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Old 01-25-2013, 03:52 PM   #1
Pickler
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Default phase 2 EJ253 variable cam timing?

was just wondering if the impreza 2.5i camshaft timing can be advanced or retarded by the ecu? sort of like how the bmw vanos advances or retards timing up to 12 degrees? or does AVLS just vary which cam shaft is opening which intake valve only?
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Old 01-26-2013, 03:45 AM   #2
rocketperson7
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Nope, you have a SOHC engine

you basically have VTEC, not VANOS
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Old 01-26-2013, 11:12 AM   #3
RaceFaceXC
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Quote:
Originally Posted by Pickler View Post
was just wondering if the impreza 2.5i camshaft timing can be advanced or retarded by the ecu? sort of like how the bmw vanos advances or retards timing up to 12 degrees? or does AVLS just vary which cam shaft is opening which intake valve only?
The subaru AVLS system on the 253 can only switch between low lift and high lift cam lobe profiles on one intake valve. The other intake valve is always on high lift. It's an on/off thing, not a infinitely variable lift type system. Cam timing is not changed.
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Old 01-27-2013, 01:29 AM   #4
Pickler
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Originally Posted by rocketperson7 View Post
Nope, you have a SOHC engine

you basically have VTEC, not VANOS
ok thanks for the vtec and vanos comparison. but im not sure what sohc has to do with this? is there a connection between sohc powertrains and variable valve timing? i mean the 1.8L by honda has variable valve timing...or do you just mean sohc subaru engines?

Last edited by Pickler; 01-27-2013 at 01:42 AM.
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Old 01-27-2013, 02:11 AM   #5
rocketperson7
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AVCS, VANOS, really any technology that advances/retards the valve opening does so by phasing the cam lobes with respect to the cam gear

if you were to do with a SOHC engine, you would change both the intake and exhaust opening/closing, which would net you nothing
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Old 02-10-2013, 04:15 PM   #6
Pickler
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ok i still don't understand, this excerpt from subaru impreza service manual claims to have different valve timings based on different engine speeds for the SOHC 2.5L:



it still seems to me that the 09 2.5i can vary intake valve timing.
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Old 02-10-2013, 11:00 PM   #7
rocketperson7
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no, it doesn't

the higher lift cam that it switches to opens and closes earlier/later

again, you have vtec..NOT vanos..
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