My question is about simultaneously quieting the exhaust and keeping backpressure to a minimum.  This would be dual exhaust, of course, with a conventional crossover pipe, and headers (for the moment, block huggers).

Here is a picture of the manifold in question, found on
mrjeffzx xtreme Nissan 280zx Turbo page:
https://www.angelfire.com/extreme/280zxt/images1/Euromanifold.jpg

One of the bellows has a crack in it and needs to be replaced or if possible repaired.
I don’t think it would be possible to weld it, at least not with my welding skills.

I tried finding this part on RockAuto, eBay, FAST, Nissan4u and a couple if other sites without any luck.
Not even a part number

Therefor I thought I should try asking here for help.

Maybe there are alternative ways of fixing this.
Any suggestions are welcome.

I have attached a picture of the damage (The white stuff is exhaust paste since I first thought it leaked around the clamps)

Thanks...

The 2nd image where the first resonator (or whatever it is?) shows where i think all the issues start, but not sure how thats supposed to be made to fit....

Looked around and everyone seems to think its supposed to fit the way it comes....  Quite annoyed 

Problem now is the hood vents are getting melted, and a bit of the fumes are getting into the car. I can either cut an opening in one of the vents to have the exhaust fully exit the hood (I had it that way before I put the hood vents on). Or have it come out the fender near the battery. I don't really want to do the fender exhaust since my battery area is mint and it probably wouldn't be good for the value of the car, but that said it would be the best place for it as there would be no worries of fumes or rain. 

What are your opinions?

I continued to press Sean and he says the market fo a 3" system is too small but I disagree since I believe this is the perfect system for high-boost RB builds as well as LS builds and god knows there are lots of these builds and many more being documented here as well as on the forums.  Sean challenged me to convince him there was a lager market so here is my start to do so.  

How many of my fellow S30 retromod fanatics would be interested in seeing Sean and Zstory create some artwork for the underside of our beasts?  I'm #1 on the list...let get a group buy together to convince him to undertake our challenge.

John Bontrager, I hope you don't mind if I share your post here since you have put up such awesome photos of Sean's work.

https://www.facebook.com/photo.php?fbid=2144201412325896&set=pcb.1030458513821437&type=3&theater

https://www.cxracing.com/CB-280ZX

I have a header similar to the pace setter that goes 3-2-then a y pipe 1 to.... was thinking y out again to two pipes (size recommendations?)  then an x pipe muffler then 2 lines to a final circular muffler.... i currently have header straight into 3" pipe with a resonater which is halfway along the driveshaft, then a magnaflow or knock off magnaflow from a local exhaust shop with a signle 2 3/4" i think inlet and 2 2" or so outlets and no tips... it sounds pretty good but it drones and i cant hold a conversation in the car ever even with some dynamat under the carpets.... 

I just want an exhaust thats sub 3-400 ish (i can fab stuff if need be) that i can hold a conversation while cruising, even if i have to talk slightly louder, but also have a sweet exhaust note

any input appreciated! thank you

edit: spelling

Thanks!

https://www.sema.org/sema-enews/2019/02/fact-vs-fiction-explaining-californias-new-exhaust-noise-law

https://bar.ca.gov/Consumer/Referee_Program/Vehicle_Exhaust_Noise_Level_Certification.html

https://jalopnik.com/why-people-are-suddenly-freaking-out-over-californias-e-1831620651

We all like to HEAR our engines. The lure of big, loud pipes calls gearheads of all ages, no matter what kind of machine their motor is attached to. Dirtbikers, riverboat racers, weekend lawyer Harley riders, Pontoon Boat captains, helicopter pilots, racecar drivers.... we ALL love our pipes.

Unfortunately, though, due to a tricky arithemtic process called squaring, whereby the radius of a pipe is multiplied by itself (and pi) to obtain the cross-sectional area (and thus, the flow capacity) of a circular pipe... Many of us find it very difficult to easily visualize and compare the differences between a 2" and a 3", and dual 2" vs single 4", and dual 1.75" versus single 3" (or was it single 2.5"?) pipe setup.

Rephrase: Comparing potential exhaust/intake tubing sizes is tricky because you have to square the difference in size. Our brains are used to comparing the difference in size in a linear manner. Thus, two falsehoods easily take root in EVERYONE'S mind (until education prevails!!):

A: The difference from 2"-3", and the difference from 3"-4", would seem to be the same;

AND

B: The capacity of a single 3" pipe should be roughly twice that of a pipe roughly half the size, 1.5".

Unfortunately, both of those statements are dead wrong.

Let me go do the math for you!!

:wc:

So!!!!!!!!!

Here you go.

The numbers in the two columns on the left are pipe diameter. This is how pipes are sold usually. The numbers in the columns on the right are cross-sectional area. THIS is the number that you compare apples-to-apples with between different size pipes when determining flow. Double the cross sectional area, you double the flow capacity. However, lets look at the cross sectional area of a pipe that is 1.75". At 2.405 square inches, we want to know what to compare our nice, new dual system to, so we double that number to get about 4.8 inches. Scroll down on the chart a few lines and there is one at 4.909 square inches. Scan back over to the left and we discover that the twin 1.75" pipes have just a hair less flow potential than the single 2.5" pipe. Further inspection reveals that it takes twin 3" pipes to beat a single 4" pipe!

These things are not as intuitive as they might seem, and the further away from Zero you get, the more drastic the changes make themselves felt. I hope this helps as much as I imagine it could.

It is real droney and loud. 

I've bought a universal catalytic converter and a Vibrant ultra quiet resonator and have another v-band on the shelf.

My assumption would be to put the cat pretty up stream like under the transmission, then put the resonator near the drive shaft where my muffler is. Is that correct? 

I think I want another V-band around there so I could drop that section to work on the transmission and the drive shaft. The exhaust is bolted to the transmission at the middle, then at the end it is bolted to the diff mount, do I need to get a flex coupler?

The fumes are a lot lessened with the exhaust out the passenger side, but would it be worthwhile to move the exhaust back towards the rear but maybe exit through the rear quarter? I'm not a big fan of the moisture kind of building up in the rear wheel well at the moment, the passenger side is far rustier than the driver side with the exhaust being blown back.

I have a header that i got as a gift from a good friend of mine. it's nothing special but i have it and would like use it on my car. Unfortunately the flange is fairly thin and  seems warped, someone has also tried to modify. Anyway i have some friends at a laser cutting place and was going to get a flange cut out and welded to my header. I was wondering if anyone had a cad or even a drawing of the exhaust flange. Square port. thanks 

https://www.youtube.com/watch?v=RWTARjxiqlo

http://www.thezstore.com/page/TZS/PROD/classic19k/15-6021

Only complaint was trying to find the center hanger for the exhaust. Ended up having to rig it a bit.

The only concern I have would be that there would be more heat in a much closer proximity to the stock fuel tank. So what would be the best insulation for the exhaust? I would assume header wrap would be plenty being that far down the exhaust system. Any input is greatly appreciated as I'm used to lifted trucks with miles of space between everything.

Thanks in advance!

To build what I have so far, I purchased two 2 1/2" mandrel 180 degree J-bends and a stick of 3" tubing from Summit Racing. Tubing cuts have been made with a miter saw with cutoff wheel, sawzall, and hole saw.

I will add a 3" dump where you see the hole in the H pipe.

Prior to the Magnaflow mufflers, including the H pipe will all be 3" pipe.

Time consuming but fairly simple to this point. I recommend anyone giving it a shot. Satisfaction of building your own exhaust will be worth it.

I am running the 3" dump to the rear. I added to pictures to show the custom oval tip as I align it for welding.

Picture after final welds is attached. System is ready for install. Once I get the headers installed, I can fabricate the header collector to H-pipe tubes.

http://www.zcar.com/forum/10-70-83-tech-discussion-forum/116053-air-injection-removal.html

I tried a 1/4 NPT steel fitting but it was much too small (diameter) to fit. I went to Lowes and the thread pitch seemed to match a 3/8 pipe plug, but it was a touch too wide. If the plug was metric I suspect it would've fit. Anyone have any ideas? I've tried a whole bunch of bolts with no luck. It's for a 260z manifold if that makes any difference. Thanks for any help.

They have no interest in making a set that'll clear an auto trans (though they previously stated they did in another forum). 

So what kind of options might I have to get around that?

My first thought was to cut just the collector off and see if I can weld another collector on at an angle, but I dont think that can get enough angle to clear. 

PS. Anyone have Hawks on a auto trans at all?