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Jeep Wrangler YJ
YJ General Discussion
Any performance advice for 2.5 4-cylinder?
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<blockquote data-quote="deadpool1" data-source="post: 441100" data-attributes="member: 21229"><p>also of the old engine can have low cylinders compression, (the test and tool) my lawn mower can do 100 psi. Model A ford does 75.</p><p>it will have low power. (called basics) if this test fails.</p><p>I've reworked engines with top rings thin as razor blades. (radially)</p><p>or seen them packed in carbon so bad they where stuck. 1 or more cylinders.</p><p>it's old, things happen. the readings are also based on altitude. 3% loss per 1000feet.</p><p>par is 120 to 180 psi. sea level. the high number is from vast posters on line reporting, i'd say <strong>150</strong> is par.</p><p>the chart that is used by all private pilots is here for the corrections.</p><p></p><p>equal is best. 10% variance is a goal (less best)</p><p></p><p>The test is based on CR, the Compression ratio, is what governs results (new engine broken in, after that wear happens.</p><p>the stock ratio is 9.1: (static CR)</p><p>The higher CR is the higher peak combustion pressure are (N/A) and power produced more, ( AFR good) (there are dynamic CR too, with cam effects)</p><p>Old tired engines are.</p><p><a href="https://www.jeepstrokers.com/forum/calculator/" target="_blank">the math is all here.</a></p><p></p><p></p><p>[ATTACH=full]122484[/ATTACH]</p><p>bad rings , bad valves., worn or scored cylinders.</p><p>the cold engine the cylinders are not ROUND< so fails. ok>? the test must be done hot or warm, or do all 3 and learn. cold warm hot 180f</p></blockquote><p></p>
[QUOTE="deadpool1, post: 441100, member: 21229"] also of the old engine can have low cylinders compression, (the test and tool) my lawn mower can do 100 psi. Model A ford does 75. it will have low power. (called basics) if this test fails. I've reworked engines with top rings thin as razor blades. (radially) or seen them packed in carbon so bad they where stuck. 1 or more cylinders. it's old, things happen. the readings are also based on altitude. 3% loss per 1000feet. par is 120 to 180 psi. sea level. the high number is from vast posters on line reporting, i'd say [B]150[/B] is par. the chart that is used by all private pilots is here for the corrections. equal is best. 10% variance is a goal (less best) The test is based on CR, the Compression ratio, is what governs results (new engine broken in, after that wear happens. the stock ratio is 9.1: (static CR) The higher CR is the higher peak combustion pressure are (N/A) and power produced more, ( AFR good) (there are dynamic CR too, with cam effects) Old tired engines are. [URL='https://www.jeepstrokers.com/forum/calculator/']the math is all here.[/URL] [ATTACH type="full" alt="altitude-x.jpg"]122484[/ATTACH] bad rings , bad valves., worn or scored cylinders. the cold engine the cylinders are not ROUND< so fails. ok>? the test must be done hot or warm, or do all 3 and learn. cold warm hot 180f [/QUOTE]
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Jeep Wrangler YJ
YJ General Discussion
Any performance advice for 2.5 4-cylinder?
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