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03-30-2004, 11:31 PM | #1 |
Scooby Newbie
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Location: Oregon
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Another ej18 query, how many valves?
Yes I searched the forum to no answer. I'm new to these boxer engines but it seams to me that a SOHC like the ej18 would be an 8 valve engine just like any other SOHC right? I have people telling me that they are 16 valve engines. Is that the truth?
How many valves does the ej18 have hmmmm?
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03-30-2004, 11:36 PM | #2 |
Scooby Newbie
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Location: northeast PA
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well, my impreza says 16 and it has an EJ18
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03-30-2004, 11:43 PM | #3 |
Scooby Specialist
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MWSOC
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Vehicle:1995 Impreza L Baja |
Yes, EJ18 is SOHC and has 16 valves.
4 valves per cyl... |
03-30-2004, 11:46 PM | #4 |
Scooby Newbie
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Join Date: Mar 2004
Location: Oregon
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Okay, so what does the DOHC setup on some of the ej25s do? I mean, if all of the ej engines are 16 valves why go to the more complex setup?
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03-31-2004, 07:43 PM | #5 |
Scooby Guru
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Location: brokenmotorsports.com
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DOHC motors allow for more precise opening and closing of valves since the intake and exhaust valves are controlled inpedently, this helps to improve mid range torque.
Among other things. Jay |
04-01-2004, 12:16 AM | #6 | |
Scooby Specialist
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Join Date: Aug 2000
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SCIC
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Vehicle:2003 Forester XS |
Quote:
OTOH, dohc does allow direct valve operation, adjustment by shim, less reciprocating mass. All of which in theory allows operation at higher speeds, or with higher valve acceleration, or with lighter springs. If you have adjustable pullies, a dohc setup can have intake and exhaust timing advanced or retarded independantly. Direct valve operation also reduces side thrust on the valve stems which increases life on the valves, guides and seats. On the downside you have extra weight, complexity and expense. |
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