Gotta '73 F100 w/ 390. my exhaust consists of true duals out right before the rear axle w/ flow original 40's. my question is what exactly does an H-pipe do for ya? just equalized the flow from both banks? thanks

 

Funny thing...I was about to ask this exact same question. Exactly what is the purpose of an H-pipe or cross-over?

Thanks for the help.

 

Balance flow, and mellow the exhaust tone. Also worth a few ft/lbs if done right.

 

I understand the "mellow the tone" part...but "balance the flow"? Why? If the exhaust is essentially straight through, as with (for example) 40 series, or 50 series FlowMasters, what good does balancing do? How would it increase torque? Would it increase scavenging?

Let's assume we're talking about an Edelbrock system...complete left bank/right bank separation from air cleaner to exhaust on a relatively stock, non-smog 460.

This is a learning curve for me. I was once told by a buddy that owned a muffler shop that cross-overs caused more trouble than they were worth, due to vibration crackes and leaks, but I'd really like to know. In my mind's eye I would think that cross-overs would cause back-pressure rather than alleviate it...but my mind's eye has been wrong before.

Thanks for the help. Any thoughts on this matter are appreciated.

 

well i've gotten perty good with my mig welder that i can use for free at work so the cost of the pipe is the only thing and that might run me 30 bucks! great!

 

Wasn't there somthing about using paint to figure out where to place the Crossover pipe? I thought somone said that where is stops burning off is the optimal place for the crossover?

 

Yup, 351M has it right.

quehele- sorry, typo on my part, I was doing 1000 other things while I was typing It helps with scavenging, and as a result will build a small amount of torque. The key is placement. Putting it in the wrong place will do nothing.

 

where is right and where is wrong?

 

woops ok just read 351m...is that correct? just paint my tubes and where it stops burning is where to put the H-pipe?

 

Thats the easiest way to do it.

 

Make sure the cross-over will not be in the way if the transmission has to be removed. Just a thought.

 

the reason you put the crossover in is to balance the flow....on a v8, for instance, if you put all 8 seperate pipes, each cyl. will blub out (is that a technical word) on its own. if you put two in each pipe, they will kinda of compliment eachother, assisting the exit of exhaust. if you combine all eight, it smoothes out the flow, each exhaust stroke complimenting another. i think this is accurate...if not, someone correct me please. thanks
chris

 

Sounds close enough for me, Ken can probly feild that one also.

 

You got it right. What you are decsribing is scavenging. Each exhaust pulse helps pull the next one along.