Improving Exhaust Systems

This month our discussion turns to exhaust systems for gas-powered motorhomes (and also pickup trucks) in response to the following e-mail from Pedro and Rose:

Q: I had a Gibson muffler installed behind the cat converter and ran an exhaust pipe out in front of the rear wheel of my 2001 E450 Ford Class C V-10. Under light throttle cruising there is a resonance in the cab, a deep vrooom, which irritates the spouse. Can this be silenced by adding a resonator of some kind, or is this just a fact of life with this muffler?

A: Pedro’s question and Rose’s concern are just the tip of the iceberg for a subject of immense importance to owners of gasoline-powered RVs.

Obviously Pedro modified the motorhome because he was not satisfied with the fuel mileage and/or the power of the engine. Unfortunately the choice of exhaust components introduced the objectionable noise problem.

The simple answer to Pedro’s question is to replace his current muffler and tailpipe arrangement with parts from Gale Banks Engineering. Installation of Banks cat back exhaust components will improve the performance and fix the noise issue at the same time, but there other very important considerations as well.

RV people always want better power and fuel mileage from their rigs, and many RVers choose to modify their vehicles in the hope of improving power and fuel mileage. Modifications are also done to repair chronic exhaust system and temperature-related mechanical problems that plague gasoline-powered RVs.

Before Banks pioneered the “PowerPack” concept, in the 1980s, RV users with heavier gas-powered vehicles faced a never ending saga of repeated exhaust manifold failures and other heat-related problems. When enough cycles of failure occur, it is inevitable that engine life becomes affected.

The main reason for the repeated mechanical problems is the effect of heat on engine components, especially exhaust manifolds. Cast iron exhaust manifolds start to warp within the first few miles of RV driving and continue to change shape as the miles and years go by. It is interesting that it is not loss of flatness that causes the trouble. Manifold failures are caused because the manifolds become shorter over time. The manifolds eventually become short enough that the bolt holes no longer match the cylinder heads, causing the bolts to start to bend with the result of stretching, bolt breakage, cracked cylinder heads, valve damage, burned plug wires and a generally shorter and more expensive service life.

You would think that Detroit would have solved this problem during the last 30 years, but there has been very little progress. A new gas-powered RV you purchase today might possibly give you 50,000 miles of service, if you are lucky, before you are forced to replace exhaust manifolds. We still are seeing many manifolds that need to be replaced by 30,000 miles.

Ford’s V10 engines are lasting well, but their exhaust manifolds are going to be big trouble as these vehicles age. The manifold bolts are smaller than in the older 460 engine and very prone to breakage as the miles accumulate. Because of the aluminum heads on the V10 and difficult access for broken bolt removal, we expect to be having to remove V10 engines in the future to make broken bolt repairs. The 8.1 Vortec engine used in the Workhorse chassis continues to have exhaust manifold issues like the prior 454 does as well.

The fix for the concerns described above is to install a Gale Banks Engineering “PowerPack” system on your gas-powered motorhome or pickup truck. The stainless “torque tube” header type manifolds will not warp and cause problems like the cast iron manifolds do. The combination of air intake improvements, headers, and the rest of the exhaust system components supplied in the Banks systems improve power significantly, improve fuel mileage and extend engine life by reducing heat loading strain on the power plant.

In the late ‘80’s I did “last chance to fix” jobs for the John Deere motorhome chassis division. Under the Washington lemon law, John Deere would negotiate one more try to make the customer happy and hire my company to make needed repairs, which included installation of a Banks PowerPack in every case. It is noteworthy that every single coach owner decided to keep their motor home after getting a chance to use it with the PowerPack and other repairs completed.

The above information and history of success with many thousands of vehicles is so compelling that I can honestly say that if you own a gas-powered RV vehicle, for which a Banks PowerPack is available, you need to install your PowerPack or else you should sell the rig early to avoid the inevitable trouble and expense.

Of course with Banks you will also avoid the annoying “Vroom” that got Pedro in trouble with Rose.

- - - - - - -

E-mail questions to askchuck@thepowershop.com. Chuck Arnold is one of three founders of The PowerShop in Enumclaw, Washington, where he helps RVers with their diagnostic, maintenance, repair and performance enhancement projects. Chuck has authored hundreds of RV articles and is a frequent guest on the Northwest Auto Show, which airs on Seattle radio station KVI Saturdays from 6 to 8 a.m. Recommendations in this column are general in nature. Vehicle owners should seek professional guidance for specific problems.