Lydell “TWIN 28” Pulse Engine 8/5/14

There are eleven high efficiency principles in this 56ci prototype automobile engine.Twin 12 HP Aluminum

1. Opposed 3.5”parallel pistons (with a 2.5”offset for overhead cam and overhead valves), minimize combustion surface.

2. Specific low HP needs.

3. Large displacement single combustion chamber strategy.

4. Quicker power stroke.

5. WOT, low rpm

6. Cooling heat utilization.

7. Exhaust heat utilization.

8. Small gas HP, high electric HP strategy.

9. Consistent RPM.

10. Variable combustion chamber size.

11. A/F ratio: The primary cylinder by the spark plug is slightly below stoichiometric at 14.7; the secondary cylinder can be leaner (maximum power is at 12.6).

 

 

OPPOSED OFFSET PISTONS:

In this scenario, less area is required for valves and there are no specific heads, so there is less combustion chamber surface area compared to other engines resulting in less combustion heat (power) lost to the cooling system.

SMALL COMBUSTION CHAMBER, STARVED INTAKE:

Creating a smaller combustion chamber but restricting the intake volume, still gives us a normal compression ratio. Therefore, the output combustion pressure at TDC is the same, but less BMEP (brake mean effective pressure) and therefore less pressure loss at BDC. 

LARGE DISPLACEMENT, SINGLE CYLINDER:

Larger cu. in. per cylinder engines proportionally have less cylinder surface to cylinder cu. in. ratio, which helps minimize cylinder quenching. 

PULSE POWER STROKE TECHNOLOGY:

We have 2/3 piston stroke in the first 90 degrees of crank rotation and 1/3 piston stroke in the second 90 degrees. The faster the initial portion of the power stroke (power pulse) the less time for high temperature heat loss through the combustion chamber walls.

WIDE OPEN THROTTLE (WOT), LOW REVOLUTIONS PER MINUTE (RPM).

As much as possible a WOT is utilized to minimize pumping losses combined with low RPM to decrease engine rotating operating losses.

EXHAUST HEAT UTILIZATION:

As this engine design minimizes heat loss through the combustion chamber, the exhaust temperature is therefore proportionally hotter, allowing the use of efficient exhaust heat reclamation systems.

    One system I utilize on my test car is a small turbo that can do three things. 1, Pressurize the intake just enough so that the intake stroke does not have to overcome any suction losses at a given throttle position, 2, higher turbo pressure for increased horsepower, or 3, direct cool non pressurized turbo air to the engine cooling fins (so that the engine does not have to power a blower) and then discharge the hot air or duct it to the intake.

COOLING HEAT UTILIZATION: 

To use the engine cooling air discharge to preheat the engine intake air and while this makes the engine less powerful, it increases the efficiency.

SMALL GAS ENGINE, LARGE ELECTRIC MOTOR:

25% of the fuel an automobile engine consumes is used just to spin the engine at road speed. Therefore, proportionally, it is wiser to have an engine operate closer to WOT for efficiency reasons. So, why have the cost and waste of a 150 hp engine in your car when it only takes about 16 hp on average to move a 3000 pound car? So we use a 56ci, 35 hp gas engine for basic motivation and a 100 hp electric motor/generator for assist when needed, and then have regenerative breaking as a bonus.

CONSISTENT RPM:

A constant rpm gas engine coupled to an infinite variable speed transmission allows for simpler engine architecture with lower construction cost and increased efficiency.

VARIABLE COMBUSTION CHAMBER SIZE AND TURBO:

Under variable driving conditions where variable horsepower is required, a small combustion space and a limited intake is used yielding low BMEP. As more hp is required the combustion space and BMEP increases, and eventually turbo boot is added.  

A/F RATIO:

The primary cylinder with the spark plug and spark trigger device, operates at an A/F ratio of 14.7:1(normal a/f ratio) and because the opposing combustion chamber is overlapping the primary combustion chamber, that second cylinder (separate intake) can run at a leaner a/f ratio (15:1 – 25:1, or leaner).