H-Pipe Placement on a 4x4?

Torque Junkie · August 30, 2001

Does anyone have any pictures or diagrams of the best place to place an H-pipe in a 4x4? It looks as though the best place is going to be right behind the T-case right in between it and the point where the DS starts downward (before the mufflers, of course)

I got my flow's hung up today, and it sounds AWESOME, but it's a little raspy above 2500 rpms at WOT.

Thanks

-Mike

August 30, 2001

For the best perfomance, H or X pipes should be halfway between the collector and the muffler.

BTW the muffler should be as far down the line as possible.

Torque Junkie · August 30, 2001

Quote: from Friz on 11:39 pm on Aug. 29, 2001
For the best perfomance, H or X pipes should be halfway between the collector and the muffler.

BTW the muffler should be as far down the line as possible.

Heh.... whoops. Too late They're right smack-dab in the middle. I'll take a pic tomorrow and post it in this thread.

76BBSub · August 30, 2001

Friz, where did you hear that further back was better? I have a few different editions of Chevrolet Power, which is Chevrolet's "off-highway" engine modification book, containing power enhancement information for Chevy engines. Their engineers recommend putting the H-pipe as close to the engine as possible, based on their testing and experience. I always went with their recommendation, because I have never run into anyone who had an opinion either way. I don't mean to second guess your answer, I was just curious as to where you heard that, or if it was from your experience, etc.

Thanks!

Jeff

August 30, 2001

HP books, "how to Hotrod Small Block Chevys".

In the exhaust section, it states to get the muffler as far back as possible.

It also says to put the "H" pipe ahead of the mufflers. I don't remember where I heard that it should be halfway, I'll keep looking.

76BBSub · August 30, 2001

I have also heard to keep the mufflers as far back as possible, can't remember if that's in the Chevy book or not, though...

Jeff

Torque Junkie · August 31, 2001

Here's a picture i just took underneath. Those Flowmasters sure discolored quickly

Here's where I'm thinking the H-pipe should go, bent under the very front part of where the DS meets the Tcase.

-Mike

(Edited by Torque Junkie at 8:18 pm on Aug. 30, 2001)

Ken73 · November 4, 2001

Mike, that's precisely where I was going to put mine, simply because it's probably the easiest spot to put one. I can't imagine it hurting performance drastically if it's not the perfect "sweet spot" really.

Ken

Jack Boelte · November 11, 2001

At the Corvette Forum, I have read to sparay some cheap sparat paint (lightly) onto the pipes, run it for a while to get it good and hot. Thensee where the paint burmed off or discolored the most. That spot is where the H pipe should go.

Torque Junkie · November 11, 2001

Quote from Jack Boelte, posted on Nov. 10 2001,10:11

At the Corvette Forum, I have read to sparay some cheap sparat paint (lightly) onto the pipes, run it for a while to get it good and hot. Thensee where the paint burmed off or discolored the most. That spot is where the H pipe should go.

That's an interesting idea.

I'm wondering (mostly becuase it's midnight and I'm tired and can't think), what is the physical and scientific reasoning for that, do you know?

Just curious

-Mike

Jack Boelte · November 12, 2001

I suspect it has something to do with the sound waves as they travel or reverberate (sp?) between the muffleror catalytic converter (restriction) and the end of the collector. If you look at how a 2 stroke motor cycle's exhaust is designed and built, my thinking is in there somewhere. (yeah, it's late) I think that when exhaust pulses meet is where the heat or restriction is built up. Just as the merged collector uses the preceding exhust pulses to scavenge the gases (create a vacuum) for the following exhaust pulse, the muffler bounces that same pulse up stream. The H pipe allows some relief for the returning exhaust pulse; it gives it somewhere to go when confronting a new exhaust pulse, just in time...

With several rum and cokes, I can see all of this quite clearly; I hope I was able to translate it to the cyber world. Hasta la vista.

TDS 854X4 · November 13, 2001

I have heard of the same method that Jack mentioned, using the paint to tell you the optimum point for the cross pipe. I got it from Car Craft or (not so)Hot Rod a while ago. It had to do with the exhaust temps and the flow, but hey, I'm no scientist, so don't ask me any tough questions about theory! ;)

But that said, what do ya do when the optimal spot is not the easiest spot, or even possible perhaps? I'd put it where I could at that point. An 'H' or 'X' pipe is supposed to benefit your system, so if it can be added, do it.

I would think that your intended spot should be pretty close to where it wants it actually, I have always heard that it should end up a short ways downstream oh the collector, and I have also heard that the muffler should be as far to the back as possible, although I've only heard that thru others...

Good luck with the project, by the way. Those pipes look good under there!