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#3379666 - 05/23/14 11:01 PM Re: Why Aren't Headers Standard Equipment? [Re: morris]
Quest Offline


Registered: 12/19/04
Posts: 7356
Loc: beaver land EH?
Originally Posted By: morris
WHY? cause car makers make cars ONLY good enough.


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#3379716 - 05/24/14 12:00 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
dailydriver Offline


Registered: 03/14/06
Posts: 8752
Loc: Bucks County, Pa.
If one is talking about full length, tuned, scavenging LONG TUBE headers, then the OEMs will NEVER use them now, since they do NOT allow the catcon(s) to be placed close enough to the exhaust ports in order to 'light off' properly, and STAY hot enough to function once the engine is running for a while.
They would never pass a 49 state sniffer test, let alone the crazy C.A.R.B standards.

If one is talking about factory/OEM length 'shorties', yes, they do allow the catcons to be placed close enough for light off and proper function (despite their worse heat retention than cast iron manifolds), BUT the OEMS would be VERY hesitant to use them due to; cost of 304/321/inconel stainless tubing material, the brittleness of this material, the aforementioned higher under hood noise issues, and the potential warping of the thinner mounting flanges and all of the exhaust/vacuum leak emissions/ECM problems that come with those leaks. frown
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#3379720 - 05/24/14 12:07 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
OVERKILL Offline


Registered: 04/28/08
Posts: 32659
Loc: Ontario, Canada
Stock M5 exhaust (foreground):



You'll note the cats are a fair ways back from the headers, which I would categorize as "mid length", as they aren't shorties and they aren't long-tubes either.
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#3379773 - 05/24/14 05:29 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
SteveSRT8 Offline


Registered: 10/10/08
Posts: 17868
Loc: Sunny Florida
Every SRT8 you see has a nifty pair of factory shorties wrapped in a sheet metal shroud. Flow well all the way to 600 crank hp or so. Quiet as a mouse!

Since many new engine designs have no exhaust manifold at all these days expect fewer headers!
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#3379794 - 05/24/14 06:43 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
edwardh1 Offline


Registered: 01/17/03
Posts: 2394
Loc: Coastal South Carolina
noise and rust
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#3379836 - 05/24/14 08:02 AM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
fdcg27 Offline


Registered: 09/25/09
Posts: 12801
Loc: OH
Apparently, some low-po cars also come with headers from the factory.
My 318i has headers, although I guess it's fairly hi-po for its displacement, and it does make a lovely snarl when wound through the gears.
The rest of what was said above explains why most engines come with cast iron exhaust manifolds.
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#3379839 - 05/24/14 08:05 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Miller88 Offline


Registered: 04/09/08
Posts: 11598
Loc: Onondaga County
Mazda skyactiv has 4-2-1 headers and play with valve timing to get the converter to light off.
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#3379910 - 05/24/14 10:25 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
GMBoy Offline


Registered: 11/22/04
Posts: 7144
Loc: Texas
A lot of the reasons OEM's do not use headers is due to noise. Traditional exhaust manifolds are quieter and cheaper to make. Also a lot of late model manifolds look almost like headers anyhow. I just looked under the hood of a new 2015 Tahoe as it went down the line.


Edited by GMBoy (05/24/14 10:27 AM)

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#3380070 - 05/24/14 02:11 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
supton Offline


Registered: 11/09/08
Posts: 9710
Loc: NH
How many cars "need" headers? A few hp gain at an rpm that few use.
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#3380211 - 05/24/14 06:19 PM Re: Why Aren't Headers Standard Equipment? [Re: supton]
fdcg27 Offline


Registered: 09/25/09
Posts: 12801
Loc: OH
Originally Posted By: supton
How many cars "need" headers? A few hp gain at an rpm that few use.


How many cars "need" more than four cylinders and two liters of displacement?
It isn't always or even usually about need, it's about want.
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#3380247 - 05/24/14 07:25 PM Re: Why Aren't Headers Standard Equipment? [Re: circuitsmith]
Trav Offline


Registered: 11/20/06
Posts: 14624
Loc: MA, Mittelfranken.de
Originally Posted By: circuitsmith

Modern cast manifolds are far better than the "log" manifolds of yesteryear.

True but the old SBC iron Ram Horns are hard to beat and perform as well as or better than many tube headers.
Header performance without the drawbacks.
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#3380470 - 05/25/14 12:33 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
TiredTrucker Offline


Registered: 01/04/08
Posts: 2703
Loc: Central Iowa
The primary reason OEM's don't do stuff like this, except in their high end offerings, is production cost, pure and simple. OEM's, like most any business right down to a mom and pop hotdog stand, will try to trim every dollar from production cost they can. To that end, they will only use what they need to get the results they need. Even a $1 part, if it is not necessary, will be trimmed off of production. When you factor the number of vehicles produced, that $1 saving runs into the millions of dollars. Sure, this is all about profits, but they have to compete in the marketplace with everyone else making vehicles. And the majority of potential customers don't think in terms of headers, superchargers, etc. They want a vehicle that does what they want, and the cheapest price they can get it for.

Hey! That is exactly what the OEM's are doing themselves!

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#3380689 - 05/25/14 10:00 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Bamaro Offline


Registered: 08/03/03
Posts: 1353
Loc: Balto.
Its a cost - benefit issue. (Cost includes durability)
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#3381064 - 05/25/14 07:37 PM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
dailydriver Offline


Registered: 03/14/06
Posts: 8752
Loc: Bucks County, Pa.
Originally Posted By: OVERKILL
Stock M5 exhaust (foreground):



You'll note the cats are a fair ways back from the headers, which I would categorize as "mid length", as they aren't shorties and they aren't long-tubes either.


Does Bimmer play with the timing/firing order/etc. in order to get the catcons to light off, like Mazda does with the high compression skyactivs??

Yes, those are about mid lengths, but it perplexes me that they did not put the catcon right at the flange of the header (already quite far away from the exhaust port) for faster/more efficient light off, and instead put it way back in the connecting/intermediate pipe. ???

I am guessing that unibody/subframe clearance and interference problems are the reason?
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M1-206 oil filter
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#3381115 - 05/25/14 08:27 PM Re: Why Aren't Headers Standard Equipment? [Re: dailydriver]
OVERKILL Offline


Registered: 04/28/08
Posts: 32659
Loc: Ontario, Canada
Originally Posted By: dailydriver
Originally Posted By: OVERKILL
Stock M5 exhaust (foreground):



You'll note the cats are a fair ways back from the headers, which I would categorize as "mid length", as they aren't shorties and they aren't long-tubes either.


Does Bimmer play with the timing/firing order/etc. in order to get the catcons to light off, like Mazda does with the high compression skyactivs??

Yes, those are about mid lengths, but it perplexes me that they did not put the catcon right at the flange of the header (already quite far away from the exhaust port) for faster/more efficient light off, and instead put it way back in the connecting/intermediate pipe. ???

I am guessing that unibody/subframe clearance and interference problems are the reason?


Subframe and transmission.

The engine has a big electric air pump that runs for a bit on cold start, I assume to aide in lighting off the cats.
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