The question of the month is; "I only need a lot of power for pulling the mountains.  I don't care about going fast on the level.  But, I don’t want the engine to hurt itself. What can I do?"

Think about this statement. I don’t want my engine to hurt itself. Engines don’t hurt themselves. It’s the man with his foot on the throttle and hand on the shifter that hurts the engine.

 Years ago an older Cummins engine technician told me that an engine should always be in a gear that will allow it to accelerate while pulling a hill. This is a true statement and applies to all engines, diesel and gasoline. Let the engine breathe and run free. If your foot is flat on the floor and the rpm’s are dropping get out of the throttle and shift into a gear that will allow the engine to pull the load using moderate turbo boost.  We always install liquid filled fuel pressure and manifold pressure gauges in the instrument panel with every performance engine we build. An NTC BCIII engine develops approximately 17 horsepower per pound of boost. If you’re pulling a mountain and using 30 lbs. of turbo boost you are developing 510 horsepower.

Now lets assume that you have installed our performance injectors, fuel pump, dual fuel line kit and mapwidth enhanced turbo on your 400 Cummins and now the turbo boost will produce 36 pounds of pressure. Take 36 times 17 and your engine is producing 612 horsepower. If the engine has stock pistons and timing you should be very careful as to how much of this boost you use to get the job done. I personally would only use 30 pounds of boost to pull long hills or mountains. Now if you rebuild the engine and installed the ceramic and Teflon coated pistons and retarded the timing without using the MVT you can safely use up to 35 pounds boost on long pulls. With the high lift camshaft and mechanical variable timing using 40 pounds of boost or 680 horsepower is relatively safe. Please keep in mind that you do not have to use all of this power on every hill or mountain.

While traveling the interstate highway system I have noticed that many of the mountains have a break in the percentage of grade about half way up the hill. Most drivers keep their motors mashed and grab the next higher gear only to drop that gear in another half mile. This driving technique never gives the engine a rest. My suggestion is stay in the lower gear, ease up on the throttle allowing the pyrometer and water temperature to decline, thus giving the engine a rest. You know that you are going to be back in that gear anyway for the rest of the mountain. Let the engine breathe and always use high RPM when working the engine. High RPM is 1800 to 2200. This rpm range gets the piston out of top dead center faster and less damage is done to the piston. At TDC using low rpm the piston is being hammered because of internal engine pressure. Your pyrometer heat may be low but if your using high horsepower and low rpm the internal pressure is high and that is what cracks pistons. By the way, most pistons crack from the wrist pin bore up to the piston dome first. Once the crack reaches the fire it burns down through the piston.

You can have a stock engine with high horsepower but you better have the proper performance gauges and know what they are telling you. An NTC 300 has 130 pounds of fuel pressure. A 350 has 157 lbs. 400’s have 176 lbs. 444’s have 196 lbs. and a 475 has 200 lbs. By having the liquid filled fuel pressure gauge in the dash you know how much power your using. Let’s take a look at what a stock engine has for fuel pressure. They develop slightly over 2 horsepower per pound of fuel. Now lets assume that the fuel pressure has been increased in your BCIII 400 from 176 to 225 pounds. Now you no longer have a 400 horsepower engine but you do have about a 475 horsepower engine. As fuel pressure continues to rise the rate of 2 horsepower per pound starts to diminish. The true way of producing horsepower is by lowering the compression ratio, retarding the timing, increasing the injector flow and turbo airflow. So by increasing fuel pressure and injector flow the horsepower increases at an alarming rate. You must think about how much power your using to get the job done and the more you use the less engine life you’ll have in the long run. Fuel pressure, boost, pyrometer, and tachometer gauges are vital to long engine life.