Performance Improvers: Curse or Cure?	Back to the Current Issue Back to Features
by Murray Jackson

For readers who may think this is about that new drug Viagra, well it's not. Rather, it's about the performance of the tow vehicle, not of the driver. In a sense, this article forms a sequel to the one in the July/August RV Times. On the other hand, it comes at the matter from a different perspective and is meant to be further informative. Often we overlook the obvious, so simply pointing that out can alone assist the future well-being of our RV's.

Anyhow, this has to do with the matter of increasing the power and performance of engines in motorhomes and tow vehicles. Every driver always wants more. HONEST ENGINE is the caption in large 25 millimeter letters. It's an article by Bruce Smith of Gale Banks Engineering. They're the U.S. company that builds turbochargers and power improvers for diesels. A picture of a 3/4 ton Dodge pickup accompanies his write-up. The tires are partially spinning and the rear half of the truck is enveloped in dust. Horsepower went from 158 to 213 H.P. and torque went from 394 to 517 ft. lbs. after installing their equipment. Great! But what will that do to the rest of the power-train? There is not a word mentioned.

You've all seen the ads which range from special wiring to special electronic chips for gas engines. Diesels have a wider range of options and of full-page ads. There are basically two kinds of performance boosters, passive ones and active, or aggressive ones. Passive ones include bigger free flowing exhaust systems and manifold headers. Maybe improved spark plugs, ignition wiring and related rigging for gas engines as well. These basically let the engine more easily do it's job as designed. Active boosters include better turbochargers, enlarged aftercoolers and more efficient fuel injection.

However, trucks and other vehicles are generally built with what can be called "systemic equilibrium". That's a high falutin' way of saying that each working component of the vehicle is built no stronger or no weaker than the other. None is overstressed if the owner adheres to the truck's GVW & GCWR. What happens when boosting engine power is that we upset this equilibrium. Diesel engines are usually well "over-built" so that power boosting is not really harmful to them. However, more engine power develops more heat and that starts to overload the capability of the original cooling system. More (larger) radiator capacity becomes necessary. Transmissions, clutches, universal joints, differentials and driveline bearings are all worked harder and stressed more. That wears them out sooner. Too often we forget that aspect.

Early Ford Navistar 6.9 & 7.3 litre diesels in the 1980's had high 21:1 compression and were not turboed. Lackluster towing performance caused owners to install either the Banks or the ATS turbochargers. No intake air aftercooling and no boost and pyrometer gauges were installed. Drivers simply drove the willing engines hard. Steady lead-footing the accelerator gave rise to burnt pistons and valves as the combusion temperatures far exceeded 1100 degrees F. Inevitably the short term cure gave rise to long term unhappiness – maybe even some cussing. With gas engines, special camshafts, ignition timing, special exhaust headers and low restriction exhaust piping are all great for lightweight race-cars. Use of the same technology on heavy-pulling RV gas engines yielded reduced performance. It took time and money to learn this.

Obviously, power improvers can be a cure for sluggish performance. But they do create a tidal-wave stress effect throughout and upset that systemic equilibrium mentioned earlier. For example, when those special fuel injection nozzles were installed in my 1991 Dodge/Cummins turbodiesel, the engine ran hotter. The combustion temperature was 150 to 200 degrees F hotter than before. That put an increased heat dissipation load on the radiator. In like fashion, increased power made the auto-tranny work harder, which made it run hotter as well, thus reducing its safety margin. Downshifting to a lower gear was required earlier to help resolve this somewhat. The radiator fan, which before had coasted along quietly, started to cut in and out more frequently. Yes too, the rear differential gears ran warmer. Increased torque on the single rear tires caused them to run warmer – especially when hill climbing or bucking winds. The truck had to have the rear axle bearings replaced recently. Probably prematurely. The universal joints are likely taking a beating and will require replacement earlier than usual. Indeed, power boosting will undoubtedly wear out other parts of the propulsion system prematurely. It's the old adage, that you don't get something for nothing. It truly starts to get costly when improving upon an originally balanced design.

Before all the improvements described last time, the engine statistics from dynamometer testing at the rear wheels was: 140 H.P. & 294 ft. lbs. torque. This is substantially below what the sales brochures would have one believe. After the additions, it was 202 H.P. & 424 ft. lbs. torque at 2500 RPM. Be advised that those measurements were taken before the addition of the new #16 turbine housing finally added early this past spring. While it did boost power and torque some more, the engine now runs 200 degrees F cooler in exhaust temperature. That's a double bonus.

Because of the greater horsepower and torque, and the perennial heating problem in the auto-tranny, a new enlarged core radiator has just been installed. Add another $575 to the previous cost of $8,050 for the after-market additions mentioned last time. That made a new total of $8,625.

But wait, that's not all. Finally, at last, a practical solution has been found to stop the overheating in the auto-tranny. The experts are presently installing a rebuilt auto-tranny that was installed in a 1996 new Dodge truck. It fits mine perfectly. It is somewhat electronically controlled and has a BD torque converter in it. The primary advantage is that a manually operated dash-located switch can be installed. This enables the driver to lock up the torque converter at any reasonable RPM, say about 1200 RPM. This reduces internal converter slippage to zero under load and the tranny then functions essentially like a stick-shift manual model. Fuel mileage is improved. The key advantage though, is that when coasting down mountain grades, the torque converter stays locked up tight. When the exhaust brake gets switched on, there will be no slippage and no excess tranny fluid heat generated like before.

Owners of the earlier 1989-1993 inclusive Dodges with autotrannies will be very happy to read this. I am told that a 1995 to 1997 vintage replacement tranny works as described. The 1998 and newer trannies are too electronically sophisticated to work readily in the older trucks. See the boys at Valley Fuel Injection in Abbotsford if you wish to follow the same fix-it route. But do remember to keep a close eye on the universal joints, the axle bearings and the differential gears thereafter. In my case the above conversion came to a gentle touch of $4,000. The subtotal cost of after-market additions to this point in the story is $12,625. But that has markedly improved the bare-bones factory truck into one that will readily handle the 17500 lb. G.C.W. that it has to move around uphill and down.

Since the previous article, your writer has been asked if maybe he didn't like that 1991 Dodge/Cummins combination. The questioner was immediately reassured. Fondness level has even extended to treating the truck at its three-year anniversary with a TF-12 Purifiner indirect engine-oil filter system. With it and Amsoil brand synthetic oil, periodic oil changes are no longer necessary. Simply change the TF-12 filter element every 6000 miles and get a laboratory oil analysis. Let them recommend when a change of oil is necessary – maybe at 30,000 miles or at 60,000 miles, or whatever. We'll see. The TF-12 filters-out particles down to one micron in size. It also replenishes the oil additives. Changing the standard original full-flow filter is now only necessary once a year. The usual cardboard element full-flow filters only catch the larger particles down to about 15 to 20 microns in size. It is suggested Dodge owners switch to the spun fiberglass element 10-micron Fleetguard LF3552 filter. The cost of the Purifiner installed was say $800. That brings the total cost of all additions to date to $13,425.

Well that figure is not quite the whole story. And no, I'm not going to even discuss or include the cost of those custom-built permanently installed armour-plate toolboxes. There's also a custom auxiliary 60 gallon fuel tank and its smooth-working solinoid switchover regulator up back there too. After all, the Mrs. here might find out about this mistress affair. So even if a good truck is a man's first love, marital harmony does rate–er, well–maybe they're tied for first place.

In conclusion then, whether or not performance improvers are a curse or a cure is hard to say overall. They are really both, depending on one's viewpoint. As will have been noted however, they can become a very costly issue no matter what else you might wish to call them. Still, it needs to be recognized that they can create as many problems as they solve.