I'm about ready to have my exhaust system built on the truck...

460 and a c-6
sanderson headers

I know the advantages of having an h-pipe setup... but I'm not sure the bender guy will know how to do it... so that will be two of us !!

how do you calculate the best distance from the collector to install the h-pipe and what should the length be between the two pipes...

this could make a huge difference and if it hits under the transmission I need to consider some flanges for removal if I have to drop the transmission in the future...

any exhaust gurus out there ???

thanks

john

 

John

I wouldn't consider myself a guru, but the H or X pipe is usually installed in the front third of the system length. Usually near the rear of the transmission. It's addition is not going to make an earth shattering difference. Especially if you use at least 2 1/2" duals. If it is going to cause too much interference grief, I'd skip it and not sweat it too much. It is also something you can add later easy enough. You can buy an H-pipe from Summit or Jegs and its an easy install for an exhaust man.

 

Cuz,

"A crossover pipe is very important in an H pipe. It must be two sizwes smaller Than the diameter of the H-pipe (i.e. 2 & 1/2" on a 3") and properly located...."

"Calculating the correct location for the crossover pipe involves some interesting fluid dynamics. However, since most hot rodders are more interested in racing than doing math, a simple and effective method is.....

Simply paint a stripe down each side of the unfinished H pipe (no crossover pipe yet) with non high heat paint (or a crayon). Make a couple of high speed passes and look at the paint stripe. You will find a point where the paint is burned. This is where the exhaust pulse changes direction and is the exact location for the crossover pipe."

source -Mustang Performance Handbook by Wm R. Mathis.

(Also has the finest article I've ever seen on blueprinting an oil pump)

Later,

 

A freind of mine that used to have a Meineke shop agrees and says its a sure way to mellow out the sound. He used it plenty on V6's with duals to make them stop blatting like 2 rice burners under the hood.

 

Simply paint a stripe down each side of the unfinished H pipe (no crossover pipe yet) with non high heat paint (or a crayon). Make a couple of high speed passes and look at the paint stripe. You will find a point where the paint is burned. This is where the exhaust pulse changes direction and is the exact location for the crossover pipe."

RMF

That is very interesting. I never heard of that before but it makes very good sense. I wonder what are the odds it will be in a location where you can actually install a cross over? Anywhere behind the transmission and you're going to be in for a tough install. Very limited amount of places you can run your muflers under these trucks if you want it out of view. It makes them sound nicer if you get the H anywhere close though. I guess that's the upside. I like the duals nice and easy to drop so I rarely run an H. You don't disassemble your exhaust pipes on a daily driver in Iowa for long without a torch.

 

John,

No exhaust guru here, but in my own humble opinon, I think H pipes are over-rated. Had one on my 65 Mustang 2+2 when I first bought it and it sounded wimpy. I removed the H pipe and felt no measurable performance loss and it sounded much better. Unless you are going for the "nth" degree of horsepower, I'd just leave it off...

 

"No exhaust guru here, but in my own humble opinon, I think H pipes are over-rated."

Vern

Perhaps it's because they are almost always installed where they will fit, rather than exactly where they belong. Now that RMF has posted this info, I wonder how far you can compromise before you're just wasting your time. There are some many variables that are going to effect it. The method RMF posted is probably the only practical way to calculate it's location. Unless you're luckier than I, you know it's going to end up smack under the tranny pan, or some other place you can't do a neat install.

I do think they improve the sound, but you can alter that with mufflers and pipe diameter too.

 

The H pipe will flatten the torque curve a bit and improve the low end.
The crayon trick has been around for decades; no need to do a high speed run, this isnt rocket science and 4-6" either side of ideal is fine.
For best results the balance pipe shoud be as short as possible so if you are building an all new exhaust bend them as close as possible keeping in mind being able to do drive system maintenance.

Im not fond of the sound either when using fat exhaust pipes but a Y Block and 1 3/4" pipes sounds OK. You might also want to experiment with muffler placement for the sound you want.

I have 3" pipes and Flowmasters on my 95 Caprice/LT1 and the exhaust is too quiet for my liking. But that tank hauls a.s!