1: Horsepower and Torque: First article

Words and thoughts from the man who started it all.

1: Horsepower and Torque: First article

Postby Fernando on June 1st, 2009, 2:00 pm


This is a very controversial subject and 99% of the mechanics who build diesel engines will disagree with what we have to say and will probably refuse to build the engine for you.

For the owner-operator who loves horsepower do not give up when you speak to the negative mechanic. There are a few good shops throughout the states that will build the ultimate performance engine. Or you can build it yourself as long as you have mechanical knowledge and tools.

BUILDING THE ENGINE: In order to have the engine live with high horsepower and run efficiently you must have the right combination of compression ratio, fuel, air and timing. Please do not try to get extreme power simply by increasing the fuel pressure on a stock engine. You will obtain some horsepower, however your compression ratio, air and timing will be wrong. The best time to obtain horsepower is during a rebuild. Since you are going to buy new parts anyway you might as well buy the right combination that produces horsepower and generally the price of the high performance parts is the same as the stock parts.

NOW TO THE NUTS AND BOLTS : The compression ratio of the pistons and the timing must go together. High compression pistons belong only in gasoline engines that are naturally aspirated. Turbocharged diesel engines must have low compression pistons in order to produce high horsepower. The lower the compression ratio the less wear on rod bearings and the lower the internal pressure will be when the injector fires. High internal pressure is very detrimental to the life of a piston. When you see a piston with a hole burned through, it's not the fault of the injector it is a result of internal pressure.

To control the pressure we lower the compression ratio and retard the timing. If you compare the compression ratio and timing of an NTC 290 versus an NTC 400 you will see the difference. Where do you think we have to be on the timing to produce 700 horsepower from an NTC?

All NTC Cummins engines manufactured after Sept. of 1987 were cut for the LPF liner. If your engine was manufactured before Sept. 1987 you will have to have your block machined to accept the LPF liner. The price to cut the block in the chassis is approximately $450. The advantages are as follows: (1) The liner is now a press fit into the block and held more securely (2) With the liner being held tightly in the block you eliminate seeping head gaskets (3) Eliminate liner cavitation or liner pitting (4) Eliminates blow-by. This may sound absurd however, when the injector fires, the pressure distorts the liner until it comes in contact with the block. Your piston rings stay perfectly round and now, with the distorted liner, the rings lose contact with the cylinder wall and thus you have blow-by. Lower press fit liners help to eliminate this distortion and (5) Eliminate cracking of head bolt-holes. With LPF the pressure from the liner is moved down in the block by approximately 3\8&";.

Please keep in mind that if the surface of your block is rough and should be resurfaced, remove it from the chassis and have it resurfaced. Inspect the block for cracks from the head bolt holes into the counterbore area. The cracks are hard to see and can be repaired by having head bolt hole repair sleeves installed. The water holes can also corrode and crack. Salvage sleeves, too, can repair them.

To build a strong running engine you must start with a good foundation, which is your block. If you ignore block problems they may come back to haunt you.

TURBOCHARGERS : One of the most important components on the diesel engine is the turbo. Many trucks come equipped with a 3-series Holset turbo. That is fine for stock engines. The 3-series Holset is adequate for engines up to 450 horsepower. For higher horsepower you must have a 4-series Holset. Preferably one with a mapwidth enhancer. The mapwidth enhancer consists of the 3 slots in the compressor housing that allows more air to the lower fin. With dual exhaust and dual air cleaners it is possible to obtain 42 to 45 lbs. of manifold pressure.

PISTONS : When building an engine that is turbocharged you must lower the compression ratio when increasing the horsepower. The efficiency gained from increasing the manifold pressure will more than compensate for the compression ratio. Cummins also offers a high strength piston that we have ceramic coated on the top and Teflon coated on the skirts. The ceramic coating helps to keep the heat out of the piston and in the combustion chamber where it can further help to burn the fuel. The cooler we keep the piston the longer it will live. The Teflon coating on the piston skirt helps to remove the piston slap on the side of the liner. Teflon is the most slippery substance known to man and will allow your engine to more smoothly and quietly.

TURBINE HOUSINGS : Many people believe that going to a larger turbo will give them an increase in power. The problem with this change is that the turbine housing of the turbo is also much larger. Which, in turn, decreases the amount of backpressure in the engine. This is good because it allows the engine to run more freely, but with the loss of manifold pressure. The engine will run much hotter. As the size of the turbine housing increases the speed of the turbine wheel and shaft decreases manifold pressure also decreases and the response time or turbo lag also increases. All are negatives.

When purchasing a larger turbo you must find out how many sizes of turbo housings are available for the particular turbo you are choosing. The larger the compressor wheel (fresh air side) the greater the volume of air available to the engine. Now, you must be able to spin the larger compressor wheel at low RPM and to do this you need a smaller turbine housing on the exhaust side to increase the velocity on the exhaust. The sizing of the turbine housing effects the speed of the turbine wheel and how fast the wheel comes up to full speed the same way lower gears in your differentials effect how fast your truck can accelerate.

If you live mostly in high country (5000 ft. elevation or greater) you will want to decrease the turbine housing size one step lower than if you lived at or near sea level.

CAMSHAFTS : The big cam I, II and III engines all used the same basic camshaft except for the flange and flangeless design. However, the lift of the injector and valves were the same.

The big cam IV 400 camshaft did have more lift to the valves. Therefore, you must use a B.C. IV piston with deep valve pockets so that the valves will not hit the pistons. Please be careful when working with a big cam IV.

For building horsepower we prefer to use the high-lift cam along with the mechanical variable timing. This particular cam has .266 inches travel to the injector where the standard cam has .224 inches travel. The longer the travel of the injector the greater the amount of fuel can be injected. Fuel makes horsepower and you need a lot of it to produce 700 to 800 HP. Manifold pressure or turbo boost burns the fuel to produce the power. However, all boost and little fuel will give you little horsepower. You must get fuel injected and atomized into the combustion chamber to produce power.

MECHANICAL VARIABLE TIMING : MVT has a very poor repore with mechanics of Cummins diesel engines. The main problem was that the steel piston in a cast-iron bore that was moved by compressed air from the air compressor would rust to the walls because of lack of lubrication. We now have an automatic oiling system that constantly lubricates the piston which makes the MVT almost trouble-free. The advantages to this timing system are many but the first and most important benefit is decrease white smoke when the engine is idling or cold.

With the mechanical variable timing your engine idles in the advanced mode and when you accelerate the timing will change to a retarded setting. The retarded mode is great for making power and the major benefit of this is piston and rod bearing life. Retarded timing is much easier on the engine components than fast timing. Many of the mechanics that work on Cummins engines do not understand the MVT and may not be able to set the timing properly. So if you decide to build an engine with mechanical variable timing please call us and we will explain it to you.

When building your high-performance diesel engine you must build a strong basic engine. However, regardless of how good your turbo, heads and pistons are, if your injector pump and injectors are not high pressure and volume, the engine just will not perform up to your expectations. You must have fuel to make horsepower. Air from the turbocharger makes it possible to burn the fuel but you must have plenty of fuel available.

The best way to increase horsepower is to install larger injectors or injectors that flow more fuel. One of the reasons for larger flow is that it helps to relieve the pressure on the camshaft. With stock injectors and stock fuel pressure there is a 3,000-lb. shock load on the push rod. Did you ever wonder why injector push rods bend? If we have 3,000 lbs. of shock load at stock fuel pressure such as 180 lbs. Just think what the shock load is at 250 or 300 lbs. of fuel pressure. It could possibly be around 4,200 lbs. on the push rod. By increasing the flow of the injector you help to eliminate the excessive pressure on the push rods and camshaft and the horsepower increases greatly. The only negative to high flow injectors is you should not idle your engine for excessive periods of time. Cummins Engine Co. states that it is three times harder on an engine when idling than pulling a load down the highway. It is much more economical to purchase a generator or a diesel-fired cab and engine heater than to idle your engine. Diesel engines are not built to be used as heaters.

When installing injectors use a mixture of STP. and engine oil (70% S.T.P. and 30% engine oil). Coat each injector o-ring with the mixture and also coat the injector hole once it is cleaned. The STP. mixture will keep you from cutting or nicking the o-rings. Straight engine oil is not slippery enough. Once the injector and the hole are lubricated place the injector in the hole and with a hammer handle push the injector into place with one hard push. It's better to seat the o-rings quickly. If your engine is cold, plug in the block heater for several hours before installing new injectors. This will allow the new injector to slide in easier thus reducing your chances of cutting the o-rings.

When setting the valve and injector clearances do not use the five in. lb. torque wrench to set the injector. Instead, set the rocker arm finger tight. You should be able to turn the pushrod once the jam nut is tightened but with a little drag. Set the valves for .011 intake and .023 for the exhaust.

Lets start with a question: Have you ever wondered why some Cummins engines run better than others even though they are both stock? Why there are over 6,000 different calibration codes? The answer to the first question is the torque curve which is determined by two springs. One of the springs is the governor spring and the other is the torque spring. These two springs can drastically change the pulling power that your engine delivers. Of the 6,000 different calibration codes we use about fifteen of them. Since 1978 we have been documenting the calibration codes of the engines that perform well versus the engines that are sluggish regardless of what you do to them. The answer has always been in the torque curve. When building your high-performance engine you must match the torque curve with the compression ratio of the pistons, camshaft timing and the injector flow rate. This is done when we build your fuel pump. It is calibrated accordingly.

Another method for increasing the torque, or pulling power, of your engine is to change the gear pump. This is the heart of the entire Cummins fuel system and it is located at the rear of the injection pump where the incoming fuel line is attached. The stock gear pump produces 1175 pounds of fuel in one hour running at 2100 RPM. The gear pump we use for performance will produce 1200 pounds of fuel in one hour at 1400 RPM. Did you notice the difference? Our high-performance gear pump produces 25 more pounds at 700 RPM. less. The greatest advantage of this gear pump is when you're cruising along the flats at 1500 or 1600 RPM. and a situation arises and you need power right now all you have to do is gently push on the throttle and your truck will accelerate as though the Jolly Green Giant reached down and gave you a push. Keep in mind that your engine will respond at 1400 RPM. as it does currently at 2100 RPM., and what a difference in pulling power it will make in the mountains, hills and against head winds out on the plains.

Another item that should be changed every six or seven years is the fuel suction hose coming from the fuel tank to the fuel filter then onto the injection pump. The diesel fuel attacks the rubber in Stratoflex and Aeroquip hose and swells it shut. This is the cause of many power problems, especially with the trucks that are from 1985 or earlier. If you are planning to build a high-performance Cummins, replace the #10 fuel line with #12 The injector pump will not have to work so hard to get the fuel out of the fuel tank.

This month we will discuss exhaust, air and fuel flow. If you restrict any of the three the result will be a loss of power or high operating temperature. The principles that apply to racing vehicles also pertain to trucks. After all, when a truck us pulling up a mountain the engine needs an unrestricted supply of fuel and air. If the engine is getting all the fuel and air it can consume can it get rid of all the exhaust that has been produced?

Let's start with the air intake system. Most truck manufacturers supply an air filter and housing with enough CFM (cubic feet of air per minute) to satisfy the horsepower of the truck when it's being built. If you purchase a used truck with a 290 or 300 HP. engine then rebuild the engine to 400 or more horsepower your air filter is too small. Almost all trucks with the air filter stuck under the hood suffer from lack of cool air. This is the new aerodynamic look with the filter under the hood. However, it is terrible for performance. Why preheat the air before it gets to the turbo? Think about how hot it is under your hood in the summer when your 3,500-lb. engine is operating at 185 degrees and your air filter is right above it. We all know what high pyrometer temperatures do to aluminum pistons. Heat and metal fatigue are a trucker's biggest enemy. If you do not own a conventional, or cannot mount your air filter out in the air stream, then mount a second filter under your hood on the opposite side of your current filter. On a cabover it's fairly simple to mount a secondary air filter and plumb it into your existing air pipe going to the turbo.

The most economical and easiest filter and housing to work with is the Farr Ecolite. At 24" long and 13.5" in diameter, this filter has an amazing capacity of 1500 CFM The price is $139 and for installations you need two clamps at $15 each. The air inlet and outlet is 7" in diameter and you will have to obtain 7" aluminum piping to complete the installation. The extra clean air entering your engine will lower your pyrometer temperature and allow your engine to run as it does on a cool, damp night.

In the previous articles we discussed what it takes to build horsepower and torque. Now we will concentrate on pyrometers, manifold pressure, liquid-filled fuel pressure and air and fuel filter restriction gauges. These five gauges work in unison to monitor your engine as you drive. It's like having a portable dyno in your cab at all times. With the gauges, we can diagnose ninety-five percent of all power problems over the phone. Most of the time you will be able to cure the problem yourself. This will help avoid expensive repairs in an out-of-town shop that probably cannot diagnose the problem properly anyway.

Let's start with the pyrometer. Always install the thermocouple, or probe, in the exhaust manifold. If you use a Hewitt pyrometer or thermocouple it will not burn off and wipe out the turbo. We have been doing this for 21 years and have never lost one. You will have to drill and tap the pulse manifold to install the probe. To do this, use a 7\16" drill bit and a 1\4" pipe tap. Install the thermocouple in the back three cylinders approximately one inch from the end of the center section where the turbo bolts onto the manifold. With the pyrometer installed on the hot side the critical temperature is 1200 deg. Do not operate the engine above 1200 deg. for an extended period of time.

Manifold Pressure Gauge : All turbocharged engines, gasoline and diesel, should have a manifold pressure gauge. This gauge is one of the best diagnostic tools a mechanic or owner-operator can have. A 290 or 300 HP. Cummins must have between 15 and 20 lbs. of boost, or manifold pressure. A 350 HP. must have 18 to 22 lbs. and a 400 HP. Cummins must have at least 25 lbs. We prefer 28 lbs. out of a stock NTC 400 HP. If you increase the fuel pressure, the boost will also increase. Manifold pressure makes it possible to burn the fuel and keep the exhaust temperature down. Every four lbs. of boost lowers the exhaust temperature by 100 degrees. If you feel your 400 is running sluggish, install the gauge. Go for an uphill ride wide open and see how much manifold pressure your engine will develop. If it's below 25 lbs. you definitely have a power problem. If boost is down then your exhaust temperature is high, which means you are killing your pistons and rings on every grade. It does not take a mountain, just a slight grade or head wind. You must have boost to have power.

LIQUID-FILLED PRESSURE GAUGES: This gauge will change your driving habits and increase fuel mileage and engine life. On high-performance engines we use as much as sixty-five percent over on our fuel settings and many times, as you are driving, you will use more power than what is necessary. This gauge will let you know exactly how much power you are developing.

As a diagnostic tool this gauge is as important as a manifold pressure gauge. When your pump is calibrated on a test stand at your local fuel injection shop and they tell you it has 170 lbs. of pressure, which is stock, and your engine is still a sled, how do you know that pump is producing 170 lbs. of fuel on your engine? Keep in mind that the pump stand drives your fuel pump. However, when your pump is on the engine, the pump does the driving. Over the years we have seen as much as 30 lbs. of fuel difference from the pump stand to the truck. When you have your own fuel pressure gauge (liquid-filled) you will know when your pump is producing what you want it to. Forget what the person says it has on the pump stand. Let's see what it says on the engine.

This month we will talk about oil filtration. Even though this is not horsepower related it is still very critical to the life of the engine. Remember the 750 luberfiners? Almost everyone has removed them by now. If you have the filter housing put it back on your truck and install a Harvard 750 filter in it. The Harvard 750 is made from one-micron paper and it actually polishes the oil. Remember, oil does not wear out. It becomes contaminated with dirt. That is why your engine will use a gallon of oil around 8,000 mi. after an oil change. The dirt gets between the rings and the liner. This forces the piston rings to ride on particles of metal and dirt. When you have extra filtration on your engine the oil stays much cleaner. Your rings, liners and bearings last much longer. Now that you will not be adding a gallon at 8,000 mi. you can extend your drain intervals to 15,000 mi.

Also, the spinner II centrifuge oil cleaner is a great idea. This unit actually spins the oil and throws the dirt and metal particles out of the oil. The particles collect on the wall of the centrifuge, which is approx. four inches in diameter. To clean it, all you have to do is remove the lid and scrape the black dirt out with a knife every 30,000 mi. I personally did not believe that the Spinner II would clean the oil until I installed one on my brother's 444XT. Now, every 30,000 mi., we clean it and the dirt is about 1\2 " thick on the centrifuge wall. The cleaner the oil the longer the engine will live.

This is a review of the major components needed to build a high-performance Cummins diesel engine:

1. TURBO: It takes a lot of manifold pressure, or turbo boost, to burn the additional fuel necessary to make horsepower. If you do not have fuel you will not have power. Burning the fuel produces the horsepower. The turbocharger supplies the necessary air to complete the burn and keep the exhaust temperature low.

2. INJECTORS: Stock flow injectors are very limited on the amount of fuel they will inject into the combustion chamber. This is where the power comes from; the injection of fuel. The more you inject the more horsepower and torque your engine will produce. Stock injectors are very hard on camshafts when the fuel pressure has been increased. Always install the next size larger injector if you want power.

3. FUEL PUMPS: Now that the injectors are larger the fuel pump has to deliver more volume and pressure. You have to have a high output pump for performance.

4. PISTONS: When performance increases the internal pressure on the piston also increases. This is why we have our pistons ceramic-coated on the top and Teflon-coated on the sides.

5. TIMING: Retarded timing will also enable your pistons to live longer. Do not advance timing in a Cummins engine.

6. FUEL SUCTION LINE: Install number twelve line and fittings from the tank to the pump.

7. AIR FILTERS: Two are much better than one. Freightliners with one filter under the hood are very restrictive: we do have an economical solution for this.

8. DUAL EXHAUST: Runs fifty deg. cooler on exhaust temperature than single exhaust.

Approximately two months ago, a young owner-operator by the name of Dwain Pyeatt from Butler, Missouri read one of our articles on horsepower and torque. He called us for the other articles. After receiving our booklet he read the articles several times, called the writer several times, then loaded his Peterbilt and headed for Pittsburgh. After spending several hours at Diesel Injection he left for Missouri loaded with high-performance engine parts. The next week he and a mechanic friend of his proceeded to convert his B.C. III 350 HP. engine to an N.T.C. 700 HP. single turbo engine. Please keep in mind that the Freightliner and Kenworth dealers in Kansas City told Dwain that it would not work and he should not build the engine. In my first article I mentioned to beware of the negative mechanic. They will disagree with what we have to say. Dwain Pyeatt kept the faith and continued to build his engine. The results are as follows: On mountains that he used to drop two gears on he can now hit the bottom at sixty m.p.h. and go over the top at 80 m.p.h. That is an increase of four to five gears. As a 350 HP. engine, Dwain averaged five and one half m.p.g. Now at 700 HP. loaded heavy, he is still at five and one half m.p.g. On lighter loads his mileage climbs as high as six and one-fifth m.p.g. Not bad, considering the two Kansas City truck dealers told him it would not run. Dwain also installed dual Vortox air filters on his Peterbilt. He already had dual-exhaust and he installed a number twelve line from his fuel tank to his fuel pump.

Mark Yoder from Calgary, Canada is another example of an owner-operator who built his engine using our high-performance parts. Mark has cleaned the clock of every Caterpillar and K.T.A. 600 Cummins in western Canada.

I have not had the pleasure of meeting Mark Yoder in person. However, I have spoken with him numerous times on the phone. We are hoping Mark can get a load to Pittsburgh and stops in to see us.

The first high-performance engine we built with mechanical variable timing belongs to Elam Riehl from Middlebury, Indiana. This engine is still running strong with 370,000 mi. on it and there is no excessive blowby or oil consumption. Elam stops in our shop once a year to have his valves and injectors set.

When you are rebuilding your engine remember this statement: The bitterness of poor quality remains long after the sweetness of a low price is forgotten.

Now let's discuss parts of the Cummins engine: One item that is always overlooked is the viscous damper located in front of the engine on the crankshaft. The damper has a large steel ring floating in a gel that resembles silicone. After a period of years or around 380,000 mi. the silicone can get hard and the damper is no longer functional.

WHAT DOES THE DAMPER DO ? Each time the injectors fire the steel disc inside the damper moves to absorb shock waves from the crankshaft. Other components that are affected by these shock waves are the camshaft and the accessory drive shaft. The bolts that hold the flywheel to the drive shaft will also snap when the viscous damper is defective. If you ever break the accessory drive shaft, front of the camshaft, or the flywheel bolts always replace the viscous damper.

If you have an N.T.C. 290, 300 or 350 and are rebuilding the engine to an N.T.C. 400 or larger horsepower engine you should update the damper to the one used on the 475 HP. engine. If you purchase this from Cummins it's rather expensive. We purchase ours directly from the manufacturer and can save you several hundred dollars the next time your engine needs a new damper. Cummins Recon will only exchange your damper like for like. You cannot trade a smaller one in for a larger one. Ours are brand new, no core is needed, and the price is less than a Recon.

One of the methods for checking the viscous damper is to remove it from the engine and "mike" the thickness at 12, 3, 6, and 9 o'clock. Or, at the top, bottom, left and right side. If your thickness varies more than 10 thousandths, scrap the damper.

Lead, follow or get out of the way. Lee Iacocca must have been driving one of our high-performance Cummins diesel engines when he came up with that statement. However, when driving one of our engines you will never have to follow. You will always lead. In fact, nobody else even comes close.

Dwain Pyeatt, the owner-operator from Missouri who built one of our high-performance engines two months ago, if you recall. We wrote about him in last month's article. Dwain loaded in New Jersey grossed out at 80,000 lbs. and drove to California. The whole time Dwain never came out of twelfth gear. I know this seems hard to believe running east coast to west coast without dropping a gear except when stopping for food, fuel and sleep. On 12-15-92 Dwain put his Peterbilt on the chassis dyno at Cummins in Strasburg, Ohio. John Lorenz, the service manager, had to use multiple chains to hold the truck to his dyno. The results are as follows: 750 horsepower at 2100 RPM. at the rear wheels. With 50 lbs. of fuel pressure remaining, John Lorenz shut down at 750 HP. because that is all the power his dyno will accept. With 50 lbs. of fuel pressure remaining, Dwain's Peterbilt could have easily topped 800 HP. to the ground. Keep in mind that this was at 2100 RPM. The fuel pump is governed much higher than that. How much horsepower is at the flywheel when you have 750HP to the ground? How about 937 HP. If you lose about 20% through the drive train. 882 HP. if there is a 15% loss, and 833 HP. if only a 10% loss of power occurs through the transmission and rears. Anyway you look at it, we are developing one horsepower per cubic inch. Not bad for diesel fuel.

A question that I am frequently asked is: How does Cummins Engine Company feel about all this power? Well, to find out I asked Dwain to stop at the factory the next time he is in the area. On 12-17-92 Mr. Pyeatt and his N.T.C. 900 HP. Cummins engine visited the factory with a gross weight of 82,000 lbs. This is what happened: After a brief meeting with the Cummins engineer, who does all of the performance testing, they went for a drive to confirm the horsepower. He was impressed with how effortlessly the engine handled the 82,000 lbs. This particular engineer is the person who has helped us with our high-performance engines So he was well aware of everything that was inside the engine.

Dwain's next stop was to the technical center where there were several Cummins employees who were non-believers. After riding and driving the 900 HP. N.T.C. Cummins they now believe that it is possible with one turbocharger.

NOW ON TO PERFORMANCE : The pistons that we use are genuine Cummins. However, they are made of a stronger aluminum alloy than standard 350 and 400 HP. pistons. We also have the top of the piston ceramic-coated and the skirt is Teflon-coated. The Teflon on the sides greatly reduces piston slap against the liner. Teflon is the slipperiest material known to man. With a film of oil on the Teflon we now have a very smooth riding piston in the liner.

The ceramic coating on top of the piston protects the piston from cracking and melting. For those people who are technical, this is how the ceramic is generated: Inside an 80-K.W. electric plasma-generating gun, an accurately controlled, high-density arc is created by ion flow between an anode and a cathode. This excites an inert gas such as Argon or Nitrogen. Metal, ceramic, carbide, cermet (ceramic particles bonded to metal), or polymer powder injected into the ionized plasma stream, is propelled at a supersonic velocity onto the surface of the piston. The "splat structure" of semi-molten particles impinging on the piston and each other forms a high-density interlocking structure.

I never try to get that technical because it takes a ceramic engineer to figure that process out. To me, it sounds like something from Star Wars. All I can say is it really works to keep your pistons alive. If you want high-performance spend the additional $358.50 to have your pistons coated.

The following article is by Dwain Pyeatt: Owner-operator.

In recent weeks, Bruce Mallinson of Diesel Injection of Pittsburgh and I have discussed the extraordinary performance on the engine that he helped me build. He asked me to let readers know what it is like to drive a high-performance engine.

As you might have read in previous articles, I contacted Bruce late last summer about designing and building a high-performance Cummins. My truck was a 350 B.C. IV. Cummins, 13 over, geared with a 3.55 ratio and running high profile 11 R 24.5 tires. I wanted an engine with 600-700 HP. I had previously talked to truck dealers and Cummins distributors about added horsepower and they informed me that it was not possible. After many hours of research and discussing the idea with Bruce I decided that he had the ability to build this engine. I have not been disappointed.

I was frequently in contact with Bruce while building the engine and I followed each of his suggestions for increasing the horsepower and life of the engine. One of these suggestions was installing gauges such as the liquid-filled pressure gauge, manifold pressure gauge and the air and fuel restriction gauges. I have never believed that these gauges have any usefulness but Bruce showed me that with them you have an engine diagnostic center in the cab of your truck. You can evaluate the performance of your engine and troubleshoot problems simply by reading the gauges.

Once the engine was built I realized the true meaning of performance. High-performance is the combining of proper parts to create an engine that snaps to life with the gentlest touch. High-performance is pushing technology to its limits to create a bigger, more powerful engine.

While driving through the Midwest and the Appalachians in the east I have never found a hill big enough to have to shift down. Therefore, I was glad to get a dispatch from Philadelphia to Los Angeles. I wanted to see what my engine would do in the southern California Mountains. During this trip I found that I did not encounter one hill that required shifting below direct. Since I usually drive in direct I never had to shift down. Probably the most incredible thing about this engine is that the fuel mileage hasn't dropped. When it was a 350 B.C. IV. Cummins I averaged 5.6 m.p.g. and my average is still the same.

Bruce asked me to stop by and let the Cummins engineers in Indiana see my engine. A couple of the engineers were skeptical about the power. They quickly changed their minds after driving the truck. They equated the experience to driving a high-performance sports car.

I also had a dyno run done on the truck at Cummins in Ohio. I was excited when we topped the dyno out at 750 HP. with 50 lbs. of fuel pressure left. We estimated that I have 800 HP. at the wheels with approx. 900 HP. at the flywheel.

So what is it like to drive a high-performance Cummins? The answer is simple. It is exciting. Each new mountain or hill is a challenge. I no longer ask myself if I will have to shift down to reach the top. I now ask myself how fast can I top the hill. It is an incredible experience to know that all you have to do is ease down on the throttle and feel the surge of power as you start up the hill. Remembering back to when I first contacted Bruce, I can recall that he told me that it would be like the Jolly Green Giant reached down and pushed me up the hill. He was right. All of my expectations have been exceeded.

End of article

Please keep in mind that all of our high-performance engines are not always built for maximum horsepower. Many owner-operators are pleased with 450 to 500 HP. This is not a problem because the same care and technology and many of the same parts are used in horsepower ratings from 450 to 700. Whatever your requirements for horsepower are we can help you obtain your goal.

Can we build high-horsepower engines in our shop here in Pittsburgh, PA? This question is asked many times by those who call for the first time, and the answer is "Yes." At our facility in Pittsburgh we have three garage bays, an overhead crane, all of the factory tools and factory-trained technicians. Our parts department is very well stocked with high-performance and standard genuine Cummins parts. We do build stock engines as well as our high-performance engines.

Our component rebuilding room has a Bacharach pump stand for custom-calibration of your fuel pump and also a Hartridge injector machine for injector blueprinting. We also rebuild turbochargers, oil coolers, aftercoolers, M.V.T. cam followers and water and oil pumps.

We are a small self-contained Cummins engine dealer that will listen to what you have to say and we will build your engine to meet your horsepower requirements. Our latest task is to build a K.T.T.A. 1150 cu. inch twin-turbo K-series engine to 1,400 HP. Talk about unusual. This engine is going to be canary-yellow and chrome per the customer's request.

TORQUE : How many foot lbs. of torque do we produce with 700+ HP? About 2200 - 2400. That's enough to get the job completed or to run east coast to west coast without dropping a gear. Several years ago Cummins had a song titled "Reserve Power. That's what a trucker needs". Well, that's the kind of engines we build at Diesel Injection of Pittsburgh.

Many people ask if their transmission, drive shaft and rear ends will hold up to the extra torque. Heavens no! Not if you drive like a maniac, do jack rabbit starts, or mash your motor in the low side of the transmission. However, owner-operators do not drive in that manner when they have a thoroughbred under the hood. Instead, they are gentle with the throttle and use the power to maintain the speed once they are up and rolling. When properly driven, the extra torque will not harm your drive train. We have been building high-performance engines for 20 years and have never had a premature failing of any drive line component. If you ever have the opportunity to drive an N.T.C. 700+ HP. engine you will soon realize that moving your big toe on the throttle is all you need to make this baby come to life.

Now let's talk about air filters and how long you should run them before changing. Dirt is a killer to any engine and if we could keep all the dirt out of the air and oil the engine would never wear out. Engines are designed to run on a film of oil. Metal should never touch metal. You obtain the dirt in the engine in two ways. One is the air, which passes through the filters, still have a small amount of dirt particles in it. New filters are 97 to 98.9% effective in dirt removal. The second way is by burning hydrocarbon fuels such as diesel fuel and\or gasoline. These fuels are dirty by nature and, after combustion, small amounts of carbon are left in the combustion chamber. That is why an engine needs good oil filtration. Now, on to the air filters. It is a proven fact that air filters that are slightly dirty filter air better than a new filter. This is another reason we insist on having larger filters than an engine actually needs. Because the cubic feet of air per minute that the filter will pass is slightly less. All trucks should have an air filter restriction gauge in the instrument panel and I don't mean the pop-up style. With the restriction gauge and by doing oil analysis you will be able to determine when your air filters are plugged.

This article is for the owner-operator who drives an N.T.C. 290, 300, or 350 HP. engine that needs an in-chassis rebuild. It never ceases to amaze me as to why you rebuild these engines to stock low horsepower. I realize that your decision is based upon the knowledge of a mechanic or service manager who doesn't understand what makes this great Cummins engine perform. After you finish this article you will know and understand what the difference is between a 290, 300, 350 and 400 engine. Now if you haul U.S. Mail, plastic, insulation or any other light loads all the time, an N.T.C. 350 HP. is fine. This information is for owner-operators who usually gross between 65,000 to 80,000 lbs. or more.

Let's look at what is the same in all N.T.C. b.c. I, II, and III engines. The block, crankshaft, camshaft, connecting rods, heads, aftercooler, oil cooler, water pump, oil pump, exhaust or pulse manifold, accessory drive, air compressor, oil pan and oil pump. Isn't it amazing how many of the components are the same regardless of the amount of horsepower the engine produces? This is one of the greatest aspects of a Cummins engine. Most of the components are identical.

Now let's discuss what the difference is between a N.T.C. 290, 300, 350, and 400 h.p. engine. The compression ratio is different. The timing of the camshaft and the offset cam key changes. Not the camshaft. The amount of fuel injected by the injector, the torque curve, and the fuel pressure supplied by the fuel pump all differ. Lastly, the amount of compressed air from the turbocharger fluctuates from engine to engine. Let's take a more in depth look at each of the differences.

Compression ratio of the piston: An N.T.C. 290 and 300 h.p. engine has a compression ratio of 15.0 to 1. A non-turbocharged diesel or gasoline engine does increase power with high-compression pistons. A turbocharged diesel or gasoline engine increases power and volumetric efficiency by lowering the compression ratio. An N.T.C. 350 engine uses a 14.5 to 1 compression piston and an N.T.C. 400 uses a 14.0 to 1 compression ratio. Can you see the difference between the 290, 300, 350 and 400 pistons? Now, think about this: the price of the cylinder kits are exactly the same. It doesn’t cost any more money for the 400 h.p. pistons so why not install them during your next rebuild? It's a step in the right direction for power.

Injectors: The price of a 290, 300, 350 or 400 injector is the same. 400 h.p. injectors do not cost any more money. So why not install them along with the 400 pistons? After all, you must increase the flow from the injector to increase horsepower.

Turbochargers : The big cam 350 and 400 engines have almost identical turbos: You can use an HT3B Holset or T-46 Cummins turbo from an N.T.C. 350 or an N.T.C. 400 engine. For 400 h.p. engines you must have at least 24 lbs. of turbo boost (manifold pressure). Purchase a manifold pressure gauge for $40 and you will know if your turbo is adequate for an N.T.C. 400. If you have an N.T.C. 290 or an N.T.C. 300 you will have to purchase a turbo for the N.T.C. 400.

Fuel pumps : The difference between a 290, 300, 350 or 400 is the torque curve which consists of two springs. These springs are very economical to purchase. However, your pump must be calibrated on a pump stand when changing these springs. If your fuel pump is fairly new, or in excellent shape, you should be able to find a fuel injection shop like ours to recalibrate your pump for around $200 to $250. Keep in mind that this is not a rebuilt pump for that price. Just a torque curve and fuel pressure change. But remember, if you want it to pull it's best let us choose the springs and do the recalibration for you.

Camshafts : You may find this hard to believe, however, all N.T.C. 290, 300, 350 and 400 h.p. cams from BC I, II and III engines are identical. The only difference is the offset key which sells for around $16. The timings are also different. A 400 is timed at 0.070 and a B.C. III 350 is timed at 0.065. Both engines use the same offset key. Only the gasket thickness on the cam follower is different. You can retime a B.C. III 350 to the N.T.C. 400 settings of 0.070 without removing the camshaft from the engine. An N.T.C. 290 and 300 are timed at 0.060 and it does use a different offset key. You will have to remove the cam from the engine to change the cam key for an N.T.C. 400 setting of 0.070.

There you have it. All the information you need to be armed with when you ask the service manager to build your engine to an N.T.C. 400 and he tells you it can't be done. Please keep in mind, that when we rebuild your engine, we always use the extra high strength Cummins pistons. They are 14.0 to 1 compression ratio and can be shipped to your shop or home via U.P.S. These pistons are available ceramic and teflon coated and they will take more abuse than the stock N.T.C. 400 piston. Insist on the best. It's a tough world out there and only the strong survive.

Last summer Diesel Injection of Pittsburgh supplied all the engine parts to a company called Translitre in Swadlincote, England. They compete in the European truck road racing circuit using day cabovers (strange looking trucks they are). Translitre assembled the engine with our parts and won first place seven of eight races and clinched the European Championship. The engine parts we sent to them are the same parts we use in our over-the-road high-performance engines for owner-operators. In Europe our competition consisted of factory-sponsored teams such as Volvo, Renault, Mercedes-Benz and other European truck manufacturers. We are proud that we were able to defeat the mega-buck factory-sponsored racing teams. That goes to prove the saying "Those who say it can't be done are usually interrupted by someone else doing it." That's us. We do it and we can help you become king of the mountain.

Our secret weapon for the Europeans this year is twin Extrude-honed turbos and a camshaft with .420" travel to the injector. A small cam Cummins injector travels .170", a big cam has .224" and our high lift cam for performance engines has .266" travel. Think how much fuel will be injected per stroke with almost 1\2" of injector travel. By the way, our manifold pressure is over 100 p.s.i. out of the twin-staged turbos that have been Extrude-honed. We blew apart two aftercoolers on the dyno testing this engine at 1,224 horsepower. Yes, it's an 855 cu. in. Cummins engine.

Now if you feel that 700 h.p. is not possible for on-highway it's only slightly over half of what Translitre will be racing in Europe this summer.

Marvin Winship from Buffalo, NY recently rebuilt his N.T.C. 475 twin-turbo Cummins using our ceramic and teflon coated pistons and other high-performance related items. He was able to put 853 horsepower to the ground. According to Cummins engineers in Columbus, Indiana that equated to 1,043 flywheel horsepower.

I realize that not every owner-operator wants or needs this type of excessive horsepower, but wouldn't it be nice to have 600 horsepower using only 500 h.p. to carry you over the mountain and having 100 h.p. left over just in case some hot Cat wants to go around you on the mountains?

In the past we have talked about Mechanical Variable Timing (MVT). I realize that 99% of the diesel engine shops are against this system. Please keep in mind that they really don't understand how it works or realize the many advantages of having Variable Timing. Mack and Caterpillar engines vary the timing with a device in front of the injector pump. That is why they will not smoke at an idle. With the MVT on an N.T.C. series Cummins you will not have white smoke at an idle. But the best advantage of the MVT is the retarded timing when the engine is developing power. Retarded timing takes the shock load off the pistons, bearings, and camshaft. High horsepower and fast timing or stock timing is a killer to pistons. The black hole that burns down through the side of the piston is a result of fast timing. Not an injector failure.

Now, how do we make the MVT operate trouble-free? First, we completely rebuild the entire unit replacing all moving parts. Second, we install an automatic oiling system which was developed by Cummins engineering. It's a shame they did not install the oiling system when the MVT was first introduced. 90% of the related problems would have been eliminated. This oiling system consists of 24" of #4 Stratoflex hose and some 1\8" brass fittings. Third, we install a toggle switch in your instrument panel or on your shifter. This is to shut off the movement of the MVT unit once you get out of the low side of the transmission. The MVT advances and retards every time you shift a gear or back off the throttle. This excessive movement is hard on the rack and pinion in the MVT that actually moves the injector cam followers on the cam. You only need the engine to advance timing when you are idling, driving slowly in traffic or pulling into or out of truck stops. After you shift your first three or four gears, trip the toggle switch to allow the MVT to stay in the retarded mode and you will not have any trouble with your unit. The MVT makes 600 + horsepower possible along with engine life.

Now let's talk again about vibration dampers. Several months ago we mentioned all of the engine failures that are associated with faulty dampers such as broken flywheel bolts, broken accessory drive shafts and camshafts. Whenever you have in excess of 380,000 miles on your damper it may be scrap. With the engines running in excess of 500,000 miles between rebuilds you should replace the damper at the time of rebuild. If you have a 290, 300, 315 or 350 h.p. N.T.C. Cummins and are going to increase the horsepower to 400 or more you should install the largest damper which costs $490 new from Diesel Injection of Pittsburgh.

The next subject is about breakdowns when you are away from home. Remember this number, 1-800-DIESELS or 1-800-343-7357. This phone number will put you into the Cummins engine factory in Columbus Indiana. If you feel you are being treated unfairly or taken advantage of please call this phone number and explain, in a nice way, your problem to one of the four gentlemen that will answer the phone. Your call may be taped so please be careful of what you say. Being belligerent and yelling will get you nowhere. This phone call may save you thousands of dollars.

Would you like to be able to increase your horsepower by 75 to 100 h.p. in one day? Sound impossible? Many may think so but they don't understand what we are doing anyhow. Remember; those who say it can't be done are usually interrupted by someone doing it. We can increase your horsepower by as much as 100 h.p. in one day by reflowing your injectors, recalibrating your fuel pump, installing a Holset high altitude mapwidth enhanced turbo and a fuel pressure gauge. Please keep in mind this is intermittent horsepower and should not be run flat out for long periods of time. Always be in a gear where your engine can accelerate. Also, when working hard on a mountain, keep your engine at 2,000 r.p.m. and in a gear where your foot isn't mashed to the floor.

There seems to be a misunderstanding in the trucking industry about horsepower and fuel mileage. Why do most people feel that when horsepower increases fuel mileage goes down? Lets talk about this: my understanding is that it takes approximately 273 h.p. to maintain 70 mph in a cabover grossing 80,000 lbs. on level highway with no head wind. This information was given to me by Cummins engineering. Now if you are driving a stock NTC 290 at 1700, your foot would be flat on the floor, like driving a 318 Detroit. We all know how miserable that can be. If you have an NTC 290, 300 or 315 that is stock and you have enough gear selections to keep your rpms at 2000 or 2100 to try and maintain 70 mph your fuel mileage will be terrible. Now please keep in mind that this is on level highway. Something we just don't have in the eastern United States. Also, in the Midwest, you're blessed with 35 mph head and side winds. Another killer to fuel mileage. In the west where the mountains are 18 miles up the low horsepower engines never get a chance to breathe.

What does all this lead to? It takes horsepower to operate a truck at a decent cruising speed to obtain fuel mileage. If your engine will produce 600 h.p. and you want to maintain 65 to 70 mph at 1600 to 1700 rpm it will only take 50 lbs of fuel pressure to accomplish this. In the small horsepower engines it will take 130 lbs. of fuel pressure and that’s all you have at 2100 rpm. Which one would you rather drive?

My personal opinion is that 450 h.p. is the minimum horsepower an owner operator should have to get the job done. Even for a company driver. Give them horsepower to maintain a decent road speed on 3 and 4% grades so traffic can move along at a smoother pace. If company executives are concerned about speed, put road speed governors set at 68 mph on your company trucks. If trucks can maintain their speed uphill, along with the cars, our highways would be safer for everyone. We all know how aggravating it is when you're following two under powered company trucks up a mountain with their 4-way flashers on trying to pass one another for no apparent reason. It's time we eliminate under powered trucks from our highways and put them to work on the farms.

High horsepower, driving at moderate speeds of 60 to 70 mph, maintaining at least 55 mph up hills, using low rpm on the flats and high rpm on the mountains will give you fuel mileage and long engine life.

Several months ago we talked about injectors and always installing them with STP slightly thinned with 15-40 engine oil. Using the STP mixture on the injector "0" rings and in the injector bore in the head will insure that you will not cut, shave or nick the "0" rings. Do Not use Vaseline, straight engine oil, Murphy's oil soap or grease.

If you cut your injector "0" rings this is what can happen: first the bottom "0" ring keeps the diesel fuel from running down the sides of the injector and into the combustion chamber. If this happens, your engine will melt a piston or score a liner. The engine will idle rough and have excessive white smoke. During a hard pull you can actually flood your engine with fuel to the point that the engine will shut down.

The middle "0" ring, if cut or shaved, will allow your fuel pressure to return back to the fuel tank. The result is a loss of power, poor idling and you will think that your fuel pump is sucking air because the throttle response will be spongy. The top "0" ring keeps the fuel oil from entering your rocker boxes. If this happens you will have fuel dilution in your engine oil.

As you can see all three of the "0" rings are very important to the longevity and performance of your engine. Always use STP slightly thinned with engine oil on your injector "0" rings.

Horsepower is determined by how much fuel is injected into the combustion chamber. Always install injectors calibrated one size larger to gain increases in power. Lately, we have been going two sizes larger on NTC 350 and 400 h.p. engines with fantastic results. John Melanson from Ontario, Canada bobtailed 750 miles to have our shop rebuild his injectors, fuel pump, install a pyrometer, fuel pressure and manifold pressure gauges. We reflowed his injectors two sizes larger, set the fuel pump to match the injector flow and the results were approximately an increase of 100 horsepower. September 2, 1993 he stopped by our shop to tell us how much he enjoyed driving his truck. It will out pull stock 425 caterpillars and he gained .5 miles per gallon and never has to run his engine wide open.
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