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Old 01-22-2013, 02:05 PM   #1
Pickler
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Default EJ253 phase-2 Exhaust Manifold

im trying to learn more about my Subaru engine. Anybody knows how long the EJ253 phase 2 intake manifold runner lengths are? I have measured the diameter at roughly 1.5in but runners seem to be over 14-16in long! This doesn't really make sense, as the runners seem to be way to long for an engine with peak torque of 4400rpm and 6000rpm horsepower? i was expecting about 8in and also there seems to be no manifold plenum? if this is true then a shortened runners can maybe create more top end torque and max power?

(intake manifold runners not exhaust manifold sorry for title)
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Last edited by Pickler; 01-22-2013 at 05:52 PM.
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Old 01-22-2013, 02:58 PM   #2
Patrick Olsen
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There is more to power and torque peaks than just the length of the intake runners.

I don't understand how you think there is not a plenum. What do you think a plenum is? The part of the intake manifold where the 4 runners come together on one side and the throttle body mounts on the other side is the plenum.
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Old 01-22-2013, 05:51 PM   #3
Pickler
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Quote:
Originally Posted by Patrick Olsen View Post
There is more to power and torque peaks than just the length of the intake runners.

I don't understand how you think there is not a plenum. What do you think a plenum is? The part of the intake manifold where the 4 runners come together on one side and the throttle body mounts on the other side is the plenum.
sorry it was sarcasm/exaggeration, compared to other manufactures the plenum is tiny.
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Old 01-23-2013, 02:22 PM   #4
Marnix
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The big plastic box on the other side of the throttle body also acts as a plenum (Helm Holz resonator). Cam profile has more inpact on rpm range than just runner length. Besides that, that intake manifold has been proven to be pretty good, too.
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