lets talk 3'' exhaust and bigblocks...

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mach1460

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72 mach 1
Ive been driving my 72 for a year now with mufflers bolted to my long tube headers and its time to finish the rest of my exhaust. Now from everything ive ever read and or heard most guys I know who are running 429/460+ strokers are running 3" exhaust but there also in jacked up mud trucks with tons of room to do anything they want with it. Us on the other hand, dont. Ive called two shops in my area and no one wants to bend 3" and just reccomend ordering pre fit exhaust.

Im almost ready to give in and just go 2.5"--- But with my 532 I think Id rather have the 3" :)

I did some searching and didnt find much for a 3" exhaust kit for our 71-73 mustangs. SO any one got the big pipes? Im curious to see some pics hopefully of 3" and some feedback from those who have it... Thanks guys

 
Not sure the size of mine. I can measure tomorrow or something. I want to say 2.5", but they look pretty damn beefy:

jj8pqa.jpg


By the way, it's a 429.

 
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i have 3 inch exhaust headpipes and 2.5 tail pipes with my 460. however, my exhaust head pipes hit the frame. i need to take my car to the exhaust shop and have them dent the area of hitting.

i'm also going to ditch the tail pipes going over the axle and just exit infront of the rear tire (i'm going to have to cover up the fuel lines with heat tape).

however, some guys go 3 inch tail pipes but go under the axle instead of over it.

 
Awesome pics guys. I'd like to do 3" all the way back with an x pipe. Well see what happens. Anyway we could get a sound clip vintage? Basically that's a similar set up as the 05+ mustangs with the muff right at the tail end. Very cool. Still some one well chime in with a kit. Looked at summit racing and they have universal sets of 3" with lots of curves and turns for 250 bucks. Kinda leaning that way...

 
I ran a custom exhaust shop for many years and have done my own exhaust since I was able to buy my first beer!

No offense to the 3" exhaust guys out there, but there really is no performance advantage to running the 3" as opposed to 2.5" unless you are pushing 600hp and you just want all out top end. There may even be a disadvantage due to the lack of backpressure. Exhaust flows just like water through a pipe, so the larger the pipe, the more free your exhaust will flow right? Well to a point, you need a little bit of restriction to help keep the pressure up and the air flowing smoothly.

If you just want it really loud and you are not concerned with off the line or low end power and you have a bunch of room, then maybe 3" is the way to go. But for everyday running, clearance and performance, unless you have a diesel, in my experience 2.5" is a more then sufficient to get the job done, and maybe even be better.

 
In one of the engine builder competitions from a few years ago, there was an FORD engine builder that had to switch from a big pipe to a smaller pipe header and was amazed that he actually increase his power/torque with the smaller pipe.

It was in something like Car Craft, or HOT ROD or something like that. Might want to do some searching.

 
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I ran a custom exhaust shop for many years and have done my own exhaust since I was able to buy my first beer!

No offense to the 3" exhaust guys out there, but there really is no performance advantage to running the 3" as opposed to 2.5" unless you are pushing 600hp and you just want all out top end. There may even be a disadvantage due to the lack of backpressure. Exhaust flows just like water through a pipe, so the larger the pipe, the more free your exhaust will flow right? Well to a point, you need a little bit of restriction to help keep the pressure up and the air flowing smoothly.

If you just want it really loud and you are not concerned with off the line or low end power and you have a bunch of room, then maybe 3" is the way to go. But for everyday running, clearance and performance, unless you have a diesel, in my experience 2.5" is a more then sufficient to get the job done, and maybe even be better.
well my motor just dyno'd at 627hp and 640lbs of tq and revs to 7000rpms. i think i need the 3 inch, but,,,,,,,,,,,,,,,,,,,,,,,,i'm running 2.5 tails.

 
I ran a custom exhaust shop for many years and have done my own exhaust since I was able to buy my first beer!

No offense to the 3" exhaust guys out there, but there really is no performance advantage to running the 3" as opposed to 2.5" unless you are pushing 600hp and you just want all out top end. There may even be a disadvantage due to the lack of backpressure. Exhaust flows just like water through a pipe, so the larger the pipe, the more free your exhaust will flow right? Well to a point, you need a little bit of restriction to help keep the pressure up and the air flowing smoothly.

If you just want it really loud and you are not concerned with off the line or low end power and you have a bunch of room, then maybe 3" is the way to go. But for everyday running, clearance and performance, unless you have a diesel, in my experience 2.5" is a more then sufficient to get the job done, and maybe even be better.
well my motor just dyno'd at 627hp and 640lbs of tq and revs to 7000rpms. i think i need the 3 inch, but,,,,,,,,,,,,,,,,,,,,,,,,i'm running 2.5 tails.
Nice and very respectable!..I was being conservative in that hp range though. There is a calculation to it, back pressure vs flow or something of the sort and I think the border where it breaks is closer to 800-900hp. Maybe do some research on it, like Wolverine suggested. I am sure that Hot Rod or some published mag has worked it all out.



Here is what we ended up with. Very unique sound with the mufflers at the rear.
Dude, that thing is sick! Very nice frame work.

 
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I know this could turn into a huge discussion/debate. Maybe ill go with the 2.5 I have been doing some reading and since its not a all out track car and will see 80-90% street I might go with the smaller diameter. I have never dynoed it but im estimating 650-700hp. Which I dont mind losing a little, its fun but a bear to drive as it is. I wish my inner madman was not such a part of me when I was deciding what to do when I built the engine. I would of been happy with 550hp but o well ill take my 650+/- :)

It would probobly save me a few bucks anyway. I did find a guy in town who does 3" mandrel bends that a fellow hotrodder told me about.

I called him today and he told me over the phone for 800 give or take 100 he would build me a stainless steel 3" exhaust system with an x pipe all tig welded. I think ill do it. After thinking of ordering the summit kit and doing all the cutting welding my self and messing with it id rather just spend the extra 400-500 and have it done and done right. Like I said that price was for 3" and probobly cheaper if I run 2.5"......I will get some pics as soon as I get something done might be a few weeks out he said tho.

 
$800 is a good price for that work. There's a lot of labot there to tig all that. Fun work though. He probably won't change it for 2.5 or 3.0" as material costs are about the same, although the 3.0" is a bit more fussy.

The X pipe really opens it up and gives it a real throaty sound. I didn't x it or put a crossover in mine, but I still may. I do like how they sound and perform.

Custom built is the way to go though. Pre bent kits suck, all pre bent kits! I don't care who makes them or what car they are for Mustang, Vette, Ferrari. I've done alot, more then I can count and every single one was a pain in the neck and were a little off. Customers want what they want sometimes. But if I have done them from scratch, they would have all came out cleaner, it would have been an easier install and it they would have looked a lot more symetric, if I had bent them myself.

Some people just want that complete Borla system, or whatever name brand you want to put in there?

 
Took a little digging,

http://www.jonkaaseracingengines.com/component/content/article/198-kaase-emc-2003.html

Headers

================

Headers are Hooker's Super Competition (PN 6201) for '71 Mustangs with 429/460 engines. The pipes are legal for the Challenge, even though they are multi-piece. While full multi-piece headers were not allowed per the rules, partial multi-piece headers like these (where a single pipe had to be crafted to go outside the unmodified factory frame rail, but the rest of the header was a single-piece unit) were specifically called out as legal per our 2003 rules. If this is the kind of header street guys need to run in cars with tight engine bays, and no mods were required to install them, we're on board. The pipes have a 2.125-inch primary diameter, with a 3.5-inch collector diameter. Primary tube length is a longish 37 inches, which Kaase felt contributed to solid torque figures. These headers will also fit '70-'71 Torinos, Rancheros, and Mercury Montegos with the 429/460 engine. The headers were teamed with Magnaflow mufflers during Challenge testing.

"I'm glad there were almost no choices for headers. I may have gone bankrupt buying different sizes and lengths. The five-year-old Hookers we use for dyno testing were sent to Swain Tech for coating. I was a believer in this heat coating after repeated dyno pulls were made with an unharmed plastic line in close proximity of a primary pipe. I know it would have burned up near an uncoated pipe.

=====================================

Mufflers

=======================================

"During the last two days of testing I finally forced myself to hook up the dreaded mufflers. Difficult as it is to believe, this elicited the largest single gain of any parts tested. At least part of the improvement was due to a mistake I made when ordering collector extensions. Looking in the Hooker catalog, I apparently experienced a 'senior' moment and transposed the part number, ordering 3.250-inch diameter collector extensions instead of 3.5-inch. Who ever even heard of 3.250-inch collector extensions? To make them work, I expanded one end to fit over the Magnaflow 3-inch muffler entry. The front end was easier to reduce its diameter to fit INSIDE of the 3.5-inch header collector. This combination of extensions and mufflers increased the low-end torque by 50 ft.-lbs.! I am convinced that the smaller diameter extensions I mistakenly ordered were a large part of the torque gain and may have even made the difference in winning or losing the contest!"

 
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