More exhaust brainstorming

[80Stang]

You warmed up with topic "Header vs. stock manifold & dual out w/ Y-pipe", let's heat the exhaust issue some more.

How about decreasing diameter gradually?

This has something to do with my near future setup. The current exhaust setup on my fox is:
-cast header
-some 2" pipe into the 2nd KAT (first KAT gone already, this pipe is temporary as I have waited the headers to arrive)
-from KAT to muffler, 2,25" pipe (stock part)
-muffler 2"
-tail 2" (stock part)

I have FSPP single out header ready to install. It has 2,5" collector, but the output of the cone Mike supplied is 2". I have new kat-to-muffler pipe, and with that plus a new 2" muffler and my new tail I could use stock pipes except for the pipe from collector to KAT-to-muffler pipe. That I have to fabricate, as I delete the 2nd KAT.

If I use the 2" cone I'd need to fabricate 2" pipe from header to the front flange of the 2,25" pipe. Then the pipe would go larger again where there is that 2,25" pipe. What I have in mind is to fabricate the pipe between header and 2,25" pipe with 2,5", modifiing the cone or replacing it with 2,5" version.

Then it would look like this:

-FSPP header with 2,5" output
-2,5" pipe (without KAT of course), some 4-5 feet in length
-from former KAT rear flange to muffler, 2 1/4" pipe, some 4 feet in length
-muffler 2" (this muffler is located in front of the read axle. I have an Australian made Red Back free flowing muffler, which was 'El Cheapo'. Can buy DynoMax Super Turbo Muffler instead, no problem)
-tail 2"

What do you think?

(for your reference, my other adventures regarding this engine setup are under topic "Your comments on my upgrades")

 

[simon]

basically that would create a funnel shape.
Now, I don´t have the slightest idea in which way that could hamper performance (should give you at least more backpressure) or alter sound qualities.

Normally, aftermarket performance exhaust systems maintain a steady pipe diameter, so I´m unsure about your setup.

I remember hedman hedders or another brand which, a few years ago, introduced their new line of headers with "power producing steps" - at those steps, the header tubing diameter opened up about 1/4" or so.

 

[addo]

I don't think it will realistically affect things. It is the exact opposite of the gradual expansion found on some motorbikes, but the exhaust flow there is often one pipe per cylinder and much more critical at their higher RPMs. Being able to disconnect temporarily at the end of the 2½" pipe would be good, to see if any change was felt.

Australian made muffler? That's new to me. While I am trying to find who imports Purple Hornies down under!

Regards, Adam.

 

[Anonymous]

The stepped headers typically start with smaller tubing in order to maintain high exhaust port velocity and produce better torque. Then they open up to progressively larger tubing to reduce system backpressure. As Adam said, realistically your proposed setup may not hurt performance to a significant degree. It is still an upgrade over the stock exhaust.
Doug

 

[Anonymous]

That's sort'a what I'm planning for my Stang, Clifford 2.5" dual out header, to 2.25" reducers into home made 2.25" dual in single out "Y" pipe (single out is about 12"), 2" into turbo muffler then 2" tail.

What got me thinking of a gradual reduction was with a dual out header at 2.5" each that's 5"total going into a 2" pipe, : , so maybe it wouldn't be as much restriction.

 

[80Stang]

I talked here also and I decided to go with that 2,5" -> 2,25" -> 2" setup for starters. It is almost free to build as I have some 2,5" piping laying around and I can utilize stock parts at the rear.

Addo; check out the pics of the Australian muffler. I got suspicious and thought, "was it Austrian not Australian" and had to check it, but so it is...

http://www.tuumacid.com/redback/redback1.jpg
http://www.tuumacid.com/redback/redback2.jpg

These sell here for some 30 US dollars worth of euros, available with 2" and 2,5" connectors. There is even a silhouette of Australia in the logo...