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#3379546 - 05/23/14 07:47 PM Why Aren't Headers Standard Equipment?
JerryBob Online   content


Registered: 04/11/13
Posts: 484
Loc: Washington, DC
I was perusing a Toyota Tacoma site and noticed that some guys upgraded their 4-Cyl by purchasing after-market exhaust headers (HERE) . They claim to get more power and better mpg.

So, other than the obvious issue of $450, I am wondering why these wouldn't be standard equipment, or at least optional? I know there is a downside (reduced filtration) to putting on a K&N racing filter on the intake side, but is there any cost (other than dollars) to putting headers on the exhaust side?

Auto manufacturers seem to go to great lengths to increase their CAFE mileage. Why not use headers?
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#3379550 - 05/23/14 07:50 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
DragRace Offline


Registered: 11/27/06
Posts: 2327
Loc: 1/4 Mile Track
Most dealerships dont like modifications of any kind.


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#3379551 - 05/23/14 07:51 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
NHGUY Offline


Registered: 10/09/11
Posts: 3381
Loc: USA
Noise.Tinny headers don't insulate valvetrain sounds like cast iron or thicker designs do.

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#3379555 - 05/23/14 07:54 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
901Memphis Online   content


Registered: 08/14/10
Posts: 6067
Loc: Northern Kentucky
Noise, durability, cost. Cast iron works.
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#3379561 - 05/23/14 08:05 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
artificialist Offline


Registered: 09/23/07
Posts: 6899
Loc: Florida
Headers dissipate heat more quickly than iron manifolds, and that can lead to slow cat light off times. Also, that extra heat may harm things under the hood in a car not built for it.

Mazda found a way around this when they created the CX-5. Search for a picture, and you will see. They gained the advantage of 4-2-1 headers without comprising cat light off time.

Some cars left the factory with pipes that are similar to headers. The 2.2 and 2.3 engine found in Honda Accords are built that way.
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#3379573 - 05/23/14 08:29 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
demarpaint Offline


Registered: 07/03/05
Posts: 21338
Loc: NY
Some compaines are incorporating the exhaust mainfold into the cylinder head, like the Chrysler Pentastar engine. I guess it cuts down on weight and costs. It would be impossible to install headers on that type of engine.
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#3379575 - 05/23/14 08:35 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
OVERKILL Online   content


Registered: 04/28/08
Posts: 26459
Loc: Ontario, Canada
Some cars come with headers from the factory. Many don't. The 302HO in the 80's came equipped with factory headers (albeit, not very good ones) and many hi-po cars come with them factory like my M5 which has 4-2-1 headers stock.

As others have noted, cast iron is the most common manifold material because of its good heat retention, durability and low cost of manufacture.
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#3379582 - 05/23/14 08:44 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
FXjohn Offline


Registered: 05/25/07
Posts: 1236
Loc: NE Indiana
too many headaches in the long run

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#3379584 - 05/23/14 08:46 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
hattaresguy Offline


Registered: 06/01/11
Posts: 5137
Loc: CT
Hi end cars do.


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#3379590 - 05/23/14 08:49 PM Re: Why Aren't Headers Standard Equipment? [Re: hattaresguy]
JerryBob Online   content


Registered: 04/11/13
Posts: 484
Loc: Washington, DC
Originally Posted By: hattaresguy
Hi end cars do.






That's about 3 times the number of cylinders that I have.... grin
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#3379591 - 05/23/14 08:50 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
circuitsmith Offline


Registered: 12/17/09
Posts: 152
Loc: Wash, DC
Why no headers?
Cost. Noise. Emissions. Durability.

Thin walled tube headers are more involved to produce and use more expensive metal than a cast header.

Tube headers make more noise under the hood as well as at the tailpipe end.
Most car buyers (especially over 30 y.o.) don't want all that noise.

Tube headers extract and cool the exhaust gases from the cylinder more quickly.
That increases HC emissions and makes the cat converter take more time to warm up.
They can also raise under hood temps.

Modern cast manifolds are far better than the "log" manifolds of yesteryear.
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#3379612 - 05/23/14 09:25 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
LT4 Vette Offline


Registered: 09/12/04
Posts: 12520
Loc: USA
I would put headers on a V-8 for performance but not spend that $$$ on a 4 cylinder engine.

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#3379623 - 05/23/14 09:52 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Kiwi_ME Offline


Registered: 10/24/08
Posts: 689
Loc: New Zealand
Amusing the interest in V8s with headers given that most high-volume V8 designs have 360 degree cranks and therefore uneven firing per bank. Same issue with V6s. Whatever good headers do, it's not going to be the same for every cylinder.

Not a problem with the in-line three, four or six however, and many smaller naturally-aspirated fours do have nicely-welded tubular designs.

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#3379643 - 05/23/14 10:30 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
morris Offline


Registered: 08/24/08
Posts: 3681
Loc: ks, wichita
WHY? cause car makers make cars ONLY good enough.

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#3379653 - 05/23/14 10:42 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
ddtmoto Offline


Registered: 12/20/09
Posts: 237
Loc: Utah
2011+ 5.0 Mustang also have stainless headers. Quad cam heads are too wide tho, can't really see the headers. Dang...
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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: 6413
Loc: beaver land EH?
Originally Posted By: morris
WHY? cause car makers make cars ONLY good enough.


popcorn2 popcorn2 popcorn2
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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: 7071
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 Online   content


Registered: 04/28/08
Posts: 26459
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: 15150
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: 1649
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: 9414
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: 6805
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: 6657
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: 4907
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: 9414
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: 9987
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: 1015
Loc: Kellogg, IA
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: 1091
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: 7071
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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#3381115 - 05/25/14 08:27 PM Re: Why Aren't Headers Standard Equipment? [Re: dailydriver]
OVERKILL Online   content


Registered: 04/28/08
Posts: 26459
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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#3382104 - 05/27/14 11:07 AM Re: Why Aren't Headers Standard Equipment? [Re: fdcg27]
supton Offline


Registered: 11/09/08
Posts: 4907
Loc: NH
Originally Posted By: fdcg27
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.


I won't disagree with you, my contention is with the OP. I don't need 2-3 more hp at the cost of reliability/durability/initial purchase price. I don't want much less "need" headers.
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#3382113 - 05/27/14 11:14 AM Re: Why Aren't Headers Standard Equipment? [Re: artificialist]
zzyzzx Offline


Registered: 05/18/12
Posts: 1703
Loc: Baltimore, Maryland, USA
Originally Posted By: artificialist
Some cars left the factory with pipes that are similar to headers. The 2.2 and 2.3 engine found in Honda Accords are built that way.


My 1995 Ford Escort looks like this as well.

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#3382157 - 05/27/14 12:10 PM Re: Why Aren't Headers Standard Equipment? [Re: circuitsmith]
rslifkin Offline


Registered: 06/27/10
Posts: 2218
Loc: Stamford, CT / Rochester, NY
Originally Posted By: circuitsmith
Tube headers make more noise under the hood as well as at the tailpipe end.

Tube headers extract and cool the exhaust gases from the cylinder more quickly.
That increases HC emissions and makes the cat converter take more time to warm up.


Headers aren't necessarily louder. On my Jeep, the under-hood noise is about the same as it was with the stock cast iron manifolds. Tailpipe noise actually dropped a hair when I put the headers on.

It does throw a little more heat into the engine bay, however. In my case, the headers allow the piping to be routed a bit differently than how the factory handled things, terminating the y-pipe further forward and allowing the cat to be moved closer (which led to it lighting off faster than stock and taking less drive time to become non-smelly) as well as making space to add a resonator where the cat originally sat to quiet it down further.
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#3382688 - 05/28/14 02:20 AM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
Scott_Tucker Offline


Registered: 12/31/09
Posts: 872
Loc: Santa Cruz, Ca.
I worked for Dinan Engineering when the E39 M5 was new. Our headers increased power almost 40 HP. The stock manifolds are extremely restrictive and are designed for emissions only.
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#3383142 - 05/28/14 02:24 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Doublehaul Offline


Registered: 05/19/14
Posts: 22
Loc: Mi.
Having owned several drag/race cars in the past its been my experience that headers are more likely to warp, crack, rust out and be a PITA than a cast manifold.

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#3383313 - 05/28/14 05:40 PM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
dailydriver Offline


Registered: 03/14/06
Posts: 7071
Loc: Bucks County, Pa.
Originally Posted By: OVERKILL
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.


Yes, it would HAVE TO BE a VERY 'high flow' air pump in order to help light off catcons that far away from the exhaust ports. wink
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#3383375 - 05/28/14 06:31 PM Re: Why Aren't Headers Standard Equipment? [Re: Scott_Tucker]
OVERKILL Online   content


Registered: 04/28/08
Posts: 26459
Loc: Ontario, Canada
Originally Posted By: Scott_Tucker
I worked for Dinan Engineering when the E39 M5 was new. Our headers increased power almost 40 HP. The stock manifolds are extremely restrictive and are designed for emissions only.


I don't recall the gains, from many posts on m5board, being that high for the headers alone shrug

Maybe for the entire exhaust system? They have that squished crossover pipe, the resonator, and the massive quad mufflers. I'm sure that stuff is restrictive. But I don't find the stock headers look that bad quite frankly. Not compared to the rest of the exhaust system anyways.
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#3385087 - 05/30/14 05:55 PM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
dailydriver Offline


Registered: 03/14/06
Posts: 7071
Loc: Bucks County, Pa.
Originally Posted By: OVERKILL
Originally Posted By: Scott_Tucker
I worked for Dinan Engineering when the E39 M5 was new. Our headers increased power almost 40 HP. The stock manifolds are extremely restrictive and are designed for emissions only.


I don't recall the gains, from many posts on m5board, being that high for the headers alone shrug

Maybe for the entire exhaust system? They have that squished crossover pipe, the resonator, and the massive quad mufflers. I'm sure that stuff is restrictive. But I don't find the stock headers look that bad quite frankly. Not compared to the rest of the exhaust system anyways.


It is close to that figure (40 rwhp) on LSxes for long tubes (at least the best ones) alone, as long as it is TUNED as well. wink
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#3385986 - 06/01/14 12:35 AM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
Scott_Tucker Offline


Registered: 12/31/09
Posts: 872
Loc: Santa Cruz, Ca.
Originally Posted By: OVERKILL
Originally Posted By: Scott_Tucker
I worked for Dinan Engineering when the E39 M5 was new. Our headers increased power almost 40 HP. The stock manifolds are extremely restrictive and are designed for emissions only.


I don't recall the gains, from many posts on m5board, being that high for the headers alone shrug

Maybe for the entire exhaust system? They have that squished crossover pipe, the resonator, and the massive quad mufflers. I'm sure that stuff is restrictive. But I don't find the stock headers look that bad quite frankly. Not compared to the rest of the exhaust system anyways.


Since Dinan only produces their parts in 'stages' you generally wouldn't buy just the headers. The whole 5 stage package produce an additional 70 HP. I can tell you that the headers were the single biggest improvement and they added about 40 HP just by themselves.

We kept the squished pipe because it was there for a reason and eliminating it didn't add any usable power. It was their to smooth out exhaust flow in the pipe and eliminating would result in check engine lights due to turbulence near the O2 sensor.

The stock manifolds were incredibly restrictive with unequal tubes of improper length. The Dinan headers are equal length tubes of the proper diameter made of extremely high quality stainless steel and jet coated. It is built up from weld els which means the diameter of the pipes is consistent throughout the header.

The muffler weren't all that restrictive.
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#3386557 - 06/01/14 09:14 PM Re: Why Aren't Headers Standard Equipment? [Re: Scott_Tucker]
OVERKILL Online   content


Registered: 04/28/08
Posts: 26459
Loc: Ontario, Canada
Originally Posted By: Scott_Tucker
Originally Posted By: OVERKILL
Originally Posted By: Scott_Tucker
I worked for Dinan Engineering when the E39 M5 was new. Our headers increased power almost 40 HP. The stock manifolds are extremely restrictive and are designed for emissions only.


I don't recall the gains, from many posts on m5board, being that high for the headers alone shrug

Maybe for the entire exhaust system? They have that squished crossover pipe, the resonator, and the massive quad mufflers. I'm sure that stuff is restrictive. But I don't find the stock headers look that bad quite frankly. Not compared to the rest of the exhaust system anyways.


Since Dinan only produces their parts in 'stages' you generally wouldn't buy just the headers. The whole 5 stage package produce an additional 70 HP. I can tell you that the headers were the single biggest improvement and they added about 40 HP just by themselves.

We kept the squished pipe because it was there for a reason and eliminating it didn't add any usable power. It was their to smooth out exhaust flow in the pipe and eliminating would result in check engine lights due to turbulence near the O2 sensor.

The stock manifolds were incredibly restrictive with unequal tubes of improper length. The Dinan headers are equal length tubes of the proper diameter made of extremely high quality stainless steel and jet coated. It is built up from weld els which means the diameter of the pipes is consistent throughout the header.

The muffler weren't all that restrictive.


good to know!
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#3386683 - 06/02/14 01:01 AM Re: Why Aren't Headers Standard Equipment? [Re: OVERKILL]
SuzukiGoat Offline


Registered: 02/04/13
Posts: 389
Loc: Louisiana
On my vehicles, the cast manifolds are works of art. So intricate and beautiful that they crack at the fourth exhaust port. Given the age, replacement isnt an option. I run long tube headers. They sound better, little else can be said for them.
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#3391431 - 06/07/14 12:06 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Now Offline


Registered: 03/19/14
Posts: 10
Loc: Alabama
Dear moderators, please forgive me for posting this horrible video. I have this terrible problem. When I hear the word "Header" I think red hot glowing.

http://www.youtube.com/watch?v=qyQi4js2fn0
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#3392014 - 06/08/14 08:50 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Cujet Offline


Registered: 02/15/03
Posts: 4188
Loc: Jupiter, Florida
I fly a 4cyl 200HP Cessna Cardinal RG. It originally came with one muffler per side, with a single tailpipe. Not exactly a tuned exhaust.

I recently purchased a "powerflow" exhaust, which is simply a tuned 4-into-1 header, with very long primary tubes, tuned for the LOW RPM of aircraft engines.

The difference in performance has been significant. I have no way to measure HP, but I can measure rate of climb and service ceiling. I gained about 300 feet per min rate of climb. Also gained about 1500 feet service ceiling.

It also increased my fuel consumption. More HP requires more fuel.

Contrary to claims about increased economy, I do not see any practical flight conditions where I can achieve better fuel economy. Put another way, a given amount of HP requires a given amount of fuel. The restrictive stock exhaust simply limited the maximum output of the engine, but when the throttle is reduced, to a given output, fuel flow matches the work required.
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#3392085 - 06/08/14 10:30 AM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
Jarlaxle Offline


Registered: 02/02/12
Posts: 4141
Loc: New England
On a plane, sure...but I have seen MPG gains from free-flow exhaust!
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#3392537 - 06/08/14 08:52 PM Re: Why Aren't Headers Standard Equipment? [Re: Jarlaxle]
Garak Offline


Registered: 12/05/09
Posts: 11644
Loc: Regina, Saskatchewan, Canada
Airplane engines are a little different, though. They are a wonderful example of an ICE turning something and adjusting output based solely on throttle and mixture (yes, Cujet, I know about variable pitch props, I'm just simplifying). No transmissions, gearing, or computer controlled injection. wink

Most of the textbook stuff one reads on ICE theory fits much more closely to the airplane engine than what we see in a car these days. Most of us certainly have seen improvements in various vehicles thanks to exhaust.
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#3392663 - 06/09/14 12:16 AM Re: Why Aren't Headers Standard Equipment? [Re: rslifkin]
TiredTrucker Offline


Registered: 01/04/08
Posts: 1015
Loc: Kellogg, IA
Originally Posted By: rslifkin


It does throw a little more heat into the engine bay


Thank God for header wrap, eh?
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#3393094 - 06/09/14 02:36 PM Re: Why Aren't Headers Standard Equipment? [Re: JerryBob]
PandaBear Offline


Registered: 08/05/02
Posts: 12473
Loc: Silicon Valley
Why? Because it is not a good use of the R&D and production money. You can get much more out of the same cost if your car is designed with better engine (i.e. variable valve timing or variable intake opening) than different tubing length / width.

Also a much bigger header only increase top end HP at the expense of bottom / mid range, so why bother?

Mazda use it for their skyactiv motor because of their piston and injector design that can benefit more from it. It is not as useful for the more common / old school engine design.
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