[1]3 9 1 4 2 , 2 8 9 United States Patent Office Patented July 28, 1964 3,142,289 IHGH OUTPUT E4NGINES John B. Pi,,itner, Detroit, and D. Moore, Birmingham, Mich., assignors to Chirysier Cornoration, Iligh5 land Park, Mich., a corporation of Delawa@.e Filed May 26, 1960, Ser. No. 31,930 16 Claims. (Cl. 123-55) This inveiition relates to high output engines for motor driven vehicles. It especially relates to ram induction 10 systems for engines of automotive vehicles designed to provide the cylinders thereof with dynamic eharging and adapted to provide such vehicles with unusual performance characteristics. The present application is a continuation-in-part of our 15 copending application Serial No. 657,153 filed May 6, 1957. In said copending application Serial No. 657,153 we have described a niimber of forms of induction inanifolding systems for use in connection with engines, for ex20 ample of the V-type, which systems are provided with long induction passages or ducts and wherein these systems and the lengths of their induction passages are such as to produce dynamic charging by harmonic reso@lant tuning and by mass movement of air (inertia effects) in 25 the cylinders of -the engine over substantiahy the full operating range (usually 1200 to 4000 r.p.m.) of speeds of the engine. It was also there disclosed that the passage lengths in inches for optimum results subject to variations in length 30 required by specific damping effe&Ls produced in parlicuJar designs, would generally fall within the empirical formula 72C 3 35 where N is the engine speed in revolutions per nlinute at which performance is to peak and C is the velocity of sound in feet per second in air in the intake passages under the atmospheric temperature and pressure conditions at 40 which the engine is to be operated. Moreover, it was there stated that where a plenum chamber feed was used, the passage length obtained above was in most cases to be considered to be the distance frori the valve inlet and the connection of the passage with the plenum chamber. 45 We also have disr-losed in said copending application a particularly novel construction utilizing the foregoing effects wherein each cylinder is provided with its own long intake passage between the inlet valve of such cylinder and the source of air-fuel mixture and wherein all the 50 intake passages for the cylinders of each bank of the engine emanate from a common air-fuel charge receiving plenum chamber in juxtaposition to the bank of cylinders of the engine opposite to that containing the cylinders it is to be feed. It was also there made apparent that by .55 varying the design details, the speed range of the engine in which dynamic charging was to occur could be predetermined and an arrangement be obtained having for example exceptional torque output in the low and mid speed range or maximum performance in the upper speed Go range. The present invention is especially directed to an application of these features to particular arrangements providing unusual performance characteristics, especiary high torque, in the medium speed range of the engine 65 enabling enough extra boost in power in s,,ich range for quick passing on present-day highways Nvithout need of kickdown or passing gears. The intake manifolding of the present invention facilitates the obtaining of this result by packing into the cylinders of the engine an ex- 70 traordinary amount of fuel-air mixture to secure a sizeable power increase as compared to conventional systems. The effect obtained is one sui)erior to normal aspiration and without the complication of costly mechanisms essential to supercharging. The increase in torque is particularly noticeable in the speed range of 2000 aiid 3800 r.p.m. with a peak boost at 2800 r.p.m. It enables an increase in torque or hosepower of 10% and more. The induction system of the present invention moreover provides this impressive acceleration at bighway speeds while also providing smooth low speed operation and by a construction precluding the mechanical difficulties normally associated with superchar.-er fuel induction and other high performance eqaipment. Furthermore it provides effective ram tuning at full throttle so that part throttle operation and economy may go unchanged from that of a conventional engine. The foregoing combination of results is obtained by an indu--tion system employing two outboard mounted multi-barrel carblretors, preferably of four barrels each but which may b@- of the dual type, in connection with a V-8 engine. In such arrangeme-it each carburetor is positioned laterally outwardly beyond the cylirider head af the bank of cylinders which is opposite to that which it is to feed, and in a plane above the same. Each carbi-iretor connects with a main plenum or distribution chamber generafly imn-iediately below such carburetor and this chamber in turn connects by separate long induction pipes, pass,,tges, ducts or conduits with the respective intake passages of the bank of rylinders it is to feed, forming therewith ram air resonator tut)es or passages. The plenum chambers feeding such conduits are preferred to be of such shipe and dimension as not to upset the free resonant condition in the pipes. The carburetor at the left bank of the engine in such an arrangement feeds the ri.-ht bank of cylinders and that at the right bank feeds the left bank of cylinders. A feature of the construction is that each conduit is separate from its neighbor and to obtain maximum induction effects each extends from its associated plenum chamber in a continuous smooth sweeping and looping curve over the bank of cylinders not contdning the cylind-.r it is to serve, to the inlet passage of the cyender of the bank it is to feed. Moreover, the plenum chambers serving the two banks of cylinders are interconnected by an equalizer or balancing tube to further facilitate the new result. The principa@l object of the invention is therefore to -Drovide an engine of the opposed cylinder type with an intake system providing unusual performance characteristics and capable of providing when desired, high torque output i-@i the medium speed range of the engine enabling quick passing of a vehicle on the highway without resorting to kickdown or passing gears. Another object is to provide a V-type engine with a long branch induction system having a pair of carburetorfed plenum chambers each outwardly of and in juxtaposition to and in a plane over one of the banks of cylinders and each connectin.- by individual long sweeping cond@dits extending over the bank to which its plenum chamber is in juxtaposition with the intake passages of the cylinders o'L the opposite bank and which pair of plenum chambers are interconnected by a balance tube. A further object is to provide an intake system for a V eng;ne as in the previous objects wherein each of the pairs of plenum chambers has an exhaust gas heated hot spol and wherein the plenum feedin@, the cylinders of one bank of the engine has its hot spot heated by the exhaust gases of all of the cylinders of the bank which it do-.s not feed and which bank is in juxtaposition to this plenum chamber and similarly the hot spot of the other plenum chamber is heated by the exhaust gases of all of the cylinders of the bank of cylinders it does not feed. A further object is to provide a hot spot heating ar-
[2]3, -@l @12,2 39 3 rangement as iii the previoiis object whcrein an exhaust gas flow restriction is provided in 'Lhe conduit means leading to the hot spot to conlrol heating of tli-. same and wherein the arran.-einent may also provid-. for return of the exhaust gases from the hot spot to the exha,,st pipe 5 of the enline iri a manner to prevent overheating of th-, hot spot by exhaust gas when the eng;ne is up 'to temocrature. Other objects and advantages of our invention w;@ll appear from the followin.- description and from the dra,,v10 ings wherein: FIGURE I is an end elevation partially i-@i s-.c,.ion of a V-engine to which the novel intake and e,,baust system of our invention has been applied and whi-@h is viewed from the front or fan end of the en,-:Ine. FIGURE 2 is a plan view, par,ially schematic, showing the intake manifolding of FIGURE I as applied to a V-8 engine and designed to provide dynam-c - ch-.rgiiig of the intake system by harmonic resonant tuning a-@id inertia effects, the long branch manii0ld illustrated b.in., 20 arranged with plenuni chambers adapted for multi-barrel carburetor feeding; FIGURE 3 is an enlarg-,d fragmentary sectional plan view of the plenum chamber o'L one of the ma-,iifold sections of FIGURES I and 2 and wh,.ch is taken at 3- 3 25 of the left hand bank of the engine of FIGURE 1, this view especially showing the individual inlets thereto froni the intake conduits; FIGURE 4 is an enlar,-ed fra.-mentary secfional pl,,in view taken at 4-4 of the left hand bank carburetor Of 30 FIGURE 1 showin.- the paired primary and pa-ired secondary throttle blades of the four-barrel carburator there shown; FIGURE 5 is a plan view partially schei-i-latic, s:@milar to that of FIGURE 2 but showing the carburetor thlottle 35 operatin- linkage and operator ther,-for; FIGURE 6 is an enlar.-ed elevational view of a 3ortion of the carburetor tbrottle linka.-c showing the manner of interconnecting th.- primary and secondary throttle blade shafts for timed op,-ration; and 40 FIGURE 7 is an elevational view partially in section typical of both banks of the en-,ine showing the exhaust manifold of the left hand bank and in'@ake hot spot heating system associated therewith for h.-atin.- the hot srot of the intake system feedin.- the right hand bank Oi. cYl4,5 inders. Referring now to the drawin.-s wherein similar numerals are used to designate sin-iiiar parts of the - structure, FIGURE I shows a cross section of a V en.-ine, for example, a V-8 engine to which our invent;on has been 50 applied. As seen ii FIGURE 1, the engine has two banks 9 and 9a of cylinders 10 each arr-,tnged at a suitable an,-le to the vertical and forniin.- for example an angle of 90' to each other in the cylinder block 11. Secured to the 55 block 11 are left and right cylinder hev@ds 12 and 12a respectively, provided with suitably shaped comblistion chambers 13 preferably of the wed.-e typ.-, immediately above each cylinder 10. It will be und-,rstood that combustion chambers of other shapes may be used, for ex60 ample, a hemispherical-type chamb-,r. The cylinders of each ba-@ik are preierably ali.-ned longitudinally of the engine as schematically illustraled in FIGURE 2, with the cylinders of the opposite banks offset longitudinally relative to each ollber. For conven65 ience of reference, the cylinders of the left hand cylinder bank which is to the left looking forwardly from the flywheel end of the en.-ine are numbered 1, 3, 5, and 7 starting such numbering at the opposite or fa-ii end of the en.-ine and those of the right hand bank are iiumbered 70 2, 4, 6, and 8 respectively, these ntimerals appearing internally of the cylinder representations in FIGURES 2 and 5. Each cylinder is provided with a piston l@l, r-.ciprocable therein and operably connected to a cr,,inkshaft 15 75 A through a coniiecting rod 16 and wrist pin 17. Cranksbaft 15 may be of a-iiy typ.- but will preferably be of the 90' type wherein double crank throws are arranged at 90' to each other, the first connectin-. with the pistons of cylinders I and 2, the second witli the pistons of cylinders 3 and 4, the third with the pistons of cylinders 5 and 6, and the fourth with the pistons of cylinders 7 and S. Alternatively the second and third throws may be interchanged such that the secotid throw is 270' of crank rotation from the first throw countin@ clockwis.- lookinPt the flywheel end of the engine whereas in the first described arrangement the second throw is only 90' of crank rotation from the first. Crankshafts of this type are de-.cribed in our Patent 2,766,743 and shown in FIGURES 6, 7, 8, and 9 thereof which disclosure is incoroor,,ited h@- rein by reference. Various firing orders are obviously possible for the two described crank arranements, an example of that for the first being 1-8-4-3-6-5-7-2 and an example for that for the second being 1-8-6-5-4-3-7-2, these firing orders providing alternate suctions between opposite banks of cylinders except for two cylinders of each bank which fire successively, to wit, the cylinders 8 and 4 and 5 and 7 in the first crank arrangement and the cylinders 8 and 6 and cylinders 3 and 7 of the alternative crank arrangement. The combustion chambers or cavities 13 of the cylinders 10, are by preference each provided with a single inlet opening or port 20, closed by an inlet valve 22, and with a single smaller exhaust outlet or port 24 closed by an exhaust valve 26, these ports and valves as seen in FIGURE 2 bein-. preferably arranged in lin-. longitudinally of the en.-ine with the inlet ports of cylinders I and 31 5 and 7, 2 and 4 and 6 and 8 in juxtaposition. It will be understood, however, that other valve -trrangements may be used, for example, those in our copending application Serial No. 657,153 wherein the intake and exhaust valves of each cylinder are arrangedtransversely of the longitudinal axis of the engine. By preference each combustion chamber has a sin.ale sparking means 27 projeciin.- therein which, as seen in FIGURES I and 2 for example, is preferably located intermediate the valves 22 and 26 in the wall of the chamber at the outer side of the bank where it is readily accessible for service. T-lie inlet and exhaust valves of both banks of the en@ine are preferably operable from a single camshaft 28 located above the crankshaft 15, th-, camshaft preferably actuating hydraulic tappets 30 and thereby the push rods 32 and 34 respectively, and inlet valve rocker ariiis 36, and exhaust valve rocker arms 38 of the inlet and exhaust valves mechanism respectively, which in turn actuate the normally spring 40 held closed valves 22 and 26. By preference, the camshaft 28 is arran.-ed to open therespective inlet valves 22 before top dead center position of the piston and to close the same sufficicntly after bottom dead center position of the piston to take advantage of the additio-iial charging inf@luence of the ram intake pipes and obtain optimuni charging. For example, for a pipe length of above 30 inches, the intake opening will preferably occ@,ir about 20' before top dead center and the intake closin.- will occur about 68' after bottom dead center. This will vary with the pipe length. Opening -,ind closing of the exhaust valves should be selected to provide optimum blow do@vn and scaven.-ing o'L the cylinders. Thus in the above example opening of the exhaust valve about 60' before bottom dead c,-nter position of the piston and closing about 28' after top dead center position will provide optimtim outputs in the engine. __As seen in FIGURES I and 2, the imiet opening 20 and the inlet valves 22 for each cylinder are located at the inner terminus of intake or induction passages or conduits in tb-. heads designated by the numeral 42 in the head 12 and 42a in the head 12a. These passages have outer terminal apertures 44 and 44arespectively in the
[3]3,142,289 inner side iaces 46 and 46a respectively of the heads 12 and 12a where th.-y coniiec@ with associated passages of an intake manifold generallv designated by the numeral 48 (FIGURE 2). The mai@fold 48 preferably compr-ises two substantially identical separable interlaced elongated 5 sections 50 and 50a respectively, fed by suitable carburetor sources 52 and 52a of air and fuel. Section 50 is supported by its mounting Fange 47 at the inner side 46 of the left bank and section 50a by its mounting flange 47a at the inner side 45a of the ri.-ht bank by bolts 51. In 10 order to permit interlacing assembly of th-- units 50, 50a, a central portion 49 of the mounting fla-@ige 47 of unit 50 is made removable and may be secured in position by the bolts 51 after the units 50 and 50a are in place. The section 50 directs a charge from its source 52 at 15 the ri,-ht hand bank 9a of the engine to the cyli-@iders 1, 3, 5 and 7 of the opposite left hand bank 9 and the section 50a feeds the cylinders 3, 4, 6, and 8 c@i'. the right hand bank 9a from its source 52a. The intake manifold sectio-.is 50 and 50a are each 20 preferably provided with relatively compact but sizeable distribution boxes or plenum chambers 54 and 54a respectively, positioned outwardly of the heads 9a and 9 of the engine for receiving air-fuel mixture from the carburetor sources 52 and 52o respectively. These p'lenum 25 chambers 54 and 54a respectively connect by groups of separate elongated tunable pii)es, ducts, passages or conduits preferably of generally rectangular cross sect-ion and of generally similar size and shape to the intake passages 42 and 42a respectinely of the cylinder head 12 and 12a, 30 there being four such conduits in each group, as shown in FIGURE 2, for servicin.- an 8-cylinder V-engine. Thus the plenum chamber 54 located laterally outside of the right hand bank 9a of cylinders connects by conduits 56, 58, 60, and 62 with the entrance aperlures 44 35 of the left hand bank 9 of cylinders 1, 3, 5, and 7 while the plenum chamber 54-a located laterally outside of the left hand bank 9 of the engine connects by conduits 56a, 58a, 60a, and 62a with the entrance apertures 44a of the intake passages of the right hand bank 9a of cylinders 40 2, 4, 6, and S. The plenum chambers 54, 54a will preferably be of such dimepsion and volume as to provide air feed to the tunable conduits without upsetting the free resonant condition in these corduits. Stated otherwise, the plenum 4,5 chambers will be of sufficient size and width as to have a minimum effect upon the overall resonant frequency of the induction systems. For example, it has been found by test that oplimum results of this character can usually be obtained when the distance from the end of the conduit 50 to the nearest odpos,.te wall of the chamber is at least about 11/2 to 21/2 times the diameter of a round conduit of equivalent section. Moreover, the walls of the chamber should preferably not intrude upon the resonating ed@.es of the conduits. 55 As particularly ev@.dent in FIGURES I and 3, the chamber 54a is of substantially generally rectangular or oval shape. The depth of the chamber is substantially the depth of the tunable cross conduits 56a, 53a, 60a, and 62a, each of which opens into the chamber 54a by in- 60 dependent apertures 66a, 68a, 70a, and 72a respectively. These apertures are preferably in th-. same vertical plane as are the cross conduits aforesaid as will be evident from FIGURE 1. It will be noted that each aperture is located on the same inner side 74a of the chamber 54a. This 65 feature operates to prevent a clash between suction i@npulses of the different cylinders of the opposite bank fed by this chamber. It will also be noted that the floor 76a of the chamber preferably forms a continuous level with the floors of the conduits 56a, 58a, 60a, and 62a.70 The plenum chamber 54 and the connections thereto Of the conduits 56, 58, 60, and 62 will be of the sam-character as that described Nvith respect to@ the plenum chamber 54a and its cross condiiits. The cross conduits 56, 53, 60, and 62 of the section 50 opens into@ 75 6 the plenum chamber 54 by similar apertures 66, 68, 70, and 72. As also seen in L@'IGURE 1, each plenum chamber 54 and 54a is provid,-d w-th a heat stove or hot spot chamber designated 78 and 73a respectively for heating the floors 76 and 76a respectively of the chambers 54 and 54a. The cross conduits of each of the sections 50 and 50a, as evident froni FIGURE 2, are in the interest of simplified interlacin.@, preferably arranged such that the conduits of each section are paired. Moreover, although these paired conduits may be independent of each other they may have, as shown, a common parting wall. Thus the section 50 has its conduits 56 and 58 paired and its conduits 60 and 62 paired while the section 50a has its conduits 56a ald 58a paired and its conduits 60a and 62a paired. It will also be observed from FIGURE 2 that these paired conduits extend smoothly with sweeping curves of somewhit urdulated pattern from their respective plenum chambers to the cylinder heads with which they connect and that the cross conduits 60 and 62 of the section 50 lie intermediate in FIGURE 2 the paired conduits 56a, 58a of the section 50a and the paired conduits 60a and 62a of this section. Moreover, the paired conduits 60,z and 62a of the section 50a lie intermediate the paired conduits 60 and 62 of the section 50 and the paired conduits 56 and 58 of the same section. Peferring now to FIGURE 1, it will be further evident t'@iat the cross conduits of each of the sections 50 and 50a are of sir@iilar shape in elevation transversely of the engine @tnd in the same general plan,-. As typifed by the cross conduit 62,t shown in s.-ction in this view, it will be seen that it and its companion conduits of the section 50a connecting the plenum chamber 54a with the intake passaaes 64a of the head 12a sweep smoothly ii-pwardly frorii their respective apertures in the chamber 54a and loop over the head 12 of the cylinder bank 9 of the engine and in relatively close proximity thereto in a smooth curve and then extend laterally downwardly in a relatively straight line at substanti-,Llly the same angle as the intake passages 42a of thp- cylinder bank 9a to connect with the apertures 46a of these passages in the inner face 46a of ttie cylinder h,-ad 12a. Manifestly, the ctirvature described with respect to the conduits of the section 50a likewise apply to the conduits of the section 50. It will be evident that by this arrangement the central portion of the sections 50 and 50a are humped above the cylinder heads 12 and 12a and their respective valve mechanism covers while their conduit ends are below the cylinder head covers, the latter facilitating a lowering of the carbtiretars 52 and 52a. With such an arrangement it is possible to <)btain a low silhouette or hood level for the engine while at the same time obtaining the proper lengtli of conduits facilitatin,@ resonant tuiiing of a character to provide the desired engine performance characteristics and an overall transverse width to f@t into a vehicle compartment. The plenum chambers 54 and 54a are each provided with upper mounting pads 80 upon which to mount either a carburetor source of air and fuel mixture 52a which in the illustrated embodiment in the drwwings is shown to be a four-barrel downdraft carburetor of the "Carter AFB" type having a built-i-@i throttle control and venturi. NVhen the manifold system is to be used with fuel injection, this unit 52a will be replaced by an air filter and intake provided with a sirnilar throttle control and the same may be Gf a single or multiple barrel character. Moreover, in such cases each of the conduits will be provided with suiiable fuel injection nozzles 79 fed as described in our prior Patent 2,791,205. The carburetor mountin.@ face 80 of each of the plenum chambers 54 and 54a will be provided with suitable vertical-ap-ertures or riserscoinciding with the corresponding barrels or throats of the carburetor or air source feeding the same. Each of the carburetors 52 and 52a, as
[4]7 evident from FIGURES 1, 4, and 5, has a pair of primary barrels 82 and 84 and a pair of secondary barrels or throats 86 and 88 which coincide with relatively short similar pairs of risers 83, 85, and 87, 39 in the carburetor mountin@ face or pad 80 of the ple-@ium chamb-.rs 54 and 54a respectively. The primary barrels and risers are preferably locat.-d as seen in FIGURES 2, 3, and 5 on the side of the plenum chambers nearest to the apertures of the intake conduits fed by these chambers. This arrangerr@ent contributes to better initial feeding of the cylinders as well as more uniforni distribtition of the air or air-fuel mixture. Moreover, in order to further improve the uniformity of distribution of the air-,'uel mixture d,- I;Very of the carburetors to the engine cylinders over the entire speed range, the plenum chambers are preferably furtlicr provided with a cross over or balancing conduit -enerally dcs;,-nated by the numeral 90 which extends across the engine intermediate the pairs of conduits 60, 62, and 60a, 62a as seen in FIGURES 2 and 5. This balance tube 90 ser-ves to lean out the mixture delivered to the cylinders at low speeds of the engine and prevents overenrichnient of the r-ylinders, wliich might occur because of the strong suction pulses of the manifold at low speeds. In order to facilitate manufacture of intake sections 50 and 50a of th.- same construction and provide for the balance ttibe structure 90, th--se intake s.-etiol)s are provided with stub connections 92, 92a which respectively connect with and open into the plenum chambers 54, 54a respectively. FIGURE 3 shows the stub connection 92a opeiiing into the chamber 54a by an aperture 94a intermediate the conduits 63a and 73a and independently thereof. A similar stub connection 92 connects with and opens into the chamber 54 in a similar manner by an aperture 94. The stub connections 92 and 92a curve upwardly respectively from the pletium chambers 54 and 54a following the shaping of the intake conduills of the sections 50 and 50a associated with such chambers and in a plane therewith. Once above the top portion of the ror-ker arm covers 93, these stub portions extend in a --,nerally horizontal plane and are cotipled together witli a straight tubular metal section 95 and short flexible rubber-like pipe sectioiis 96 by coiventional screw-typ@- clamping unions generally desi-nated by the numeral 98 (see FIGURE 5). These rubber s.-ctions 96 permit relative inovement between the intake s-@ctions during engine operation. The exhaust ports 24 and valves 26 are associated with exhatist gas passa,-es 104 in the cylinder head 12 and passages 104a in the cylinder head 12a, these passages conducting the exhaust @as,-s to a pair of exhauist manifolds 106 and 106a respectively, secured to the outer faces 103 and 108a resp,-ctiNely, of the cylinder heads 12 and 12a respectively, as seen in FIGURE 1. The left hand bank exhaust manifold 106 includ,-s a header or runner 110 which connects by side branch-.s 112 with the passa-es 104 of the '@icad 12. The ri.-ht hand bank exhaust manifold 106a includes a header or runner 110a which connects by side branches 112a with the exhaus t passa,-es 104a of the head 12a of the right hand cylinder bank 9a. As best seen in FIGURE 7 showing the exhaust manifold structure -tO6a at the left hand bank and which is typical of that of the ri-ht hand bank, each of the exhaust headers 110 and 110a is comprised of two integral longitudinal runner portions designated by the numerals 114, 116 for the left hand runner and 114a and 116a for the ri.-ht hand run-.ler. These integral portions extend toward each other and curve downwardly in a V formation meeting in a common generally central dischar,-- chamber 120 controlled by a thermostatically op-.rable beat valve 122 whose blad-- 124 is Prranged to move from a closed position (shown) durin.- cold starting of the en-,ine to a full open position when the en.-ine is up 3,1-'.P,,289 OU to ten--iperature. This chamber 120 has a fi-,tnged discharge otitlet 126 below the throttle 124 to wbich an exhaust pipe 123 connects the latter conveying the out moving exhaust gases to a muffler 130 (see FIGURE 1) suitably located on the vehicle. It will be understood that the disch,,irge conduit or chamber 120 for either or both of the exhaust manifolds may if necessary because of space requirements be located fore and aft of the position shown in FIGURE 7, adjacent one end 10 thereof. The central connection is, however, preferred from the standpoint of power output. Each of the exhaust runners 110 and 110a is also provided with a lateral conduit outlet designated 132 ahead of the V on one of the sectio.,is thereof shown as the section 114 of the runner 110, and desi-nated 132a 15 on the rutiner I!Oa which outlets 132, 132a respectively, connect by conduits 134, 134a of generally elbow shape with the hot spots 78a and 78 respectively of the plenum chambers 54a and 54 respectviely, as seen in FIGURES 20 1 and 7. These elbows 134, 134a are preferably of reduced section at the end connecting with the hot spot so as to provide a restriction 136 of suitable size to control the amount of exhaust gas passing to the hot spot through openin.@s 137 in the runners and prevent 25 overheatin,@ of the floors of the plenum chambers. The exhaust gases flowin.@ to the hot spots 78 and 7$a from their respective exhaust headers 110a, 110 pass thereftom through a discharge opening 139 in the bottom thereof into a conduit 140 which connects downstream :30 of the heat control valve 122 with the exhaust pipe 128, as seen in FIGURES I and 7. A further feature of the invention is the connection of the discharge conduit 140 with the exbaust pipe at the outer side 142 of the curved bend made by this pipe. 35 By placing the connection at this point the velocity pressure of the discharging exhaust gases when the valve 122 is open reduces to a minimum any tendency ol' exhaust gas to flow through the hot spot 78 through the pipe 140. In operation, when the engine is cold, the automatic 40 h@-at valves 122 will be closed and the exhaust gases in manifold 110a from cylinders 2, 4, 6, and 8 of the right bank will be directed through the restricted opening 136 of elbow 134a to the hot spot 78 to heat the air or charge entering the plenum cbamber 54 to feed the 45 cylinders 1, 3, 5, 7 of the left bank. Similarly the exhaust gases of cylinders 1, 3, 5, and 7 of the left bank will be directed by the independent exhaust manifold system 106 of the left bank to the hot spot 7$a to heat the air charge entering the plenum chamber 54a for feeding 50 cylinders 2, 4, 6, and 8. In each instance the exhaust gases after scrubbing th.- floors 76, 76a of the plenum chambers will pass from the hot spots through openings 139 into the discharge pipes 140 and thence to the exhaust pipes 128. When the engine is up to temperature, the 55 heat valves 122 of each exhaust system will open and the exhaust -ases will pass d:rectly to the exliaust pipe 128 through the chamber 120 and only minor flow of exhailst gases will tak-e place to the hot spots. Provision may also be made adjacent the plenum chamber floor heatii)g chambers 78 and 78a respectively for suitable heating compartments 144 (see FIGURE 7) directly in the path of the hot exhaust gases entering with upward movement through the openings 137 which may receive some of such exhaust -ases while passing through the chambers 78 and 78a to heat thermo65 stats 145 enclcsed in heat exchange casin,-s 146 located in the compartments 144 which thermostats may actuate rods 147 of automatic choke mechanisms (not shown) of the en-.ine. 70 The carburetors 52 and 52a are as seen for example in FIGURES 1 and 5, arranged with their throttle blade axes extending longitudinally of the engine. Such positioning is contrary to the conventional carburetor arrangenients where these axes are normally it 90' to the longi75 tudinal axis of the engine. It has a two-fold advantage
[5]3,142,289 in the present inve-.ition. First, as previously described, it enables the positioning of the primary barrels of the carburetors on the inner side of the engine immediately adjacent the connections of the tunable cross conduits of the intake manifolds with their respective plenum 5 chambers. Secondly, it facilitates provision of a simple control linkage arran,@ement between the carburetors such that both carburetors may be simultaneously operated from the accelerator 150. Thiis as seen in FIGURES 5 and 6, the accelerator 10 pedal connects by a suitable link 152 with a lever 154 on a rocker shaft 156 supported on the intalce manifold sectio-@i 50. Shaft 156 carries a double-ended lever IL58, one end of which is connected by a suitable clevis 160 and link 162 with the conlrol arm 164 of the primary 15 throttle shaft 166 of the carburetor 52 while the opposite end of the lever 153 is connected by a similar clevis 160 and link 162 with the primary throttle control lever 168 secured to the primary throttle blade shaft 170 of the carburetor 52a. Depression of the accelerator 150 20 will cause operatioti of the throttle levers 164, 168 in a direction to move the primary throttle blades 171 to open position. As seen in FIGURE 6, such operation will move the lever 164 counterclockwise in this figure rotating the 25 shaft 166 to whir-li it is fixed in the same - direction. Such will also similarly rotate the paired throttie blades 171 and also a lever 17Z fixed to the shaft 166 at th.- opposite side of the carburetor. Lever 172 has a pair of fingers 174, 176 at an angle to each other, the latter having a 30 rounded end 178 normally engaged with a cam face 180 of a secondary throttle operating lever 182. The lever 182 is fixed to a shaft 184, rotation of Nvhich operates the pair of secondary throttle blades 186. Rotatabl y mounted on shaft 166 is a further lever 183 having a 35 facial projection 190 engageable by the finger 174 of lever 172. Lever 183 is interconnected -@vith lever 182 by a wire link 192. It will be observed that rotation of the shaft 166 and lever 172 by lever 164 opens the primary throttle but 40 initially has no effect on the secondary tbrottle. Once, however, the finger 174 has moved into abutting relation with the projection 190 of lever 188, the latter is caused to rotate counterclockwise and through the link 192 move the lever 182 clockwise and blades 186 of 45 the secondary barrels in a similar direction to open position. Suitable tension springs (not shovm) are associated with levers 164, 168 to rettirn the primary throttle 171 to closed position upon release of the accelerator 150. In such operation lever 176 will engage the lever 182 at 50 the cam face 180 to rotate this lever counterclockwise to return the secondary throttle blades 186 to closed position. It will be noted that the engagement betv/een levers 176 and 182 is such as to permit lost motion be' 55 tween them once the secondary throttle is closed such permitting the primary throttle 171 to return to ftilly closed position after the secondary throtlte is closed. In order to prevent too rapid a return of the throttles to closed position, a vacuum type dashpot 200 is preferably provided in the throttle operating linkage. As 60 seen in FIGURE 5 the dashpot is secured by a bracket 202 to the intake section 50 adjacent one end of lever 158. In such position its operating plun, aer 204 may abut the lever 158 or clevis 160 in their throttle closing move ment and cushion or slow-up the same. 65 We
