2.5 is usually enough. 3-3.5 you start to loose pressure


Jameson

 

Back then the popular thinking seemed to be that a slightly smaller pipe promoted low end torque while bigger favored high RPM horsepower.

 

Ok what does the "X" do for performance or whatever? Cuz i dont get how that helps anything at all.

I have a (1974 highboy STD Cab 8') 390 with mild cam (crower level 3 performance cam), short/ chassis headers, and seems like i can go with 2.5 or 3" exhaust.
What id like to know is the optimal setup.
A) do i do 2.5" or 3"?
B) do i need the "X" or do i just go straight to each muffler?
C) anything im missing

 

X and h pipes help balance the pressure between the two sides of the exhaust.

I would recommend 2.5 with straight into mufflers


Jameson

 

Hm ok so do i do 2.5" with the X into the exhaust? Will it help at all or not?

And what about 2.5" into the mufflers and 3" out? Good, bad ?

Currently i have the h, 2.5" in and 3"out

 

Tying the two pipes together with either an X or a crossover helps produce torque. I don't remember all the science behind it but it has to do with balancing back pressure, exhaust scavaging, and resonance. The X set up is better and the closer you can get it to the collectors the better. One thing I don't like about it, though, is the sound. It takes a cool rumpity rump big cam idle and high throaty RPM definition and blends it all together making it a mellow drone.

As far as the size goes either would probably be fine.

I just realized that you're not far from me. I'll be in Del Mar next Monday morning. I can bring the pipes if you want to see them.

<a href="http://s742.photobucket.com/albums/xx65/Fordworth/Exhaust/?action=view&amp;current=IMG_20110920_135357.jpg" target="_blank"><img src="http://i742.photobucket.com/albums/xx65/Fordworth/Exhaust/IMG_20110920_135357.jpg" border="0" alt="Photobucket"></a>


<a href="http://s742.photobucket.com/albums/xx65/Fordworth/Exhaust/?action=view&amp;current=IMG_20110920_135349.jpg" target="_blank"><img src="http://i742.photobucket.com/albums/xx65/Fordworth/Exhaust/IMG_20110920_135349.jpg" border="0" alt="Photobucket"></a>

 

Oh cool! I have scool though 8-10, then 1105-100ish, then back later Will you be driving the 75? Id love to see that sometime

And as for the X now im stuck cuz i like the way my cam sounds.....

 

I won't be driving the pickup, I'll be delivering a tractor to Fairbanks Ranch with the KW at 7:00 then picking up another at the horse park at Via de la Valle/El Camino Real after so I guess that won't work. After that I'll be making two more trips down there to pick up trailers from the horse park so maybe later would work out. If you're serious shoot me a PM and we can talk about it.

 

Not Fairbanks Ranch country club is it? I belong there and my dads office and is down the street and best part, two of his office neighbors drive highboys 1 sec ill look for the pics of them.lol

And a pm might be in order here

 

Truck 1

And #2

IDK why is sideways....
http://s1083.photobucket.com/albums/...=0CA1OKZDF.jpg

 

I'm not familiar with the country club, but I'm going to the equestrian center just inside the Circa del Norte gate off San Dieguito.

Those are cool trucks.

 

Yup thats literal right next door Cool! Ill pm you

 

Here is what mine looks/sounds like. I also dumped mine in front of my rear tires for ease of installation. I just wanted to throw on something quick and relatively inexpensive so it sounded better than the burned out glass packs that were on there.

https://www.ford-trucks.com/forums/1...l#post11890548

 

Mine exits right before the rear tires, even with a 390, 3" from the headers back and flowmaster 10 series it's not bad, loud, but not obnoxious. The neighbors definitely know when I start it though.

 

I'm not sure on the sizing, but I'm running a single pipe with FM Super 40 right ahead of the pass rear tire. Reflects nicely off curbs and walls puts some noise in the cab, but acceptable. I have a 73 250 with the 390.