hey all, was planning on getting true duels and heard that we should not get full on straight pipes due to loss of torque. i also got a piece of info from the other exhaust forum that X pipes were better than H, but at the end of that post it said that X wasn't all it was cracked up to be!! to me, i think X pipes are better due to less flow constrictions than an H pipe would render. any inputs or links to thread here on the forum to help me out with all this? thanks all! now let's see if MAX M could hook up a cool pic for my question, since he's being doing so well so far!!!

 

Ask and you shall receive.

Quote 1- "Why is an "X" pipe better than an "H"? The reason an X-Pipe crossover works better than an H-pipe crossover isn't more flow because of volume, but more effective use of exhaust gas velocity. Exhaust gas (or air) has surface tension, and flows much like liquid would through the same pipe system. As the cylinders of each bank on a "V" style motor fire, they create a pulse in the system. The pulses will alternate back and forth from bank to bank as the motor runs. With multiple cylinders, such as a V-8, the eight cylinders alternately fire creates lots of pulses in the system. If you put your hand behind the tailpipe, it would feel like a constant flow of air, but what it really is a lot of singular pulses giving the impression of constant flow. The idea behind the H and X style crossover is to unite the two banks of cylinders for better exhaust gas scavenging. Instead of two separate banks of four cylinders doing their own work, the crossover uses the pulse created by a firing cylinder of one bank to create a vacuum in the other bank because of surface tension. When a cylinder of the other bank is ready to fire, instead of the piston having to force the exhaust gas out of the cylinder, the vacuum that was created by the other cylinder bank helps suck the exhaust gas out of the cylinder, hence the term "scavenging." Whenever you can reduce the load on an internal combustion engine, you are likely going to see performance and efficiency benefits. The difference between an H and X crossover is a smoother path for the exhaust gas to follow. Exhaust gas, like a liquid, will follow a path with the least amount of resistance. An H crossover has a path with two sharp 90-degree angles that are close together. An X crossover has a path with a much more gradual bend to allow the exhaust gases to continue their path back out to the ends of the tailpipes, rather then turning sideways for a short distance, then turn again to head out the tailpipes. Smooth flow with high velocity means more power by use of scavenging. Using an exhaust system with too large of piping diameter work against scavenging in the same way that running an exhaust with too small of tubing chokes the motor and forces it to work harder to expel the exhaust gases."

Quote 2- "For any performance exhaust system, some type of crossover connecting the two sides of a dual exhaust system is important because it acts to balance the two banks of the engine. The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. In an X-pipe system, however, where the two sides of the system intersect, the gasses have no choice but to intermingle as they pass through the junction. This promotes improved scavenging effects by smoothing out uneven exhaust pulses from the engine’s firing order. It also helps quiet down the exhaust, resulting in a mellower, less raspy tone. The faster acceleration of the gasses through an X-pipe causes them to flow in a linear fashion parallel to the walls of the tubing rather than tumbling. This “laminar” flowing gas is much quieter than tumbling gas, resulting in an exhaust tone up to 8 decibels quieter than a traditional H-pipe."

 

kneel down ye sinners to max mitchell!.......Max Mitchell has spoken and answered with the holy grail of wisdom. His cup runneth over with knowledge set forth by the exhaust gods from high above on mount Flowmaster to the valleys of Magnaflow to the Borla forests!!


HFSM!!! thanks again max! while using the X pipe conversion, it will lower the tone of the flowmasters...while improving performance, while having and H conversion, it will make it louder, but down grade performance! is there a way to keep up the tone and growl of the flowmasters while improving performance? while i might end up doing the X pipe conversion, i still want that growl, but like every one here, want to keep up performance! but now that i think about it, while having 2 flows will still sound like one with the reduced sound supplied by the X pipe correct?
......bow down all ye who cross this thread with questions to the holy one....

 

You're Welcome ! The humorous photo wasn't intended to be any relation to me. As you probably know, I don't recommend using true dual exhaust systems or Flowmasters on these F-150s. Guesswork exhaust systems generally reduce low-end torque and mileage, negatively effecting drivability. Also, the "typical" true dual exhaust system design on F-150s doesn't accommodate proper placement of the balance tube. In a beneficial application, I would use an X-pipe and forget the marginal sound difference.

 

so in your honest opinion, what is there to gain from duesl on the F150? let's use mine for example. 5.4L, airaid, and chip down the road. i already have SISO flowmaster 40 with an after market Y pipe. so what am i to gain from going to single exhaust to duels with a X pipe? basically do you MAX, or anybody for that matter think that it will be worth 2 bills for parts and install? Willie

 

The only benefit I know of is a slight boost in top-end WOT power. My opinion is that it's not worthwhile. If I'm remembering correctly, you already installed a complete single 3" system including the 3" Y-Pipe. Besides your muffler choice, I think you have the best configuration for a lightly modded street driven F-150.

Ok guys, give hime some more opinions !

 

what is WOT?

 

wide open throttle!

 

Max knows what he's talking about.

True duals are good if you have forced induction like a turbo or blower, a single 3" system is plenty for a non-boosted truck.