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Old 10-17-2014, 09:30 PM   #1
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Default Cut "shelf" thread

So, I have come to a crossroads in my turbo build. Cut the "shelf" to make a downpipe fit on my manifold, or sell my manifold and buy a new (likely log) one. I'm curious who all has cut theirs, and how much. Looking at the previous threads that pop up, it seems like most people either cut the sheet metal only to the bulkhead, or remove everything all the way back to the firewall. "Every v8 miata has them cut out"

In order for mine to fit, it is going to take at least the 1/2" sheet metal area, and only if I switch to a smaller diameter dp or to a SGDP. If I go with the 3" downpipe as planned, a fair bit would have to be removed.

What i'm looking for is people who I have actually removed it to say:

Amount removed: "Cut that bitch entirely out" or "Cut back 1" into the bulkhead"

Any reinforcements done: Gusset plates, etc.

Any opinions on why this shouldn't be done, or why it is acceptable are also welcome.

EDIT: Bonus props for pictures.

Picture of my personal situation. Even removing the v-band and welding straight to the 3" reducer, not much room. Welding a SGDP to a segregated flange still won't really leave much room.


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Old 10-17-2014, 09:49 PM   #2
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I'm pretty sure M2cupcar cut his with a plasma cutter. I'll look for the pics...
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Old 10-17-2014, 09:55 PM   #3
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Here you be:
Quote:
Originally Posted by m2cupcar View Post
Got the ledge under the brake booster sectioned (plasma cutter win- again) and welded up with some L shaped plate - now have a place to run the down pipe.





Also got -10AN fittings brazed to the stock heater core tubes. Welded steel tubes (salvage from an old bike frame) to the steel AN fittings and then swaged the brass heater tubes for a slip fit. Then went to work with some silver solder and heat- just like sweating copper pipes. I'll weld some tabs on the fittings so they anchor to the firewall for support.

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Old 10-17-2014, 09:57 PM   #4
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Quote:
Originally Posted by Monk View Post
Here you be:
Interesting. That would probably be about what I have to do, and i do have access to a plasma cutter. Weld back in some sheet metal to replace some of the structural integrity. Spray it.
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Old 10-18-2014, 06:12 AM   #5
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a nissan downpipe elbow usually works with that style of manifold
5 Bolt Elbow Down Pipe T25 Turbo Downpipe for Nissan s13 s14 S15 240sx | eBay

or you could fabricate a downpipe that has a bend at flange
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Old 10-20-2014, 09:12 AM   #6
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I am the one working on building Schuyler's down pipe. The way that MP2Cupcar has his shelf cut would make the down pipe easy to make. I just don't have an NB at the moment that I can hack up to build it on.

Quote:
Originally Posted by sturovo View Post
a nissan downpipe elbow usually works with that style of manifold
5 Bolt Elbow Down Pipe T25 Turbo Downpipe for Nissan s13 s14 S15 240sx | eBay

or you could fabricate a downpipe that has a bend at flange
I actually tried the stock down pipe piece with the manifold on my NA and it seemed to fit. I will try to put it on an NB in the next day or so to see if it fits in there also, and may just go that route.
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Old 10-20-2014, 10:15 AM   #7
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Are those zipties a stage 8 or stage 10?
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Old 10-20-2014, 10:50 AM   #8
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we all notch the frame rail to fit.

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Old 10-20-2014, 11:08 AM   #9
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Quote:
Originally Posted by Mazdaspeeder View Post
Are those zipties a stage 8 or stage 10?
TSE stage 8 zip ties.

Quote:
Originally Posted by fooger03 View Post
we all notch the frame rail to fit.

Clearance at the side frame rail is actually more then fine. I will make sure if we do decide to cut the rear shelf to make it a bit cleaner then what failflora did.
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Old 10-20-2014, 11:12 AM   #10
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I trimmed it flush with the firewall all the way over to the steering shaft.
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