CA1094417A - Controlled flow cooling system for engine head for low weight reciprocating engine - Google Patents

Abstract

CONTROLLED FLOW COOLING SYSTEM FOR ENGINE
HEAD FOR LOW WEIGHT RECIPROCATING ENGINE
ABSTRACT OF THE DISCLOSURE

A light metal die-cast head employs a low volume cooling system which eliminates the conventional intricate water jacket and replaces it with continuous grooves which wrap hemi-cylindrically about each combustion cylinder in a thinly spaced relation. The grooves are exposed along their length at the deck surface of the head. There is a critically located straight drilled passage along with two such grooves in the head, the combination of which is restricted in throat area when compared to the throat area of similar grooves in a cast iron engine block. This results in a high velocity flow in the head and a low velocity flow in the block when they are connected in series flow relation. The straight longitudinally drilled passage, which may include one or more of such passages, is located in the head separating the exhaust and metal valve guides; the passage has a throat area equal to or less than the throat area of either of the grooves in the head.
Heat extraction is more easily and flexibly programmed to achieve not only a more uniform wall temperature throughout the head and block, but permit a desirably slightly higher average wall temperature than conventional light metal heads for improvement in fuel economy and thermal efficiency.

Description

~n~4l7 The present invention relates to engine heads and to cooling the same.
This application is a division of copending appli-cation Serial No. 290,629 ~iled November 10, 1977.
It is desirable to operate an engine at temperatures as close to t~e limits imposed by oil properties and strength of the materials as possible. Removing too much heat through the cylinder walls and head lowers engine thermal ef~cienc~ However, prior art cooling systems have tended to overcool in some zones and undercool in others; the pr~or art systems have been a rough compromise des~gned to remove approximately 30 to 35~ of the heat produced in the com~ustion chambers resulting from the com-~ustion of an air-fuel mixture. The systems have typically been oE the forced circulation type utilizing a water jacket placed around the engine cylinders. Through the years, the water jacket has evolved as an immensely intricate casting with intersecting channels and intersecting bosses delicately cored within the metal casting. Principal emphasis has been to allow water to circulate freely within a bath adjacent the cylinders and ead valves. On some engines, water distributing tubes or nozzles have been used to direct the-flow of the cooling water into the water jacket reserwir in the hopes of regulating heat transfer.
~ecause of the need to extend bolts, shafts and shanks through the water jacket cavity, flow therein is interrup-; ted and detrimentally affected. The water jacket has now become a labyrinth of passages which do not con~ribute to controlled fluid flow.
The need to improve the cooling system, increase fuel economy, and economize on the use of cast material has only , 10~17 recently become acute. Prior to this there was greater emphasis given to ease of casting and the benefit of having a large safety factor in block strength by making the engine block large and relatively heavy. Now there is a clear necessity to reduce the weight of the engine, utilize less casting material, while at the same time increase the efficiency of the cooling system.
The present invention is directed to an engine head and to a method of cooling the same. The engine head forms part of an engine housing which forms the subject of the parent appplication referred to above.
In accordance with one aspect of the present invention, there is provided an engine head for an internal combustion engine, com~rising: (a) an elongate housing comprised entirely of aluminum and having walls defining a top closure for a galley of aligned cylinders opening onto the bottom face of the housing, the housing having walls defining passages for inducting a combustible mixture and exhausting combusted gases, the closure wall extending upwardly from the bottom face of the housing, (bl means defining a series of interconnected hemicylindrical grooves in the housing extending upwardly from the bottom face of the housing and consecutively along aach of the cylinders, the grooves limiting the lower portion of the top closure walls to a thin-sectioned cylinder, the grooves being so interconnected as to leave a solid siamese connection between each of the thin-sectioned cylinders.
In accordance with another aspect of the invention, there is provided a method of cooling the head of an internal combustion engine, comprising: (a~ form the head as a cast body consisting of a metal having a thermal conductivity exceeding .~8 cal-cm./sec.-cm2-C, the body being provlded with a flat bottom, opposed sides, first walls defining a series of cylindrical portions arranged side-by-side with each portion extending through the bottom, having second walls defining a plurality of gas passages with each extending between one cylindrical portion and one side of the head, and third walls defining a plurality o~ valve guide cylinders each extending ~rom the top of the head into one cylindrical portion, the third walls having a portion serving as a separation between the exhaust gas passages and the valve guide cylinders, (b~
convey cooling fluid through the first walls in at least one laminar non-turbulent first flow path extending from : one end of ~he head along the sides of each of the cylindrical portio.ns to the opposite end of the head, and convey cooling fluid through a cylindrical boring in the pQrtion of the third walls in a laminar non-turbulent manner while in parallel flow with the first flow path, the flow rate and flow area of the flow paths being

2~ adjusted to carry heat away from the metal at a rate equal to or greater than the thermal conductivity of the metal whereby any nucleate boiling at the interface between the flow and metal is limited and controlled to increase the thermal heat transfer thereacross.
The invention is described further, by way of illustration, with reference to the accompanying drawings, :: in which:
: .
Figure 1 is an. exploded perspective view of part of the engine housing of Figure 6; the housing being broken :- 30 away alony a sectional plane;

Figure 2 is a schematic composite view of the bodies 4 ~

10~4417 of cooling fluid, detached from the engine of Figure 6, showin~ the fluid paths and flow character for the overall cooling system;
Figure 3 is a schematic elevational view, partly broken away, of an internal combustion engine depicting a conventional cooling system in accordance with the prior art;
Figure 4 is a composite view of several separated core clusters used to define passages in a prior art head and of their nested or stacked position;
Figure 5 schematically illustrates the body of cooling fluid, detached from the engine of Figure 3, with flow lines disclosing the character of flow;
Figure 6 is a partial sectional elevational view of an internal combustion engine embodying the invention herein;
Figure 7 is a view looking directly down upon one galley of c~rlinders of the head illustrated in Figure 7 together with the sealing gasket superimposed thereon;
Figure 8 is a plan view looking directly down upon the galleys of cylinders in the engine block;
Figure 9 is an exploded perspective of various sectioned portions of an engine head constructed in accordance with the prior art;
Figure 10 is a view similar to Figure 7 but depicting a head constructed according to this invention;
Figure ll is a top view of the engine head of Figure 7 and taken in the direction of the arrows shown in Figure 7;
~igures 12 15 are graphical illustrations of various physical parameters of the cooling system for the embodiment 10944~ 7 of Figure l;
Figure 16 is a composite diagram and chart depicting valve guide and seat temperature conditions in a hea~
employing this invention and for a head employing con-ventional principles; and -- Figures 17-23 are graphical illustrations of various engine parameters plotted against engine speed for an engine according to this invention.
One of the principal features of this invention is the ability to provide an engine housing water jacket which is significantly decreased in volume and yet is arranged to provide improved cooling over that of conventional engines. This is brought about in part by a series flow concept, and in part by using different flow velocities in different portions thereof, including a critically placed cylindrical ~oring to carry fast laminar cooling flow between the exhaust gas passages and the valve guide cylinders in the engine head. For the series flow concept, the fluid is allowed to enter the engine block at one end, 20 ~ separate into two wide bands of fluid which move parallel to each other and along opposite contours of the cylinder gallery without merging except at the opposite end; at such end the paths are permitted to merge and turn upwardly into the engine head where the flow again proceeds to separate into two, three or four channels which move back ` ~ transversely across the head, two of which are located ~similarly but oppositely to that in the block. Fluid in said bands is designed to move in a laminar or controlled flow manner, the bands being so thin that they appear as convoluted sheets of fluid. The fluid bands are differential in size so as to provide a relatively low fluid flow velocity 1~)94417 in the block from a given pump source and a higher 1uid velocity in the head. ~hen the series flow concept and differential velocity system is combined with a system of using high thermally conductive material about the high velocity flow and a lower thermal conductivity material about the relatively lower velocity flow, the new total cooling system herein emerges and obtains optimization of energy usage.
The series flow concept can best be appreciated by comparing the schematic illustration in Figure 2 (repre-senting the invention) and the schematic illustration in Figure 5 (representing the prior art), and also comparing the structure of Figure l with that of Figures 3 and 4.
~ Grooves or passages lOa and lOb are defined in the block 11 to pro~ide primarily two fluid paths 12 and I3 ~indicated by arrows in Figure 1 for each cylinder galley) which begin at one end of the block and are supplied through an inlet-17 from a conventional engine pump (not shown). The fluid flows in said grooves consecutively along each series or galley of in-line cylinders 14, the paths being so defined that the body of cooling fluid, if separated from the engine would appear as wide bands 15 and 16 of fluid which moye in a laminar or controlled manner toward the remote or opposite end of the block.
The bands are thin and adapted to conform to the undulating contour of one hemi-cylindrical side of each of said cylinders in the galley. Upon reaching the opposite end, ;~ the fluid paths merge and the fluid is directed upwardly through arcuately aligned slots 18, 19 and 20 in a gasket 21 (see Figure 7) separating the block 11 and head 9, such slots being dimensioned to place an ingate effect upon said - 7 ~

109~417 fluid flow stimulating an increase in velocity for the head. Fluid flow passes through the slots and again divides into three paths 44-45 and 52 providing two fluid bands 22-23 and one fluid cylinder 52, all shorter in height and/or smaller in area than the bands iIl the block. The bands 22-23 proceed back along the undulating contours of the cylinder galley to the end 9a (see Figure 10) where they are permitted to return to the radiating system through outlet 24. In the head 9, the third path 25 provides a most important function; the path is defined by a central boring 8 located at the top of the head and spaced above and midway between the two fluid bands 22-23 and is adjacent to the engine valve guide cylinders 51. The boring defines the fluid cylinder 52 which is fed by a column 32 of fluid.
In addition, small volumes 26-27-28-29-30-31 of fluid are permitted to be sequestexed from the first two fluid bands 15 and 16 before reaching the end llb of the block (see Figure 7) thereof in minute quantity and only for purposes of acting as vortex shedders at the inner contours of the upper two bands 22-23. These small volumes do not form a part of the normal cooling flow, but rather are hydro-dynamic flow guides.
The block 11 is made from a casting having grooves extending from the casting parting surface 43 downwardly along each of the cylindex walls 14, the cylinder walls being defined as rather thin-sectioned walls ~about .15 inches thick~ which stand free ~xcept for a solid connection 42 (about .3 inches thick) between each of the cylinders in a siamese fashion. The walls surrounding the cooling grooves are exposed to ambient temperature conditions and are about .12 inches thick. The two paths of fluid 12 and 13 10~4417 through the block undulate around the hemi-cylindrical shaped groovings lOa and lOb. In the head, paths 44 and 45 are formed by groovings 46 and 47 extending upwardly substantially the same height as the roof wall 48 or closure for each cylinder. The third path 25 defining a straight cylinder of fluid 52 extends substantially along the area of the casting which is above the intake and exhaust passages 49-50 and between the exhaust gap passages 50 and the valve guide cylinders 51.
Such series flow concept is dramatically different than that which is now experienced within conventional engine cooling jackets (turn to Figures 3-5). Here, fluid is permitted to enter the block casting at one station 33 and because of the design of the passages of the water jacket, fluid is permitted to tumble and turbulate within the fluid body 35 of block 40, such as at 34, to result in a turbulent bath with no specific requirement that the 1uid pass along a streamline flow to the opposite end of the housing before being permitted to move upwardly into the ~ody of fluid 36 in the head 9. In fact, openings throughout the entire gasket 21 separating the head 9 and block 11, permit fluid to be short circuited in large quantities at several points, such as at 37, insuring that substantially all of the fluid will not move from one end lla of the block to the other end llb before entering the head ~ or exiting at 24. Thus, fluid flow can be considered, in Figures 3 and 5, to be the opposite of series flow. 0~7er 90~ of the fluid traverses the full length of each of the block and head for the present ~ - 30 invention, whereas in the prior, only up to 65~ of the fluid - may do so. The rather widr bulky passages in the bloc]c and .. g _ 10~417 head 9 are incorporated more for convenience of casting than for control of ~luid flow. Such passages are best illustrated, for example, by viewing the sand core clusters 54 and 53 used to define the cooling passages in the head (see Figure 4). These components are nested - with the core cluster 55 used to define the intake and exhaust passages (as shown at the right).
In prior art constructions, there is no intention or desire to create only a thin sheet of fluid which is directed along the walls of the cylinders. To the contrary, a flooding concept is employed where as much fluid as possible is placed as a bath adjacent the cylinders without specific regard to the volume of fluid or the character of the flow induced as a result of the unavoidable interruptions of such fluid bath. In some prior art constructions, the bath approach is modified to achieve a thermal siphon action, but the latter lacks adequate response to the variable cooling need~. As a result, heat is extracted at a rate which is non-uniform and difficult to assess; usually the rate results in undercooling at some portions of the cylinder walls and overcooling at other portions; a non-uniform wall temperature is created which prévents attainment of the goals of this invention.
A preferred method of cooling an internal combustion engine according to the invention would comprise at least two essential aspect's: (a~ providing a housing with first walls (such as 56-58~ and second walls (such as 57-59) ; together defining a series of cylinders for carrying out combustion, the second walls surrounding that portion of the cylinders within which ignition of a combustible ~ mixture takes place and said first walls providing for :
- ~ lQ

expansion of said combusted mixture, said second walls being comprised of a material having a higher thermal conductivity than said first walls by a factor of at least 1~5, and (b) conveying cooling fluid through at least one continuous passage (such as 10 in the block and ~6-47-48 in the head) extending through and between both said first and second walls, said passage having a smaller throat area for the flow in said second walls than in said first walls to establish a higher velocity fluid flow through said second walls than through said first walls (compare visually cross-sectional area of grooves 10-46-47 and hole ~ shown in Figure 6). The passages should extend in a manner to carry fluid consecutively along each of the cylinders in the first walls before extending in series into the second ,walls where again the passages split and extend consecutively along each of the cylinder portions and each of the valve guides, in the second walls. The flow velocity of fluid flow in the second walls should be higher than the flow, velocity in the first walls by a ratio of about 5:1. The weight of the fluid system in a 5 liter engine when incor-porating such cooling method, can be about 8 lbs.; this i8 significantly low when compared to 17.9 lbs., the weight of fluid required in a conventional engine for an equivalent application. This is a net weight saving in fluid of 9.9 lbs.' ~;~ ; The placement of the inlet 17 will influence the velocity distribution between the inboard flow 12 and the outboard flow 13 in the block. For example, if the inlet 17 is located as in the schematic inset for Figure 13, then the velocity distribution in the block will be as plotted in the graph for Figure 13. ~epending on whether 10~4417 there is a need for greater or less cooling on one side or the other, the inlet can be relocated to render coolant velocity tailored to such needs or establish equal velocities in both passages.
Since the effective inlet to the head is slots 18-19-20 at one end of the head gasket and since the slots direct flow upwardly therethrough, the velocity distribution will substantially be similar to that in the block and as shown in Figure 12, but of much higher value due to throat area. Moreover, the drilled passage 8 in the head will exhibit an even greater increase in its velccity pattern with the same flow in the head, indicated in Figure 14;
the passage 8 must do a superior cooling job in a remote region of the head and does so in conjunction with the right metal material. For example, the throat area of passage 8 is about .55 in2, and the throat area of passage 46 or 47 is about .6 in2. The total throat area of the head passages is about 1.70 in2 compared to 8.5 in2 for the block. This will typically result in flow velocities of 120-130"/sec. in the head and about 20"/sec. in the block, assuming the liquid coolant has a viscosity of about .81 centipose at 190F.
Turning now to Figure 15, the pressure head loss resulting from using this method of increasing flow velocity in the head (see plot 63~ is less than that experienced by merely limiting the cooling volume (see plot 603 when compared with a conventional 1~75 302 CID
production system ~see plot 61~ or a conventional 1966 428 CID production system (see plot 62).
The passages 46-47 and 8 in the head play a key role in controlling wall temperature. They are comparatively 10~4417 small, but flow velocity is high. This in conjunction with the high thermal conductivity of aluminum diffuses heat more uniformly. Passages 46 and 47 are joined by small bleeding flows at the inner undulation; this is necessary to drive away any formation of vapor at these locations generated by cavitation and to act as a compressor on the fluid above to retard boiling.
Turning now to Figures 6-11, a preferred engine housing, incorporating the cooling system herein, comprises a V-type cast iron block 11, two aluminum alloy cylinder heads 9, an aluminum intake manifold 65, preferably a double-walled exhaust manifold 66, conventional 4-barrel carburetor 67 and air cleaner 68, and aluminum alloy pistons 69. The pistons 69, movable within the cylinders of the block, are preferably comprised of aluminum of conventional design having typical sealing rings. The cast iron block is preferably constructed by way of a sand cast method using the cavityless method of casting whereby a oam pattern is surrounded by unbonded sand. Deep grooves, defining the inboard and out~oard water passages, as well as the cylinders, are by a comm~n sand core cluster which is introduced from one side of the pattern. The resulting casting should have thin walls defining a first galley o~ cylinders 65 on one side o the block and a second ; galley 66 of cylinders on the other side, in a V-8 configur-ation. The bylinder walls 67 and 68 are open at both ends, one end (67a or 68a) terminating at the parting surface 43 and being exposed to the gasket 69 mounted thereon separating the block from the head. The other end (67b or 68b) is exposed to the crankcase chamber.
~dditional walls outboard walls 70 and 71, and inboard walls 109~417 72 or 73, define the cooling fluid channels or grooves 10a and 10b. Other wall portions 74-75-76 respectively define sleeves 74a for rocker arm actuator rods 77, webbing and walls for mounting the engine crankshaft, mounting ~eet for the block, and cylinders 78 for mounting tension bolts (not shown), and auxiliary equipment.
One ~eature of the cast iron block of this invention is the open deck access to all of the cooling passages therein; sand cluster corings may be employed in the casting pattern and are readily removable. It is desirable that the pattern for such block be formed o~ a material that is consumed and burned upon contact with molten metal, such as polystyrene. This should be carried out according to the technique of cavityless or evaporative casting procedures.
The head 9a is preferably comprised of aluminum material thereb~ rendering thermal conductivity in excess of .28 calory-centimeter per second-centimeter squared-C, a minimum for purposes of this invention.
Prior art heads have been constructed o~ aluminum, but their configurations have consistently required or contained cooling passages which prevented controlled :
series flow. For example, in Figure 9, a prior art head `
80 is illustrated having non-straight intake and exhaust passages 81-82. Water passages were created wherever space would permit;ithis resulted in non-uniform and interrupted passages 83~ 84 and 85, which in some cases provided excessive flooding of some head zones and in other cases provided inadequate cooling flow. The cooling - 30 passages are not of the open deck type, ~ut rather are ~ cored passages which do not have any regular or uniform - ~ ~4 -' , ~09~l~17 cross-section. The passages 83, 84 and 85 occupy any available space in the solid walls adjacent the heat centers, such as the roof of the cylinder and exhaust passages. Very little, if any, of the cylinder roof is exposed to ambient air conditions for radiation, but rather is substantially enclosed by a water jacket. Each of the passages have intersecting portions; fluid passing through such varying passages will experience a non-laminar flow and considerable turbulence causing a deficient heat e~change relationship with the casting material.
The head of this invention (Figure 10~ eliminates such cooling disadvantages~ It is preferably constructed by wa~ of a semi-permanent mold die-casting technique again having an open deck by which one sand core cluster may be deployed to define the intake passages while three mating permanent dies define all other aspects of the head. More specifically, a bottom die is used to define the deck surface 86, grooves 46-47, cylinder roof walls 48 and other contours, such as 87, of the lower portion of the head. The upper right die piece is used to define the various bolt cylinders 78 and rocker arm bosses or walls 74, and other upper surfaces 88. The upper left hand die piece is used to define the exhaust passages 50, sloping wall surface ~9 and bolt bosses 90.
The grooves 10 extend substantially to the general height of the roof wall 48; the grooves are spaced apart on opposite sides of the cylinders and are spaced from the boring 8 b~ at least 3 inches. The grooves are adapted to closely conform to the periphery defined by the aligned hemi-cylindrical shapes at one side of each cylinder galley. In a sense, the loc~tion of the three fluid paths 10944~7 passages (~4-45-25) form an equilateral triangle which, when incorporated with a high thermal conductivity material, provides more efficient heat extraction and maintenance, a more uniform and desirable wall temperature without the necessity for greater cooling fluid volume and greater weight of the solid mass.
After casting of the head, a longitudinally extending passageway 8 is drilled through the head material and interconnected with the grooves 10 by way of upright - 10 passage (not shown). The head casting has an outlet opening 24 which when compared to the outlet opening 87 of the prior art head side of the head housing, illustrates the velocity difference necessary to render an equal volume displacement. The walls are of a predetermined thickness substantially surrounding the roof portion of each of the cylinders and are consistently thin throughout the remainder of the casting. For example, the thickness across 7 (Figure lO) is about .25-.3 inches and the thickness across 6 (Figure 1~) is no less than .28 inches, and typically about .3 inches.
Saddled between the V-shaped block and heads for said engine is a cast aluminum intake manifold 65 which employs intake passages emanating from a series of four apertures in the top wall thereof (not shown), two of which communicate with a first labyrinth of passages 88 leading to the seriés of four intake passages at one side and the other communite with a second labyrinth of passages 89 leading to the four intake passages on the other side. The intake manifold is of a cross~low con-struction whereby exhaust gases are sequestered and allowed to pass through passages 90-91 underneath the .0~

labyrinth of passages 88-89 in heat exchange relationship for facilitating vaporization of the combustible mixture on its delivery to the intake passages. The heat exchange surface 92 is provided with a series of extended heat absorbing surfaces in the form of ribs 93-94.
- Mounted at outwardly facing sides of each of the heads 9a is an exhaust manifold 66 of the double-walled (96-97~ insulated construction type, where exhaust gases are permitted to enter a recirculating or turbulizer chamber 95 and finally exhausted through a central aperture 98 at the far end and where the exhaust gases are then brought forward of the engine to be exited through an exhaust system which may include emission control elements.
An additional thermal control feature of the head ~ is the exhaust port shape. As previously stated, this port can be formed during the casting process by a metal die piece. This is possible because of the elimina-tion of the conventional water jacket passage or core as used in conventional head construction which allows a large size straight in exha~st port to be used. Because of the exhaust port size (or area~ and straight in design, a thin metal exhaust port liner ~100~ can be slipped into the exhaust port during engine assembly. The inner surfac~ of the slip-in liner shape conform to that of an ideal exhaust port surface configuration and has excellent gas flow properties. The liner is insulated against heat transfer to the aluminum head by a gasket (101) at the head face and an air gap (102) between the - 30 liner and the alumlnum exhaust port wall. The liner, because it is thin and well insulated from the aluminum ~9~417 head, heats up very fast and speeds up the oxidation reaction process of the exhaust gases for better emission control. Exhaust ports, which are surrounded by water, as in conventional cylinder heads, cannot be as large in area or as straight, thus making it difficult, if not impossible, to design a good flowing slip-in liner. Most of the prior art designs try to cast in the exhaust port liner; this is inferior because the liner and aluminum head will be in contact at several points including the forward and rear ends; this results in a considerable increase in heat transfer over the insulated slip-in . ~ , :
; ~ design. Excessive heat transfer results in increased heat .
rejection to the coolant, which requires a larger radiator, and also results in a lower exhaust gas temperature which reduces~the ga~s oxidation process which in turn~results in~ higher emission feed~gas levels.
As a result~of the unique cooling concept of this inVent~ion~ an engine~will not emit more hydrocarbons at 0mewhAt~less compression ratios;~the~octane rating of 20~ ;the~required~fue1 does~ not need to ~be lowered to accommodate slightly~lower~campresslon ratlos. Furthermore, the adjustment: of~the~air~fuel ratio for the engine need not e~resorted;to~in order ~to run the engine at a lower wall temperature~level~ The~latter has been a typical remedial méAsure~to reduce~the sever~ity of cooling problems, since the combustion température lS lower if the air/fuel ratio s~ri~her.

30~ ~

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An engine head for an internal combustion engine, comprising:
(a) an elongate housing comprised entirely of aluminum and having walls defining a top closure for a galley of aligned cylinders opening onto the bottom face of said housing, said housing having walls defining passages for inducting a combustible mixture and exhausting combusted gases, said closure wall extending upwardly from the bottom face of said housing, (b) means defining a series of interconnected hemi-cylindrical grooves in said housing extending upwardly from the bottom face of said housing and consecutively along each of said cylinders, said grooves limiting the lower portion of said top closure walls to a thin-sectioned cylinder, said grooves being so interconnected as to leave a solid siamese connection between each of said thin-sectioned cylinders.

2. The engine head of claim 1, wherein said hemi-cylindrical grooves cooperate in forming two independent flow paths on opposite sides of a centerline extending between each of said cylinders, each of said flow paths extending transversely and consecutively from one cylinder to the next.

3. The engine head of claim 2, wherein each of said flow paths are arranged at opposite sides of said housing when viewed in cross-section, said housing also having a third flow path arranged as a cylindrical boring located at the upper side of said housing spaced generally midway between said grooves, each of said three flow paths are commonly supplied with fluid from one end of said housing.

4. The engine head of claim 1, wherein said grooves are closed on all sides except for their intersection with the bottom face of said housing.

5. The engine head of claim 1, which further-comprises gasket means supported at the bottom face of said housing and adapted to close said grooves for defining a closed fluid passage except for a slot in said gasket providing an ingate for a supply of said fluid to said head, the pressure head across said groove inducing a relatively high velocity flow through said fluid passage.

6. The engine head of claim 1, wherein said housing is defined as an aluminum casting with the parting surface of said casting defining said bottom face, said grooves being formed by coring supported through said parting surface.

7. The engine head of claim 1, wherein said passages for exhausting combusted gases contain a liner to isolate heat therein, said liner being supported independently of said head and spaced-therefrom when assembled in an engine.

8. The engine head of claim 1, wherein the wall section separating said grooves in the interior of said cylinder has a dimension no less than .28 inches.

9. The engine head of claim 1, wherein the walls for said cooling passages are defined so as to insure a substantially laminar or controlled turbulence flow through-out.

10. The engine head of claim 1, wherein said cooling passages are defined as continuous bands of fluid arranged in a chained series of hemi-cylinders, the inter-connection between said hemi-cylinders having additional fluid passages directed transversely therethrough to shed any vortices occurring at such interconnection.

11. An engine head having a body comprised entirely of aluminum, said body having a flat plane bottom and having opposed sides, the body comprising:
(a) first walls defining a series of cylindrical combustion chamber portions arranged side-by-side, each extending through the bottom of said head, each chamber being the site of an intense periodic heat source during engine operation, (b) second walls defining a plurality of exhaust gas passages, each extending between one chamber portion and one side of said head, said exhaust passages serving as a second site of an intense heat source during engine operation, (c) third walls defining a plurality of valve guide cylinders extending from the top of said head into each chamber, said third walls having a portion serving as a separation between said exhaust gas passages and said valve guide cylinders, (d) first means constituted by a series of inter-connected cylindrical grooves extending upwardly in said first walls from said flat plane bottom and defining a pair of streamlined liquid cooling flow paths extending in parallel along the sides of each of said chamber portions through said first walls, said grooves limiting the lower portion of said first walls to a thin-sectioned cylinder, said grooves being interconnected as to leave a solid siamese connection between each of said thin-sectioned cylinders, and (e) second means defining a streamlined, liquid cooling flow path disposed in said portion of said third walls separating said valve guide cylinders and exhaust gas passages, said first and second means being effective to carry heat away from said heat source sites at a rate equal to or greater than the thermal conductivity of said light metal.

12. The engine head of claim 11, wherein said second means comprises a straight cylindrical passages.

13. The engine head of claim 12, wherein said cylindrical passage is drilled thereby possessing a smooth machined surface, the average area of said cylindrical passage being about .55 in2.

14. The engine head of claim 11, wherein the rate of flow of said cooling fluid through said first means is in the range of 120-130 inches per second and the rate of flow of said cooling fluid through said first means exceeds the rate of flow in said second means, the total average area through which said flow is conveyed in said first and second means is about 1-2 in2.

15. The engine head of claim 11, wherein said cast metal body forms a solid interconnection between first, second and third walls, said walls and interconnection having a transverse dimension in any direction exceeding .3 inches.

16. The engine head of claim 15, wherein the use of said first means results in the definition of an outer wall conforming in configuration to the flow path there-through, said outer wall having a transverse thickness dimension in the range of 0.25 to 0.3 inches.

17. A method of cooling the head of an internal combustion engine, comprising:
(a) form the head as a cast body consisting of a metal having a thermal conductivity exceeding .28 cal-cm/sec-cm2-°C, said body being provided with a flat bottom, opposed sides, first walls defining a series of cylindrical portions arranged side-by-side with each portion extending through said bottom, having second walls defining a plurality of gas passages with each extending between one cylindrical portion and one side of said head, and third walls defining a plurality of valve guide cylinders each extending from the top of said head into one cylindrical portion, said third walls having a portion serving as a separation between said exhaust gas passages and said valve guide cylinders, (b) convey cooling fluid through said first walls in at least one laminar non-turbulent first flow path extending from one end of the head along the sides of each of said cylindrical portions to the opposite end of the head, and convey cooling fluid through a cylindrical boring in said portion of said third walls in a laminar non-turbulent manner while in parallel flow with said first flow path, the flow rate and flow area of said flow paths being adjusted to carry heat away from said metal at a rate equal to or greater than the thermal conductivity of said metal whereby any nucleate boiling at the interface between said flow and metal is limited and controlled to increase the thermal heat transfer thereacross.

18. The method of claim 17, wherein a heat flux path from either said cylindrical portions or exhaust gas passages through the cooling flow will substantially traverse a greater dimensional in said metal while maintain-ing a more uniform average metal temperature.

19. The method of claim 17, wherein said metal is aluminum and said first flow path consists of parallel portions, each portion extending only about an independent side of said cylindrical portions, said second flow path being spaced from said first flow paths by at least 3 inches.