The Definitive Exhaust Upgrade Pictorial

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Slownrusty
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The Definitive Exhaust Upgrade Pictorial

Post by Slownrusty »

Hey guys - I am the king of dreaming-up projects, typically way faster than I can execute them! Continuing with that theme, I've been wanted to free the M30 of the restrictive exhaust noose and liberate that sweet straight six.

Based on that, I decided to "design" a few options which I present to you below.

At first I was just going to install the Ireland Engineering cat-back system and be done. But the more I slept on it, I felt I could do better than their system, plus with their set-up you still have to decide to re-use your cat, install a new high flow cat or fabricate a new section if you're not going to run a cat . I would like to mention that IE's set-up has 1.75" O.D pipes, which I feel is on the small side for the M30, plus I did not like their heavy rear muffler, the caveat here is I do like their products and service and I am going to use their ceramic headers as pictured below to replace the stock cast manifolds. As an aside, the header downpipes are 2.0" O.D.

Side note - The stock exhaust with the cast iron manifolds weighs just over 100-lbs (!)

Another side note: I will be using stainless flex joints, all stainless pipe, and I will V-Band the exhaust no matter which setup I choose. I have $600 into this little science project..so not too bad.

Ok so onto the options I came up with, the stock exhaust is shown as a comparo below too, by the way I had lots of fun thinking about this and putting it together:

Option 1 Side Exit: Twin 2.0" O.D pipes into a single Magnaflow and exit in front of the rear right wheel.
Pros: Nice and short, fairly easy to fabricate, light, probably will sound cool, looks cool and good power.
Cons: Heat might damage the paint on the rocker and trim right above that.
Image

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Option 2 Full length: Twin 2.0" O.D pipes into a single Magnaflow and exit with a 2.5" pipe and twin tips in the stock location
Pros: Will sound cool, looks cool also and good power.
Cons: A bit more complicated to fabricate and heavier than the side exit option.
Image
Image

Option 3 Ireland Engineering Cat Back system: 1.75" O.D pipes into a resonator and long barrel muffler and exist with 2.0" tips in the stock location
Pros: Fairly easy to install and fabricate the section where the cat would normally be placed. Decently priced
Cons: Heaviest of the three options, maybe adds a little less power (smaller 1.75" pipes) than the above two?
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What do y'all think?

Yasin
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jps635
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Re: The Definitive Exhaust Upgrade Pictorial

Post by jps635 »

If you want the cool factor go for the side exit but with twin pipes exiting at 45 degrees - cut parallel with the sills. One of the oz guys did a side exit so have a search. He posted a video of the finished product spitting flames.

I wouldn't count on any significant increase in power unless doing a bunch of other things

Be prepared for the dreaded drone. My first system was home made, twin pipes into a single central edelbrock muffler with twin pipes out the back. It sounded cool and was tolerable on short trips but the drone on long trips was too much.

Personally, not keen on larger tips
'85 635csi JPS (RA2-66)
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Slownrusty
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Re: The Definitive Exhaust Upgrade Pictorial

Post by Slownrusty »

Thanks jps635...I might look and see if I can find some side exit tip that have that look.

Also thanks for sharing your set-up's experience.
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86_6series
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Re: The Definitive Exhaust Upgrade Pictorial

Post by 86_6series »

I posted this to your thread @ Bimmerforums also.

Here's a thread of a major problem with a flex pipe. Page 5 explains the solution.
Just a heads up on flex pipes.

http://www.mye28.com/viewtopic.php?f...9250&start=100

I installed the IE cat back 2 yrs ago, sound is great and no droning.

This year built the engine with b34 bottom, b35 Hatrge head, b35 intake, custom JE pistons etc. Going to use

IE coated headers with x pipe 2 inch dummy cats and custom down pipes. All 2 inch into the 1 3/4 cat back.

I don't think the restriction to 1 3/4 will cause that much loss in the overall scheme.

We'll see when it gets tuned with a stand alone. Not going for all out power.

IE stuff is affordable bolt on quality. IMHO
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hornhospital
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Re: The Definitive Exhaust Upgrade Pictorial

Post by hornhospital »

That link comes back with "The requested topic does not exist." :(
Ken Kanne
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Slownrusty
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Re: The Definitive Exhaust Upgrade Pictorial

Post by Slownrusty »

Made some great progress last night after work, I should be finished up this afternoon. Its falling into place really nicely.

Image

Image

More pictures to come.
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Slownrusty
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Re: The Definitive Exhaust Upgrade Pictorial

Post by Slownrusty »

It is 100% complete now, total fab. time was 9.5 hours. I'm excited to hear the car sounds and runs, still need to button up a few things before I turn the key.

Here is the last section from the muffler to the tailpipe:
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GRNSHRK
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Re: The Definitive Exhaust Upgrade Pictorial

Post by GRNSHRK »

Nice work there, but I hope you read this :-k
Be prepared for the dreaded drone. My first system was home made, twin pipes into a single central edelbrock muffler with twin pipes out the back. It sounded cool and was tolerable on short trips but the drone on long trips was too much.
BTDT as well, these cars don't do well without a resonator, personal experience applies here, of course [-X

Those SS flex joints are cool :shock:
:mrgreen:
Bobbo
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Slownrusty
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Re: The Definitive Exhaust Upgrade Pictorial

Post by Slownrusty »

Follow-up, I really like the sound of the exhaust, it has that straight six low growl when the toodling around that is not intrusive but barks when you hit the "wow" pedal. I know this as my wife accompanied me on the maiden voyage and she is very sensitive to loud, drone-y exhausts. If I went with the side exit, the story would be certainly different.

The new exhaust is about 50lbs lighter than the old system too. In terms of performance its hard to tell how much additional power I picked up (I should dyno'd the car before...grr!), but seat of the pants is in the 15-20hp range.

Here is a quick video, enjoy and tell me what you think!:
https://www.youtube.com/watch?v=ynI4Y-imtPQ
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