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Old 10-08-2010, 07:32 PM   #1
jackolafedon
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Default Equal length header question

Looking through available EL headers for the EJ25x motors I've been wondering to myself if using one of the EL turbo headers would work on a ej253. Main downfall is that the primary/secondary tubes tend to be shorter the then EL headers designed for the 2.5RS. This will lower the top end scavenging ability. I'm wondering if its that big of a difference to be worth paying what seems to be nearly double the price for some of the better RS headers. Any thoughts from the N/A power gurus?
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Old 10-08-2010, 09:18 PM   #2
RaceFaceXC
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Quote:
Originally Posted by jackolafedon View Post
Looking through available EL headers for the EJ25x motors I've been wondering to myself if using one of the EL turbo headers would work on a ej253. Main downfall is that the primary/secondary tubes tend to be shorter the then EL headers designed for the 2.5RS. This will lower the top end scavenging ability. I'm wondering if its that big of a difference to be worth paying what seems to be nearly double the price for some of the better RS headers. Any thoughts from the N/A power gurus?
They will require modification to bolt up to the n/a exhaust... performance wise I digress but doubt they will be ideal
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Old 10-08-2010, 10:16 PM   #3
chazly413
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I would stick with the ones meant for NA. Just gonna be a lot easier, and cheaper as you mentioned.
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Old 10-09-2010, 06:02 PM   #4
jackolafedon
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Regardless of the new header I choose, I'll be getting a new Header back exhaust made so fitment isn't an issue. Currently no one makes a EL aftermarket header that matches to the OE cat location for the 06+ cars so its going to be a required addition to any header I choose.
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Old 10-11-2010, 09:49 AM   #5
PA-Outback2000
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u can get the random tech or stromung cat section and it will bolt up, with the header, to the stock location. where would u get ut cat if u go custom? or would u go cat-less?
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Old 10-11-2010, 01:41 PM   #6
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The modification will be in making the header not go up and over the crossmember like the turbo headers do.....

Eliminate that aspect and they should make decent shorty type headers.


Jay
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Old 10-11-2010, 11:44 PM   #7
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Primary diameter and length both play a part in the scavenging effect. The key issues are exhaust flow velocity and return-pulse phasing. Flow velocity decreases with pipe diameter, so a wider pipe is optimized for a higher RPM. Return pulse phasing shows a longer time delay with a longer pipe, so a longer pipe is optimized for higher RPM. Both aspects are critical for correct scavenging. A pipe optimized for a turbo is going to be far too fat for good velocity scavenging on an NA. Also, primary length is a little more flexible than you think it is. Any header you can actually fit under a car is going to be using the 4th or 5th order reflection anyway as a 1st order pipe would be 30+ feet long.
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Old 11-08-2011, 09:00 PM   #8
jackolafedon
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Bumping this from the grave as this winter I'll be doing some sort of exhaust replacement (header and all) Planning to purchase a agency power equal length ebay clone header, cut it at the collector and have a quality 4-1 merge collector welded in. This should take care of the main complaints with both the ebay header (fitment) and the issue I see with the factory header (really crappy collector)
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Old 11-08-2011, 09:33 PM   #9
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If the AP header is tuned to be even remotely good for the turbos, it'll be absolute crap for NA. The design requirements are very different.
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Old 11-08-2011, 09:39 PM   #10
KillerBMotorsport
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Turbo and N/A headers have different design parameters. You'd have maximum gains with a header designed for n/a vs. hacking a turbo version, although it may be better than stock
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