So what are the gains losses between running a X pipe over a h-pipe w/ dumps? why would some guys run a h-pipe while most put x-pipes on their car...


thanks for any help!

Tim

 

I will be running an H pipe when I do my duals. I Like the h pipe sound better, And am more worried about low end torque then 7000 rpm horsepower. I think that you will find most people do disagre with me, but to each their own.
heres a quick article about x and h from dr gases website

The most common way of reducing this out of sync imbalance is with rebalancing crossovers such as H pipes and over-and-under X style crossovers. These provide both noise reductions and efficiency (power) improvements. H pipes are effective only at low and mid range. The over-and-under X crossover works a little better but still does not completely rebalance the exhaust at high RPM.

All V-8 engines with 90-degree cranks have an imbalance in the firing order between the right and left cylinder banks. The firing order imbalance is a necessary sacrifice so that a dynamic balance of the rotating and reciprocating assembly (crank, rods and pistons) can be maintained. Each time the firing order is complete (two full revolutions of the crank), two cylinders within each bank fire and exhaust within 90 degrees of each other. Because of this, this pair of cylinders will be exhausting into the header collector (on one bank) almost simultaneously. This overlap creates a back pressure. Meanwhile, the header on the opposite bank has no activity (or pressure) in it at all. Conventional full-length four-tube headers help separate the exhaust in the cylinders until it reaches the collector. After the header primary tubes dump into the collectors, the two cylinders close to each other in the firing sequence again are fighting for space in both the collector and exhaust pipe. This results in reflected pressure waves traveling backwards though the exhaust system. What you get is more backpressure, diminished power and fuel economy, and the V-8's characteristic growl.

Wouldn't a traditional H-pipe crossover, or equalizer, allow some of this excess pressure to bleed over to the "quiet side" of the exhaust system? Jere Stahl ran 330 gallons of fuel through a pair of street engines in part throttle dyno testing to find out. One was a 350 small block, the other a 400 small block. Testing at 2550 RPM and 3050 RPM, primarily at part throttle, in HP ranges from 35 to 125, Stahl found that a balance tube actually hurt fuel distribution on every manifold/header combination he tested. It never helped at full-throttle power, either.

Some people have found small low and mid-range torque improvements using an H-pipe. But at high RPM, the gases cannot bleed across the H-pipe fast enough to help power very much. The double cross, X-crossover, is an improvement beyond the H-pipe, but does not resynchronize pulsing and pressure spikes completely.

 

That's the best info on H and X pipes I've ever heard. Thanks TA

 

wow, thanks for that~


Tim

 

I had an H setup before, I did it because it was cheap.

I am doing an X right now. I have friends in the low 9's and high 8's who reccomend it.

 

With an X-pipe, the "crossover" pulse has to make only
one right-angle turn. In an H-pipe setup it has to make
two. If the X-pipe is made with a larger center plenum
then it effectively makes no turns (except the clean
45s before and after the junction, which shouldn't
matter).

I think the X-pipe will be superior to the H-pipe at high
RPM because of the lesser flow jerk-around.

 

ta12sec, you should have finished quoting the article which shows that a siamsed (two pieces inline with each other) x-pipe will make the most power on an exhaust setup.

The part you quoted shows the h-pipe isn't good at the high end, and a over-and-under x-pipe (whatever that is, I've never seen one) is better than the h-pipe but still not good at the high-end.

Then the rest of the article follows where it says that a siamsed x-pipe is the best for power.

Dr. Gas, Inc. has developed a new generation of crossovers that uses a tangentially siamsed junction, in place of the H or over-and-under X. It evenly splits, smoothes, and synchronizes exhaust pressures at all engine speeds. The high and low pressure pulses in the two pipes are evenly imposed on each other, leveling out the pulse time history pressure differences between right and left cylinder banks. Re-synchronizing the exhaust pulses reduces back pressure, cancels sound, and provides additional scavaging. Tests have sound 6 dBa (75%) reduction in sound levels, and increases of 10 to 30 hp, and up to 40 ft-lbs. of torque! Economy, and throttle response are improved. Exhaust flow after the crossover is completely smoothed out. The job the headers started is finished.

One of the most appealing benefits of this system is the modified exhaust note. The deep growling and popping sound is replaced by a higher pitched smooth sound. The exhaust note is similar to a 180 degree header system without the nightmare of tubing.

Dr. Gas crossover kits replace the first 3 to 4 feet of the exhaust system with pre-bent mandrels pieces. Simply measure, cut and weld into place. The system is universal fit for most header applications. After the crossover, any type of dual exhaust, converters, or mufflers may be used with little or no effect on power. Vehicles that have problems meeting sound limits at local area tracks can also benefit with an increase in power tool. And so, the piston engine can go HUMM!



Here's the links
http://www.drgas.com/art-sync.html
http://www.drgas.com/art-syncronicity.html

An x-pipe will make the most power.

Here's another quote from the article you didn't use.

That's where the Dr. Gas Crossover differs. It evenly splits the flow in the crossover junction. The pressures on both banks are equal and pulse-free after the crossover, regardless of RPM. In addition, secondary scavenging of the entire collector system occurs in both banks are equal and pulse-free after the crossover, regardless of RPM. In addition, secondary scavenging of the entire collector system occurs in both banks. Volumetric efficiency and power are improved at all engine speeds. Engines with high overlap cams (a typical race engine) will also see an improvement in idle quality.

 

I wasnt trying to advertise anything just go through the x vs h thing.

I have never seen a "over under x" either.
Also I am fully aware that a x pipe would stand a much better chance for more power, But I am yet to see anyone do a h pipe on a ls1 so I am gonna give it a shot, maybe ill get lucky and have a killer "under the curve" maybe I will lose 100 hp. I do know that I likt the H sound better then the x.

 

I've had a h-pipe and x-pipe on my car.

The h-pipe did have a meaner, racier sound, but the x-pipe made more power at peak and a little more under the curve.

The h-pipe made more under the curve then my Loudmouth but had the same peak numbers as it.