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Old 11-23-2008, 09:38 PM   #1
Zefy
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Join Date: Jan 2006
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Location: Coquitlam, BC, Canada
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1979 BRAT / 01 RSTI
99 2.5TS (DEAD) / 87 GL

Default header design question

i know headers questions annoying as the topic has been beaten to death but i need your opinions.

i am custom building a header for my ej22 swapped 79 brat (because nothing really fit the way i like) and my starting point (ebay wrx headers) were free.

the way it sits right now it is an UEL header design with the collector on the passenger side. due to the limited space in the brat i determined the most space effective solution is to have the driverside ports run in different directions around the oil pan. the front one will wrap around the front of the oil pan to the collector (similar to borla) and the rear port would wrap around back of the oil pan into the collector. (this is a 4-1 collector)

so will having different length tubes for ALL the ports (especially driverside) make it a power sucker? OEM headers don't fit so don't ask.
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Old 11-23-2008, 10:17 PM   #2
alejo
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It would be better to get a phase II ej22 engine. they are single ported but have a better flowing cam design. Then again, if you CAN'T get it try to have them the sam size. good luck
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Old 11-24-2008, 12:46 AM   #3
Zefy
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Default

i'm not going to get another engine. plus it won't fit. different head design = wider engine = won't fit. i'm already doubling the stock power by going with this engine.

and you didn't answer my question at all...? all the runners are the same size but they are going to be all different lengths. getting a different engine won't do anything for me except make me re wire the entire car again.
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Old 11-24-2008, 01:11 AM   #4
williaty
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The car will run, but it will make substantially less power than it could. You're almost certainly going to have a weird torque curve as well. It'll also eat gas.
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Old 11-24-2008, 11:01 AM   #5
alejo
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Quote:
Originally Posted by Zefy View Post
i'm not going to get another engine. plus it won't fit. different head design = wider engine = won't fit. i'm already doubling the stock power by going with this engine.

and you didn't answer my question at all...? all the runners are the same size but they are going to be all different lengths. getting a different engine won't do anything for me except make me re wire the entire car again.
By same size I meant in lenght as well (my bad sorry). Still, you are getting more power into it. Maybe we are lokking into a potential sleeper? Good luck with it
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Old 11-24-2008, 11:35 AM   #6
ballitch
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Well im glad to hear that more people are doing EJ swaps. I love mine, awesome mod for an old car.

If you can measure the stock runner engths, and try to stay close to that, it shouldnt be too bad.

I would try to find a stock header portion (w/o the cat) and fab up a pipe to go from your stock midpipe to the EJ stock header. This is what i'll be doing im my EJ swapped EA car, the stock single port EA headers I modded to fit the EJ motor are a restriction. Now that im swapping in dual port heads with cams in them, cant have any restrictions.

In short, I would try to stay away from weird funky header desgins, if you stay close to stock, or stock, you dont have to go through as much trouble. If one runner on one side of the head is 10'' longer than the other port for the same head, i can guess that would really hurt performance.


~Josh~
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Old 11-24-2008, 08:21 PM   #7
neonneil1998
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what about a long-tube header design that collects farther back, giving you longer distance to throw some bends in, help even out lengths.
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Old 11-24-2008, 09:45 PM   #8
Back Road Runner
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A lot of what I collected in my own search on exhaust design and proper header design.
http://forums.nasioc.com/forums/show....php?t=1080151
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Old 11-24-2008, 10:38 PM   #9
Zefy
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Default

thanks for the links! one of the constraints i am trying to keep is my cheapness. I don't want to buy anything else to make this happen.

i have this botched together ebay header that i'm working on right now and also a modified rusted out stock legacy header that currently serves the purpose. but it leaks like mad and it has huge restrictions as it was one of my first welding projects and it is a modified version of an exhaust that was designed for the little EA71 engine. (1.6 liter for those not fluent with the old school)

i'll try to snap some pics of what i'm working on and the space i have to work with so people get a better idea. as it sits right now it looks like i'm going to be scrapping (re-using) what i have right now.
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Old 11-25-2008, 01:30 PM   #10
Zefy
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1979 BRAT / 01 RSTI
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Default

i just picked up the book you mentioned in your thread (schientific design of exhaust and intake systems).

i haven't really looked at it yet but this book was published in 1968 so a bunch of the intake bits don't really apply as they deal with carbs. university libraries rock... i also found a bunch of subaru service manuals.
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