[austinla335d]

Originally Posted by starrfyr

Your geometry is slightly flawed. 2 x 2.5" pipes are not equal to a 5" pipe. The cross-sectional area of two 2.5" pipes is equal to (2)(25/16)(Pi), while a 5" pipe is equal to (25/4)(Pi). A 5" pipe is twice as large as two 2.5" pipes.

By comparison, a 3" pipe has a cross-sectional area of (9/4)(Pi). If you compare a 3" pipe to two 2.5" pipes you can ignore Pi and the ratio of two 2.5" to a 3" is 25/18 or about 139%. Since the 2.5" pipes are probably cheaper and lighter than 3" pipes, and since two 2.5" pipes have almost 40% more flow capacity than the 3" down pipe, it seems prudent to go with the 2.5" pipes after the intersection.

However, if a 3.5" DP were used then with 2.5" pipes the excess volume drops to just over 2% which isn't enough. One might consider 3" pipes in the case of a 3.5 or 4" DP. And, yes, I recognize that a 4" DP, and probably a 3.5" as well, is clown-shoes excessive. I only mention it because twin 3" all the way to the tips also seems excessive since twin 2.5" pipes provide nearly 40% more flow than a single 3", which is the practical maximum for the down pipe.

I just wanted to give you the chance to do what ya did there. 40% greater flow, double, whatever. I was just stating it would free up more CFM at the Y junction from 3".

[austinla335d]

Originally Posted by iaknown

Here's a little teaser of my exhaust. Almost done it. Sorry for the crappy pic. I'm doing like 5 things at once on the car so it'll be a little bit until I can post sound clips. This will be an affordable solution for aftermarket exhaust on our cars, just have to figure out how to make sure it fits everybody's cars with different downpipes (like those that fit and those that don't ). You can't see the tips but they are 3.5" although I will be hacking mine off to put quads on. More info to come later....

Glorious.

[iaknown]

Backend so far.....

[DieselRacer]

Originally Posted by iaknown

I am the fabricator Unfortunately it is not that easy as there is nothing in production for the mid section that is even close. There is not much room on our cars to work with and I still need to come up with a mount near the trans area like the factory pipe. But hopefully I can find a way to streamline the process afterwards so it's not too much work to make more....

very cool, you do great work...

[GreekboyD]

iaknown, what's your rationale behind keeping two mufflers as opposed to one or none altogether?

[Puerto Rican 335d]

Iaknown oustanding work but my question why do u hvae mufflers I believed the DIESELS dont need it, I would love to hear the sound the mufflers from that other company sounds wicked

[Puerto Rican 335d]

I cant get into their website(Im at work)

http://www.cartecjahn.de/

but they also are in Facebook

https://www.facebook.com/#!/cartecjahn

[DieselRacer]

The mufflers will help with drone, a resonator would work but the op says the space was tight so the mufflers are the way to get the drone out and make it all fit, myself, no mufflers just straight pipe...

[iaknown]

Before I go any further let me say this....this system is roughly based on an existing 3 series exhaust I had laying around. So while I'd like to take credit for all those pretty mandrel bends, a lot of the rear section was already in the ballpark of fitting....sort of. I still had/have to mod it to get it to fit and unfortunately the mid section wasn't close at all as one would expect, that part I am fabbing up completely.

That being said, mufflers were mentioned. They are on here because they were already existing, however there is a chance they may get hacked off and replaced with straight pipes. I definitely want to be able to hear the exhaust, but I also don't want it obnoxious.

Resonators were mentioned. They are on the system as well, see the first pic I posted, just past the mid section.

[GreekboyD]

Originally Posted by iaknown

Before I go any further let me say this....this system is roughly based on an existing 3 series exhaust I had laying around. So while I'd like to take credit for all those pretty mandrel bends, a lot of the rear section was already in the ballpark of fitting....sort of. I still had/have to mod it to get it to fit and unfortunately the mid section wasn't close at all as one would expect, that part I am fabbing up completely.

That being said, mufflers were mentioned. They are on here because they were already existing, however there is a chance they may get hacked off and replaced with straight pipes. I definitely want to be able to hear the exhaust, but I also don't want it obnoxious.

Resonators were mentioned. They are on the system as well, see the first pic I posted, just past the mid section.

Yep I noticed the resonators with GottaBeKD the other night when a bunch of us met up. Would be interesting to see how it sounded with just the resonators and then with the resonators and mufflers.

[modobrew]

iaknown, that looks fabulous. Please keep us updated. This is something I'd love to do to mine down the road. subscribed.

[BB_cuda]

Originally Posted by iaknown

Here's a little teaser of my exhaust. Almost done it. Sorry for the crappy pic. I'm doing like 5 things at once on the car so it'll be a little bit until I can post sound clips. This will be an affordable solution for aftermarket exhaust on our cars, just have to figure out how to make sure it fits everybody's cars with different downpipes (like those that fit and those that don't ). You can't see the tips but they are 3.5" although I will be hacking mine off to put quads on. More info to come later....

IA, this is uber cool.

[GreekboyD]

Originally Posted by iaknown

Before I go any further let me say this....this system is roughly based on an existing 3 series exhaust I had laying around. So while I'd like to take credit for all those pretty mandrel bends, a lot of the rear section was already in the ballpark of fitting....sort of. I still had/have to mod it to get it to fit and unfortunately the mid section wasn't close at all as one would expect, that part I am fabbing up completely.

That being said, mufflers were mentioned. They are on here because they were already existing, however there is a chance they may get hacked off and replaced with straight pipes. I definitely want to be able to hear the exhaust, but I also don't want it obnoxious.

Resonators were mentioned. They are on the system as well, see the first pic I posted, just past the mid section.

Any videos of your exhaust in action?

[iaknown]

Car is still on the lift, exhaust is in pieces and trying to get my meth kit in. So not yet.....

[GreekboyD]

Originally Posted by iaknown

Car is still on the lift, exhaust is in pieces and trying to get my meth kit in. So not yet.....

Sweet man.

Stay away from hobos.

[GottaBeKD]

Originally Posted by GreekboyD

Sweet man.

Stay away from hobos.

Moose. Beavers. Squirrels. Hobos. What's next?

[2deerwhistlers]

Originally Posted by GreekboyD

Sweet man.

Stay away from hobos.

More importantly.. Stay away from meth

[dzlmoose]

Originally Posted by 2deerwhistlers

More importantly.. Stay away from meth

[DieselRacer]

Coke is a joke then your broke, that's why my car prefers METH...

[Puerto Rican 335d]

so is it suffice to say 3" all the way back or 3" splitting into two 2.5"

[iaknown]

Exhaust is done. Here is what I finally came up with for those who interested. Hope to have sound clips tomorrow if all goes well (how do I post sound clips anyway?).

Also looking forward to taking the car out tomorrow. It sounds good in the shop and I hear lots of turbo whistle I'm curious to see how it sounds on the road. Looking for feedback as well. I have been in touch with a manufacturer to produce these for our cars if I can get him a prototype. It may take a few months for the 1st batch but the price will be reasonable. Just have to guage the interest to see if its feasible....

[iaknown]

And another....