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Old 06-18-2008, 03:59 AM   #21
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Quote:
Originally Posted by m2cupcar View Post
Cheaper but at a price: less work and 50% more cells.
How is "less work" a cost/price?? :-p

Any chance of you both measuring the OD of the middle part?

It's not much different to comparing the flow through an intercooler via overall area and surface area. I forget the figures, but my GTR cooler is something like 25% or 33% larger in area through the core than through the end pipes. Those cats look similarly proportioned. The flow should just about match a straight piece of pipe if you oversize it the right amount for the effect the walls of the cells have on average velocity.

Considering 3" is plenty big anyway, I'd hazard a wild guess and say the 300 cell one would still be adequate in flow for more or less any bp of fe, and way way big enough for any b6. I'd also guess that the 200cell one would be pretty much similar to a piece of tube. Wild guesses though :-)

Given the new noise laws that JUST came into place in NZ I think I might end up with a cat just to muffle things a bit further.

Fred.
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Old 06-18-2008, 07:46 AM   #22
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Not going to be easy for Rob to measure the one under his car. Looks like mine is 4" - .053x2 for the tubing thickness. If you zoom in and take your time you can count the "winds" of material in the core. I'm far to lazy though.
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Old 06-18-2008, 08:27 AM   #23
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Originally Posted by Braineack View Post
welding and v-bands are overrated.

c-clamps are where it's at....mmmm and look at all the diff fluid.
Easy Seal are much better than c-clamps. More clearance with the bolts still facing down. Pretty cheap too.



Frank
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Old 06-18-2008, 09:14 AM   #24
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Originally Posted by fmowry View Post
Easy Seal are much better than c-clamps. More clearance with the bolts still facing down. Pretty cheap too.

Frank
Those are what I use.
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Old 06-18-2008, 10:09 AM   #25
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I had ordered two band clamps when i bought the resonators....dunno where they are....I guess i should call, i was expecting them friday before i installed it.
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Old 06-18-2008, 10:58 AM   #26
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re: Cost - my obscure effort at confirming the differences. Believe it or not cost is used in reference to things other than $.

All the 3" metal cores have a 4" center section/body AFAIK. I might have considered the magnaflow but didn't realize it existed- and the sales dood didn't mention it. But at the time I was aiming at a 200 cell unit based on what I was reading. Of course seeing the difference between this 200 and the old 400 ceramic, I doubt there's much of a difference between the 200 and 300 metal cores (at our power levels).
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Old 06-18-2008, 11:01 AM   #27
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with our powers combined.....we need to find a 200 cell with a magnaflow body, averaging a $93 price tag.
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Old 06-18-2008, 11:21 AM   #28
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figure out what size hole saw needs to go through the center of the 300 cell to make it 200
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Old 06-19-2008, 07:36 AM   #29
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Originally Posted by m2cupcar View Post
figure out what size hole saw needs to go through the center of the 300 cell to make it 200
Why not just use http://www.siliconeintakes.com/produ...ee3024d3f8d80a:


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Old 06-19-2008, 09:32 AM   #30
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that's awesome^ that'd pass here... they just stick a "bomb" mirror under the car and look. I decided to be legal on this one and keep the guts, but I'd considered running a 3" pipe thru an old cat can I have. Tho at that price $40, it wouldn't be worth the work. I'm surprised its polished- that's a little conspicuous.
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Old 06-19-2008, 12:05 PM   #31
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Originally Posted by rb26dett View Post
Is it possible to buy a tree hugger one that also flows well?
I seem to recall a while back that Corky built an exhaust system which had two "normal" cats in parallel. I would tend to expect that such a system would be a real winner, both from a performance and an emissions standpoint.

It's a shame that I can't seem to find any before / after data comparing a traditional high-density ceramic cat to a coarser spun metal cat on a smog-check dyno. Seeing those numbers would mean a lot...
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Old 06-19-2008, 12:31 PM   #32
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it really depends on how big the core is. it takes roughly two 2-1/4" pipes to equal a 3" in terms of flow area so you have to start there. but most cats use the same cores dont they? in theory you'd get half the restriction.

I wonder what it does to the heat in the catalyst. and how you'd fit it. I've always envisioned a simple offset setup to reduce the width (or height).
Code:
___/-CAT1-------\_____
   \-------CAT2-/
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Old 06-19-2008, 01:06 PM   #33
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Quote:
Originally Posted by y8s View Post
it really depends on how big the core is. it takes roughly two 2-1/4" pipes to equal a 3" in terms of flow area so you have to start there. but most cats use the same cores dont they? in theory you'd get half the restriction.
Most cat manufacturers seem to have about a half-dozen or so basic body styles for the center section, and then a hundred different combination of pipe welded onto the ends. I suspect that for any given body style, all pipe combinations for it will use the same core.

I noted that my new 2.5" Magnaflow cat appears to provide about 75% greater frontal area on the core than the OEM cat did, with roughly identical core construction. So that's gotta be a signifigant improvement.


Quote:
Code:
___/-CAT1-------\_____
   \-------CAT2-/
That is exactly what Corky did. I wish I could find a picture of it.
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Old 06-19-2008, 01:25 PM   #34
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I'm familiar with the photo- it was somebody's high dollar high hp Miata...
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