Official "custom" exhaust thread, for all engines Options

[demmahom34]

What kind of cat you guys use?
I've been looking at the magnaflow universal one and the one thats bends
http://store.throtl.com/magnaflow/magnaflo...it/g-54038.aspx
Will they fit?
On my 5sfe the cat is right after the manifold so how do i put the second o2 sensor on? a bung on the down pipe and longer wires? The first o2 sensor is on the ebay headers im gonna buy so thats good.

And also the harness clip for the o2 sensor is different then the regular ones do i have to solder or crimp it on if i want a new one?

This post has been edited by demmahom34: Mar 12, 2018 - 12:05 PM

[BonzaiCelica]

for those of you with a 3rd or 4th gen 3S-GE motor needing to make your own Front/Ypipe Exhaust pipe. here are the dimensions for the stock flange Just need to figure out, how to convert into correct file type for CNC Shop so it can be machined out of 409 or 304 stainless.

20220926_093003 by Justin Towers, on Flickr

You can buy this 409 grade flange to mate to your catalytic or test pipe.

2boltflange by Justin Towers, on Flickr

This post has been edited by BonzaiCelica: Dec 15, 2022 - 1:23 PM

[bryanf]

The Celica turned twenty-five years old in 2018. That made it exempt from future emissions tests after the 2018 test, which it passed easily, as usual.
This gave me the opportunity to build a custom exhaust system. I did use a catalytic converter, and it would still easily pass emissions.
But with improved flow, lighter weight, and better sound.


Stainless header and downpipe

I started with a 4-into-2-into-1 "tri-Y" non-sequential stainless steel header made for a Corolla.


Fitting header

These two pieces saved fifteen pounds and they look a little bit better too.

New and old parts

I got the header and downpipe ceramic coated. This keeps the engine compartment much cooler and it keeps the exhaust hotter, reducing back pressure and improving catalyst performance.


Ceramic coated header and downpipe


Installed ceramic coated header

I decided to go with 2-1/4" tubing and a 2-1/4" catalytic converter, resonator, and muffler.


Exhaust system components

I selected a Magnaflow stainless catalytic converter with a built-in resonated core for further weight savings. I also selected a Magnaflow oval muffler.


Connection to cat


Bracket to use factory hanger


Installed bracket

I installed the downstream oxygen sensor after the catalytic converter where it belongs.


Installed cat and O2 sensor


Mid pipe fabrication


Mid pipe bracket to use factory hanger


Routing over the rear subframe


Hanger at front of muffler


This is the first rear muffler hanger

For some reason I had trouble making a rear muffler bracket that I liked and over time I ended up making four before finally settling on the bottom one.


Muffler rear hangers

I also made a long straight pipe that can be used to replace the muffler which was easy since the muffler has central inlet and outlet.


Tail pipes

Along with the exhaust system I advanced the ignition timing from the stock 10 degrees up to 15 degrees BTDC.

The end result, lighter weight, better sound, and a little more power.

[enderswift]

wow,

you did a really nice job. I like the quality of the execution, it all looks well thought out

[bryanf]

wow,

you did a really nice job. I like the quality of the execution, it all looks well thought out

Thanks!!

[Bitter]

What's the number for that cat converter? I've never heard of a resonated converter but you've peaked my curiosity.

Wow that is some amazing fabrication work! If you find yourself wanting even more heat containment under hood you can wrap the upper section of the header and it'll run cooler than the OEM part. I had an un-coated wrapped header just like that for about 5-6 years before the car left me. I pulled the wrap back a couple times in random spots to check on it and the stainless underneath just had typical 304 surface roughness and cosmetic rust. No rot, no cracking. Not as pretty but certainly effective.

With your timing advance keep an eye on knock, I *think* you could use one of those DIY knock sensor alerts or but definitely a SAFCII to keep an eye on it, I ran at least mid-grade fuel with my 7A with about the same kind of mods because I did hear a little ping with regular 87 octane. Are you still running the stock airbox intake snorkel that runs up and behind the headlights? I assume it's pretty similar to the Corolla/Prizm, it's a surprisingly large restriction and in my case with the vehicle stock it's removal resulted in a very noticeable improvement in low end torque and got rid of this weird flat spot around 2000-2200 RPM.


Interesting side note, that flange between the upper and lower sections and it's gasket are a standard commodity part, if you need a new gasket there I believe it's the same as a Subaru 2.5L from like a 98ish Forester etc. WALKER 31613 which may also be the same flange/gasket a couple posts above for the 3S turbo stuff. It's like they're all picking from the same parts bin or something idk lol.

[bryanf]

Thanks for your post, Bitter. Very helpful. That's a MagnaFlow 94405. About 7.5 lbs. I'm quite happy with it. They are available in other sizes. With the straight pipe in place of the rear muffler it's amazing how quiet it is. Too noisy for my taste but much quieter than a fully open exhaust would be.

It's amazing how cool the engine compartment runs now, it almost feels like you could touch the header while the engine is running. I am using 93 octane and I think it's safe but I will look into the knock sensors.

I am still running the stock intake including the snorkel. I should try removing it.

Updated photo of the rear muffler bracket:

[BonzaiCelica]

yes very nicely done exhaust system.

that front pipe gasket will probably fit his 7afe aftermarket header.

will def not fit the 3sge unit.

[BonzaiCelica]

yes very nicely done exhaust system.

that front pipe gasket will probably fit his 7afe aftermarket header.

will def not fit the 3sge unit.