X or h pipe, your thoughts guys

[BCOWANWHEELS]

Your thoughts........... 72 c10 lwb sbc,, 400 th trans , 2.5 exh system. Pic,s appreciated

[Andy4639]

I've never done one on a vehicle. For what ever gain you get is it worth the extra money to have it done? Not from what I've read it's not, not for a street vehicle.
When saying this I mean can you feel, tell a difference in how the vehicle performs! Yea I'm sure a dyno sheet can show you a benefit but is it worth all that/

[tim_mc]

The PO of my truck had duals just past the cab with Flowmasters that droned quite a bit, so I had full length 2-1/2" dual exhaust with Magnaflows extended over the rear end and out at the bed corners like factory. I had them install a 2" H-pipe just past the transmission tail housing while they were at it. It really smoothed out the exhaust note. Some guys mentioned that it improved low-end torque. I *think* it did, but it may just be my imagination. There are several threads on here that discuss X & H-pipes.

http://67-72chevytrucks.com/vboard/s...d.php?t=297754
http://67-72chevytrucks.com/vboard/s...d.php?t=690801
http://67-72chevytrucks.com/vboard/s...d.php?t=411700
http://67-72chevytrucks.com/vboard/s...ad.php?t=93187

[BCOWANWHEELS]

Great pic tim. I,am going with 2 caddy eldorodo mufflers. I dont want the noise but rather performance. My 350 is pretty hot perf wise

[tim_mc]

Thanks...I decided it was worth adding an H-pipe to balance out the exhaust pulses and (maybe) pick up some gains on the low end. The shop only charged me a few bucks extra while it was on the lift. There are some pics of other setups on the threads I posted along with some good feedback. Many believe it adds low end, and I think it improved mine. As Andy mentioned, it might not be worth adding if it requires a special trip up the lift, but if you're doing the whole exhaust anyway then it might be a nice upgrade.

This is the science behind it:
Older SBC firing order is 18436572 or LRRLRLLR, which causes more exhaust pressure when cylinders 8&4 and 5&7 fire in succession.
LS firing order is 18726543, or LRLRRLRL, (the 4/7 swap) which improves the alternate firing over the original order.

So an H-pipe on an LS might be less effective for noise cancelling, but would probably still help with flow.

[Sheepdip]

I had a H pipe added to my 1 ton a while back, I was looking for tone/deceleration rap cancelling which it probably knocked 80% of the rap out and 50% noise reduction.

I was told they are a Magnaflow copy cat type of muffler which I was also told are straight thru like a glass pack. A little too loud for me but they were on the truck when I acquired it, a brand new complete nice looking done right muffler job, so I left it as is and added the H pipe.
Can't speak for performance and don't care but it sounds one hell of a lot better $40 and took less than 1 hr total

['68OrangeSunshine]

I have an H-Pipe behind the 350/465/205 on my '71 GMC.
On my '68 C/10 Stepside w/ 292 L6, I have an ''N'' Pipe, since the 1-2-3 collectors are not quite a foot forward from the 4-5-6 collectors.
Same function, however.
Not sure about the moto/metaphysics of it all, but it cuts off some of the frequencies audible to the human ear.
Dogs and overly-sensitive car alarms [especially in underground public garages] can still pick up the vibrations, however.
I have no experience with X pipes.
I would think the X junction would get really hot. Possibly also cause restrictions. IDK

[special-K]

I've never been sure what people mean by drone when talking about exhaust. I know what drone means and I don't think anything I heard on my trucks are it. I say this because the whole crossover thing came about one day when I wasn't looking. I never heard of anybody doing them on custom dual exhaust and that includes me. I have never had an exhaust guy ask about or suggest one. I have yet to install a crossover on anything and I have put dual exhaust on dozens of vehicles. Maybe ignorance is bliss here for me, because I don't see any reason for them and they are usually hard to find a good spot for them. Especially on a 4wd. I also feel the less welded joints in my exhaust the better.

[Andy4639]

Originally Posted by special-K

I've never been sure what people mean by drone when talking about exhaust. I know what drone means and I don't think anything I heard on my trucks are it. I say this because the whole crossover thing came about one day when I wasn't looking. I never heard of anybody doing them on custom dual exhaust and that includes me. I have never had an exhaust guy ask about or suggest one. I have yet to install a crossover on anything and I have put dual exhaust on dozens of vehicles. Maybe ignorance is bliss here for me, because I don't see any reason for them and they are usually hard to find a good spot for them. Especially on a 4wd. I also feel the less welded joints in my exhaust the better.

I've never installed these either Tim. I guess older we get less noise we hear! Maybe something to it but as I stated in my post you want feel anything when driving it I bet. I turn my hearing aids off when driving so that maybe why I don't hear the drones flying around me.

[sick472]

My ignorant theory...H/X pipes are a nice addition to an otherwise finely tuned exhaust system that is coupled with a finely tuned high performance engine. Kinda like...why port the heads if the exhaust manifolds/headers and intake are not ported also... and the carb is not flow tested/tuned for the motor specs, and the valve/springs/pushrods are not dialed in too (I think we could all go on about the tricks to build up a power plant). It all goes into squeezing the last available HP from the vehicle.

With that said, if you have the time and the money...do all that you can to "supe it up", but use good judgement as to where you put your time and money.

As far as sound, I have gotten past loud pipes and the desire to push the engine beyond street-able, I like to drive in peace and if the H/X pipes tone it down...I'm all for it! A "one horse per cubic inch motor" (that's how I build them using the phrase "there's no replacement for displacement') won't see a noticeable difference with the H/X pipes as far has power is concerned, but it will change the sound. Think of Side Pipes...you hear the sound from one side and all your getting is that bank of cylinders...then think of the sound from tailpipes...they blend the two banks...Put an H/X pipe in and the cylinder noise is blended internally and it smooths the sound out from any angle. This could be good depending on your tastes.

Horse power/torque advantages aside...I kinda like the tone change as I walk around the vehicle. Just my opinion. It may not be advantageous to getting that extra "Umph", but I will gladly sacrifice a few ponies to treat my ears given that I the motor is just mildly built.

[tim_mc]

I think it depends on the exhaust setup as to how beneficial an H-pipe can be. Adding an H-pipe to headers and low restriction mufflers cancels out the exhaust pulses by tying both banks together. Someone running manifolds and a full length exhaust with more restrictive/quiet mufflers would not likely see as much noise cancelling effect.

As for the benefits of a cross-over, I installed a Hooker Blackheart X-pipe cat-back system on my '02 Z28...definite improvement in performance. The scavenging effect improves exhaust gas flow, but not so much on the noise cancelling in that case.

[mike88a]

Not sure of the benefits of one over the other but when I put the motor in my truck and took it to the best exhaust guy in our area and asked him he said for a mild to mid performance street motor "H" pipe for a more high performance motor say closer to 500 hp and up "x" pipe. He said he doesn't let any classic with any motor work done leave without at least an "H" pipe. I love the sound of my truck. 350 with small cam and sanderson shorties 2 1/2 threw super 40's.

[Killer Bee]

I'm no engineer and I'll sock a guy for calling me one

but couple of lay person observations..

laminar flow > turbulent flow so the X would likely outperform the H

what sounds better? sound tuning an exhaust system would have to be salt-to-taste..

as for why crossover tubes or balance tubes are installed at all, my vague memory recalls the purpose having something to do with the firing order and number of cylinders on exhaust from one bank to the other.. but don't quote me, I'm just a dumb mechanic..

I have had them installed by recommendation but never asked for them..

and agree 100% with above, show me the time slips or the dyno sheets to prove a performance claim..

cheers and good luck!

[68panelman]

Straight up classic true duel exhaust for me, no need for fancy here

[bigsnookmaster]

I have a pretty healthy 406 and I run a 3" mandrel bent exhaust with an X pipe. Really smoothes out the exhaust sound IMO. I have ran them for years.

[BCOWANWHEELS]

I think a h pipe is for me.

[chiggins]

https://www.youtube.com/watch?v=Dd43rwLHEW4
I believe there is also an Engine Masters episode where they compared them on a dyno. From what I remember in reading and watching, H-pipes are better for a bump in lower end power, while X-pipes are better for higher RPM's. I believe they saw about 10-15 HP increases in both setups over straight pipes.

[tdangle]

I just went over this with my exhaust guy. I had a new 2 1/2" system with stock ram manifolds and Dynomax mufflers installed extending to the rear bumper like the new Ram trucks. He claimed an X pipe would mellow out the thump in a mild cam more than a H pipe. Both quiet the exhaust note and an H pipe is a little better for low end while X pipe is better for high rpm. He suggested just going with the H pipe as it had to be installed a ways back (just behind the trans) The X pipe wouldn't work as well installed that far back.

BTW: The exhaust sounds great and is fairly quiet in the cab.

[GASoline71]

10-15 hp isn't enough for me to worry about modifying my dual 3" with Flowmaster 40 series. If it was good for a 40 to 50 hp gain... then i'd seriously consider it.

It might make the exhaust note a tad different. but anything gained you'll never feel it in the "seat of your pants".

Gary

[k2rm]

My results are like Tim's, although I kept the Flowmasters. Without the H-pipe, the drone was exhausting on highway drives. After the H-pipe was installed, no more drone and the exhaust sounds much better overall. I wasn't looking for or expecting performance gains.

[slammed57]

say x-pipe because they just look freakin cool!

[Molino]

Originally Posted by BCOWANWHEELS

Your thoughts........... 72 c10 lwb sbc,, 400 th trans , 2.5 exh system. Pic,s appreciated

I really was hoping that someone with an oxygen sensor on their exhaust would chime in to this thread. I’m curious as to the tuning/jetting changes that are required to get the air/fuel mixture to optimum after tying the exhaust together. Changes to the exhaust will have changes to the induction, but how much, if any.
Old school guys used to say that if the intake plenum was shared between both banks of an engine that the exhaust should be tied together also.
Russ

[special-K]

^^^ I don't expect any of that to apply here. BTW, what is an oxygen sensor?

Maybe start a thread in the Engines forum or Racing and Hi-Perf

[LockDoc]

-
Yes, there is such a thing as drone. I had it at 60-65 miles an hour with the '67 Panel Truck, and it has an LS1 engine with Series 40 knockoffs. It also has 02 sensors so that applies here too. I didn't have to re-tune anything. My wife wouldn't ride in it any more until I fixed it. I haven't seen this mentioned in this thread, but I installed "J" pipes on it and cured it immediately.

You might try a set of "J" pipes. The guy at the muffler shop I go to had never heard of them. He couldn't believe what a difference they made in the exhaust sound after he got them installed..... Exhaust still sounds good, just no drone.

Chart below the picture to calculate the length you need.

They are just a pipe shaped like a "J", installed just behind the mufflers. They are capped at the end and the frequency bounces back and cancels itself out. You can't just make them any length and expect them to work. That's why I recommend doing some reading on them. I think mine are 23.5 inches long.
---------------------------------------

Posted by another member:

When you look at LockDoc's chart you will see that lower the RPM the longer the tube. Those tubes really do work. The science is sort of cool. Basically they are a quarter wave and bounce wave back onto the incoming wave to cancel it out. RPM, temperature and other variables are at work but with a little adjusting/tuning you will get it and be pleased, I think.

Tim... I'm wondering if this whole thread belongs in one of those other forums.... Dunno'

LockDoc

[Molino]

Originally Posted by special-K

^^^ I don't expect any of that to apply here. BTW, what is an oxygen sensor?

Maybe start a thread in the Engines forum or Racing and Hi-Perf

You are right, if you don' know what an oxygen sensor is, none of it applies or matters. Point being , if you install a crossover there may be some jetting/tuning involved...
or not..
Russ