True Dual Exhaust with Dual High Flow Cats and Flowmaster Delta 50's

[Evolution1980]

The posts here have suggested that it balances the flow, which assists with breathing and smooths things out.

The 2 1/4 inch pipe didn't drop any of the low end torque, something I was warned about if I went to 2 1/2 with the low horsepower 77 engine.

The X-pipe is supposedly known for increasing low-end torque. My mechanic suggested one for my car, but as happy I am with the sound of my car, I didn't want to mess with it. If it ain't broken...

 

[77-4speed]

Actually, the H-pipe is recommended for better low end torque and the X-pipe is recommended for better top end hp. Both X and H pipes are said to help reduce the "gurgle" and "popping" on deceleration.

At least, that's what I've gathered so far. Who knows anyway. The tests that I've seen published show a 3-5 hp improvement on the top end with an X over an H pipe, and ~2-3 ft-lb torque improvement with the H over the X in the low end.

Both offer ~6-9 hp and torque improvement over no pipe at all.

Russ

 

[Evolution1980]

You're correct. I was thinking H and typed X...

 

[vettte_wings]

X-Pipe

FLP Exhaust's full-length headers for LS1/LS6 C5 Corvettes give you the best of both worlds...high-flow catalytic converters for the street, and off-road test pipes for the strip!

These 1-3/4" primary tube headers have a 3" collector which flows into a 2.5" diameter X-Pipe. FLP headers are fully ceramic coated (even the x-pipe and off-road pipes are ceramic coated!) and they come complete with all hardware necessary for the install.

These headers are an excellent choice for cars with stock cam/heads, but they really shine on cars with aftermarket camshafts, cylinder heads, or other power-adders such as a nitrous or superchargers.

 

[vettte_wings]

x and h pipes.......

Remember that radio and TV commercial about the piston engine going "Boing-Boing," when it out to go HUMM? Well, all V8 engines with 90 degree cranks, have an out of sync imbalance in their firing order between the right and left cylinder banks. Yes, they do go "Boing-Boing." The firing order imbalance is a necessary sacrifice for dynamic balance of the rotating and reciprocating crank, rods and pistons. Each time the firing order is completed (two full revolutional), two cylinders within each bank will fire and exhaust within 90 degrees of each other. These two cylinders will be exhausting into the header collector or exhaust manifold almost simultaneously. This overlapping condition creates a lot of back pressure and a pop sound. Meanwhile, the opposite exhaust manifold has no activity (or pressure) in it at all. This is where the characteristic, low harsh popping V8 sound comes from.

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.

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!

 

[Bob Chadwick]

Bob- I just thought of something.With that all welded together,what if you need to drop your tranny or pull you rear end out.Don't those pipes go through the crossmember?

Dave

Dave

Your concern came to fruition. The next day off I am going to have the drive shaft rebuilt. Couldn't get it out with the welded H pipe. Took it back and they cut the H pipe out and put flanges on the H pipe and the piping so I can bolt them in and out. $40.

Bob

 

[Dave L.]

Bob - sounds good. That will make it easy if any more repairs require exhaust removal down the road. 40 bucks is very reasonable.

Dave