The heavier the weight of the air charge and the denser the charge, the later the intake valve can be closed to establish a low “effective” compression ratio and yet capture a charge volume and weight to produce the needed power, and the less heat is developed during compression in the cylinder. In a 4-stroke engine the sole intake charge can be boosted in pressure by as much as 4-15 atmospheres or greater and if the engine’s effective compression ratio is low enough, say 2:1 to 9:1, even spark-ignited there would be no problem with detonation, even with diesel air-fuel mix. The expansion ratio would be very large for spark ignition or for diesel operation.

The “effective” compression ratio is established by the displaced volume of the cylinder remaining after the point has been reached by a piston in the compression stroke that the intake valve was closed, being divided by the volume of the combustion chamber. This point is alternatively varied and variable. The expansion ratio in all cases is greater than the “effective” compression ratio.

Fuel can be carbureted, or it can be injected in a throttle-body or the fuel can be injected into the inlet stream of air, injected before top-dead-center of the compression stroke or process, injected into a pre-combustion chamber, and/or injected through the intake valve, and/or it may be injected directly into the combustion chamber and/or it may be injected during part of the expansion stroke.

Compression continues after closure of valve and the air-fuel charge is ignited by spark or compression near piston top-dead-center and the gases expand against the piston for the power stroke. Near bottom-dead-center in the reciprocating engines at the opportune time exhaust valve(s) open and piston rises in the scavenging (4th) stroke, efficiently scavenging the cylinder by positive displacement, after which the exhaust valve(s) closes. This completes one power cycle of the 4-stroke engine.

The intake valves can alternatively be opened at piston, top-dead-center, the compressed air flowing from the manifold, through open valves which valves remain open through the intake stroke or process, through bottom-dead-center, and until a pre-determined point in cylinder is reached during the compression stroke that when the valves are closed, the cylinder will have captured the proper weight of charge required to produce the power and torque demanded of the engine. In this case, the cylinder quickly fills during the intake stroke and at piston bottom-dead-center turn-around, part of the charge will begin to be expelled from cylinder at a similar pressure. Alternatively, this excess charge goes back through the intake valve, into manifolds, or again alternatively, an ancillary outlet valve and appropriate conduit is used to direct any excess compressed charge to the air intake of the compressor providing provisions are made to put adequate back-pressure on the exiting charge to prevent a drop in charge pressure. The latter charge reduction system could be utilized as another stage of compression. Closing time of valves is alternatively from 25% to 75% or more of the piston travel during the compression stroke, and may alternatively be as late as piston top-dead-center if charge weight is sufficiently high. The time (point) of closing is variable and varied, preferably controlled by an engine control module (ECM). An alternate system to open intake valves to induct the charge into cylinder is to determine a point during the intake stroke or perhaps even as late as piston bottom-dead-center, or even at any point during the compression stroke, that will have allowed to have time to open, fill the cylinder and close at a desired point in the compression stroke (perhaps from 25% to 75% or more of stroke, as specified above) that when valves have closed the cylinder will have captured the weight of the dense charge predetermined to fulfill power requirements of the engine.

This opening and closing should also be late enough that the valve will have remained open long enough to assure the charge is rapidly entering the cylinder, to have filled same and perhaps with some of it exiting, at closure of valve, in order to create and maintain tremendous turbulence in the cylinder and the combustion chamber. The closing time of valve is alternatively from 25% to 75% of piston travel during the compression stroke. The intake valve may alternatively be held open much longer, perhaps as late as piston top-dead-center providing the charge is dense enough to provide adequate charge weight.

The time of opening and the time of closing of the intake valve, and the dwell time while open is alternatively, varied and variable and controlled by an engine control module. The closing time of valve is alternatively between 25%-75% of piston travel during the compression stroke.

Another advantage of opening and closing the intake valve as late as possible is that there will be less compressed charge to pump out. The timing of the opening of valve should be calculated so that these valves would be opened as late as possible yet allow cylinder charging, and allow the closing of intake valves at just the right time during compression to create maximum turbulence in the combustion chamber, to retain adequate weight of charge required for engine power, and to establish the “effective” compression ratio desired. The valve(s) are now closed, compression continues and at piston near top-dead-center, the charge is ignited and the power stroke occurs, followed by scavenging to complete one power cycle.

Because of the very dense, cooled air or air fuel charge this engine with a normal sized combustion chamber can produce much greater power and torque, perhaps double or greater than that of current engines.

Operation of Design 1(b): Alternatively, for greater power the engine can be fitted with a larger than normal combustion chamber, perhaps up to double in volume as compared to existing engines. When then charged with the very high density charge, the power and torque can be as great as double that of the normal volume cold air charged engine described above and as much or more than quadruple that of current technology engines.

In engines of both design 1(a) and 1(b) the Stroke and Bore are alternatively enlarged to match the charge expansion for maximum thermal efficiency.