Building my 360/390 for towing

[DuckRyder]

I would measure the outlets on the manifolds, they are probably 2.25".

Personally, for a low RPM towing type of exhaust, I would run 2.25 (or 2.5 if not mandrel bent) from the manifolds down to a single 3" through a good quality muffler, my choice would be a DynoMax ultra flow.

[eggman918]

Proper back pressure is important.My 390 is running 2.5" but not mandrill bent with stock manifolds.It seems about right,but I don't spin her any faster than necessary

[Tweetie69]

This is great! I wish i would have read this before I posted my engine inquiry. I'm getting a lot of questions answered. Not to post jack, but since there's already several people on the subject, would a 390 out of a galaxy put out more power than a 390 out of my truck? Both are 2v, 8 bolt exhaust. Am I understanding correctly that car 390's have higher CR's than trucks? Sorry, that's it and i'll butt out.

[1971ford]

I would measure the outlets on the manifolds, they are probably 2.25".

Personally, for a low RPM towing type of exhaust, I would run 2.25 (or 2.5 if not mandrel bent) from the manifolds down to a single 3" through a good quality muffler, my choice would be a DynoMax ultra flow.

Sounds good... how should i make the two 2.25" tubes come into one 3" thoug? I don't think ive seen this before
I'm guessing output tubing size doesnt matter so how about 3" as well. How's this.. http://www.summitracing.com/parts/WLK-17221/

[Tweetie69]

I would measure the outlets on the manifolds, they are probably 2.25".

Personally, for a low RPM towing type of exhaust, I would run 2.25 (or 2.5 if not mandrel bent) from the manifolds down to a single 3" through a good quality muffler, my choice would be a DynoMax ultra flow.

Sounds good... how should i make the two 2.25" tubes come into one 3" thoug? I don't think ive seen this before
I'm guessing output tubing size doesnt matter so how about 3" as well. How's this.. http://www.summitracing.com/parts/WLK-17221/

Daul inlet single out muffler.

http://www.summitracing.com/parts/WLK-21533/

The pick shows a single in single out but the features say dual 2.5" inlets and single 3" outlet

Just an idea

[1971ford]

I would measure the outlets on the manifolds, they are probably 2.25".

Personally, for a low RPM towing type of exhaust, I would run 2.25 (or 2.5 if not mandrel bent) from the manifolds down to a single 3" through a good quality muffler, my choice would be a DynoMax ultra flow.

Sounds good... how should i make the two 2.25" tubes come into one 3" thoug? I don't think ive seen this before
I'm guessing output tubing size doesnt matter so how about 3" as well. How's this.. http://www.summitracing.com/parts/WLK-17221/

Daul inlet single out muffler.

http://www.summitracing.com/parts/WLK-21533/

The pick shows a single in single out but the features say dual 2.5" inlets and single 3" outlet

Just an idea

ahhhhhhhh that makes so much more sense. I didn't read Duckryder's post right. I was thinking he meant to make the two 2.25's and combine them into a 3" before hitting the muffler. I was pretty confused but it makes perfect sense now. Thanks

[1971ford]

Hmm Summit does not have a Dynomax (any dynomax) muffler with dual, 2.25" in, and single 3" out.
These are all the mufflers for dual 2.25" in and single 3" out
http://www.summitracing.com/search/Depa ... Rank%7cAsc

Here are the mufflers for dual 2.25" and dual out
http://www.summitracing.com/search/Depa ... Rank%7cAsc

[Tweetie69]

I looked around a little on there but couldn't find any decent ones. I'm sure if you shop around you should find something. I'll do a little research to see if I can find something for ya.

[1971ford]

THanks that would be great, I'm not sure where to look. I don't know much about exhuast.

Oh and should i run an H or Y pipe? Where?

[Tweetie69]

Personally I've always liked X or H pipes, but that's only for dual exhaust. also because i've been a big stang banger for years. You're talking about a 2 into 1 exhaust so you NEED a Y pipe unless you find a dual in single out muffler. It would be pretty easy to fab up a simple Y pipe if you had a welder and the right cutting tool. I did it in high school. it was a bit crued because i used a resip saw but it worked. If you COULD do that it would simplify your search for the muffler.

[1971ford]

True, i wasn't really thinking
How should i get the drivers side exhaust tube over to the passenger side to Y into it? How far before the muffler should it Y into the passenger side or does it not matter? I guess I'll just hang the muffler to the passenger side of the driveshaft, and have the exhaust dump in front of the passenger side tire. Unfortunately not many bumpsiders post pictures of their Y pipes so i'm not sure how to cross over..

[Tweetie69]

Depending on the headers, you could do it right behind the engine under the tranny or something.
there's a plethora of ways to do it. Just be creative.

http://cache.autoanything.com/images/pr ... h_cats.jpg
http://images.autoanything.com/images/p ... y_pipe.jpg
http://media.photobucket.com/image/ford ... /photo.jpg (this is like the one i made, but nicer)
http://www.autopartswarehouse.com/image ... y_pipe.jpg

just some examples for ideas. let me know if those pics load. they're from google images.

[Tweetie69]

Heres one that goes right under the tranny it looks like.

http://media.photobucket.com/image/ford ... 0_5472.jpg

[1971ford]

Thanks for the pics. I figure right under the tranny will be fine.
I'll be running manifolds, not headers. A lot of people seem to find that the manifolds are just as good if not better for a 390 build like mine. Plus i have a good set of manifolds now. I'll update once the exhaust is made. I still need to pick out an exact muffler though, I'll keep looking around.

[fomocoguy]

Ryan, here's a nice high flow y-pipe. It's made just like a header collector: http://cgi.ebay.com/ebaymotors/Flowmast ... ccessories

If you like the sound of your Flowmaster but hate the drone you should try a Hooker Aero Chamber muffler. They basically have the same sound but no drone. I've got Spintech pro street mufflers on my truck and they are also a chambered muffler that sound fantastic with no drone. If you want one you can save a few bucks buying them here: http://cgi.ebay.com/ebaymotors/SPINTECH ... ccessories