Technical Page























Refer to U.S. PATENT NO. 4,800,719, 4,953,352, & 6,964,161

Campbell X-PIPE™ Acoustic Super Charger® exhaust, what is it?
How does it work?

Please take a moment to understand why the Acoustic Super Charger® powered Campbell X-PIPE ™ exhaust is such a powerful and profitable invention. The Campbell X-PIPE™ exhaust is the most cost effective and simplest way to make real horsepower on any engine.

Background. To better understand the Campbell X-PIPE™ exhaust, first look at the extremely successful 4into1. The 1940 era 4into1 was "tuned" (timed) by joining multiple equal length head pipes into a single, larger diameter collector to communicate and maintain momentarily, a periodically produced scavenge (suction) pulse generated by the high velocity exhaust gasses alternately exiting each head pipe. The collector allows this scavenge to 1. reduce atmospheric pressure in the non-exiting pipes, and 2. exist slightly longer within the exiting pipe to help extract residual exhaust gasses from that cylinder. When introduced, the 4into1 was a remarkable improvement over the log manifold used on the poor flowing flat head engines of the day.

However, 4into1 limitations became apparent over the years as engines, but not 4into1s, evolved;

1. 4into1 tuning is static and limited. Modern engines lose low rpm torque. The fixed head pipe length creates a minimum rpm torque range because atmospheric air has time to push hot exhaust gasses back into the head pipe between exhaust pulses, filling the cylinder and even the intake manifold, reducing power.

2. The power band drops off at high rpm. Exhaust pulses are slowed down and stack up as they enter the larger collector cross sectional area, creating excessive back pressure. (As a result of these constraints (1 & 2), a highly tuned 4into1 will usually have a very narrow power band.)

3. As engine cylinder head design improves air flow, scavenge becomes over-scavenge (as unburned air/fuel from the intake manifold can more easily loop through intake and exhaust valves during overlap, to be sucked out the tail pipe as unburned air/fuel; HC emissions).

4. Air/fuel mixture varies radically depending upon rpm; at low and high rpm, the mixture has full strength, but at the tuned rpm over-scavenge removes unburned air/fuel, weakening the mixture and reducing dynamic cylinder pressure.

5. *High compression pistons are used to improve reduced dynamic cylinder pressures at tuned rpms.

6. *High octane fuel is used to prevent detonation during un-tuned periods of normal dynamic cylinder pressure.

7. Special cam shafts are used to improve the high rpm power. Long duration exhaust cams open the exhaust valves earlier, cutting into the power stroke, to dump additional combustion energy into the head pipes (robbing combustion energy from the power stroke) to increase exhaust gas pressure to overcome top end back pressure. Because the power stroke event duration is decreased, the engine loses thermodynamic efficiency.

Enter the Campbell X-PIPE™ exhaust! It changed everything. 1. Tuning is not based upon head pipe length and can be dynamic. 2. The power band is much broader because scavenge is not lost at low rpm and back pressure is not produced at high rpm. 3. A high performance engine will not be over-scavenged because the Campbell X-PIPE™® Acoustic Super Charger® exhaust does not need to create and maintain suction to work. 4. Without over-scavenge, engine mixture does not vary between too rich and too lean and back to too rich as rpm increases. 5. High compression pistons are not needed because dynamic cylinder pressure is not lost. 6. High octane fuel is not needed because high compression pistons are not needed. 7. Special 4into1 cam shafts are not needed because additional exhaust duration is unneeded and wasteful.

(* Although not needed, these items can be added to the Campbell X-PIPE™ exhaust for improved performance.)

So, where does the HP come from, with the Campbell X-PIPE™ exhaust? The engine is more thermodynamically efficient (it generates a greater dynamic cylinder pressure while using a longer, more efficient power stroke), it is more fuel efficient (due to reduced over-scavenge) and it works with fewer engine modifications. As a bonus, since the Campbell X-PIPE™ exhaust can work with a short duration exhaust cam (allowing a longer power stroke) exhaust gas temperatures (EGTs) are cooler. Cooler EGTs can allow the tuner to lean the mixture to make even more power, on less fuel!

The Campbell X-PIPE™ exhaust is not a something for nothing device. Rather, it gives you what you thought your 4into1 promised: More Power, Everywhere! In addition, the Campbell X-PIPE™ exhaust gives you a broader power band and greater fuel economy.

Now, you know why!


Copyright 2000- 2006, Monty A. Campbell.
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Campbell X-PIPE™
, Acoustic Super Charger®, X-PIPE Header™, X-PIPE™ Cross-OverTM, CPU X-PIPE™, and X-PIPE™ are Trademarks of Monty A. Campbell. All rights reserved.