H-pipes for dual exhaust?

[Explorer X]

I am custom making my own dual exhaust for my Explorer. I am ordering 2 Flowmaster 40 series mufflers, one for each side. I am going to leave the stock system in and just put in cutouts before the cats. Anyway... I was wondering about H-pipes. Do I need to put one in before the mufflers or something, because at the Flowmaster website it says that H-pipes are recomended in all dual-exhaust applications. What does an H-pipe do???

 

[jssong]

i believe it allows the equal pressure to be dispersed between both pipes, but im prob wrong. normally the h pipes are done before mufflers i think. not sure if anyone has done an h pipe, but many have done the 40s duals without it.

 

[Paul Gagnon]

The h-pipe(crossover pipe) balances out the exhaust pulses of each bank of cylinders. This helps with scavenging (removes more combustion gases from the cylinder) and generally improves or smooths out the power from the engine. You don't absolutely need to have a crossover but there is no really good reason not to. The h-pipe should be before the mufflers but after the cats. Exact placement dictated by the space you have available.

 

[gavin]

after the cats?
The h-pipe was stock on B2s before 88 I believe it was. It's before the cat.
And yeah, the h-pipe equalizes the pressure. It helps most when the pipes are dif lengths before the h-pipe.

 

[TheRookie]

I am confused with your plans. You want to leave your stock system entirely in place and run cutouts prior to your cats to feed the twin flowmasters??? Why in the name of god would you do that? How do you think you are going to fit that under the truck? and lastly , are you bending this or having someone do it for you?

 

[Explorer X]

My mom is stupid. She doesn't want me doing anything to my car. So... I have to do things that my mom won't notice, otherwise she won't let me live at home. I will have a high powered servo attached to the cable on the Mr. Gasket cutout so I will be able to swich from the stock exhaust system to the loud 40 series mufflers with the flick of a swich... If everything goes as planned, and there is plenty of room under the car to fit the mufflers. There are two big empty spaces under the car, they are to the outside of the framerails.

 

[TheRookie]

Dude, Nothing personal but just skip this. Its going to cost a good deal to get this bent. Also FEW places will even considder doing it.

 

[Explorer X]

I'm making it myself. I'm buying pre mendrel bent pipes, and welding them together. It's all completely custom. It will cost me about $400.

 

[odxtoxic]

hey bro....good luck to you and your project.....and hello from SW minnesota

 

[Bill Kemp]

Whats it worth to you so I dont tell your mother?

 

[Campo]

Back in the day, I had a 76 Ceby Luv with a 4 banger. I took a 289 from my buddies malibu and cut, beat, forced and bleed it into the Luv.. then I put a cast iron cutout from JCW (might of been a quality thing) so my dad wouldn't notice the louder exhaust. you know switch it when I'm getting close to the house, switch it when I'm out and about....

Word to the wise, do one or the other, not both.. it's more of a PITA than anything you can imagine, the castiron cutouts will not last until your tail pipe get's it's first speck of rust (3mo's) on it before the cutout flap fails (ie.. just burns up) and it's running out both exhaust's (NOT GOOD). when that happend, I couldn't get above 30mph( 0 (read zero) backpressure)

I've done the "dual alternate exhaust thing" and have built many drag cars and talked to many other drag/gearhead's and they and I advise against it..
it's a waist of time and money....

 

[Explorer X]

Is there any other way to swich between two exhaust systems besides using cutouts? Or is there a "good" kind of cutout to buy that the flap wont "burn up?"