As I begin this piece, CaptnWil is sitting in a RV Park in Wichita KS with a broken spring on the RV. There's no blue water or yachts anywhere close, and CaptnWil is about a quart and a half low on Trawler. For almost two months, we have been on a summer land cruise to the West that has included the high mountain country of California, Utah, and Colorado as well the heat of Death Valley. But this list is about trawlers and other boats. What does CaptnWil's land cruise have to do with the "World Trawler List?" It could be argued that people who go places in RVs and Trawlers have a lot in common, but that is not a strong enough link to justify using the TWL bandwidth. And besides, writing about non-boating things is against the rules. The strong link is that Trawlers and many RVs use diesel engines. While there are some differences in the application of diesel engines in the two groups, both groups share many common concerns about the selection and operation of their prime mover. It is to this point that this piece is directed. If there are those interested in the full land cruise story, drop me a line with your E-Mail address, and I'll collect the list and send the whole thing to that list. As longtime members of the list know, I have been investigating oil bypass filters and other considerations concerning diesel engines for over a year. This investigation began with a Lehman-Ford 135 in my Kadey-Krogen 42 and has continued with an ADC-Ford 140 and now a Cummins 6BTA5.9 in my pickup that pulls my Travel Trailer. The observations on this trip are of particular interest because much of the engine time was at full load and high altitude. These conditions produced very severe conditions for the engine and magnify every weakness of its operation. We'll get into the observations that have a direct bearing on trawler operation as we go along. SELECTION AND OPERATION Before we get to the specifics, we'll discuss the primary tool used in both the successful selection and operation of any diesel engine in any application. That tool is a graph that shows the most important characteristics of the engine. Cummins calls it the Engine Performance Curve. It may be referred to by different names by other manufacturers, but they all show similar information. A complete curve will show horsepower (hp), torque, and brake specific fuel consumption (bsfc) in graphical form as well as a host of other information in non-graphical form. The curve should always show the standard on which the data is based -- such as SAE J1349. Since performance differs in different atmospheric and other conditions, two engines can only be compared if the data is based on the same standard. Hp Curve This curve shows hp at each RPM and its concept is not foreign to most people. In most diesel engines, the hp increases from idle RPM in a gentle curve that tends to flatten out near maximum RPM with max hp being reached at max RPM. It is important to recognize that FULL LOAD is different at different RPM. Engine hp is stated at maximum RPM, but few engines are selected to operate at maximum RPM. Maximum hp at any RPM is shown on the curve and FULL LOAD is reached whenever the load meets that hp at any particular RPM. When the load exceeds that hp, we start to get into trouble. For example, my 6BTA5.9 develops 180 hp at 2500 RPM, but only 128 hp at 1500 RPM. The not-so-obvious importance of this observation will be developed a little latter. The important thing to remember is that FULL LOAD is developed whenever the actual load meets or exceeds the horsepower indicated by the curve at any particular RPM. That is almost always less than the published horsepower for the engine. Torque Curve Horsepower in the US is most often defined as 33,000 ft. lbs. per minute and is a complex term that, in a diesel engine, is the result of the torque generated at a given RPM. Torque and hp are directly related by RPM in such a way that hp = torque * RPM / 5252 (almost) where torque is expressed in ft. lbs. It is helpful to remember that torque describes the force to turn the crankshaft and some authors give the quantity as lb. ft. to make sure the reader knows it is a force that tries to cause rotation instead of a force acting in a straight line. While the hp curve describes the total energy an engine can develop, one important use of the torque curve is to describe how the engine reacts to CHANGES in load. The torque curve generally rises from idle RPM to a peak somewhere below max RPM and then falls in a gentle curve to max RPM. Peak Torque is a very important point on the engine curve and knowing how to use it is critical to successful selection and operation of any diesel engine in any application. In a diesel engine, the RPM of Peak Torque is always less than max RPM, and the percentage of torque increase from maximum RPM to Peak Torque RPM is so important that it has a special name -- Torque Rise. Note carefully that if the engine RPM is greater than Peak Torque, the TORQUE INCREASES AS THE RPM DECREASES from max RPM to Peak Torque RPM. My 6BTA5.9 has a Torque Rise of 18%. That means that the torque in ft. lbs. is 18% greater at 1700 RPM than at 2500 RPM. In general, the greater the Torque Rise, the better the engine can handle a varying load IF NORMAL OPERATING RPM IS GREATER THAN PEAK TORQUE. The advances in turbocharger design and understanding have allowed manufacturers to increase the horsepower of a diesel at max RPM and to increase its fuel economy. In addition they can tailor Peak Torque to meet many situations. For example, the current production 6BTA5.9 in the Dodge pickup produces 235 hp with a Peak Torque of 460 ft. lbs. while mine produces 180 hp with a Peak Torque of 445 ft. lbs. That's 30.5% more hp at max RPM, but only 3.3% more Peak Torque. Cummins makes other 6BTA5.9s with 230 hp and 605 ft. lbs. of Peak Torque. The most likely reason for the small increase in Peak Torque in the Dodge is to protect the drive train. You have noticed that two engines may have the same horsepower at max RPM but different values for Peak Torque. In this situation, the engine with the greater Peak Torque will develop that Peak Torque at a lower RPM than the other engine because you can't change the link between horsepower, torque, and RPM. The ability of modern engine manufacturers to customize the same engine block for many different design requirements is a great boon to all of us diesel engine users. Brake Specific Fuel Consumption The bsfc curve displays the amount of fuel the engine burns for each horsepower it develops at each RPM. Note that the Horsepower curve shows the maximum horsepower the engine can develop at each RPM. The horsepower it develops depends on the load. The bsfc curve displays the fuel consumption for each hp it develops for that actual load. This curve for most diesel engines decreases in a gentle curve from idle RPM to a little past Peak Torque and then increases in a gentle curve to max RPM. The lower the values, the more efficient the engine. It is very interesting to note that most diesel engines are most efficient near and slightly above Peak Torque. The reasons for that are left as an exercise of the reader. The bsfc curve generally shows fuel consumption as lb/hp-hr. That practice makes it a little difficult for most of us to get a feel for what it means since we think in terms of gallons per hour. We need to convert lbs. of fuel to gallons of fuel. The specification for No. 2 diesel calls for a specific gravity of from 0.80 to 0.85. Since a gallon of water weighs 8.33 lbs, a gallon of No. 2 diesel weighs between 6.664 and 7.08 lbs. We'll use a value of 7 lbs per gallon. My 6BTA5.9 shows 0.35 lbs/hr-hp at 1400 RPM, 0.34 lbs/hp-hr at 1700 RPM (Peak Torque), and 0.36 lbs/hr-hr at 2500 RPM (max RPM). We can convert those figures to horsepower per gallon burned using: hp-per-gallon = 1 / (lbs/hr / 7). That calculation will show that my 6BTA5.9 operates almost exactly on Paul Kruse's rule of thumb of 20 horsepower per gallon burned. Using this information, you can make a good estimate of just how much horsepower you are using to drive your boat if you keep a record of how much fuel you burn per hour. If your bsfc shows 0.35 at your cruising RPM and you burn 2 gallons per hour, your engine is producing 2 * 20 = 40 horsepower (approx). I suspect that result is a surprise. So What If possible, a diesel engine should always be operated under load above Peak Torque RPM. The engine will run easier, at greater efficiency, and operate cleaner than lugging at less than Peak Torque RPM. When additional load is applied to the engine while its RPM is above Peak Torque, the RPM tends to drop, but the torque increases. This situation tends to keep the RPM from dropping further without increasing the throttle setting and makes maintaining the RPM by increasing the throttle much easier than if the RPM is less than Peak Torque RPM. By contrast, when additional load is applied below Peak Torque, the torque decreases as the RPM tends to drop. This leads to ever-decreasing RPM and lugging the engine with the telltale black smoke. Anytime you increase the throttle and the RPM does not increase, you are overloading the engine. Diesel engines with modern fuel systems tell a complete story with smoke. No smoke means all is OK. Blue smoke means the engine is burning oil -- trouble. White smoke means that there is incomplete combustion because the engine is too cold -- most often associated with cold weather starting -- don't apply load until the white smoke goes away. Sometimes you will see white-blue smoke in this situation. Both cases mean it is not yet time to apply any load. Black smoke always means that more fuel is being put into the cylinders than the engine can burn and convert into horsepower. The least problem is that some of the expensive fuel you paid good money for is going up in smoke and not making you go across the water. The other evils are that more pollutants are going into your expensive oil and more stress is being put on your engine. Everything possible should be done to never see black smoke. In modern diesels, keeping the RPM above Peak Torque will almost always prevent black smoke. It is easier to maintain this proper RPM in land-based engines that have several gears to take care of changing loads than with the general configuration encountered in recreational boats. Our trawlers generally have only one gear ratio available. Most of the time we had nothing to do with its selection and cannot change it without some major expense. The fact that the propeller provides a lot of slip hides many problems with less than optimum configuration of propeller, transmission, and engine at cruising RPM. It is possible to make corrections if the cruising RPM is at the wrong point on the engine curve, but that should be considered only after some major consultation with experts in the field because the expense could get pretty high. If your cruising RPM is less than Peak Torque, you must be very careful with your throttle control and increase it slowly so that you don't lug the engine. Most of the time you can't see the black smoke while at the helm. That means you should make observations with someone else at the helm to see just what the situation is. These problems are greatest in boats that cruise near the rated power curve of an engine. Boats like the KK-42 that require 40 to 60 horsepower at cruising speed and are fitted with a 120 to 135 hp engine suffer less. In any event, careful throttle control is required whenever the engine is operated under load at less than Peak Torque, and the loads are increased by wind, current, wave action, fouled bottoms, etc. Most of us have seen our cruising speeds decrease dramatically because of dirty bottoms, foul currents, or big waves. Whenever the boat slows down and/or the RPM decreases at the same throttle setting, the load has increased on the engine. The exception to this could be that the boat slowed down because the propeller is fouled in a way so it does not transmit full power to the water. Those who have the opportunity to build a new boat or re-power an existing boat should make sure the cruising RPM is correctly determined. If you do, you'll like the results. CAPTN WIL'S 6BTA5.9 The total load on my 6BTA5.9 is 17,180 lbs and the engine is geared with a 5-speed manual transmission and 3.52 rear-end to meet all the objectives described above. The engine is turbocharged to 20 psi and after-cooled with engine coolant water. As stated above, this gives a maximum rating of 180 hp at 2500 RPM. The basic un-turbocharged engine develops about 115 hp, but is modified upward in every configuration I have seen by use of the turbocharger. I have seen this engine rated at 275 hp in highway operation and at least 300 hp in marine applications. Earlier textbooks stated that increasing the hp by use of a turbocharger was limited to about three times the basic rating. If that is still so, 350 hp is about tops for this block - but who knows what they are doing now. I feel comfortable with this engine rated at 180 to 240 hp, but 300 hp makes me uneasy. But then I'm from the old school. I installed this engine in 1992 for a land cruise to Alaska. It performed well as expected and as I became more involved with trawler operations it was pretty much neglected. The Lehman-Ford and later the ADC-Ford in my Kadey-Krogen got my full attention. Those engines performed very well and many facts about experiences with bypass filters, etc. have been reported about those engines. When we decided to make a major land cruise to the high country of the West, the 6BTA5.9 again received my full attention. I became very interested in comparing experiences between the Fords and the Cummins. The first difference to surface is that the Fords were seldom, if ever, fully loaded, but the 6BTA5.9 would be severely loaded most of the time. Another major difference was the nature of the load. The total trip was 10,081 miles. More than half of it was at elevations above 6,000 ft. and some 3,000 miles was above 8,000 ft. Many miles were above 10,000 ft. and the highest point was on Trail Ridge Road above 12,000 ft. Adding to the load is the fact that 6BTA5.9 is de-rated 4% per 1,000 ft of altitude. At 10,000 ft. the engine has lost 40% of its power and 48% at 12,000 ft. In addition to making it harder to carry the load, this altitude made it almost impossible to keep from over-fueling the engine. I had to work hard to keep from having black smoke at these altitudes and was not always successful. At these altitudes, I always got black smoke when starting the load from a stop. Death Valley made life for the engine horrible because of steep long grades in 115-degree temperatures. Full load at such temperatures is something the cooling system had not been designed for. Trying to sleep in Death Valley in just slightly cooler conditions is something CaptnWil had not been designed for either. That night it got down to 99 degrees -- no air conditioning. I, like most of you, have been in many places and circumstances where safety depended on an engine starting and/or running. That dependence was never more vivid in my mind than when I tried to sleep in the 99-degree night in Death Valley. In most of my other times in similar situations, the all-important engine was already running. I had every confidence that the engine would start next morning, but I was relieved when did. I made a new vow to continue to do everything I know how to make sure it will start and run when needed. GULF COAST FILTERS AND THE 6BTA5.9 In April of 1999, I took the pickup to Gulfport and Charlie Sims of Gulf Coast Filters installed an O-1 bypass oil filter, O-1 Jr. diesel filter, and O-1 Jr. coolant filter. At the time, the 6BTA5.9 had 52,150 miles on it. The Shell Rotella 15W-40 oil had 1,000 miles on it. At the time of filter installation, an oil sample was drawn and a Portable Oil Analyzer (POA) reading was done. The sample was sent to Titan Laboratories for full laboratory analysis. The POA reading was 1.1, and the laboratory analysis was that of a new engine and new oil. The POA is a very important and large part of my effort to keep my engine "Just Like New." POA The Portable Oil Analyzer is a portable instrument that allows analysis of the over-all quality of the engine oil to be made in the field at any time. It compares the electrical capacitance of a used sample of oil to the electrical capacitance of new oil. It produces a single numerical result that indicates the condition of the oil that ranges upward from 0.0. The concept is that the capacitance values of oil increase as the contamination increases. The meaning of the reading is: Reading Action 2.5 Change GCF Element 3.6 Have Laboratory Oil Analysis 4.6 Change Oil and Full Flow Filter The unit is calibrated at 4.6 and is most accurate at that value. There are also means of determining special problems such as water or antifreeze in the oil. I consider the POA to be the most important tool available to know, on a continuing basis, the real condition of any engine. I recommend giving it a top priority in the maintenance budget for any engine. In a later part of this report, you will see how getting real information from such a tool shows just how chancy most of our theories, and those of the experts, about oil change intervals really are. I made 10 POA readings in 59 days. That's about one every six days, but that's not what CaptnWil recommends. He recommends one every two days, but he also gets lazy when there are so many other interesting things to do. But do consider that I got more information with these ten readings in 59 days than I have ever had before. THE THEORY I already knew that the 6BTA5.9 is one very good engine. I knew that it didn't take one drop of oil between normal oil changes -- 5,000 miles. I expected to negotiate the flatlands between here and the Rocky Mountains with no adverse affect on the oil. I expected the hard, long climbs at high altitude and reduced oxygen to produce much more contaminates in the oil, and I expected the POA to verify my theory -- full load operation at high altitude would pollute the oil in short order. After all, CaptnWil is an engineer and that hypothesis just makes good engineering sense. THE RESULTS Miles On POA Reading O-1 Filter Reading Location 6,056 1.7 NC to TN 7,121 1.4 Mid West 8,282 1.6 8,722 1.6 9,598 1.6 Rocky Mt. High 11,164 1.9 12,022 1.9 13,169 1.8 Rocky Mt. High 14,330 2.0 Plains & Home 15,039 2.0 End NC I show you this to demonstrate just how brilliant CaptnWil is with his logic. The total increase in the POA reading was 0.3 in 8,983 miles. I can 't find any difference in the results in easy and hard service. Please note that there is a total of 15,039 miles on the GCF O-1 with a reading of just 2.0. The filter doesn't need to be changed until the reading reaches 2.5, and by extrapolation you can see that it will not need to be changed until another 14,971 miles have passed. But using CaptnWil's demonstrated unfailing logic he boldly states that the filter will load up quicker at the end of its cycle than at the beginning. Also remember that an oil change is not called for until a reading of 4.6. In case you are wondering if one can put full faith in the POA readings, I have sent a complete sample off to the lab for complete analysis to answer both your and my questions. The mail hasn't returned the lab report, but I called today for the result. The response was, "Thumbs up. Just keep doing what you are doing. We'll send the details in the mail." 15,039 miles on the GCF O-1 filter and 16,038 miles on the oil. Wonders never cease. But then there's a Detroit diesel that has gone over 1,000,000 miles with the similar results. THE GULF COAST O-1 BYPASS OIL FILTER There are many bypass oil filters on the market. I have every reason to believe that they all work very well. The Gulf Coast Filter manufacturer does not claim his competitor's filters don't work. I have not heard any competitor in this market make charges that another's doesn't work. That is a very refreshing situation. I believe that the evidence from all of the sources I have been able to check -- which includes technical reports from Shell Oil Co., North Carolina Department of Transportation, and the US Military; observation of the Detroit diesel engine that was about to complete 1,000,000 miles with just one oil change; inspection of many laboratory oil analysis reports; and my own observations of my personal engines for more than a year -- leaves no doubt that bypass oil filters will prolong diesel engine life and reduce oil changes to seldom or never. Cold Startup I can't leave this subject without commenting on the issue of major engine wear at engine startup. I paid the price in installation complication to get a real bulb thermometer and real oil pressure gauge for my system. It was well worth the effort since it gives me a lot of real information that isn't available from the electric senders in most installations. The oil pressure gauge shows that no matter what the outside temperature, the oil pressure in my engine is well above 60 psi every time I start it. The oil pressure stays above 60 psi for many minutes -- more in cold weather than warm, but for many minutes in any temperature. One of the nice facts included in my Cummins Owners Manual is that the oil bypass valve opens at 60 psi. The implication of this is serious. When the pressure is above 60 psi, a lot of oil is not going through the full-flow oil filter. I don't know the answer, but the question is how much of the extra wear at startup is caused by the fact that much of the oil bypasses the full-flow filter during warm-up? One of the things the bypass oil filter does is to stay on duty all the time. The extra clean condition of the oil as a result of the bypass filter must make a difference during cold startup. Having said all of that, I will not disagree with you if you decide that the investment in this equipment is not economical for you. WHAT THEN IS THE POINT? The point I want to make has now become a CaptnWil "Hard Saying." A hard saying is more than just a theory, but not quite a law -- yet! No one can predict when the oil in any engine or its filter should be changed. The only way you can tell for sure is to test it. With the current state of the art, that gives you two alternatives -- Laboratory Oil Analysis or Portable Oil Analyzer readings. The best way, by far, is to use both. Use the POA often to tell you when to do the Laboratory Oil Analysis. Do rely on the analysis results and don't use any rule-of-thumb oil drain interval from anyone. You can know the truth if you will do your own testing, and the truth will increase the life of your engine and set you free. There's a little more about some of the other things, but this is enough for now. CaptnWil