Has anyone done a H-Pipe instead of an X-Pipe?

[Tomislav]

Why the preference of one to another?

[Sean05]

The only one i know of is akra uses H and X pipe on the evo

[1MOREMOD]

my understanding of it is that an H pipe allows some equalization of pressure from side to side thus reducing backpressure to a small degree but an X pipe brings the two sides together allowing scavaging of exhaust gases from the other side creating a much greater pressure drop hence freer flowing exhaust.

[Raptor251]

Akra has both!

[e90m3japan]

I have amuse/ericsson full exhaust set-up with H and X pipe.
less sucking sound when releasing the throttle.

[1MOREMOD]

Most of us probably like a sucking sound!

[kitw]

Originally Posted by chriszeh

my understanding of it is that an H pipe allows some equalization of pressure from side to side thus reducing backpressure to a small degree but an X pipe brings the two sides together allowing scavaging of exhaust gases from the other side creating a much greater pressure drop hence freer flowing exhaust.

No, they function the same way. Just different ways of tuning the scavenging, you can really only vary the position and size of an X pipe, where you can vary the width, position and size of an H pipe. Akrapovic's Evolution (and Gt4) midpipe use both X and H pipes. I haven't seen a significant difference, I ran both the Akrapovic and Challenge mid pipes and they both work pretty similarly and sound similar too.

[crabman]

Originally Posted by chriszeh

Most of us probably like a sucking sound!

lol, that one almost went by me.

[m3an]

there's some good articles to be found if your search re: h-pipes vs. x-pipes on v8 engines. Basically the idea behind both is to equalize the constantly changing pressure/velocity in each bank. The x-pipe design forces the cross-over whereas the h-pipe using the exhaust own scavenging to pull exhaust from one pipe to the other to equalize pressure.

[E90///M3`]

Originally Posted by e90m3japan

I have amuse/ericsson full exhaust set-up with H and X pipe.
less sucking sound when releasing the throttle.

this sounds interesting and i'd like to hear the sound as well as know any whp numbers you may have gained.

[m3an]

it would be interesting to see a test done with all other things equal and just swapping the x-section for an h to observe the power difference

[Tomislav]

This poses my next question then, why not just go with non-connecting pipes?

[m3an]

Originally Posted by Tomislav

This poses my next question then, why not just go with non-connecting pipes?

it won't make as much power and will most def be louder

[Raptor251]

Just wanted to give a little update to this thread. I've been really curious as to why Akra has both a H/X pipes and seeing as how they make one of the best systems out there I figured they were on to something. I decided what the hell, since I've already cut up my RPI x pipe to add resonators and H pipe cant hurt! All I can say is WOW! The car sounds totally different, it has a much deeper tone and the intake noise is insane. The car was also a little raspy from 3-4k before and now the sound is so clean! I need to do a dyno asap! Sorry for the bad pics. You can see where I added the H in the second pic just behind the tranny

[Keik E92 M3]

amazing!

[E90///M3`]

i see the X... i don't see the H?

it can't be in the second pic, cause the second pic only looks like a bar connecting the catalytic convertors. i thought an h-pipe actually had a hollow bar connecting the two pipes.

[m3an]

Originally Posted by E90///M3`

i see the X... i don't see the H?

it can't be in the second pic, cause the second pic only looks like a bar connecting the catalytic convertors. i thought an h-pipe actually had a hollow bar connecting the two pipes.

look at the polished piece to the right

[Raptor251]

Originally Posted by E90///M3`

i see the X... i don't see the H?

it can't be in the second pic, cause the second pic only looks like a bar connecting the catalytic convertors. i thought an h-pipe actually had a hollow bar connecting the two pipes.

The H pipe is the new shiny piece welded in right before the resonators. (Those are resonators NOT cats). I bent and notched a piece of 2.5" stainless and then marked where the down pipes needed to be opened up to allow exhaust flow. I used the plasma cutter to open up the down pipes and cleaned up the opening with the air sander and a flap wheel. The piece of stainless was then fit back in and I mig welded it to match the rest of RPI's welds. Again sorry for the nasty pic. On another note I drove the car around all day and words cant describe the amazing difference in sound quality!! Oh and I also added that piece of 1/4 flat stock to the resonators to try and cut down on vibration noise and its helped! The factory clamps on the down pipes were removed from my OEM exhaust and fitted to the RPI system as their POS tabs snapped off a long time ago. Between the new tranny down pipe clamps, plate on the resonators for stiffness and the H pipe this thing sounds amazing. I think my favorite part about this car is how easy it is to work on!

[E90///M3`]

Originally Posted by talontid

look at the polished piece to the right

oooohhhh hahaha... damn i'm blind.

[Raptor251]

bump for some thoughts from the experts!

[Singletrack]

Originally Posted by Raptor251

bump for some thoughts from the experts!

H-pipe on the Akra is located strategically.

Here is a thread in which Sal @ Evolve talks about the H-pipe on their former exhaust:

http://www.m3post.com/forums/showthread.php?t=384925

[Raptor251]

Thats an interesting thread, I would be curious to hear what Sal has to say about this almost two years later!