Leak (Down) Compression Test - LPE Supercharger
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Joined: Feb 2000
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From: Henderson NV
Leak (Down) Compression Test - LPE Supercharger
Got an appt for installing the Intercooled Magnacharger at Lingenfelter, but in the contract I looked at, they say that engine over 20,000 miles have to be leak tested beforehand.
I asked about this, and they said any engine that has a greater than 10% leak doesn't pass and they wouldn't install.
Is this the same test as a leak/down or compression test, and will most auto/performance shops do the test. Want to have it down locally before driving a couple thousand miles.
I asked about this, and they said any engine that has a greater than 10% leak doesn't pass and they wouldn't install.
Is this the same test as a leak/down or compression test, and will most auto/performance shops do the test. Want to have it down locally before driving a couple thousand miles.
Le Mans Master
Joined: Jul 2002
Posts: 6,147
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From: Dallas TX
Re: Leak (Down) Compression Test - LPE Supercharger (lutey)
Unless there are some issues with the motor, you should be fine.
Usually you dont see anything over 7% or so on a normal motor.
I had a leakdown down on my motor after about 10k miles and all the cylinders were between 5-6%.
BTW, its different than a compression test but most performance shops should be able to perform it for you for a small fee. maybe a hundred bucks
Usually you dont see anything over 7% or so on a normal motor.
I had a leakdown down on my motor after about 10k miles and all the cylinders were between 5-6%.
BTW, its different than a compression test but most performance shops should be able to perform it for you for a small fee. maybe a hundred bucks
Melting Slicks
Joined: Jan 2001
Posts: 2,635
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From: Aloha, Oregon
Re: Leak (kumar75150)
also, how/when the test is performed will influence the results. A motor that has been sitting cold for a very long time will have a greater leakdown than one that just ran, everything else =. But, yes, get the leakdown check done before you head to LPE just to make sure.
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St. Jude Donor '03-'04
Re: Leak (Down) Compression Test - LPE Supercharger (lutey)
Here is a response I got from a member on LS1Tech.com:
Pretty easy, get a leakdown guage via summit and remove all the sparkplugs from the holes, hook the guage up to your air compressor and inject 100 psi of air into each cylinder at its TDC, you can find tdc by injecting say 20psi and listening for TDC or also its right after the crank gets super hard to turn to super easy. Once at TDC inject 100 psi, look at the 2nd leakdown guage on the tester. if it says 90 then then that cylinder has 10 % leakdown. Also you need to listen to where it is leaking from. If it is going into the oil pan you have blowbuy IE ring/pison issues. If it is out the intake then your intake valve is fuxored. Likewise if you here air escaping out the exhaust its your exhaust valve. If you see bubbles in you coolant than you have a head gasket issue. Its a really cool test to do especially being able to hear wear the problem lies. Also anything above 10 % is real bad, 7-10% is still bad but ok. 4-7 is pretty damn good. Under 4% and your leakdown % is rivaling race cars. I could be wrong slightly on the above % but basically anything up to 10% is ok with 9 and 10 % being iffy.
Pretty easy, get a leakdown guage via summit and remove all the sparkplugs from the holes, hook the guage up to your air compressor and inject 100 psi of air into each cylinder at its TDC, you can find tdc by injecting say 20psi and listening for TDC or also its right after the crank gets super hard to turn to super easy. Once at TDC inject 100 psi, look at the 2nd leakdown guage on the tester. if it says 90 then then that cylinder has 10 % leakdown. Also you need to listen to where it is leaking from. If it is going into the oil pan you have blowbuy IE ring/pison issues. If it is out the intake then your intake valve is fuxored. Likewise if you here air escaping out the exhaust its your exhaust valve. If you see bubbles in you coolant than you have a head gasket issue. Its a really cool test to do especially being able to hear wear the problem lies. Also anything above 10 % is real bad, 7-10% is still bad but ok. 4-7 is pretty damn good. Under 4% and your leakdown % is rivaling race cars. I could be wrong slightly on the above % but basically anything up to 10% is ok with 9 and 10 % being iffy.
