with the renewed interest in headers everyone seems to be over-looking the options...
06-07-2006, 06:19 AM
#1
AudiWorld Super User
Thread Starter
with the renewed interest in headers everyone seems to be over-looking the options...
<center><img src="http://pictureposter.audiworld.com/711/afcexh.jpg"></center><p>
available to each of us. Before I stumbled into my set of equal-length headers I had a contingency plan. I knew there was almost no chance I'd ever end up with a pair of headers and the $4k-$7k prices for "really" good stainless, mandrel-bent regardless of runner length didnt appeal to me. Especially since not one header-maker other than the guy that did Stasis 12V headers had anything I could see to gauge first-hand the quality I might expect before pre-paying for a custom set. And he wanted $7k a pair for "mild gauge" steel and not even stainless and they werent very attractive weld-wise and not exactly "equal-length!"
Given that and that whining/moaning about the lack of headers or cost of headers was NOT serving my needs I decided to "do something." Do anything except **** and moan and groan about the walls I was hitting at every turn.
The stock cast iron manifolds are not "bad" per se and do flow CFM numbers well in excess of what the car exhales. Its not the best set-up for "scavenging" exhaust gases but hey, like I said; whatcha gonna do when there are NO headers and you MUST have exhaust flow improvement. And remember, complaining does NOT feed the bulldog!
So I did the next best thing... an option I could do in-house with existing tools. Tools that many here acquired for the intake manifold workshop. If ya cant find what you want, innovate!
Buy a set of junk manifolds for your AAH/AFC motor from the junkyard. They're DIRT CHEAP! Why? Because they NEVER fuggin break!! If junkyards cant sell parts to replace broken ones these become boat anchors to them... simply rusting junkyard lumps lying around. I bought 2 pair, 1pr AAH and 1pr AFC exhaust manifolds along with some other bits & pieces for $20!
Now you've got the manifolds and you dont have to rush or remove your existing ones to get these you can take as long as ya like. The car wont suffer even one split-second down time until the project is finished and installation commences.
And the results, well even a half-assed job will easily net you 25-30 additional CFM of flow and a GREAT job can easily double that! But remember, unless you've done other mods to get more air in these arent magic, they cant get even 1 additional CFM of air "out" thats not first going "in."
And while the DIY job of porting/polishing exhaust manifolds is many things "fun" is not among them. Nothing hard or even very difficult about it but it aint FUN! These manifolds after 100k+ miles of heat treating are anything but soft. They are harder 'n Chinese arithmetic to an English teacher! Getting them as smooth as these pics is not a task that can be done in an hour or two. This is grueling work and time consuming but the results speak for themselves as you can see in the pics. While glass-smooth is NOT what you want on the intake side it is EXACTLY what you want on the exhaust side. To get a piece of rough cast iron looking this way takes time and LOTS of it. It takes a LOT of "coarse-to-fine" grinding media to achieve this and even longer if you finish with polishing compounds/rouges of varying grits.
When finished you have as close as you can possibly come to a pair of unequal-length headers without actually having "headers." You've done better than you were provided with and more importantly you've actually done something pro-active. You picked up a set of manifolds and "did something" instead of whining/sniveling or compalining about the lack of 12V mods available to you. Hell if I'd sat back and waited for mods to come to me we'd all have a bored throttle body of dubious quality and Nology spark plug wires and thats it.
Yet another option that'll net the same or even better finish quality is to send the exhaust manifolds to Extrude Hone in California of Pennsylvania. They'll gasket-match, if you provide them a gasket and extrude hone the internals to a mirror finish. I've used them for many things over the years and they do an exceedingly beautiful job on every component they touch. But on these plan to pay about $600 tho I wouldnt complain about the price in light of the profound lack of "other" available options. And you "will" have the best-finished and highest flowing stock exhaust manifolds on the planet!
Do something, anything, just DO it! There's NEVER only "one way" to skin a cat.
available to each of us. Before I stumbled into my set of equal-length headers I had a contingency plan. I knew there was almost no chance I'd ever end up with a pair of headers and the $4k-$7k prices for "really" good stainless, mandrel-bent regardless of runner length didnt appeal to me. Especially since not one header-maker other than the guy that did Stasis 12V headers had anything I could see to gauge first-hand the quality I might expect before pre-paying for a custom set. And he wanted $7k a pair for "mild gauge" steel and not even stainless and they werent very attractive weld-wise and not exactly "equal-length!"
Given that and that whining/moaning about the lack of headers or cost of headers was NOT serving my needs I decided to "do something." Do anything except **** and moan and groan about the walls I was hitting at every turn.
The stock cast iron manifolds are not "bad" per se and do flow CFM numbers well in excess of what the car exhales. Its not the best set-up for "scavenging" exhaust gases but hey, like I said; whatcha gonna do when there are NO headers and you MUST have exhaust flow improvement. And remember, complaining does NOT feed the bulldog!
So I did the next best thing... an option I could do in-house with existing tools. Tools that many here acquired for the intake manifold workshop. If ya cant find what you want, innovate!
Buy a set of junk manifolds for your AAH/AFC motor from the junkyard. They're DIRT CHEAP! Why? Because they NEVER fuggin break!! If junkyards cant sell parts to replace broken ones these become boat anchors to them... simply rusting junkyard lumps lying around. I bought 2 pair, 1pr AAH and 1pr AFC exhaust manifolds along with some other bits & pieces for $20!
Now you've got the manifolds and you dont have to rush or remove your existing ones to get these you can take as long as ya like. The car wont suffer even one split-second down time until the project is finished and installation commences.
And the results, well even a half-assed job will easily net you 25-30 additional CFM of flow and a GREAT job can easily double that! But remember, unless you've done other mods to get more air in these arent magic, they cant get even 1 additional CFM of air "out" thats not first going "in."
And while the DIY job of porting/polishing exhaust manifolds is many things "fun" is not among them. Nothing hard or even very difficult about it but it aint FUN! These manifolds after 100k+ miles of heat treating are anything but soft. They are harder 'n Chinese arithmetic to an English teacher! Getting them as smooth as these pics is not a task that can be done in an hour or two. This is grueling work and time consuming but the results speak for themselves as you can see in the pics. While glass-smooth is NOT what you want on the intake side it is EXACTLY what you want on the exhaust side. To get a piece of rough cast iron looking this way takes time and LOTS of it. It takes a LOT of "coarse-to-fine" grinding media to achieve this and even longer if you finish with polishing compounds/rouges of varying grits.
When finished you have as close as you can possibly come to a pair of unequal-length headers without actually having "headers." You've done better than you were provided with and more importantly you've actually done something pro-active. You picked up a set of manifolds and "did something" instead of whining/sniveling or compalining about the lack of 12V mods available to you. Hell if I'd sat back and waited for mods to come to me we'd all have a bored throttle body of dubious quality and Nology spark plug wires and thats it.
Yet another option that'll net the same or even better finish quality is to send the exhaust manifolds to Extrude Hone in California of Pennsylvania. They'll gasket-match, if you provide them a gasket and extrude hone the internals to a mirror finish. I've used them for many things over the years and they do an exceedingly beautiful job on every component they touch. But on these plan to pay about $600 tho I wouldnt complain about the price in light of the profound lack of "other" available options. And you "will" have the best-finished and highest flowing stock exhaust manifolds on the planet!
Do something, anything, just DO it! There's NEVER only "one way" to skin a cat.
06-07-2006, 06:24 AM
#2
AudiWorld Super User
Thread Starter
Here's what you want...
<center><img src="http://pictureposter.audiworld.com/711/exhpp1.jpg"></center><p>Gasket-matched ports and mirror-finished runners. Actually better gasket-matching and smoother wall micron finish than either of the Lloyd-made headers came with as stock. When you cant get "as good" as someone else's finished product you compensate and improve EVERY place you can!
06-07-2006, 08:27 AM
#4
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Re: After final polishing with jeweler's rouge...
They're beautiful. I love the look of good clean cut metals. It's like "XXX" porno. If I don't succeed, that is defenitely what I will do. But I would like to be someone that has done something and actually make some headers. That would be the coolest.
06-07-2006, 07:43 PM
#7
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Thread Starter
due to its design (dual plane) they wont accept it without a HUGE set-up charge...
they would have to build block-off plates for all 6 secondary runners and 6 primary runners on the lower half and another block-off plate for the secondary runners in the upper half as well as throttle body and ISV plates.
I sent them one 3-4 years ago to look at and they told me there simply wasnt enough interest on 12V Audi engines to make this a feasible IM they could make out on due to initial setup costs to do only one. That no one had ever inquired before about doing one and they interpreted that as insufficient promise of doing additional ones if the built the parts to do them.
When I asked about doing just the one I sent the man said between $4,200/$4,500.
I sent them one 3-4 years ago to look at and they told me there simply wasnt enough interest on 12V Audi engines to make this a feasible IM they could make out on due to initial setup costs to do only one. That no one had ever inquired before about doing one and they interpreted that as insufficient promise of doing additional ones if the built the parts to do them.
When I asked about doing just the one I sent the man said between $4,200/$4,500.
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06-08-2006, 05:31 AM
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That is SMOOTH. At first I didn't notice a difference between the intake
and exhaust, but I see it now. What would the grain or grit difference be between the two? Exhaust looks mirror smooth while intake looks just under that level.
06-08-2006, 05:31 AM
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Could you clarify something for me?
I only have a limited knowledge base when i comes to fluid dynamics, but previously in your posts about the TB and IM you mentioned that it would be best to leave a surface finish of about 160 grit (or something around there). To my understanding that would be to allow the air's boundary layer to adhear to the walls of the part creating better laminar flow correct? Why did you choose to mirror polish these parts as opposed to leaving a slightly abraded surface?
