2nd Generation Specific 1986-1992 Discussion

Replacing old exhaust manifold

Old 03-27-2006, 01:36 AM
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I got a hold on a cheap header through a friend of mine and I was wondering

if I would have any issues with my Auxilary ports(5th & 6th Ports).



My car is equiped witha straight mid-pipe to two small HKS mufflers (more like bafflers).

Anyways I was just wondering if putting back my mid-pipe with the Cat would be beneficial?



I also iintend on adding additional grounds, Where might the best spots be?



On that same note would header-wrap also be a good idea?



Thanks
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Old 03-27-2006, 03:57 AM
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Backpressure = bad. Free flowing is the way to go.
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Old 03-27-2006, 08:06 AM
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Old 03-27-2006, 08:39 AM
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As far as the grounds, the top of the engine block (where the wiring harness gound is), intake manifold, throttle body, bellhousing, altenator. Those will probally give you the best results.
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Old 03-27-2006, 02:09 PM
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Originally Posted by ShadowX' post='810290' date='Mar 27 2006, 04:57 AM
Backpressure = bad. Free flowing is the way to go.






not true. in a turbo yes, the more free flowing your exhaust the better.







in an n/a, specifically an s4 you need backpressure, not only to activate the aux ports but also for the engine itself.







i'm running RB header and presilencer ...that's it (straight pipe to the rear bumper, no muffler) and have enough backpressure in front of the presielncer to open my aux. ports. ( s4 n/a)







I've heard of it not working on other s4's, but it does work fine on mine.







as for header wrap...unless you're getting good qualit headers dont do it, itll rust them out and make them disintegrate.







and like i said, this is only for n/a's, on t2's you want as free-flowing as possible, my t2 has 0 restrictions from the t78 to the rear.







kevin.
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Old 03-27-2006, 03:46 PM
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Originally Posted by teknics' post='810369' date='Mar 27 2006, 03:09 PM







not true. in a turbo yes, the more free flowing your exhaust the better.







in an n/a, specifically an s4 you need backpressure, not only to activate the aux ports but also for the engine itself.





kevin.


I think thats a misconception, (all but the S4 aux port thing). Dont confuse backpressure with exhaust scavenging. Backpressure kills the scavenging effect.
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Old 03-28-2006, 12:28 AM
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Originally Posted by teknics' post='810369' date='Mar 27 2006, 12:09 PM

not true. in a turbo yes, the more free flowing your exhaust the better.







in an n/a, specifically an s4 you need backpressure, not only to activate the aux ports but also for the engine itself.







i'm running RB header and presilencer ...that's it (straight pipe to the rear bumper, no muffler) and have enough backpressure in front of the presielncer to open my aux. ports. ( s4 n/a)







I've heard of it not working on other s4's, but it does work fine on mine.







as for header wrap...unless you're getting good qualit headers dont do it, itll rust them out and make them disintegrate.







and like i said, this is only for n/a's, on t2's you want as free-flowing as possible, my t2 has 0 restrictions from the t78 to the rear.







kevin.




Do you think I would benefit from installing my mid-pipe with the cat for added backpressure?





Thanks for everyones replys.





'='
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Old 03-29-2006, 11:27 PM
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Would a high temperature paint help to retard rust?



What temperatures could be expected on exhaust manifold ?





'='
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Old 03-30-2006, 08:38 AM
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Honestly, i'd leave the cat out unless you need it for visual state inspection...



I ran a straight pipe from my manifold to the stock mufflers on my NA and never had an issue... The headers will help w/ exhaust scavenging, creating more backpressure may defeat those affects (which is one of the biggest benefits of headers). After all, you can just hook the aux ports open another way... let the motor breathe.



I'm running a true dual setup on my 12A, and even though i havent driven it yet... I'm confident this will yield the most results...
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Old 03-30-2006, 11:21 AM
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Originally Posted by One320B' post='811085' date='Mar 30 2006, 08:38 AM

Honestly, i'd leave the cat out unless you need it for visual state inspection...



I ran a straight pipe from my manifold to the stock mufflers on my NA and never had an issue... The headers will help w/ exhaust scavenging, creating more backpressure may defeat those affects (which is one of the biggest benefits of headers). After all, you can just hook the aux ports open another way... let the motor breathe.



I'm running a true dual setup on my 12A, and even though i havent driven it yet... I'm confident this will yield the most results...


doesn't mazdatrix show a dyno chart with the true duals from RB on their site. If i remember correctly, it was up to around 40 hp gained or so
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