Thread: compression ?
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930turbo 930turbo is offline
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Join Date: Jul 2006
Location: Valrico Florida
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10% or less is the key. Every tester will deliver a different number depending on the internal volume of the gauge & line, cranking speed, etc. 7:1 is a static measurement. Dynamic compression takes valve opening into consideration. Your actually measuring trapped stroke compression which can vary considerably based on valve timing. The achilles heel of these motors is the exhaust guides. They will wear to catastrophic failure while a compression - or even leak-down test will pass with flying colors. Listen to your valve train. If it still goes clickity clack after an accurate adjustment, beware. That's you exhaust valves rocking side-to-side in the void as it opens and closes. There's no where for the heat to go and they eventually snap off.
'77 930 turbo Garretson I/C 1 BAR spring, (2) '82 Triumph Bonneville Royal Wedding Edition
Past rides: '74 914 1.9 liter twin plugged track car, '83 928S, '87 924S, '75 911S w '78 ROW 3.0, '72 911T, '70 911T and various other insignificant domestic examples. Happiness is a grey tailpipe! Turbo's worth the wait!
Old 02-09-2009, 10:20 AM
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