" width=\"500\" height=\"413\" srcset=\"https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-OEM-air-fuel-ratios-300x248.jpg 300w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-OEM-air-fuel-ratios-768x635.jpg 768w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-OEM-air-fuel-ratios-363x300.jpg 363w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-OEM-air-fuel-ratios.jpg 838w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><span data-offset-key=\"duq0k-0-0\"><span data-text=\"true\">It has to be understood that these targets are within the context of the OEM tune. The boost pressure targets, ignition timing targets, and variable timing targets are all taken into consideration when selecting the appropriate air fuel ratio. On top of this, economical operation is a strong requirement for the OEM.<\/span><\/span><\/div>\n<p>&nbsp;<\/p>\n<div class=\"\" data-block=\"true\" data-editor=\"2vlui\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\">When\u00a0pushing the car beyond the factory setup in order extract maximum effort from the engine, all variables including the air-fuel ratio must be reconsidered and retested.<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\">When commanding a higher output the engine requires more in-cylinder cooling in order to avoid detonation (knock) while maintaining maximum performance.\u00a0This is the case with other internal combustion engines we have worked with but we had to put the hypothesis to the test for the EA888 Gen3 as well.<\/div>\n<p>&nbsp;<\/p>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\">The <a href=\"http:\/\/www.stratifiedauto.com\/index.php?main_page=index&amp;cPath=240_254\">COBB Accessport<\/a> gives us a very powerful analysis and datalogging tool at a high sample rate of 12hz (that means we get 12 datapoints per second for each sensor or actuator signal we log)<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><a href=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1406\" src=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport-300x131.jpg\" alt=\"vw-gti-mk7-cobb-accessport\" width=\"500\" height=\"219\" srcset=\"https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport-300x131.jpg 300w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport-768x336.jpg 768w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport-1024x448.jpg 1024w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport-500x219.jpg 500w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-COBB-Accessport.jpg 1587w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\">We tested this hypothesis in a controlled environment where we only varied air-fuel ratios. We made sure that this was done on a hot day with 91 octane fuel that is knock prone. This was done such that we can clearly see the effect of the air-fuel ratio without any other variables interfering.<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"duq0k-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><a href=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1407\" src=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-300x230.jpg\" alt=\"vw-gti-mk7-stratified-tune-dyno\" width=\"500\" height=\"383\" srcset=\"https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-300x230.jpg 300w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-768x588.jpg 768w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-392x300.jpg 392w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno.jpg 842w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><span data-offset-key=\"86mk6-0-0\"><span data-text=\"true\">Here you can see that the richer run did produce more power. The question now is why? We looked at the knock traces from both runs for to get an answer to this as boost and temperatures were identical. The graph below answers this question.<\/span><\/span><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"\" data-block=\"true\" data-editor=\"2vlui\" data-offset-key=\"86mk6-0-0\">\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><a href=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1426\" src=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock-300x78.jpg\" alt=\"vw-gti-mk7-stratified-tune-dyno-knock\" width=\"500\" height=\"131\" srcset=\"https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock-300x78.jpg 300w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock-768x200.jpg 768w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock-1024x267.jpg 1024w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock-500x131.jpg 500w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Knock.jpg 1268w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\">As you can see, the leaner AFRs do not offer the necessary in-cylinder cooling to prevent the engine from knocking. Yes, the engine knocks in both runs because we have setup the test as such to ensure we see a contrast between the two sets of data. However you can see that the richer air-fuel ratios result in a diminishing knock trend which in turn results in the engine making more power and staying safer!<\/div>\n<p>&nbsp;<\/p>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\">Finally, we have to ensure the data is repeatable. For this we have two back to back runs of the richer tune. You can see that the data is repeatable within\u00a02-3whp which gives us further confidence in the test results<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><a href=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Repeatable.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1410\" src=\"https:\/\/stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Repeatable-300x253.jpg\" alt=\"vw-gti-mk7-stratified-tune-dyno-repeatable\" width=\"500\" height=\"422\" srcset=\"https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Repeatable-300x253.jpg 300w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Repeatable-768x648.jpg 768w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Repeatable-356x300.jpg 356w, https:\/\/www.stratifiedauto.com\/wordpress\/wp-content\/uploads\/2017\/07\/VW-GTI-MK7-Stratified-Tune-Dyno-Repeatable.jpg 810w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a>The conclusion to all this &#8211; when calibrating a vehicle outside of the OEM parameters, all variables and hypotheses need testing in order to optimize the new set up.<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\"><\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\">Happy Tuning,<\/div>\n<div class=\"_1mf _1mj\" data-offset-key=\"86mk6-0-0\">The Stratified Team<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Calibrating an engine\u00a0revolves around solid data analysis and testing of any hypotheses. In the case of the MK7 GTI,\u00a0the OEM ECU calibration commands a relatively lean air-fuel ratio (AFR) target during wide open throttle operation. For the majority of a &hellip; <a href=\"https:\/\/www.stratifiedauto.com\/blog\/does-a-leaner-air-fuel-ratio-result-in-more-power-on-the-mk7-gti\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,11,16],"tags":[],"class_list":["post-1403","post","type-post","status-publish","format-standard","hentry","category-tech_talk","category-tuning","category-volkswagen-gti"],"_links":{"self":[{"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/posts\/1403","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/comments?post=1403"}],"version-history":[{"count":5,"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/posts\/1403\/revisions"}],"predecessor-version":[{"id":1427,"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/posts\/1403\/revisions\/1427"}],"wp:attachment":[{"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/media?parent=1403"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/categories?post=1403"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.stratifiedauto.com\/blog\/wp-json\/wp\/v2\/tags?post=1403"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}