PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE 5/08 K:IProjIAcc&Pres/ClRC/DateDue.indd ABSTRACT A TECHNIQUE FOR INSTANTANEOUSLY SELECTING EITHER "FULL ENGINE" OR "HALF ENGINE" PERFORMANCE BY Mohammad Loghavi Deactivating half of the cylinders of an engine to require the remaining cylinders to work at a higher per- centage of their capacity is an effective means to improve the fuel efficiency. A mechanism has been developed to deactivate and reactivate the cylinders by controlling the Opening of the valves. The operator can instantly select the full engine for maximum power or the half engine for improved fuel economy. Approved: Major Professor Department Chairman A TECHNIQUE FOR INSTANTANEOUSLY SELECTING EITHER "FULL ENGINE" OR "HALF ENGINE" PERFORMANCE BY Mohammad Loghavi AN AB 811 TECHNICAL PROBLEM REPORT Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agricultural Engineering 1975 ACKNOWLEDGMENTS The author wishes to express his gratitude to Dr. Robert H. Wilkinson for his helpful suggestions, guidance and encouragement during this study. To Professor Ernest H. Kidder I express my deep appreciation for his editorial assistance. Appreciation is also extended to Dr. John B. Gerrish and Dr. Larry J. Segerlind for their guidance and percep- tive criticism during this research. ii TABLE OF CONTENTS INTRODUCTION . REVIEW OF LITERATURE . PART I DEVELOPING THE MECHANISM The Problem and Approach Parts Used in the Engine Conversion . Rocker Arm Deactivating Mechanism Rocker Arm Reactivating Mechanism PART II ENGINE PERFORMANCE TESTS Objective Test Procedure . .Analysis of Test Results Results and Discussion CONCLUSIONS . . RECOMMENDATIONS REFERENCES . . . . . . . . iii comm-54> 17 17 17 . 19 . 20 34 35 36 Table Table Table Table Table Table Table Table LIST OF TABLES Four-cylinders operation performance data. Test No.1(a) Eight-cylinders operation performance data. Test No. 1(b) Four-cylinders operation performance data. Test No. 2(a). . . . Bight-cylinders operation performance data. Test No. 2(b) Four-cylinders operation performance data. Test No. 3(a) Eight-cylinders operation performance data. Test No. 3(b) Four-cylinders operation performance data. Test No. 4(a) 24 24 25 25 26 Eight-cylinders operation performance data. Test No. 4(b) iv 26 LIST OF FIGURES Page Figure l. Deactivated Rocker Arm . . . . . 7 Figure 2. Deactivated Rocker Arm with Push Rod Retainer Spring . . . . . . . 7 Figure 3. Prototype Unit . . . . . . . 9 Figure 4. Modified Rocker Arm . . . . . . 11 Figure 5. Hinged Link . . . . . . . . 11 Figure 6. Push Rod--Hinged Link Configuration . . 11 Figure 7. Electrical Circuit Diagram . . . . 14 Figure 8. Fuel Consumption Comparison Test No. 1(a,b) 27 Figure 9. Fuel Consumption Comparison Test No. 2(a,b) 28 Figure 10. Fuel Consumption Comparison Test No. 3(a,b) 29 Figure 11. Fuel Consumption Comparison Test No. 4(a,b) 30 Figure 12. Fuel Consumption at 1200 rpm . . . . 31 Figure 13. Fuel Consumption at 1400 rpm . . . . 31 Figure 14. Fuel Consumption at 1600 rpm . . . . 32 Figure 15. Fuel Consumption at 1800 rpm . . . . 32 Figure 16. Fuel Consumption at 2000 rpm . . . . 33 INTRODUCTION The traditional and typical U.S. automobile is large by world standards and usually has a powerful engine that is not noted for fuel economy. Until the recent advent of shortages and higher fuel prices the need for increased efficiency was of little concern to the average U.S. driver. Now, however, with the awareness and concern for energy conservation that has been occurring throughout the world during the last two years, many in the U.S. have been prompted to consider ways to improve the efficiency and hence the economy of operation of existing automobile engines. Deactivating half of the cylinders of an engine has been shown to be an effective means to improve the fuel efficiency (Gerrish et al., 1975). When pulling a trailer or driving in the mountains, etc., it would be desirable to instantly reconvert to the larger "full" engine. This suggests that a dashboard controlled switch for quick conversion would be highly desirable, thus allowing the driver to quickly select the type of engine performance needed. REVIEW OF LITERATURE In 1917 the Enger Motor Car Company used the idea of changing an engine from a twelve to six cylinders by holding the exhaust valves on the left block of the V-lZ in an open position, and by closing a butterfly valve in the intake manifold to the left block (1). This technique was abandoned later, probably because of the pumping losses through the exhaust ports. A concept advanced by Gerrish, Wilkinson, Baker and Kampe of the Agricultural Engineering Department at Michi- gan State University was to reduce the horsepower output of the existing engine. These engineers argued that by deactivating half of the cylinders of an engine, the re- maining ones would be forced to work at a higher output per cylinder to achieve the same horsepower output as the full engine. The "half engine" could easily deliver the needed power and the cylinders could be working at a higher volumetric efficiency, hence a fuel saving would result. This theory was tested by Gerrish et al. using a 1968 Chevrolet 307 cubic inch V-8 engine (3). By closing the valves on four cylinders, the engine was made to run as a V-4. The fuel economy on road tests was measurably improved. 2 3 The E.P.A. Tests at Ann Arbor (2) confirmed that the car had a lQ-percent improvement in fuel economy. Performance was sacrificed to get the higher fuel economy, but this was not considered a major disadvantage on most roads with a steady moderate speed. Gerrish et al. were im- pressed with the result of "big car comfort and safety and small car economy." Primary disadvantages of the Gerrish engine are that: l) Modification requires several hours to complete, and 2) Once converted a "half engine" is not readily changed back. The driver-owner is committed to a low performance engine. PART I DEVELOPING THE MECHANISM The Problem and Approach Designing, building and testing a mechanism to activate or deactivate some of the engine cylinders at the driver's discretion was the challenge of this technical problem. Deactivation of the cylinders by closing both intake and exhaust valves was shown by Gerrish et al. to be the least detrimental to engine performance, as pumping losses were minimized. It was decided to use this method of cylinder deactivation. Several approaches were considered. A promising idea was suggested by Dr. R. H. Wilkinson to interrupt the valve-opening mechanism by means of individual solenoids mounted on the rocker arms of the four deactivated cylinders. By energizing or deenergizing the solenoids, the engine could be operated on either eight cylinders or four cylinders as driving conditions required. This approach was followed and required the develop- ment of a special mechanism to carry out the function of activating and deactivating the cylinders. 5 A 350 cubic inch V-8 Oldsmobile-Rocket engine was used for this experiment. This engine was run on an electric dynamometer to carry out performance versus fuel consumption tests. The original firing order was 1-8-4-3-6-5-7-2. Every other cylinders 8-3-5-2 were de- activated in the four-cylinders operation to give a new V-4 firing order of 1-4-6-7. Four-cylinders operation was considered to be the best engine running mode to achieve maximum fuel economy, and eight-cylinders operation was to be the temporary running mode when there was a demand for high speed or high power output. Parts Used in the Engine Conversion 1. Eight 12-volt D.C. continuous duty Guardian solenoids. 2. Eight new rocker arms. 3. Eight 5/16 x 1-1/4 stove flat head bolts with eight tightening nuts (used for clearance adjust- ment). 4. Eight spring holding collars (made in research lab) with eight tightening screws. 5. Eight compressive type spring (no. of active coils - 4, coil diameter - 7/16", wire diameter = 3/64"). 6 6. Eight thin wire springs for spring loading the solenoid plungers. 7. Sixteen 6-32 steel bolts (used for solenoid installation). 8. Two spst toggle switches. 9. Two rectangular 22" x 5" sheet metal plates (used as temporary rocker arm cover). Rocker Arm Deactivating Mechanism To disengage the rocker arms on the deactivated cyl- inders the point of contact between each rocker arm and its push rod was drilled out to permit the push rods to move up and down through these holes without activating their respective rocker arms. The cylinders became in- active as their intake and exhaust valves remained closed regardless of the cam and push rod position. Figure 1 shows a rocker arm deactivated by this procedure. To prevent the push rods from being "kicked out" by the cam action and to reduce noise by maintaining lifter and cam contact at engine running speeds, a push rod retainer spring was installed as shown in Figure 2. Each push rod was fitted with a spring retaining collar and a set screw. A flat spot was made on each push rod to receive the set screw and secure the collar position. These springs kept the push rods and lifters in contact providing smooth operation, were also necessary Rocker Arm Rocker . . Drilled Retainer Arm Portion Valve Sprin; #:6._ 4;, ' push Rod an... Valve Stem 1 (I... + Figure 1 -- Deactivated Rocker Arm Retainer Spring Spring Collar Retaining Collar . q! I v I . n?» ll\\\Seti‘: 4 Screw ' Figure 2 -- Deactivated Rocker Arm With Push Rod Retainer Spring 8 for proper functioning of the rocker arm reactivating mechanism as described next. Rocker Arm Reactivating Mechanism To reactivate the previously deactivated cylinders for eight-cylinders operation, a mechanism was needed to transmit push rod motion to the rocker arm to restore normal valve operation. A practical approach appeared to be a movable stop on a rocker arm to intercept the push rod motion and transmit it to the rocker arm and valve. This movable stop or hinged link is shown in Figure 3. A prototype unit was made in order to test the feasibility and validity of the rocker arm reactivating mechanism. All parts were put together by screws, so the unit was not highly durable for extended use. A few minutes of operation proved that this mechanism was able to perform as intended. The results of the prototype test were encouraging. A solenoid to swing the hinged link was mounted on each of the eight rocker arms to be deactivated. A rectangular bracket was welded on each rocker arm to provide a frame for installation of the solenoids. A U-shaped bracket was welded to each rocker arm as a base for installation of the hinged link (Figure 4). The upper end of each hinged link was pinned to the solenoid plungers. Each plunger was spring loaded to keep the lower end of the hinged link clear of the push rod Spring Solenoid ”“ \ NINE, k Hinged Link Q¥$* Hinge II (a) Rocker Arm Activated (b) Rocker Arm Deactivated Figure 3 -- Prototype Unit 10 strokes during the four-cylinders operation. Energizing the solenoids causes the plungers to be pulled inside the solenoids and the hinged links are rotated to obstruct the drilled push rod holes. The solenoids cannot rotate the hinged links until the push rods are moved down to their lowest position by the re- tainer springs. At engine running speed this process takes place in a fraction of a second. The initial tests showed that little or no clearance was desirable between each push rod and its corresponding hinged link bottom. Minimum clearance prevents alteration of valve Opening and closing time, change in valve range and noisy operation of the valve system. An adjusting mechanism was added to each rocker arm to maintain a zero or minimum clearance. This consisted of an adjusting bolt with its tightening nut over each valve stem (Figure 4). Valve clearance was adjusted to just permit free swinging of the hinged link. NO extra gap was necessary because hydraulic valve lifters were employed on the engine. The valve system was lubricated by an oil duct through each push rod originating from the lifter and ending on the top of the push rod head. The hinged links were provided with an oil groove to permit lubrication of the valve train during the eight-cylinders Operation (Figure 5). The hinged link bottoms were shaped in such a way to match the push rod head curvature in order to increase the contact area and reduce the contact stresses. 11 Clearance Re§§:2%giar Adjusting A Screw U-shaped Tightening Bracket Nut ”WDWMMMW Figure 4 -- Modified Rocker Arm Hinge Axis Oil Groove Figure 5 -- Hinged Link Hinged Link 'ush Rod Figure 6 -- Push Rod--Hinged Link Configuration 12 Figure 6 shows that each hinged link must be installed in a position such that the line extending along the push rod passes just to the right of the hinged axis, otherwise the moment applied by the push rod about the hinge axis overcomes the solenoid pulling force and the hinged link will be forced back to its neutral position. The violent oscillations of the rocker arms, especially at high engine rpm, was one of the critical factors in the design and installation of the parts and elements. The rapid oscillation of the rocker arms caused the solenoid mounting screws to work loose from the brackets during eight—cylinders operation. This problem was partially solved by safty wiring the two solenoid installation screws on each rocker arm. Steel wire and solder was used for this purpose. The rectangular and U-shaped brackets were arc welded to the rocker arms. An important factor which made the problem of inertia force on solenoids more severe was the fact that the rocker arms were mounted in pairs, leaving only one side of each rocker arm free to mount the solenoid. Connecting the solenoids to their mounting frames by just one face causes the inertia force to produce a twisting moment in the solenoid frame. This particular method of rocker arm mounting also prevented a more compact installation, which would help to reduce inertial stresses. Both rocker arm covers removed for installation of the modified rocker arms would not fit over the new 13 components. To prevent oil spilling from the rocker arms, two rectangular 22" x 5" sheet metal partitions were installed in place of the rocker arm covers. In order to energize the solenoids a simple circuit, using a spst toggle switch was made to connect all of the solenoids to a lZ-volt battery. But disconnecting the whole circuit, which consequently deactivates all of the intake and exhaust valves at the same time, was expected to have the following hazard. If the valves were deacti- vated just after the intake and before the exhaust stroke in one of the four part-time working cylinders, the exhaust valve on that particular cylinder would remain closed at the end of the power stroke. The trapped high pressure combustion products in that cylinder could cause a violent shock and possibly damage the engine. TO eliminate this problem, two spst toggle switches were employed in such a way that the solenoids mounted on the exhaust rocker arms and those mounted on the intake rocker arms could be energized independently. The switches were labeled "intake" and "exhaust" switches (Figure 7). With this arrangement, deactivating the intake valves prior to the exhaust valves even by a fraction of a second eliminates the possibility of trapping the burned gases. Turning both switches on at the same time reactivates the rocker arms without introducing any problem. After completing the electrical circuit, the modified engine was ready for test. The engine was 14 scouumm pHo>-NH __ __ Emuwmfia uflsopwu Hmowhuuoflm -- n whamfim 1~ . T fib/luoxmch umsmzxm 1n .xw 1L] [2 15 started on eight active cylinders; i.e., all of the solenoids were energized. The engine started normally and the modified rocker arms functioned well. Starting with only four active cylinders was expected to require a higher starting torque due to the compression in the first dead cylinder. However, when this piston gets through the top dead center, it recovers most Of the energy of compression which assists in the remaining starting operation (Gerrish et al., 1975). Later tests showed that the engine could be started with four active cylinders without any significant hesitation or delay. After a few cycles of running the engine on four active cylinders the amount of air inside the dead cylinders reaches an equilibrium which is less than the amount of air at starting point. This stress relief probably leads to a smoother operation. When the engine is running with four active cylinders, the amount of work which is done to compress the air inside the dead cylinders in each up- ward stroke will be recovered by expansion on the next down stroke. When the engine was switched to the four-cylinders running mode by turning off the intake and exhaust switches, and with the throttle set at a fixed position, the engine rpm increased. Conversely, switching from four- to eight- cylinders Operation decreased the rpm. The reason for this is suspected to be due to the change in air capacity 16 or volumetric efficiency. Variation of volumetric efficiency is in turn due to sudden change in suction rate of the four- and eight-cylinders running conditions. The initial tests of the valve deactivation tech- nique were impressive and encouraging. The concept of the rocker arm deactivating mechanism was shown to be possible and practical, needing only more work to improve reliability. PART II ENGINE PERFORMANCE TESTS Objective To determine performance characteristics of the modified engine under both eight and four cylinders running conditions. Fuel economy was the main consider- ation and thus the principal basis Of comparison between the two running modes. Test Procedure Preliminary tests showed that comparing the perform- ance data while keeping the throttle plate at the same position both under four and eight cylinders Operation was not a reliable approach. The main reason was the significant loss of volumetric efficiency in the eight- cylinders running mode, especially at low throttle sets. Then an attempt was made to maintain the same manifold pressure at similar rpms of eight- and four— cylinders operation. This method also failed to give relevant data for a conclusive comparison because at any specific manifold pressure, eight-cylinders running always gives higher power output. 17 18 A test procedure was arranged to maintain a similar power output range while running on both eight and four cylinders. An electric dynamometer was used to load the engine for different running conditions. A vacuum gage was installed to indicate the value of manifold vacuum pressure at each reading point. The fuel consumption rate was measured by a Rotameter. The engine temperature was kept constant by connecting the radiator to an external continuous water flow. No attempt was made to reduce engine performance to standard atmospheric temperature and pressure. A simple comparison between the four- and eight-cylinders engine performance was desired and tests were run one after the other under the same conditions, so comparison was on the same basis. In each test the speed was varied from 1000 to 2000 rpm by ZOO-rpm increments. Four ranges of Brake Horsepower were to be obtained in four pairs of tests for eight— and four-cylinders running conditions. Each pair of tests was started with case of four active cylinders at 2000 rpm with an arbitrary low or medium applied load. With the fixed throttle set the applied load was increased gradually and the values of applied load, fuel flow and manifold vacuum were taken at each ZOO-rpm increment. Then the engine was switched to the eight—cylinders running mode and the same test procedure was repeated. 19 But in this case at each ZOO-rpm increment the horsepower output was maintained equal to its respective point during the four-cylinders running test by varying the throttle and load. A single curve representing the variations of B.H.P. versus rpm for both running modes was obtained. Three additional pairs of tests were carried out at differ- ent ranges of power output to provide data over a relatively wide range. Analysis of Test Results Fuel economy was the primary concern in these comparative tests and is given in the form of Brake Specific Fuel Consumption (B.S.F.C.). Brake Specific Fuel Consumption is defined as the pounds of fuel used per hour for each horsepower developed (5). It is a comparative parameter that shows how efficiently an engine is converting fuel into work (4). Its value can be evaluated by knowing the Brake Horsepower developed and the rate of fuel consumption. Gallon per hour is used to designate rate of fuel consumption and the parameter B.S.F.C. has been presented here in terms of gallon/BHP-Hr. The Brake Horsepower developed, B.H.P., can be com- puted as follows (4). B.H.P. = 21rPLN = PLN 20 where P is the applied load in pounds, L is the dyna- mometer arm length in feet and N is engine rpm. The values of applied torque PL, often abbreviated T, are tabulated in Tables 1 through 8. In this case the arm length L was 1.5 ft. Results and Discussion Tables 1 through 8 contain some measured and cal- culated parameters required for studying the performance characteristics of the modified engine. Fuel economy was the main objective in these tests, thus fuel consumption data as a function of engine speed and horsepower developed was taken. Curves of Brake Specific Fuel Con- sumption (B.S.F.C.) and Brake Horsepower (B.H.P.) versus engine rpm and Brake Specific Fuel Consumption (B.S.F.C.) versus Brake Horsepower at specified speeds have been plotted in Figures 8 through 16. Figures 8 through 11 each consist of two Brake Specific Fuel Consumption Curves representing the engine performance at eight- and four-cylinders running conditions, and one Brake Horsepower Curve representing engine power output which is the same for both running modes. Figures 8 through 11 show that in the range of 5 to 23 B.H.P., eight-cylinders operation has always higher values of Brake Specific Fuel Consumption than four-cylinders Operation. Figure 11 indicates that running the engine in 21 the range of 23 to 28 B.H.P., either with four or eight active cylinders gives almost the same values of B.S.F.C. The same figure shows that four-cylinders operation at more than 28 horsepower output gives higher values of B.S.F.C. than running with eight cylinders. Figures 12 through 16 confirm these results. Figure 16 shows that by keeping the engine speed at 2000 rpm, we could get better fuel economy with four active cylinders than eight active cylinders as long as the Brake Horsepower output did not exceed 32 B.H.P. There were several factors which contributed to the improved fuel economy with four active cylinders at low and moderate power outputs. Higher volumetric efficiency and reduced burning time losses are thought to be of primary importance. Tables 1 through 8 show higher values of manifold pressure at four-cylinders operation which in turn leads to more efficient and complete combustion. The following relation shows how indicated mean effective pressure, imep, is improved by increasing the volumetric efficiency, n (5). V imep = (71' F eC ni- J/144)nV where: Inlet air density, 1b/ft3 .3 H. II Fuel-air ratio “Tl ll 22 eC = chemical energy per pound of fuel ni = Indicated thermal efficiency J = 778 ft-lb/Btu In this relation, F can be assumed constant at moderate manifold pressures. Burning time losses are those losses due to the motion of the piston during conbustion process. High intake pressure which is a characteristic of the four- cylinders operation increases the density of the cylinder gases. Higher gas density leads to higher velocity of the flame front which in turn reduces the burning time losses and improved efficiency is achieved (4). Loss of fuel economy at power outputs greater than 28 BHP (variable speed) and 32 BHP (at 2000 rpm) was thought to be due to the excessive enrichment by the carburetor economizer system at very high manifold pressure. The economizer is actuated by manifold pressure to ensure maximum-power mixture and also to give additional enrichment for detonation control at high outputs (5). Although Table 7 shows that power output was not very high, the vacuum level in manifold was low enough due to the four-cylinders operation to actuate the economizer system for excessive enrichment. Very high inlet pressure also increases the tendency to detonate because of its effect on the shortening of delay period (5). This may be a factor which contributes 23 to the reduction of the four-cylinder running efficiency at high power outputs, but detonating was not observed. Table 1. Four-cylinders operation performance data -- Test No. 1(a) LOAD VACUUM GAL/ TORQUE B.S.F.C. RPM 1b. In. -Hg FLOW HR ft-lb BHP Gal/BHP-hr 7000 8.0 15.0 67 1.13 12.0 4.57 0.247 1800 11.8 14.0 67 1.13 17.7 6.06 0.186 1600 17.0 13.0 64 1.08 25.5 7.76 0.139 1400 22.0 11.2 58 0.98 33.0 8.79 0.111 1200 25.5 9.6 57 0.97 38.2 8.74 0.110 1000 29.0 7.8 53 0.90 43.5 8.28 0.108 Table Eight-cylinders operation performance data. Test No. 1(b) RPM “iii? $9332 FLOW (MAI/2 @895 BHP 2.112%... 2000 8.5 19.0 100 1.68 12.75 4.85 0.346 1800 --- --- --- --- --- --- --- 1600 17.0 18.0 82 1.37 25.50 7.76 0.176 1400 21.5 17.5 78 1.32 32.25 8.59 0.153 1200 25.5 17.0 70 1.18 38.25 8.74 0.135 1000 29.0 16.0 64 1.08 43.3) 8.28 0.130 24 Table 3. Four—cylinders operation performance data. Test No. 2(a) L22? m; “:14 T2599: Barr... 2000 24.0 11.7 84 1.41 36.00 13.70 0.103 1800 29.0 10.6 82 1.38 43.50 14.90 0.092 1600 32.0 9.2 80 1.34 48.00 14.62 0.091 1400 37.5 8.0 80 1.34 56.25 15.00 0.089 1200 51.5 6.6 85 1.43 77.25 17.65 0.081 1000 56.0 5.0 75 1.26 84.00 16.00 0.078 Table 4. Eight-cylinders operation performance data. Test No. 2(b) L22? m: “as as? 3.0.5.3.. 2000 24.0 18.0 120 2.05 36.00 13.71 0.149 1800 29.0 17.6 112 1.90 43.50 14.90 0.127 1600 32.0 17.2 100 1.68 48.00 14.62 0.115 1400 37.5 16.8 95 1.62 56.25 15.00 0.108 1200 51.5 15.0 100 1.68 77.25 .17.65 0.095 1000 56.0 13.4 87 1.46 84.00 16.00 0.091 25 Table 5. Four-cylinders operation performance data. Test No. 3(a) LOAD VACUUM GAL/ TORQUE B . S . F . C . RPM lb. In -Hg FLOW HR ft-lb BHP Gal/BHP-hr 2000. 38.0 8.0 120 2.05 57.0 21.70 0.094 1800 43.0 7.2 116 1.98 64.5 22.10 0.089 1600 48.0 6.8 105 1.78 72.0 21.93 0.081 1400 54.5 5.4 112 1.90 81.7 21.79 0.087 1200 58.5 4.5 100 1.68 87.7 20.05 0.084 1000 62.0 3.2 80 1.34 93.0 17.70 0.076 Table 6. Eight-cylinders operation performance data. Test No. 3(b) LOAD VACUIM GAL / TORQUE B . S . F . C . RPM lb. In. -Hg FLOW HR ft-lb BHP Gal/BHP-hr 2000 37.5 14.0 146 2.55 56.25 21.42 0.119 1800 43.0 15.5 140 2.43 64.50 22.10 0.110 1600 48.0 15.0 130 2.23 72.00 21.93 0.101 1400 56.0 14.2 121 2.07 84.“) 22.39 0.092 1200 59.0 14.0 106 1.80 88.50 20.22 0.089 1000 63.0 9.0 103 1.74 94.50 17.99 0.096 26 Table 7. Four—cylinders operation performance data. Test No. 4(a) L32? m: “a: as? 5.0.13. 2000 61.0 3.2 200 3.64 91.50 34.84 0.104 1800 65.0 2.5 185 3.32 97.50 33.41 0.099 1600 65.5 2.2 168 2.98 98.25 29.93 0.099 1400 69.5 2.0 145 2.53 104.25 27.79 0.091 1200 70.5 1.8 124 2.13 105.75 24.16 0.088 1000 71.0 1.2 94 1.6 106.50 20.27 0.079 Table 8. Eight-cylinders operation performance data. Test No. 4(b) “2:” m “a: as? am.- 2000 62 13.2 184 3.30 93.0 35.41 0.093 1800 65 13.0 172 3.05 97.5 33.41 0.091 1600 65 12.8 152 2.65 97.5 29.70 0.089 1400 69 12.3 146 2.54 103.5 27.59 0.092 1200 71 12.0 120 2.05 106.5 24.33 0.084 1000 71 12.0 103 1.74 106.5 20.27 0.085 Brake Specific Fuel Consumption (Gal/BHP-hr) 0.28 0.26 (L24 0.22 0.20 0.18 (L16 0.14 0.12 (L10 (L08 (L06 (L04 0.02 27 1(1)) I ' I I / / r 1 B.H-P~ / l(a,b) ‘ > 4-Cyl. 4 —————— 8-Cy1. 1000 1200 1400 1600 1800 2000 Engine Speed (Rev/min) Figure 8 -- Fuel Consumption Comparison Test No. l(a,b). H O O“ 00 Brake Horsepower A N (Gal/BHP-hr) Q Brake Specific Fuel Consumption (L20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 1000 28 Engine Speed (Rev/min) Figure 9 -- Fuel Consumption Test No. 2(a,b). 2(b)l B.H.P I I 4’ 2(a,b) / /’ B;§;E—q;""’ /,/’ uw ',,’ asno ‘ j 4-Cyl. ______ 8-Cy1. 1200 1400 1600 1800 2000 Brake Horsepower Brake Specific Fuel Consumption (Gal/BHP-hr) 29 B.H.P. 1______;3(a,b).22 .20 , .20 .18 L {18 .16 L 16 .14 *14 .12 > ’,..3(b) 412 ' II” 4 10 .10 \\~ B S.F.C_;_ ”’/ 3(a) B .F.C .08 / J 8 .06 r 6 .04 l 4‘C>’1° . 4 _____ 8-Cy1. .02 . 2 1000 1200 1400 1600 1800 2000 Engine Speed (Rev/min) Figure 10 -- Fuel Consumption Comparison Test No. 3(a,b). Brake Horsepower 1r) 1 ‘1 ic Fuel Consumption (Gal/BHP 4.3 Brake Soeci 30 Engine Speed (Rev/min) Figure 11 -- Fuel Consumption Test No. 4(a,b). .36 34 .32 .20 .30 .13 .28 .16 .26 .14 124 .12 .22 20 .lOr ' ' ‘~—B_§LQD-— ‘‘‘‘‘‘ 4(b) .08 .18 .06» .16 .04» 4’Cyl .14 ______ 8-Cy1 '.021 112 - . . - . 10 1000 1200 1400 1600 1800 2000 Horsepower Brake 31 2? "F E: EB (L125. \ H m 8 (L100. c o -:-4 H g 0.075. m C‘. 8 '3 0.050 P 4'Cy1. L2 —————— 8-Cy1. 0 (L025. "-1 (H "-4 U Q) L - (52)! L A - 0 5 10 15 20 25 .% Brake Horsepower 5-4 a: Figure 12 -- Fuel Consumption at 1200 rpm. ’2 "F E m \\ H q E“ 0 150 ’ \ 8 ° \ .... \ E”. 0.125 . \\ \"x (I) 53. “x 0.100 ' ‘~-_ ____.- r—1 --—-- ‘ 8 {-1.4 u (L075 ' -r-{ If. 8 4-Cy1. &% 0.05)’ 'g ______ 8-Cy1. :- 0.025 I m 0 5 10 15 20 25 Brake Horsepower Figure 13 -- Fuel Consumption at 1400 rpm. Brake Specific Fuel Consumption (Gal/BHP-hr) Brake Specific Fuel Consumption (Gal/BHP-hr) .175 .150 .125 .100 .075 .200 .175 .150 .125 .100 .075 32 0 10 20 Brake Horsepower Figure 14 -- Fuel Consumption at 1600 rpm. 4-Cy1. T _____ 8-Cy1. 0 10 20 30 Brake Horsepower Figure 15 -- Fuel Consumption at 1800 rpm. Brake Specific Fuel Consumption (Gal/BHP-hr) .275 _ .250 ' .225 .200 .175 ' .150 .125 - .100 - .075 .050 ' .025 33 4-Cyl. ______ 8-Cyl. 0 10 20 Brake Horsepower 30 Figure 16 -- Fuel Consumption at 2000 rpm. ooooonm—o- m tboooonoooo. D-C.-o CONCLUSIONS The rocker arm deactivating and reactivating mechanism was shown to be a practical approach for switching the engine running mode from eight- to four-cylinders Operation and vise versa. Violent oscillation of the rocker arms,especially at high speeds, was the most critical consideration in the design and installation of the rocker arm reactivating units. Improved fuel economy was achieved by running the engine with only four active cylinders at low and moderate power outputs. The most efficient (economically) range of power output with four active cylinders was 15 to 25 BHP. The four-cylinders operation in the range of 1800— 2000 rpm had better fuel efficiency than eight— cylinders operation up to about 30 to 32 BHP. The manifold vacuum level was a good indicator of the four-cylinders running efficiency. 34 RECOMMENDATIONS Special oil-proof solenoids which can also with- stand violent mechanical vibrations must be designed and constructed for this purpose. A compact design must be provided to minimize the magnitude of inertia forces on the solenoids. Engines which do not employ the U-shaped paired rocker arm retainers should be more adaptable to a compact, less troublesome rocker arm modification. Unmodified rocker arm covers may also fit the modified system. Carburetor modifications, like plugging the main jet, enrichment jet and accelerator pump nozzle in the unused side of the carburetor at four-cylinders operation is expected to provide further fuel saving. These modifications must be synchronized with the rocker arm switching function to restore the normal carburetor conditions at eight-cylinders operation. 35 REFERENCES Enger Motor Car Co., 1916. A Twelve or a Six at the Turn of a Lever. Motor Age 46-47, September 14. Evaluation of the MSU 4-Cylinder Conversion Tech- nique for V-8 Engines. 1974. Emission Control Technology Division, Environmental Protection Agency. Ann Arbor, Michigan. Gerrish, John 8., Robert H. Wilkinson, L. Dale Baker and Dwight Kampe, "MSU Engine Modification." AEIS No. 324, Agricultural Engineering Department, MSU. Obert, Edward F., 1950. "Internal Combustion Engines Analysis and Practice," second edition. International Textbook Company. Rogowski, A. R., 1953. "Elements of Internal Combustion Engines." McGraw-Hill Book Company. 36 MI HIGAN STATE UNIVERSITY LIBRARIES 3 1193 03062 5473 II