Cylinder head for internal combustion engine

A cylinder head for an internal combustion engine has a substantially greater height than conventional cylinder heads, and intake and exhaust ports which extend angularly upwardly in the head from the combustion chamber to a respective surface of the head. Intake and exhaust valves are provided in the head for controlling flow through the intake and exhaust ports, and the valves are tilted both longitudinally and laterally with respect to the head. The intake and exhaust ports are skewed in the head to closely align the axes of the ports with the angle of the respective valves. Valve operating components are recessed into the top surface of the head, enabling a flat valve cover to be used for enclosing the valve operating components. The invention is particularly directed to a cylinder head having a generally wedge-shaped combustion chamber, and the height of the head in a specific construction is about six inches, with the intake ports angled upwardly at about 30.degree. and the exhaust ports angled upwardly at about 60.degree.. The ports are longer and straighter in the head of the invention than in conventional heads, resulting in improved flow of intake and exhaust gases.

FIELD OF THE INVENTION 
This invention relates to internal combustion engines, and more 
particularly, to an improved cylinder head for high performance engines. 
DESCRIPTION OF THE PRIOR ART 
Ever since the advent of internal combustion engines, there has been 
continuing effort to improve the performance and/or economy of operation 
of such engines. These efforts have included supercharging, turbocharging, 
fuel injection, improved carburetors, streamlined exhaust headers, special 
intake manifold designs, special combustion chamber shapes, multiple 
intake and exhaust valves for each cylinder, and the like. Individuals and 
groups involved in racing have also developed ingenious modifications to 
valve and port designs, the use of special materials for lighter weight 
and better performance, and similar modifications to basic engines. 
Most of these efforts have been based on conventional engine technology, 
including essentially standard overall cylinder head configurations, 
albeit with improved ports and valves and the like. Cylinder head 
improvements generally involve polishing and shaping the existing ports 
and valve seats to obtain improved flow of the incoming air/fuel mixture 
and the outgoing exhaust gases. 
Conventional cylinder heads of the so-called wedge type generally have an 
overall height or thickness on the order of about three inches. Intake 
ports enter through one side of the head and lead to the generally wedge 
shaped combustion chamber on the bottom surface of the head, while exhaust 
ports lead from the combustion chamber through the side of the head 
opposite the intake ports. The relatively low height of the head requires 
that the intake and exhaust ports bend through a relatively sharp radius 
in order to enter the combustion chamber at an angle aligned as closely as 
possible with the axis cf the respective intake and exhaust valves. The 
intake port, for example, typically extends nearly parallel with the 
bottom surface of the head over a substantial portion of its length, 
taking the shortest path to the adjacent head surface. Similarly, the 
exhaust port may be curved throughout its length. This sharp radius and 
the relatively short length of the intake and exhaust ports hinders flow 
of gases into and out of the combustion chamber, impairing performance and 
economy of operation. 
Moreover, the valve train sits on top of the relatively "short" 
conventional cylinder heads, requiring an upstanding valve cover and 
gasket seals in order to prevent oil leaks. 
The spark plug in conventional wedge head designs also enters the 
combustion chamber at an angle that is usually directed toward the intake 
valve. This requires an advance of 38.degree. or more to the ignition 
spark in high performance engines in order to obtain adequate burn of the 
air/fuel mixture in the combustion chamber. 
Other problems encountered in conventional cylinder head designs include 
shrouding of the intake and exhaust valves, and uneven burn or flame 
travel through the combustion mixture within the combustion chamber. 
Shrouding is the effect produced by too close positioning of the edge of 
the valve relative to the side of the combustion chamber, or other 
shielding of the valve, with the result that flow of gases around the 
valve is impeded in that area of the valve. 
One example of a prior art cylinder head which attempts to overcome at 
least some of the above-identified problems is described in U.S. Pat. No. 
4,73,382. In this patent, a special shape is given to the roof of the 
combustion chamber. Specifically, a built-up area is provided at the 
juncture between the intake and exhaust valve seats to shape and improve 
exhaust flow. Special shaping is also given to the intake port to increase 
the velocity of the air/fuel mixture. However, the head is still of 
relatively "short" height, and the length of the intake and exhaust ports 
is therefore substantially conventional. That is, the ports are short, and 
the intake port also bends through a sharp angle as it approaches the 
combustion chamber. Thus, although this head represents an improvement 
over conventional prior art designs, it still does not achieve the maximum 
performance potential possible with a wedge head design. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
improved cylinder head having generally wedge shaped combustion chambers, 
which is taller than conventional heads and thus enables longer and 
straighter intake and exhaust ports and concomitant improved flow of both 
intake and exhaust gases, as well as better mixing of the air/fuel 
mixture. 
Another object is to provide a cylinder head having intake and exhaust 
ports which are relatively straight and are angled upwardly in the head 
for more close alignment with the respective intake and exhaust valves to 
improve flow of intake and exhaust gases. 
A further object is to provide a cylinder head in which the combustion 
chamber shape and positioning of the spark plug enhances flame travel 
through the combustion gases, enabling the ignition spark to be less 
advanced than in conventional designs, thereby producing more power. 
A still further object of the invention is to provide a cylinder head in 
which the valve train is recessed into the top surface of the head, 
enabling more effective sealing of the valve cover. 
A more specific object of the invention is to provide a cylinder head in 
which the intake and exhaust ports are twisted or skewed in the head so 
that they extend angularly from the respective head surfaces to the 
combustion chamber, enabling them to be essentially straight and aligned 
axially wi&:h the respective valve, thus improving flow while at the same 
time producing a swirling action in the intake gas and achieving thorough 
admixing of the air and fuel. 
An even further object of the invention is to provide a cylinder head which 
has an increased height relative to conventional heads, enabling the 
intake and exhaust ports to be straightened out and lengthened for 
achieving improved flow characteristics, and providing space for recessing 
the valve train components into the top surface of the head. 
Yet another object of the invention is to provide a cylinder head for 
so-called big block engines, or engines having a displacement greater than 
about 400 cubic inches, which has a relatively small combustion chamber 
volume on the order of about 60 cc. 
In carrying out the above and other objects and advantages of the 
invention, a cylinder head in accordance with the invention may either be 
cast or made from a billet. The intake and exhaust ports extend upwardly 
at an angle from the combustion chamber to their respective sides of the 
head, and are relatively straight throughout their length, curving through 
a large radius turn just above the valves. The ports are longer than the 
ports on conventional heads, and are aligned substantially axially with 
the respective intake and exhaust valves. The ports are also skewed in the 
heads so that they align more closely with the axis of the respective 
valves, thereby improving the shape of the ports and thus enhancing flow 
of gases through the ports. 
The intake and exhaust valves are also angled in the head so as to be 
aligned closely with the axes of the intake and exhaust ports, and the 
faces of the valves subtend an angle of only about 12.degree. with respect 
to the face or bottom of the head. 
A head constructed in accordance with the invention has a height 
approximately the same as its width. More specifically, the present 
invention is directed to a cylinder head of the so called wedge type, in 
which the combustion chamber is generally wedge shaped. Such heads 
typically have a width of about seven inches. The head of the invention 
has a height of about six inches. 
The inlet end of the intake port is raised approximately two inches from 
the bottom surface of the head, and the outlet end of the exhaust port is 
raised about three inches from the bottom surface. This results in the 
intake port extending upwardly from the combustion chamber at an angle of 
about 30.degree., and the exhaust port extends upwardly at an angle of 
about 60.degree.. Obviously, these specific angles will vary depending 
upon the specific dimensions of the head, but in any event the ports 
extend upwardly and away from the combustion chamber and thus align more 
closely with the axes of the respective valves. In a head having this 
height, and with the ports raised as described, the ports are 
exceptionally straight and long in comparison with conventional head 
designs. For instance, the roof of the intake port or runner has a length 
of about seven and one-half inches, while the floor of the runner has a 
length of about four and one-half inches. The roof of the exhaust port or 
runner has a length of about five and five-eighth inches, while the floor 
of the exhaust port or runner has a length of about three and one-quarter 
inches. 
The combustion chamber in the head of the invention preferably has a volume 
of only about 60 cc, as compared with conventional heads for big block 
engines, in which the combustion chamber typically has a volume of 75 cc 
or greater. 
The spark plug enters the combustion chamber substantially midway between 
the intake and exhaust valves and is angled toward the exhaust valve to 
promote burning of the air/fuel mixture. 
In a head having the above dimensions, and with an intake valve diameter of 
2.375 inches and exhaust valve diameter of 1.940 inches, approximately two 
to three horsepower per cubic inch of displacement can be obtained on a 
conventionally aspirated gasoline burning engine. In a supercharged 
alcohol fuel burning engine, approximately five horsepower per cubic inch 
displacement can be obtained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring more specifically to the drawings, a cylinder head in accordance 
with the invention is indicated generally at 10. The cylinder head may be 
cast or formed from a billet, and includes a bottom surface which is 
machined or otherwise finished for mating engagement with an engine block 
B (FIGS. 3-7) to close the upper ends of the cylinders C in the block. 
A plurality of combustion chambers 12 of approximately kidney shape in plan 
view are formed in equally spaced relationship along the surface 11 for 
mating cooperation with the upper ends of the cylinders. The combustion 
chambers 12 are of the wedge type, tapering from a burn control surface or 
quench zone 13 at one side of the chamber and that is coplanar with the 
surface 11, to a maximum height of about 5/8 of an inch where spark plug 
opening 14 enters through the roof of the chamber, and thence curving 
downwardly to the opposite side of the chamber. In a preferred 
construction, the combustion chamber has a volume of only 60 cc, much 
smaller than the volume of the combustion chamber in conventional heads 
for large block engines, which may exceed 75 cc. 
As seen best in FIGS. 4 and 6, the spark plug SP enters the combustion 
chamber at an angle of about 50.degree. and has its tip directed generally 
toward the exhaust valve. This positioning of the spark plug places it 
approximately centrally of the combustion chamber, and together with the 
flow characteristics of the head, to be later described, and shape of the 
chamber results in good flame travel and uniform burn of the air/fuel 
mixture flowing across the chamber. 
The cylinder head 10 is substantially greater in height H than conventional 
wedge heads, and as seen best: in FIGS. 4, 5 and 6, the intake port 15 has 
its inlet end 16 raised a distance A (two inches in a specific 
construction) from the bottom of the head, while the outlet end 18 of the 
exhaust port 17 is raised a distance B (three inches in a specific 
construction) from the bottom. This not only enables the ports to extend 
nearly straight from their respective head surfaces to the combustion 
chamber, but results in them being substantially longer than conventional 
ports. 
In a specific construction, for example, the roof of the intake port has a 
length of seven and one-half inches, while the floor has a length of four 
and one-half inches. The roof of the exhaust port, in this construction, 
has a length of five and five-eighth inches and the floor has a length of 
three and one-quarter inches. 
As seen best in FIGS. 1 and 2, the intake and exhaust ports are skewed in 
the heads, with the inlet end 16 of the intake ports and the outlet end 18 
of the exhaust ports being rotated about their respective axes so that the 
ports angle through the heads and line up substantially axially with the 
axes of the respective intake and exhaust valves 20 and 21. As clearly 
seen in the drawings, the ports are relatively straight and bend through 
only a small angle with a large radius of curvature. The net result is 
very efficient flow of gases through the ports and exceptional breathing 
for the heads. Moreover, the air/fuel mixture flows spirally through the 
intake ports, achieving thorough admixing of the air and fuel prior to 
entering the combustion chamber. 
As represented by the arrows in FIG. 4, the relationship between the intake 
and exhaust ports and the combustion chamber is such that a very smooth 
transition occurs from the intake port, through the combustion chamber and 
thence outwardly through the exhaust port. The flow of intake and exhaust 
gases and the location of the spark plug are very similar to the flow 
characteristics and spark location in combustion chambers of hemispherical 
design, thereby achieving the superior breathing of such heads in a wedge 
head design. 
As depicted in FIGS. 5, 7 and 8, the intake valve 20 is tilted 12.degree. 
in a direction parallel to the longitudinal dimension of the head (FIGS. 7 
and 8) and is also tilted toward the intake side of the head to 
substantially axially align the valve with the axis of the intake port as 
it enters the combustion chamber (FIG. 5). The rocker arms 25 for the 
intake valves are mounted on individual studs and are inclined to match 
the angle of the valve stems. As shown in the particular example described 
and illustrated herein, roller tappets 26 are used, and conventionally 
positioned push rods 27 operate the rocker arms from a cam, not shown. 
An exhaust valve 21 is depicted in FIGS. 6 and 8. As represented 
schematically in FIG. 8, the exhaust valve also is inclined at an angle of 
12.degree. in a direction parallel to the longitudinal dimension of the 
head, and as shown in FIG. 6 is also inclined transversely of the 
longitudinal dimension of the head toward its intake side. The positioning 
of the exhaust valve and construction and orientation of the exhaust port 
is such that flow of exhaust gas from the combustion chamber past the 
exhaust valve and through the exhaust port is very efficient. A rocker arm 
30 with a roller tappet is mounted on a stud shaft for operation of the 
exhaust valve in a manner substantially identical to the previously 
described operation of the intake valve. 
The valve train, including the valve springs, spring retainers, rocker arms 
and the like, are recessed into the top surface of the head as shown best 
in FIGS. 3, 5 and 6. This enables a flat valve cover 40 to be used, and 
which may be effectively sealed to the head with an o-ring or similar 
sealing gasket 41 placed in an annular channel 42 formed in the top 
surface of the head. This arrangement virtually eliminates oil leaks which 
commonly occur between conventional valve covers and head surfaces, and 
provides more rocker clearance. Moreover, it is possible to remove and 
replace the valve cover without having to replace the gasket each time, as 
is generally necessary on conventional designs. 
If desired, fuel injection lines 50 can be extended along the top of the 
head, with branches 51, 52, etc. leading to respective intake ports behind 
the intake valves, as illustrated in FIGS. 5 and 9. These lines could be 
used for gasoline, alcohol, or other fuels depending upon the use of the 
engine. 
The cylinder head shown in the drawings and described herein is configured 
for use on Ford engines, but obviously may be adapted to other engine 
designs by providing alternate means for securing the head to the engine 
block, and by rearranging the intake and exhaust valves to correspond to 
other engine designs. The increased height of the head, and the relatively 
straight and long ports, angled spark plug and valve orientation all as 
described above can be adopted to such other engine configurations, with 
corresponding improvements in performance. 
Moreover, the substantially improved breathing achieved with the cylinder 
head of the invention can be utilized for increased fuel economy as well 
as improved performance, and can be adapted to small block engines of six 
and/or four cylinder design. Conventional technology, including fuel 
injection and computer monitoring of engine performance can be 
incorporated into the cylinder head of the invention, with all of the 
advantages achieved by such technology. 
With the exception of the novel features described above, the head has an 
essentially conventional configuration and may be cast as easily as 
conventional head designs. Of course, for special applications it may be 
formed from a billet, if desired, and can be made of any conventional 
materials, such as cast iron, aluminum, etc. 
It is anticipated that a normally aspirated engine equipped with cylinder 
heads constructed in accordance with the above could achieve two to three 
horsepower per cubic inch of displacement when using gasoline as the fuel; 
and on supercharged engines burning alcohol, up to five horsepower per 
cubic inch of displacement could be achieved. 
The following tables show results obtained with a prototype cylinder head 
constructed in accordance with the invention and having the dimensions 
described. The tests were conducted on an SF 600 Flowbench at Engine 
Systems in Tucker, Ga. In conducting these tests, the ports and chambers 
were left unmodified, i.e., there was no special shaping or valve work to 
enhance performance, other than to incorporate the features of the 
invention. 
Table 1 shows results obtained for an intake port, with the port being 
symmetrically oriented in the head, i.e., unskewed, as contrasted with the 
skewed position of the ports shown in the drawings. Tests 1, 2 and 3 were 
conducted on orifice four of the flowbench, which will flow 297 cubic feet 
per minute (CFM) at 100% efficiency. Tests 4-8 were conducted on orifice 
five of the flowbench, which will flow 441 CFM at 100% efficiency. All 
tests were conducted at 28 inches of water. 
Table 2 shows results obtained for an exhaust port, again with the ports 
being unskewed, as contrasted with the skewed orientation shown in the 
drawings. All tests were conducted on orifice number four of the 
flowbench, and at 28 inches of water. At 100% efficiency, this orifice 
will flow 313 CFM. 
Table 3 shows results obtained for an exhaust port under conditions 
identical to that for table 2, except that the port was skewed to the 
orientation shown in the drawings. The dramatic increase in flow obtained 
by the simple expedient of skewing the port is apparent from a comparison 
of the data in this table with the data in table 2. 
TABLE 1 
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(Intake, Unskewed) 
Test No. 
Valve Lift 
Flow, CFM Efficiency, % 
Orifice # 
______________________________________ 
1 .200 169 57.5 4 
2 .300 223 74.6 4 
3 .400 269 90.0 4 
4 .500 304 69.5 5 
5 .600 343 77.0 5 
6 .700 374 83.8 5 
7 .800 397 89.0 5 
8 .855 410 92.0 5 
______________________________________ 
TABLE 2 
______________________________________ 
(Exhaust, Unskewed) 
Test No. 
Valve Lift 
Flow, CFM Efficiency, % 
Orifice # 
______________________________________ 
1 .200 128 41.0 4 
2 .300 188 60.0 4 
3 .400 225 72.0 4 
4 .500 250 80.0 4 
5 .600 266 85.0 4 
6 .700 282 90.0 4 
7 .800 288 92.0 4 
8 .855 291 93.0 4 
______________________________________ 
TABLE 3 
______________________________________ 
(Exhaust, Skewed) 
Test No. 
Valve Lift 
Flow, CFM Efficiency, % 
Orifice # 
______________________________________ 
1 .200 138 44.0 4 
2 .300 191 61.0 4 
3 .400 235 75.0 4 
4 .500 263 84.0 4 
5 .600 282 90.0 4 
6 .700 293 93.5 4 
7 .800 302 96.4 4 
8 .855 310 99.0 4 
______________________________________ 
Although the invention has been described with reference to a particular 
embodiment, it is to be understood that this embodiment is merely 
illustrative of the application of the principles of the invention. 
Numerous modifications may be made therein and other arrangements may be 
devised without departing from the spirit and scope of the invention.