Header options for RHD N52 cars

[Taskmaster]

Well, I found your problem.

You have the N52B30 that is running the restrictive program. Even without headers, a tune brings up power on the 125i 50hp+ and with headers, another 15-20hp isn't unheard-of.

Your lift is lower, the vanos isn't optimized, you're running less ignition timing, it's a wonder you made any power at all by just putting on headers.

Do a tune. Do it now.

[chris82]

Originally Posted by MBan

This is how they look out of the box? They look nice man, top quality from what I see.

[Taskmaster]

Can I make some recommendations? Lose the secondaries - otherwise increase the diameter of the piping, stock is 56mm which is 2.20" so stock to 2.25. Move the Y pipe back to the stock location for the most toque gains.

And please, please, please get a tune damn it.
check it
http://www.e90post.com/forums/showth...=916863&page=6

And
http://www.e90post.com/forums/showth...=916863&page=8

Do a tune, and stop wasting your time dude!

[MBan]

chris82 - they really do look well made. Lots of attention to detail and quality workmanship. From an optimised design perspective I couldn't say though.

TheAxiom - before I bought my car, I did a bit of research - including on this forum - and worked out the 125i had a detuned N52 and there were excellent gains in a tune alone. If that potential wasn't there, I would have bought an E87 130i.

I did the headers before the tune because that seemed like a logical order. I'm tempted to get a tune now but my plan is to space out the modifications, otherwise I'll do everything I want to and I'll need a new hobby...

[MBan]

Originally Posted by TheAxiom

Can I make some recommendations? Lose the secondaries - otherwise increase the diameter of the piping, stock is 56mm which is 2.20" so stock to 2.25. Move the Y pipe back to the stock location for the most toque gains.

And please, please, please get a tune damn it.
check it
http://www.e90post.com/forums/showth...=916863&page=6

And
http://www.e90post.com/forums/showth...=916863&page=8

Do a tune, and stop wasting your time dude!

Taking the high flow cats out will leave me with none which isn't an option although the exhaust shop recommended going that way too. The factory exhaust has the 2-into-1 join in the resonator and my new y join is pretty close to that spot. I've read some of you conversations on y pipe design and mine looks pretty agricultural in comparison. However, when headers, etc only netted me 6hp I don't have confidence changing y pipe design and location will make much difference but thanks for the suggestion.

What's the theory behind increasing pipe diameter? If the cats are my biggest bottle neck in that section, increasing pipe diameter before and after shouldn't make much difference?

[Taskmaster]

Originally Posted by MBan

Taking the high flow cats out will leave me with none which isn't an option although the exhaust shop recommended going that way too. The factory exhaust has the 2-into-1 join in the resonator and my new y join is pretty close to that spot. I've read some of you conversations on y pipe design and mine looks pretty agricultural in comparison. However, when headers, etc only netted me 6hp I don't have confidence changing y pipe design and location will make much difference but thanks for the suggestion.

What's the theory behind increasing pipe diameter? If the cats are my biggest bottle neck in that section, increasing pipe diameter before and after shouldn't make much difference?

If you can, at worst it's decreasing exhaust gas velocity. Anyhow, the biggest issue here is you need a tune, you're really not going to gain much of anything without it.

[Dafttt]

Originally Posted by TheAxiom

If you can, at worst it's decreasing exhaust gas velocity. Anyhow, the biggest issue here is you need a tune, you're really not going to gain much of anything without it.

I'm under the impression that people were making 10-15whp with SS/AA headers, stock. Regardless, I agree about the tune. It'll optimize both your headers and DISA intake manifold.

[Taskmaster]

No real gains to be had when the stock programming is trying to restrict power.

[chris82]

OP, the ARMA headers are catless right? and you welded some magnaflow cats into the headers? Am I getting that part correctly?

[Taskmaster]

Originally Posted by chris82

OP, the ARMA headers are catless right? and you welded some magnaflow cats into the headers? Am I getting that part correctly?

No, the headers come with Cats. He replaced the secodaries with high flow units.

[Dafttt]

I'm curious as to what this setup sounds like.

[chris82]

Originally Posted by TheAxiom

No, the headers come with Cats. He replaced the secodaries with high flow units.

Ohhhh, thanks for clarifying

[MBan]

Originally Posted by TheAxiom

No, the headers come with Cats. He replaced the secodaries with high flow units.

Actually, it's neither of those.

The headers are cat-less and didn't come with separate cats. The pictures show them exactly how they came from ARMA. Those bulges are either expansion chambers or a sound deadening device, they're not cats.

When I had the headers installed, I added in a pair of magnaflow cats well downstream of the headers. They actually sit about where North American cars have their secondaries.

Aus-delivered 125i only have two cats in the headers, they don't have secondaries. If I had of just installed the headers I would have had no cats which is why I added the Magnaflow cats.

[MBan]

Dafft - I'd heard the same thing about the SuperSprint and Active Autowerke headers but in the applications I've seen, extra cats haven't been added to replace the two that are lost when removing the stock headers. So, my theory is that a portion of the quoted gains come from having two less cats and, therefore, fewer restrictions. This is just an uneducated guess though and I'm happy to be proven wrong. As TheAxiom says, I won't really know how much benefit the ARMA headers give until I get a tune... And I won't really know then either since I don't have a tune alone dyno to compare with a tune + header.

The sound is pretty subtle. It's a bit louder and deeper and sounds kind of gravely. I can also hear a few burbles when coming off the throttle. I'm still not sure if it's given the note and volume I'm after but I won't be making any more exhaust changes for a while regardless.

[Taskmaster]

Who are you going to have do the tune?

[MBan]

At the moment I'm leaning towards Evolve. Unlike Active Autowerke, Evolve have a local distributor which should mean better support if I need it and I can pay in $AU which is a big plus because our dollar is performing pretty poorly at the moment.

[Taskmaster]

Originally Posted by MBan

At the moment I'm leaning towards Evolve. Unlike Active Autowerke, Evolve have a local distributor which should mean better support if I need it and I can pay in $AU which is a big plus because our dollar is performing pretty poorly at the moment.

I'm not exactly impressed with Evolve's header tune personally, I woukd strongly suggest talking to someone who can give you a dyno tune.

[MBan]

Originally Posted by TheAxiom

I'm not exactly impressed with Evolve's header tune personally, I woukd strongly suggest talking to someone who can give you a dyno tune.

A custom dyno tune? I don't know of anyone local to me who has the know-how to tune a 125i to 130i spec, so I'd be a guinea pig and I'm not sure I'm up for that. A local tuning shop I know wants to do more Euro cars and offered to give me a discount if my car can be used for development but being the first is generally means being subjected to teething problems.

Ps. I found out that there is an Australian distributor for AA but I think their tunes require you to send them your ECU?

[Taskmaster]

Originally Posted by MBan

A custom dyno tune? I don't know of anyone local to me who has the know-how to tune a 125i to 130i spec, so I'd be a guinea pig and I'm not sure I'm up for that. A local tuning shop I know wants to do more Euro cars and offered to give me a discount if my car can be used for development but being the first is generally means being subjected to teething problems.

Ps. I found out that there is an Australian distributor for AA but I think their tunes require you to send them your ECU?

You're making this out to be bigger than it should be dude - custom tune will get you the most out of the car. If the shop has a good reputation and a good price, don't turn your nose up at them, this could be a good thing - otherwise yes, a canned tune is a solid option.

If you do an AA tune, they have a few different ways to tune a car, including sending you the cable to flash it yourself.

[MBan]

Originally Posted by TheAxiom

You're making this out to be bigger than it should be dude - custom tune will get you the most out of the car. If the shop has a good reputation and a good price, don't turn your nose up at them, this could be a good thing - otherwise yes, a canned tune is a solid option.

If you do an AA tune, they have a few different ways to tune a car, including sending you the cable to flash it yourself.

Thanks for the advice. I'm not doing the tune for a while so I've some to do a bit more research.

[Taskmaster]

Originally Posted by MBan

Thanks for the advice. I'm not doing the tune for a while so I've some to do a bit more research.

Just don't do Evolve...

[_Ryan_]

Originally Posted by TheAxiom

Just don't do Evolve...

Why?