I think H-pipes smooth out the engine. X-pipes actually help purge exhaust gases from the exhaust ports.

 

Dyno testing shows that the H pipe is good for an increase of 5-15 hp, depending where it is, mufflers, etc. Don't think Ford put them on there for show. Ford didn't spend 2¢ on these cars unless there was a payoff.

Basically, the H spreads the "pulse" of the exhaust note between both mufflers, reducing average back-pressure. It also makes the exhaust note deeper, and less harsh.

Ford mounted the pipe where it was because that's as close as they could get to the engine, which is desirable. The Fuelie 'Vettes had the crosspipe wrapped around the engine.

 

The H-Pipe really plays very little in terms of performance at the oem location- nor does it reduce backpressure in any way- it was installed to reduce noise- nothing more.

An H-pipe (and x-pipe) will increase HP if it is installed at the "area of confusion"- but that area is identified by painting a small strip on the ehaust pipes about 1/2 way between the engine and the axle- the area of cunfusion will cause increased heat and blister/burn the paint at that location- that's where the H or X pipe would be installed- and eliminates the air flow disturbance by sending alternating pulses in that location which acts as a "vacume" if you will to push & scavage the remaining and incoming air out.

 

I cannot see how an H pipe can do much, if anything, at street legal rpm's.

But it does make for a nicer sounding exhaust.

 

I can't think of how an H pipe on a single muffler setup could be a good idea. I can only imagine turbulence being created as the exhaust tries to flow back up the other side. With two mufflers it would allow pressure to be reproved through the second muffler. :shrug:

 

Now I'm confused. Single muffler systems use a Y pipe, not an H pipe.

 

I had dual exhaust and no H or X pipe. I added the H and it did change the tone on the exhaust a littie. I am not a racer or a mechanic but I like the sound with the H pipe much better. ( 69 351W 2v)

 

22GT check the op. 1 transverse muffler with 2 Intakes and 2 exhausts. I just don't see what an H pipe could do??

 

Ah, mystery solved. That's not one muffler, it's two mufflers in one case.

 

it should help equalize the exhaust back pressure on both sides on the engine no ? maybe resulting in a little more power and smoother acceleration, and / or idle ?

yeah normally an H crossover pipe will make the exhaust smoother and deeper souding but I'm not sure with that muffler set up. Are those mufflers crossflow or seperate chambers ?

I don;t see how adding one could make anything worse, it seems it could only have benefits. However if I were adding a crossover I would only be thinking an x pipe for a little more power, and more exotic sound but the sound of an x pipe might be more of a risk than an H pipe with that muffer set up unless it's super quiet already then you can't really tell the difference in H and X crossovers. Off road (no cats) with performance mufflers is very obvious difference in H and X sounds.

 

My 68 has the full stock exhaust with the H, cross flow muffler in the rear and resonators. I've been told the resonators are to reduce noise as well.

My 67 has straight pipes with turbo mufflers and no H pipe. I actually like the sound of my 67 better. It is slightly louder and sounds deeper than the 68 at idle. On the other hand, the 68 gets pretty loud as I wind it up.

So, long stroy short, your results may vary.

Dave

 

My 68 has the full stock exhaust with the H, cross flow muffler in the rear and resonators. I've been told the resonators are to reduce noise as well.

any audio of that set up ?

 

22GT I''m gonna start a list of the things I learn daily on this forum. What a great idea ! I wish I had thought if it !!

 

The 2 experiences I had with adding H-crossovers involve 2 completely different vehicles with very similar results.

1. 1990 F150 351w. Had aftermarket true duals when I bought it (2 cats and 2 glass packs, no H-pipe). Engine always seems to idle and run rough. Finally replaced that exhaust with a system that had an H-pipe and it totally smoothed out the engine in all regards.

2. 1994 Harley Davidson FLSTN. I replaced the stock exhaust that had a crossover with a Vince&Hines that did not. Engine accelerated much better but was rough feeling. Replaced that V&H system with a better V&H that had a crossover and the engine was immediately smoother in all regards.


In summary, I think they smooth out an engine that has dual exhaust.

 

Finally,,, my area of expertise,,, Exhaust! I have over 25 years experience doing stock, performance & full-out racing exhaust systems.

There is hardly Nothing worse than a dual exhaust setup without some type of crossover pipe in it,,, Unless you'll be constantly running around 7,000 rpm(or higher). Like Beechkid says,, putting one in the sweet-spot is always nice,,, but not usually accessible,,, so up close to the front is better,, around the tranny.

In the years where carbs were used on engines,,, I have cured well over 300 vehicles that came into the shop with newer duals on them but no crossover pipe(daily drivers). I could care less about the sound difference,,, but the performance difference,, especially low speed throttle response,, stutter/hesitation was night & day. I had many,, many customers that actually had replaced their carbs due to that problem with no affect,,, until I added an H-pipe.

Low rpms are where the affects are noticed the most(1,500-4,000). I've done tons of circle track cars,, with carb engines,, dual straight pipe exhaust systems,,, and racers would always tell me how much more umph they could feel coming out of the corners after we added an H to the system,, and how much Smoother it felt.

The best setup(in most cases) is an X-pipe dual setup,, followed Closely by a 2-into-1 system(a fancy, special, y-pipe setup),,, and then the H-pipe system. These are the 3 most common crossover styles of exhaust systems.

It's also important,, that for it to works it's best,,,make sure there are No Leaks,,especially in front of the crossover.

Doug

65 Mustang Restoration

 

X-pipe and H-pipe

Hello,

You have some questions on X-pipes and H-pipes. The advantages to a X-pipe or cross over pipe is it scavenges the exhaust gases, the X forces the exhaust pulses to cross each other one pulse helps the next pulse to extract faster, this creates a vacuum at the bottom of the X and helps extract the exhaust gases. They also help balance the cylinder heads. This is why NASCAR and other big engine builders use X-pipes.

I have seen dynos done on the difference between H and X pipes and the X pipes always produce the most RWHP and Torque. In some cases with a SB depending on mods a gain of up to 5 to 7 HP, BB engines 9 to 10 HP. H pipes do not help extract gases form the cylinder heads, they do help balance the exhaust. After about 2500 RPM the air across the H begins to cause cavitations blocking the exhaust gases.

So far as mufflers you want a straight through wide open design without baffles or chambers that will restrict air flow and create interior noise or drone.

Please feel free to call, email or PM me anytime for questions or pricing.

Regards
Don
JDP Motorsports
888-308-6007

 

I'm not sure about your muffler, but in a true dual system, a cross pipe makes a noticeable difference. In both of my systems, there was a noticeable increase in torque, and the exhaust note was less harsh.