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how can you test compression with engine out?

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Old 06-30-06, 12:21 AM
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how can you test compression with engine out?

i have a turbo engine out of the car and i would like to do a compression test before starting to put the engine into the car; i don't know any prior status on the engine; right now is in short block form, i'm able to turn the engine easily by hand and i'm getting a healthy "whoosh" sound;

i have a regular piston engine tester but i found on the forum how to use it on rotaries, but do i have any chance to measure the compression with engine out?

i don't know ... maybe i say stupid thing... but hook up the tester and to try to rotate the engine? or i'd better hook up the tranny and to try to rotate the engine by connecting the starter directly to a battery?

let me know guys
Old 06-30-06, 12:23 AM
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Poor mans test is all I know, www.rotaryressurection.com, they have a section on that
Old 06-30-06, 01:02 AM
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It'll be pretty hard to get a real life number.

To get true number you need a warm engine and you can't exactly run an engine outside unless you have a full test stand.

All you can really do is do the audible woosh test.

I'm in the same boat.
I've got a supposed 2700 mile engine and I am about to install it tomorrow.
I can only hope that it hold good compression.

While it is out check that all the apex seals move freely as well.

You may be able to get a semi test from doing the cumulative test with hand cranking.try to keep it quickly and constant if you do tr though.

Last edited by Digi7ech; 06-30-06 at 01:04 AM.
Old 06-30-06, 01:22 AM
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i was in the same boat...
do it like me

get a tranny and put it together with your engine... 2 screws are enough... then get a starter and put it together with your tranny/engine...

get some nice jumper wires and connect them to the +12 and ground wires from the starter, the other side to a battery in a running car... take your com. tester... jump the contacts on the starter with a long isolated screwdriver and thats it

so i've did it... get me some nice compression numbers on 100-115psi on cold engine wich was laying around for 4 years *happy*

hope that helps
Old 06-30-06, 12:06 PM
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Originally Posted by SpAm@FC
i was in the same boat...
do it like me

get a tranny and put it together with your engine... 2 screws are enough... then get a starter and put it together with your tranny/engine...

get some nice jumper wires and connect them to the +12 and ground wires from the starter, the other side to a battery in a running car... take your com. tester... jump the contacts on the starter with a long isolated screwdriver and thats it

so i've did it... get me some nice compression numbers on 100-115psi on cold engine wich was laying around for 4 years *happy*

hope that helps
Nice
Old 06-30-06, 12:43 PM
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thanx guys; i'll try to do smth this weekend
Old 06-30-06, 12:55 PM
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REST IN PEACE DAVE!!!!!!

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what if you get a impact gun,put it on the eccentric shaft nut??? then comp test it,while turning the engine with the air gun... dont know how good it would work but its just an idea...
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