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myth buster: exhaust manifolds...


PatAllen

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I think I need to jump in here. The design of these manifolds has a bit more to it then just how much air you can push thru. I think if you could put each of your manifold on the same engine and run them on a dyno that you would see some difference. The affect on the engine as the gases pulse thru the manifold I don't think will show up on your flow bench. It is also been scientifically proven the the ceramic coating used by some manufactures increase engine performance. That also will not show up on your flow bench, again cause there is a bit more to the science then how much air you can push thru it. Just my 02 cents on the subject, thanks tom 02Again.com

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Pat -

I appreciate the steps you've taken to provide CFM numbers in the various parts (intake and exhaust manifolds). One part may provide different results when bolted to different engines. The total package of M10 intake/cylinder head/exhaust was optimized by BMW over many years while trying to satisfy the EPA requirements of USA-bound cars. There have been many writings claiming of increased performance of any 2002 if you use the ti/tii exhaust manifold and ignition distributor - not sure if they are 100% true.

I recommend commercial ceramic-coating applied inside and outside the exhaust manifold to help reduce underhood temperatures as well as longevity. Increased performance? Not sure.

Before

IMG_0624.jpg

After

c19916cd.jpg

Jim Gerock

 

Riviera 69 2002 built 5/30/69 "Oscar"

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I recommend commercial ceramic-coating applied inside and outside the exhaust manifold to help reduce underhood temperatures as well as longevity.

I had the 4-1 header of one of my bikes dipped and coated with the standard aluminum finish. It remained intact for years.

I also did the stock header of my Ducati done in "stock" color. People have asked me how it stays so clean.

We also did the tops of the pistons.

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  • 4 months later...

AS i was cleaning up my home basement today, i fallen on my set of manifolds and decided to test-flow them again, just to see if my flowbench was "stable" (almost a year ago i made the test).

The results are the same...

Note that i am not stipulating one manifold is better than one other, i just rely of their flow capability alone.

Upon further investigation and measurements, the smog manifold with its injection tubes removed has to flow more, there is no crimped area at the inlet of the ports at all, the surface area is much larger.

All other manifolds, including the Tii one has thoses bumps to clear the studs on the exterior of the runner. The smog one dont. With just a deburr of the casting flash and some honing, it outflows the Tii manifold i have.

2006 530xi, 1974 2002 Automatic summer DD
1985 XR4TI, 22psi ±300hp
1986 yota pick-up, 2006 Smart FT diesel

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I've been cutting an old head apart with my new- to- me bandsaw.

It might be fun to section a manifold, too. I know I have at least

one cracked one....

Why they let me have things like bandsaws I have no idea.

It DOES cut through valve seats, much to my surprise. I thought

they would have been too hard. The spring seats, though,

cause problems, so I have to take them out first.

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Excellent information. Now to send my Tii exhaust manifold to extrude hone get it to flow better and afterthat Jett Hott to give it the "chrome" look. Yeah bling bling flow flow. Hopefully it will flow better than a header because the header is $900 cheaper.

Enthusiastic as hell but dumber than a box of rocks. 1974 tii Atlantik Blue 2780099. Gobi Lux Interior.

1974 Tii Chamonix 2781879 Sunroof coupe, Gobi Interior- parting out

1994 318IS M42 project abandoned. parting out

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I think I need to jump in here. The design of these manifolds has a bit more to it then just how much air you can push thru. I think if you could put each of your manifold on the same engine and run them on a dyno that you would see some difference. The affect on the engine as the gases pulse thru the manifold I don't think will show up on your flow bench. It is also been scientifically proven the the ceramic coating used by some manufactures increase engine performance. That also will not show up on your flow bench, again cause there is a bit more to the science then how much air you can push thru it. Just my 02 cents on the subject, thanks tom 02Again.com

I think you're right, Tom.

I know for sure that there is a performance difference between the various cast iron manifolds. When I switched from a 73 smogger manifold (with air nozzles plugged and ground down) to a "tii" manifold that I got on ebay, I noticed a HUGE performance improvement. Note: This was on an engine with 9.5:1, and a mystery regrind cam.

The "tii" manifold also lacked the little "stud bulges" inside, the runners were round and wide open, not constricted looking inside like the stock manifold. I suspect that presence of these bulges is what determines a good performing manifold from a power robbing manifold.

From the anecdotes in the archives, I also suspect that there are some "smog" manifolds out there that do not have these bulges, and therefore perform equally as well as "tii" manifolds. And there might even be some "tii" manifolds that have these bulges, and therefore don't perform any better than a non-tii, de-smogged manifold.

I just ordered a new "tii" manifold. Judging by the stories in the archives, I don't have full confidence that it will perform as well as the old "tii" manifold that I once had installed (or as well as the 02Agian shorty). Seems like kind of a performance crap shoot with cast iron of any flavor. For all I know, these new cast iron manifolds that are out there are just smog manifolds that haven't been drilled out. Who knows. At any rate, I plan to do some porting to it just for good measure.

73 Riviera Daily driver 2002 - MS, 9.5:1, cam, LSD

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fwiw all Tii manifolds ive seen in my life had the bulges inside of them, exactly like the one pictured above with the nice silver paint.

i would actualy realy like to see a Tii manifold without thoses.

2006 530xi, 1974 2002 Automatic summer DD
1985 XR4TI, 22psi ±300hp
1986 yota pick-up, 2006 Smart FT diesel

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fwiw all Tii manifolds ive seen in my life had the bulges inside of them, exactly like the one pictured above with the nice silver paint.

i would actualy realy like to see a Tii manifold without thoses.

I no longer have the manifold that I was referring to. Perhaps it did have some degree of bulging, but 2 things are for sure:

1) The tii one performed much better than the non-tii one, and

2) The bulges (if they were there) were much less pronounced than in the non-tii manifold that I had. I remember remarking on the difference at the time.

73 Riviera Daily driver 2002 - MS, 9.5:1, cam, LSD

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I have one confirmed tii exhaust manifold... it has the bolt bulges.

It also has a 'pudge' on the outside surface that none of the other non-

air manifolds do.

I long ago gave up on the cast manifold issue and, if weight or power's a

concern, just run something tubular.

The 02Again part's pretty, there are 4-1 and tri-y options-

it's just not worth the price premium for an 'apples to slightly bigger apples'

gain.

That's me

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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  • 8 years later...
On 1/14/2012 at 6:33 PM, Tito3 said:


... Now to send my Tii exhaust manifold to extrude hone get it to flow better and after that Jet Hot...

 


Pulling up an oldie here. But it appears that Tito3 has not been active on this forum since 2012. So I might not get closure from Tito. ?

 

My first and primary question: have others here tried the “Extrude Hone” process on ‘02 components, e.g., cast iron exhaust manifolds, cast aluminum intake manifolds, cast aluminum tii intake runners? To illustrate:

 

 

With my tii beginning its engine overhaul, I’ve been wondering if there might be any benefit whatsoever in tweaking the intake and exhaust flow beyond a focus on head porting and port-matching. Note that this is a “stock” rebuild: stock camshaft, stock Kugelfischer, 9.5:1 compression ratio. And mine is a ‘73 tii, so E12 head, aluminum intake runners, one-piece intake manifold.

 

Let’s take one component at a time:

 

1. Throttle body. Anything? Rebuild it and leave it alone?

2. Aluminum plenum. Is the throttle-body port already a nearly-perfect match for the throttle body (first photo)? Would a Jet-Hot internal coating provide any benefit?

3. Aluminum intake runners. Extrude Hone? Port-match on both the plenum and intake manifold ends? Again, Jet-Hot internal coating? (Second photo)

4. Aluminum intake manifold. Port? There’s a bit of a ridge in there on most I’ve seen (circled in blue on third photo). Is that a design feature or simply a casting tolerance? I intended to port-match on the head side, but should I also be port-matching the runner side? Again, Jet-Hot coating?

5. Cast iron exhaust manifold. Do we need to leave an anti-reversionary lip at the head-manifold face? Again, Extrude Hone? Again, Jet-Hot coating? (Fourth photo)

6. Downpipe. Yes, I realize a good header could possibly improve on the factory manifold-downpipe combination, but my car is going to appear stock, so a header is off the table. I had the downpipe (and manifold) on my ‘76 Jet-Hotted inside and outside. Benefit? I have no clue.

7. What else?

 

Thanks and regards,

 

Steve

 

34FB1D53-E3C6-41B3-AE7E-6DA50B5D9485.jpeg

54514A04-A392-4560-85F3-D67D4C0336DF.jpeg

8C565E9B-E529-4EA2-AF4A-10CBA689E939.jpeg

341059DB-AEF1-4DDC-85B5-C9CB068073A6.jpeg

1976 2002 Polaris, 2742541 (original owner)

1973 2002tii Inka, 2762757 (not-the-original owner)

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Downpipe it is

These are 4 different exhaust options 2 tri-y and 2 tii headers with different downpipes
on an otherwise (apart from jetting to acommodate for the different behavior of the exhausts) unchanged but extensively tuned engine. But if you don't rev beyond 5.5k on a most of the times everything's good if you leave it standard.

Screenshot (360).png

Edited by uai
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1 hour ago, uai said:

Downpipe it is

These are 4 different exhaust options 2 tri-y and 2 tii headers with different downpipes
on an otherwise (apart from jetting to acommodate for the different behavior of the exhausts) unchanged but extensively tuned engine. But if you don't rev beyond 5.5k on a most of the times everything's good if you leave it standard.

Screenshot (360).png

Air flow begins to crap out on all of them at around 5300 rpm given AFR is the same for all.

A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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4 hours ago, Conserv said:

Let’s take one component at a time:

 

7. What else?

 

Thanks and regards,

 

Steve

 

 

 

 

 

Steve - if it was me - I'd do the port-matching at each interface, using gaskets as templates.  Make's it better - even if just for the engineering precision over any huge flow gain. For the intake, you don't want super smooth - a roughened surface finish is preferable, so only deburring in there.  Use those ceramic coats on the exhaust side if you like.

 

I have no experience to offer on Extrude-hone... Nor do I pretend to know if 'port-matching' is frowned on for such tii parts by the purists or white-glove crowds.

 

Are you planning to retain the 'patina' on all the exposed aluminum, or restore it to a factory-fresh look?

 

Happy Holidays btw,

Tom

 

 

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Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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