Judging engine health by vacumm reading...
#1
Rotary Enthusiast
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Judging engine health by vacumm reading...
I know taking compression test would tell the health of an engine...but if compression test is not available could one tell by vacumm reading?
#3
2/4 wheel cornering fiend
Also the position of the air bleed screw underneath the throttle body. The larger the opening, the more air that gets past the throttle body plates, and the less vacuum generated.
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#10
2/4 wheel cornering fiend
Originally Posted by KX500FD
it's pretty useless...just do a compression check and know for sure
Also, the vacuum reading will change with idle rpm as well. One person's "17 in Hg" will be another's "14in Hg...is my motor blown?"
#11
Rotary Freak
Mine has been at about 13 inches at 750 rpm (stock build as far as I know) for the past three years. Every time I read threads like this, I used to think my engine only had days of life left.
I took my vert into the dealer to get some work done. He told me my engine had bad compression (and bad vacuum readings) and that I should be ready to replace it soon. That was ~7 years and 60K miles ago.
I took my vert into the dealer to get some work done. He told me my engine had bad compression (and bad vacuum readings) and that I should be ready to replace it soon. That was ~7 years and 60K miles ago.
#12
Banned. I got OWNED!!!
yup comp and vac readings are bullshit!
on my street ports with all new engine parts and full blue printed assembly (much higher tollerance than from factory) you will get 10 to 11" @ 1000rpm idle and 89psi comp after run in of 2000km.
Porting has a massive effect and as such no generalizations can be made except those by your engine builder who has experience of your particualr specification engine set up.
on my street ports with all new engine parts and full blue printed assembly (much higher tollerance than from factory) you will get 10 to 11" @ 1000rpm idle and 89psi comp after run in of 2000km.
Porting has a massive effect and as such no generalizations can be made except those by your engine builder who has experience of your particualr specification engine set up.
#15
For the win...
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Originally Posted by dgeesaman
Now I think everyone will agree that you should know where your idle vacuum is, so that if one day it's not running right you can check to see if the vacuum has changed.
Dave
Dave
Just like the crank RPM has a huge factor in a compression test, so does the rpm/intake/port setup with the reading.
-R4tw
#16
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Originally Posted by dgeesaman
Now I think everyone will agree that you should know where your idle vacuum is, so that if one day it's not running right you can check to see if the vacuum has changed.
Dave
Dave
#17
Eats, Sleeps, Dreams Rotary
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i wish i bothered to look at the vacuum my motor pulled just after it blew.
i dont even remember for sure what it pulled when it was "healthy", erm i guess best way to put that is not blown.
had 130k on a original bone stock s4 t2. i think i remember about 14" which seemed really good for the miles and low compression s4 turbo motor. not positive though
i dont even remember for sure what it pulled when it was "healthy", erm i guess best way to put that is not blown.
had 130k on a original bone stock s4 t2. i think i remember about 14" which seemed really good for the miles and low compression s4 turbo motor. not positive though
#19
faq should hold what your looking for.
or just click here http://www.fd3s.net/compression_test.html
or just click here http://www.fd3s.net/compression_test.html
#20
Originally Posted by RICE RACING
yup comp and vac readings are bullshit!
Comp readings bullshit! How so???
Even if they were (given compression tester result can vary widely), at the very least comrpession test is extremely important to compare compression on the front / rear rotors for example.
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