Purpose of H or X crossover pipe in exhaust. Problem if I run straight duals???

Blk91stang · Jun 12, 2006

I want to run a "different" muffler setup and plan on splicing it into my H-pipe which means getting rid of the "H" junction in my Offroad H Pipe. I know on 4 of my father's corvettes, his sidepipes are not connected in any way and they run like raped apes (Despite everyone saying how much not running an X or H pipe would hurt horsepower)

Would it be a problem on a mustang? I don't see how it's any different than on my father's corvettes or should I run the hassle of integrating a crossover pipe somewhere in my exhaust stream?

I have searched and I've heard all the "theories", but the guys out there that run Straight Duals with no Crossover pipes have not complained and loved their setup.

What do you guys think?

25thmustang · Jun 12, 2006

For the last half of last year I have had a complete seperate exhaust system. This wasnt much by choice, but I tried to pass emissions and the catted pipes I bought had no crossover. The car actually sounds much different than when it had a crossover, and even with the cats was louder than the prochamber.

Not sure if it hurt anything other than performance, but I didnt notice anything!

Synned · Jun 12, 2006

From what I have read, most of the complaints seem to be that with straight duals you have a big loss of backpressure, which results in less power.
I don't know how straight pipes sound on a mustang, whether crossover pipes sound better or what.
But with your car, you have enough power that I don't see the loss of backpressure hurting anything (if it even does it the first place.)

Blk91stang · Jun 12, 2006

25thmustang said:
For the last half of last year I have had a complete seperate exhaust system. This wasnt much by choice, but I tried to pass emissions and the catted pipes I bought had no crossover. The car actually sounds much different than when it had a crossover, and even with the cats was louder than the prochamber.

Not sure if it hurt anything other than performance, but I didnt notice anything!

I think I'm gonna give it a shot and if it's too loud I plan on using those inserts to quiet it down some. The exhaust setup I plan on using is one I've never seen on a mustang before and am very curious to see how it sounds. I don't wanna give away all the details until I get it on the car in about a month to make sure it sounds like I am hoping it will. I'll have pics and vids up when the time comes!

Boss 351 · Jun 12, 2006

needing backpressure is a myth... the best exhaust system is one that's not there. A good exhaust system will allow a scavanging effect by not letting the air cooldown before it exits the system.

I've had a straight dual setup (offroad H-pipe, was broke and fugged up, no crossover). Then I put an offroad x-pipe. The only difference I felt was in the upper rpm but it wasn't a huge difference, the sound is a lot nicer with the x-pipe however (opinion of course).

criticman · Jun 12, 2006

The point of the crossover is to equalize the pressure. It is supposed to allow for more efficient scavenging of exhaust from both sides of the block.

Not sure how much difference in power it provides though, but I know that it was intended to run with a crossover, so I will keep mine that way in some form (presently off-road H).

rx7speed · Sep 4, 2006

Synned said:
From what I have read, most of the complaints seem to be that with straight duals you have a big loss of backpressure, which results in less power.
I don't know how straight pipes sound on a mustang, whether crossover pipes sound better or what.
But with your car, you have enough power that I don't see the loss of backpressure hurting anything (if it even does it the first place.)

then an x/h pipe must really hurt power as it allows for better scavenging which is going to cause a much strong lower pressure zone behind each exhaust pulse.

thumper460 · Sep 4, 2006

Look at this... the engine fires.. the pulse leaves the engine and goes out a single pipe!! and uses so much engery to do this... NOW split the exhaust in two, thru a crossover pipe.. now the engine fires.. the pulse goes out two pipes.. thus using less engery.. and now you have MORE HP thru better exhaust!! the H pipe was the older way ( and any exhaust shop can do and H pipe) and now there is a smoother flowing X pipe!! ( more money , and actually not that much more HP over a properly installed H pipe!!)

Dyno your engine with straight thru NO mufflers!!
Then install an H pipe or and X pipe and you will see A LOT of gain!! Now dyno the car with the Crossover pipe installed and install a straight thru muffler ( like the Glasspac that you can see straight thru ..) and then remove the straight thru muffler and install the Flow master.. again there is a HUGH HP increase with the newer tec of the flo-master!! From the 2 straight thru pipes to the crossover and flo-masters can be as much as 30 HP!! And that is a LOT!! SOOOoo... ditch the straight pipes!! cool??

Just me...................................

Thumper

90NotchBack · Sep 4, 2006

I've been run straight duals on my Mustang and my Falcon for awhile now. I never did any dyno runs with a crossover but to me a crossover is just add money and does nothing to gain any horsepower but it does give a diiferent sound if that's what your after. Every car I see at the track with a lot of horsepower runs straight dual with dumps. The sound of straight duals sound some much better in my own opinion.

http://videos.streetfire.net/video/faf35627-0458-4306-a2bf-3b9314fba8b7.htm

http://media.putfile.com/7-28-06-pass-2

thumper460 · Sep 4, 2006

IF you JUST add the H pipe into your system.. you WILL drop .2 to .3 off your ET!! Is that worth it to you?? The Dumps are where those cars are making power.. cap one up and have him make a pass.. bet he slows down alot!!

Just me....................................

Thumper

Vinnietbird · Sep 4, 2006

I like my off road x -pipe.It's been great.The car runs great and sounds good.I have always had a crossover pipe on my cars,since the early 80's when I started driving legally.My '76 Grand Prix had a Trans Am 455,duals,"crossover",and capped dump tubes out to the side for an occassional blast down the track.I've always thought that the crossover helps the car equalize back pressure,thus helping the overall performance.

Euphoric306 · Sep 4, 2006

general opinion here is right, equalizing the backpressure helps more consistent scavaging and that means more power

the reason is that the firing order of our engines does not alternate cylinder banks. twice in our firing order, the same cylinder bank fires twice in a row, therefore creating unequal pressure in that exhaust side.

dunno bout corvettes, but if they alternated firing order on cylinder banks they should be able to use true duals with no loss of pressure.

88 Fox GT · Sep 4, 2006

I've always been informed that H and X pipes help create a better equalization of pressure between both pipes and helping to suck or pull the exhaust out of the car faster. I would never run without an H or X pipe of some sort.

90NotchBack · Sep 4, 2006

You guys read to many magazine. Try your own real world test. An X pipe slowed my Falcon down 5 hundreds an 1 MPH. That with back to back test down the track. When I did my mustang I just set it up like my Falcon because I did all the R&D with my Falcon. I have since took off the exhaust on my Falcon. Just adding exhaust slowed it down 2 tenths.

88 Fox GT · Sep 4, 2006

90NotchBack said:
You guys read to many magazine. Try your own real world test. An X pipe slowed my Falcon down 5 hundreds an 1 MPH. That with back to back test down the track. When I did my mustang I just set it up like my Falcon because I did all the R&D with my Falcon. I have since took off the exhaust on my Falcon. Just adding exhaust slowed it down 2 tenths.

Even if an H or X does nothing, I don't see how it could hurt the flow.

90NotchBack · Sep 4, 2006

I just don't see spending that kind of money for really nothing. My compete exhaust system cost $160.00 and it works great. Everyone has there own opinion. I wouldn't of thought it would of slowed it down that's why I tried it.

rx7speed · Sep 4, 2006

thumper460 said:
Look at this... the engine fires.. the pulse leaves the engine and goes out a single pipe!! and uses so much engery to do this... NOW split the exhaust in two, thru a crossover pipe.. now the engine fires.. the pulse goes out two pipes.. thus using less engery.. and now you have MORE HP thru better exhaust!! the H pipe was the older way ( and any exhaust shop can do and H pipe) and now there is a smoother flowing X pipe!! ( more money , and actually not that much more HP over a properly installed H pipe!!)

Dyno your engine with straight thru NO mufflers!!
Then install an H pipe or and X pipe and you will see A LOT of gain!! Now dyno the car with the Crossover pipe installed and install a straight thru muffler ( like the Glasspac that you can see straight thru ..) and then remove the straight thru muffler and install the Flow master.. again there is a HUGH HP increase with the newer tec of the flo-master!! From the 2 straight thru pipes to the crossover and flo-masters can be as much as 30 HP!! And that is a LOT!! SOOOoo... ditch the straight pipes!! cool??

Just me...................................

Thumper

flowmaster is by far not one of the greatest mufflers out there for power. the original glasspack mufflers are not a very good straight through muffler either. something to do with the louvers in the pipe that create a bit of resistance to flow.

rx7speed · Sep 4, 2006

90NotchBack said:
You guys read to many magazine. Try your own real world test. An X pipe slowed my Falcon down 5 hundreds an 1 MPH. That with back to back test down the track. When I did my mustang I just set it up like my Falcon because I did all the R&D with my Falcon. I have since took off the exhaust on my Falcon. Just adding exhaust slowed it down 2 tenths.

.05 et difference and 1mph? couldn't that be weather, driver, track, car, or other things?

either way I have seen some bracket racers come up with a little more margin then that. while keeping the same setup same day back to back.

also you can come up with issues like tuning and such. I've seen some situations where by replacing parts on the car will result with a loss of power as well. till the tune that is then you end up with more then before the mods

Georgie · Sep 4, 2006

fuuuuuck the exhaust..just the headers and thats it

90NotchBack · Sep 5, 2006

rx7speed said:
.05 et difference and 1mph? couldn't that be weather, driver, track, car, or other things?

either way I have seen some bracket racers come up with a little more margin then that. while keeping the same setup same day back to back.

also you can come up with issues like tuning and such. I've seen some situations where by replacing parts on the car will result with a loss of power as well. till the tune that is then you end up with more then before the mods

My car is deadly consistent. These where back to back test. I would make one pass down the track come back put the X pipe on make another it slowed down took it off and it picked up again. Then put it back on slowed down. That what they call R&D. Research and development. When we try new things we want to know if it's helping or hurting.

Purpose of H or X crossover pipe in exhaust. Problem if I run straight duals???

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