Since I am in the process of taking care of the exhaust clearance issue with the 69 Mustang gas tank swap I got from the fine folks in this group.. Question I have now is the exhaust.. I like to stay 1 step ahead if I can.. Gonna run 2 1/2 inch exhaust. Haven't made my mind up on either a X,H,Y-pipe.. Are there any issues with trying to run either 1 ?? And what I mean by issues is clearance issues. Are there any clearance issues with either 1 ?
Hi Chief: I've run " X " type exhausts on seven cars over the years and I think it gives better performance. I'm running one now on my Comet with 2-1/2" size pipes. We made our OWN X-PIPE setup by cutting two mandrel 180 degree bends and then welding them in the configuration best suited for each car. Afterwards we install a " gusset" to insure nothing ever moves. I don't have much faith in H-Pipes simply because exhaust cannot turn Left or Right .. The exhaust flow CAN veer slightly to a common location and then exit .. NASCAR runs the X-Types for decades now. They must know " something " ..That's MY opinion for what its worth . Cometized (Chip)
I used a Thrush dual exhaust kit for an early mustang. Came complete with H pipe, mufflers and tailpipes. No real fitment issues, had to clearance one of the rear footwell corners, even with the stock late model tank. Think it was 250$ shipped from amazon
Just to throw this out there... I ran 2-1/2" on a moderately built 5.0 +.040 for several years, with straight duals, and with an H. Most recent muffler guy had no 2.5 and tubed it up using 2-1/4 and the X-pipe, and it runs WAY better now. Sort of counterintuitive, but believe me, it has much more low-end torque. Should be a little easier to run 2-1/4 pipe around everything, too.
If you have headers(hopefully you don't have the ones with a 3" collector on that little motor)?.. use the 2.5 x-pipe and continue on with that size until you hit the mufflers. Then come out the back of the mufflers with a 2.5" pipe over the axle. Preferably using mandrel bent tubing whenever possible. If you don't have headers?.. going any larger than 2.25" out the backside of the mufflers will just add useless weight and cost you torque where you need it most on the street. A handy and easy trick you might try for making your own x-pipe is to use a decent sized disc sander(the larger the better) to literally sand large flats for the mating junction between the two 180/90 degree bends. It seems like it would be very time consuming at first(surely use heavier grit paper, 50 works good) but they turn into big holes rather quickly once you remove that bends peak. Basically, center it at the mid-point of outside radii and take off the U's highpoint. Now bear with me here and I know it sounds silly.. but to take that trick even further you first "dimple" the pipe by literally slamming the U's.. or L's work fine too.. against flat steel or smooth concrete right smack dab against the peak of the pipes outside radii. Yep.. that's right. Smack the pipe against a hard flat surface until it looks like they are about 1/2" from mating flush with each other during the mating mockup. THEN.. grind away as mentioned above. The beauty of this technique is that you actually end up removing metal only on the outside diameter of that light to moderately caved in dimple. As you start to grind away the outer perimeter of the dimple you'll work towards centering the witness marks around the circumference of said dimple(IF you dent is centered well enough). After about 2 minutes of grinding this big smoking hot dimpled pipe.. a rather large oblong piece of tubing wall just falls away into the pipe. That's just that much less metal to have to sand away on. Saves on sanding discs too. A bandsaw works pretty decent too. Then just grind the razorsharp edges inside the X's transfer port holes, clean it, and weld it all up tight.
That's a pretty good little trick.. May half to try it.. And I am running headers.. Hedman equal length shorty headers. I do believe they are 2 1/4 at the collector, maybe 2 1/2. It's been awhile will half to double check.. Thanks again..
The H pipe works because when one side of the H has an exhaust pressure pulse the other side has depression between pulses. It also tunes the acoustic waves in the exhaust. Some of the newer Corvettes have an H pipe with only a 5/8" hole in each exhaust pipes. Strictly for tuning acoustic and reflected waves. What NASCAR "knows" is that X pipes work great on engines turning 7000 rpm for 500 miles at a time. On a street car you're hard pressed to see an advantage of one over the other. Just pick which one sounds best to you.
What I don't like about the x-pipe is that I lose the side to side engine lope and rock at idle. Still there a little, but it doesn't rock the car at red lights like it used to. What I do like is the extra low-end torque. This car has really woken up with the x-pipe and slightly smaller tubes. Never going back. The bigger tubes and long headers and straight duals sounded GREAT, but shorties, smaller tubes, and the X make it ride WAY better.
