compression numbers
#1
compression numbers
I was just on the phone with a mazda dealer and he said 5 and up is a good reading for a compression test as long as all the numbers are close?? Is that true or is 5 a little low?
Thanks
Thanks
#8
Banned
iTrader: (3)
Neither do you. You shouldn't be allowed to post in technical threads.
__________________________________________________ ________
In addition to what Team and Dan said, you also need to correct the charted results for altitude. That chart (from the updated FSM) assumes sea-level as the reference.
I realize that I am going to get barked at about how the compression checkers are relative measuring devices and should measure pressure as a reference to local pressure, not absolute, but you find that compression results are tied to altitude.
If I wasn't feeling so foggy, I might bother with an explanation, but it was a long day.
Last edited by MazdaManiac; 07-01-2011 at 01:44 AM.
#9
I appreciate the help. So as I under stand it, it should be 250 rpm to get an accurate reading? If elevation has anything to do with it, elevation here is 4500...
Since I am new to the forum, I apologize for duplicate questions. I have searched compression etc ,but havent had much luck. Is there a place on the forum that shows graphs and more technical info on the engine so I wont have to bother everyone? :0)
Since I am new to the forum, I apologize for duplicate questions. I have searched compression etc ,but havent had much luck. Is there a place on the forum that shows graphs and more technical info on the engine so I wont have to bother everyone? :0)
#10
Out of NYC
iTrader: (1)
mscamp02 and monchie ... wtf ...
Factory and some 3rd party compression tester have a "flip" switch and will convert the numbers automatically for you.
5 might pass but it depends on what rpm you did the test on. but either way, it still means your engine is going south.
As for elevation level, 4500 is pretty high so your numbers might get a little lower. There is a formula to convert it back to sea level but I just don't remember it now.
Factory and some 3rd party compression tester have a "flip" switch and will convert the numbers automatically for you.
5 might pass but it depends on what rpm you did the test on. but either way, it still means your engine is going south.
As for elevation level, 4500 is pretty high so your numbers might get a little lower. There is a formula to convert it back to sea level but I just don't remember it now.
#11
Registered
Ambient pressure at 4500 feet is about 85% that at sea level. So an engine at the minimum 6.8 at 250 rpm at sea level would be about 5.8 at 4500 feet.
5 still does not cut it.
Ken
5 still does not cut it.
Ken
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