Does your motor have trouble breathing?

If the engine of your RV has problems breathing in air and exhaling waste gases then your engine is working too hard. It's also wasting fuel and precious power that could be used to turn your wheels.

The effort used to bring fresh air in and push exhaust out is often called pumping losses. For instance, most stock engines have an exhaust system that creates at least some restriction, compromising the engine's ability to exhale. At the other end, the manifold system of a typical V8 engine forces exhaust gas from each cylinder to compete with the exhaust from other cylinders. This is backpressure and the by-product is heat build-up. These two conditions waste fuel and power.

Many manufacturers of mufflers use sound absorbing techniques such as bent tubing to slow down gases and fibreglass packing to lower the noise level. These noise reduction techniques also create backpressure and a loss of power.

Automotive engineers often use gaskets between the manifold and the engine block to prevent exhaust leaks, but all too often these gaskets blow out and prevent heat in the manifold from flowing back into the engine block. During acceleration and hill climbs the manifolds can become very hot and then cool rapidly as the driver lets his foot off the accelerator. This expansion and contraction can crack cast iron manifolds or shear off bolts.

The automotive aftermarket has been attentive to these problems and several brands of air management and free flowing exhaust systems have appeared on the market over the years.

I decided to try the Banks Power Pack system on my motorhome. The first improvement was an added air duct that draws cool air from outside the vehicle instead of from the hot engine compartment. This air is forced into the engine through a duct that increases the pressure on the intake side of the engine. This improves efficiency. Now the power stroke from another cylinder is not wasted pulling air into the engine.

Replacing the stock manifolds is a tuned pipe exhaust system, which is mandrel bent, (reducing internal restrictions at the bends). The length of each pipe is designed to allow a free flow of waste gas from the engine. These lengths of the pipes are also tuned to make the exhaust from each side of the engine arrive at the muffler at different times thereby creating a low pressure scavenging effect that draws exhaust away from the opposite side.

Banks uses a single muffler with two inlets. It is a straight-through system with three acoustically tuned chambers. Each chamber in the muffler is tuned to reduce a specific frequency of noise. Finally the size of the tailpipe is increased to three-and-a-half inches to make it easier for the exhaust gas to escape.

The system increases horsepower by about six percent on average and reduces backpressure from a stock nine or ten pounds to about one-half-pound. There is no significant sound level increase.

Before the Banks installation I measured the temperature of the cast iron manifolds at idle. It was 595 degrees and rose to 725 degrees after a half-hour drive. Normal operating exhaust temperature was 730 degrees at 40 mph and rose to 900 degrees at 75 mph. Going uphill was another story. My exhaust temperature at the manifold went through the roof, up to 1100 degrees, after a short climb.

After installing the Banks Power Pack system, my idle temperature dropped to 535 degrees. Maximum temperature at 75 mph was 695 degrees, and during the uphill climb the temperature (on the same hill) did not exceed 900 degrees.

My 0 to 60 mph acceleration time was 29 seconds before Banks. After, I cut off 7 seconds for an improvement of 24.1 %. I was also pleased with the uphill acceleration. From a stoplight, it took 24 seconds to achieve 55 mph. The acceleration from 40 to 60 mph improved by 4 seconds, dropping to12 seconds.

With the Banks system I was able to climb hills without the fear of holding back the flow of traffic. Gas mileage went from an average of 8.52 mpg to 9.35 mpg, which included towing our car behind our 35-foot Citation Class A. This was an improvement of 9.46% in fuel economy. Some owners I have talked to tell me that their mileage figure dropped off after the installation. I assume this is because they now become more aggressive with the extra power.

We chose the aluminized-steel muffler, rather than the full stainless steel treatment. Our motorhome does not have a catalytic converter so the extra heat protection of the 304 stainless-steel muffler was not needed.

While there are savings to be had from increased fuel economy don't expect the fuel savings to pay for the system. Look instead at the added benefits of increased acceleration, better hill climbing ability and lower engine compartment temperatures. With lower engine temperatures, components last longer since lubricating oils do not lose their ability to protect moving parts.