"Quote of the month."

"When health is absent, wisdom cannot reveal itself, strength cannot be executed, wealth is useless and reason is powerless."

  This month we are going to feature a particular NTC 444, CPL 821 which is in a 1987 W900B Kenworth owned by Don Stouffer of Dixon, Ill.

Before we talk about the performance enhancements that were performed to this 444 I would like to thank Chuck Norton of Truckin’ Magazine for printing our articles for the past five years. Chuck is the owner/publisher of Truckin’ Magazine and is taking a temporary leave of absence from the world of publication.

Now on to horsepower and torque: About 4 years ago an owner operator by the name of Don Stouffer contacted us to see what could be done to his NTC 444 Cummins engine to gain more performance. The engine had recently been rebuilt and was running fine as a stock 444. However Don Stouffer is addicted to performance and is not satisfied with stock horsepower. His Kenworth does have dual exhaust and dual air cleaners, which are a must for performance. The transmission is a 14-6-13 speed and the rears are 40,000 lbs. and a ratio of 3:70. So he had many of the right components. The first changes were to build a much larger set of STC injectors, a high volume, high pressure fuel pump, mapwidth enhanced turbo with a turbo boot, dual fuel line kit and a liquid filled fuel pressure gauge. The boost gauge and pyrometer were already in the instrument panel however the thermocouple for the pyrometer was in the exhaust pipe so Don installed another pyrometer and installed the thermocouple in the exhaust manifold right in front of the turbo.

The next item installed on this truck was a Harvard 750 Luberfiner bypass oil filter. The Harvard element is a 1-micron paper element that will absorb water and actually polishes the oil.

The cooling system: all Cummins engines were equipped with a low flow cooling system since 1986 so we had Don install another air tank and run coolant lines from the block to the tank and back to the water manifold to add seven more gallons of coolant.

Timing of the engine: As horsepower goes up the timing must be retarded to ensure piston life. Fast timing will crack pistons. Being an ex drag racer Don had no problems doing his own mechanical work and changing the timing.

The end result of this work is one terrific running NTC 444 CPL 821 Cummins engine. This engine now has 345,000 miles since the high performance parts were installed and there is no oil consumption, no leaks of any kind and Don recently checked the main and rod bearings and they were fine.

Driving this KW gives Don great pleasure. The additional 300 horsepower removes the boredom from those long weeks where he has to drive up to 4,000 miles. Don says that his Cummins never dies on a hill or a mountain. When pulling the long grades he usually keeps the fuel pressure around 200 PSI and the boost around 30 PSI. The pump will develop 350-lbs. of fuel pressure and the turbo will produce 42 lbs. of manifold pressure. However there is never any reason to run this beast wide open and if you do you can feel the power right up through the seat. Don claims that he is a power nut and the engine gives him a thrill on every hill and with all of the gauges monitoring the engine its amazing the picture you get while working this beast. Don Stouffer is a very knowledgeable gentleman. If you ever have the chance to have dinner or run down the interstate with him you will enjoy his company.

At this time I would like to mention a father and son team that are very good friends of mine. We snowmobile, ski and go truck pulling together. Their names are Jim and Jon Anderson from Allison Park, Pennsylvania. Their shop is located just south of exit 4 of the PA. Turnpike. Jim has been involved with trucks for 40 years and his son Jon was a jet engine technician for Delta Airlines. Their main business is selling and building tow trucks and rollbacks. I don’t think that there is a man alive today that knows more about wreckers than Jim Anderson. As for his son Jon, he is one sharp fabricator and welder. He is also a drag racer and he won the national street car drag championships this past October in Gainsville Fl. with a time of 8.01, 176 MPH in his big block 1978 Malibu. Jon, his other brother Ken and father Jim built this car in their clean facility in Allison Park. At the present time Jon is building a sub frame under a T600 Kenworth cab and double bunk sleeper and at the rear of the subframe will be a Cabmate 3 bag 4 shock air ride system. We are using Dodge pickup cab mounts in front to help absorb road shock and noise. 

  Diesel fuel, you’ve got to get it into the combustion chamber quickly, air free, and at the precise time in order to develop horsepower and torque. Once ignition occurs the piston is forced downwards creating the power stroke. Then on the upstroke the exhaust or burned hydrocarbons must be evacuated from the combustion chamber. All camshafts have what is called valve overlap and what that means is the intake valve begins to open just before the exhaust valve closes. This is the beauty of a turbocharged engine. The compressed air or intake manifold pressure enters the combustion chamber and forces out the burned hydrocarbons or exhaust. This process is called scavenging the combustion chamber. Now, what happens when all of the exhaust doesn’t get evacuated out past the exhaust valves and through the turbocharger? Simply put if the exhaust backpressure is greater than the intake manifold pressure, the exhaust will enter the intake manifold once the intake valve opens during valve overlap. This is not a good situation and you certainly don’t want this taking place in your engine. The results of excessive backpressure are high exhaust temperatures, poor fuel mileage and a tight running engine. What do I mean by a tight running engine? If your engine feels like you always have to push it, your foot is always into the throttle, the engine feels as though its being choked at highway speeds it just doesn’t want to glide along the highway, this is what I call a tight running engine. Too small of an air cleaner can also cause this problem, however in this article we are going to concentrate on the turbocharger and exhaust system. In today’s society everybody wants more boost or intake manifold pressure and to obtain more boost you decrease the size of the turbine housing (exhaust housing) of the turbocharger. Now that the exhaust has to pass through a smaller orifice or turbine housing, the velocity of the exhaust increases and the turbine wheel (exhaust wheel) spins faster which in turn spins the compressor wheel forcing more air into the intake manifold. Now all of this may sound good so far however once the size of the exhaust housing is decreased the piston on its upstroke must now work harder to force the exhaust out of the combustion chamber through the turbocharger.

The smaller the exhaust housing of the turbocharger the greater the back pressure in the exhaust manifold and combustion chamber, the tighter the engine will feel, and this is not so good. Now don’t be thinking that going to a larger turbine housing is the answer because if you go to the large the back pressure will drastically drop and so will the intake manifold pressure and the exhaust gas temperature will rise. So how do we keep the boost up, exhaust manifold pressure down and also keep the exhaust gas temperature down so that we can have a free running engine?

No. 1: Make sure that your truck is equipped with dual air cleaners and they are large enough for your engine, remember as horsepower and intake manifold pressure increased so does the required CFM (cubic feet of air per minute). A stock BCIII 400 uses 1060 CFM when boosted to 500 H.P. the CFM is 1325, at 600 H.P. the CFM is 1590, 700 H.P. is 1855 CFM. Large air cleaners outside of the engine compartment are invaluable.

No. 2: Dual exhaust with straight through mufflers, 6" or 7" exhaust is much better than 5" keep the 90 deg. bends to a minimum.

No. 3: Install a turbo boost gauge in the exhaust manifold before the turbocharger. Drill a 29/64" or 7/16" hole in the exhaust manifold and tap the hole with a 1/4" pipe tap. Now install a brass fitting with 1/4" pipe threads and a coupler for 1/4" dia. brass or steel tubing. Use about 3’ of the 1/4" tubing then you can reduce down to 1/8" plastic tubing to go through the fire wall and into the instrument panel and couple the tubing to the boost gauge. Now you have two boost gauges, one for the intake boost pressure and one for the exhaust manifold pressure.

What are these gauges going to inform you of? During cruising speeds on the level the exhaust backpressure should be approximately 66% of intake pressure. While pulling moderate grades the exhaust backpressure will increase more than the intake pressure will however it should still be less than the intake. At wide open throttle the exhaust pressure may be greater than the intake pressure but only by 2 to 3 pounds of pressure.

What does all of this mean? If most of you trucking is on level ground or rolling short hills, its best to have a larger turbine housing to minimize the back pressure. If the majority of your trucking is in the city with a lot of stop and go driving, than a slightly smaller turbine housing is preferred. The smaller housing is good for quick turbo response and instant boost, however on the open road the backpressure may be too high.

High altitude operation of 5,000 feet or more will also require a smaller turbine housing because at 10,000 feet elevation there is one half of the molecules of oxygen than at sea level and a loss of 3% horsepower for every 1,000 altitude your climbing. So at the Eisenhower tunnel on I-70 in Colorado the altitude is 11,400 feet and your 400 horsepower engine is now 268 horsepower. The pyrometer heat or exhaust gas temperature will be about 200 degrees hotter at the top of the mountain also. If you spend the majority of your time at high altitude you may have to experiment with several different turbos to find the one that meets your particular requirements.

What works good for your friends truck might not be the ideal set up for you. Naturally trucks that run along the East Coast and stay near sea level are the least complicated to work with. About the East Coast, high humidity displaces oxygen so that can throw another monkey wrench into the equation.

Now that you have this additional knowledge you’ll find out that there is no perfect turbocharger for all situations. You have to compromise. What’s good for the city driving is not perfect for highway driving. What’s good for the open level road isn’t perfect for high mountains.

Wastegated turbochargers are not the answer. The wastegate is set to open at a predetermined PSI setting and at cruising speeds. The backpressure is usually equal to the intake pressure. Wastegated turbos usually use a very small turbine housing for quick response. This is great for city driving, but not ideal for over the road. At high altitude why would you want to dump the exhaust overboard when you need the extra boost to keep the engine cool.

The newer turbos that are used on the electronic engines should not be installed on the older mechanical engines. The electronic engines use very high compression ratio pistons, which produce less exhaust volume so they need smaller exhaust housings than the older low compression mechanical engines.

Westbound and down and you’ll never guess who is back on the road once again. In 1989 this man parked his last truck to devote more time to his oil business. Four years ago I had the pleasure of meeting the man who developed the finest fuel conditioner that we have ever tested in our 21 years with Cummins diesel engines. We invited Forrest Lucas to join us for a day of testing and he was shocked at how 800 horsepower walked 80,000 pounds over Indio Mountain. That feeling of power has stayed with Forrest for the past four years and this past month had the opportunity to purchase a T-800 Kenworth with a Diesel Injection of Pittsburgh NTC 800+ horsepower Cummins engine. At the time of this writing Forrest Lucas and his T-800 KW are in our shop being super tuned by Pete Sharp our vice president.

There is an old saying, "You can take the driver out of the truck, but you can’t take the truck out of the driver." This is a very true statement and this T-800 KW is going to be used by Forrest to take an occasional run across this country to deliver Lucas oil products to his clients.

Forrest is a circle track stock car driver and is known to be aggressive on the track, so if you see a dark green T-800 KW charging up the mountain behind you, move over because here comes an ex truck driver with a new toy!

The KTA 525-600 Horsepower, 1150 cubic inch Cummins engine is still the largest engine ever developed for on highway use and this is our engine of choice for heavy hauling. Another old saying is "You can’t beat cubic inches." That certainly holds true for this engine. We still have high performance parts available such as twin turbo’s, high flow injectors and high volume high-pressure fuel pumps. If you want 800 to 1,200 horsepower this is the easiest way to get it.

In the United States, and probably the world, we have two king of the highways when it comes to brute power, Butch Shuman from Tye Texas and Ken Hopkins from Rhode Island each have approximately 1,200 horsepower Cummins Diesel engines.

I sure wish Hawthorne Power Equipment, the Caterpillar distributor in southern California, would have their Dyno Days again. We would show them and the world that Cummins is the undisputed power champion of the world.

Good luck and have fun, please write to me with your intake and exhaust back pressures, lets make your engine run more freely.