It seems to me that since hydrogen is a fast burning gas, simply changing timing is a very impractical modification.
I believe that to get the most from hydrogen, a realitively moderate change might bring real results. What do you think of this?
The goal is to change a 4 cycle to 2 cycle- eliminating the compression stroke and combining the power stroke with the intake stroke.
All that would be required would be to change the cam drive from 2-1 ratio to 1-1 ratio, grind the trailing side of the cam lobe of the intake valve to allow the valve to close about 115-120 degrees after TDC, and change timing to fire at 117-125 degrees after TDC. On a three or six cylinder engine, just setting the timing at TDC and moving the wires to different plugs would get timing very close.
The advantages should be huge. The compression stroke robs a lot of power, and running 2 strokes will also make more power. Even if the initial power stroke does not have as much power as before, the combined benefits of this mod. should easily outweigh any disadvantages.
I think heat and wear will also decrease. Piston lateral stress will be nearly eliminated. An engine like this will probably be able to be turned by hand, the starter won't need nearly the power as before.
The engine should make more low end torque, allowing lower rpm use. I think injecting metered hydrogen just before the valve would be best, and air flow might just be regulated by a spring loaded butterfly valve.
This engine should also be very quiet. Normally running on gas, you ignite the fuel before the piston even reachs the top to start it burning, and it continues burning even after the exhaust valve starts to open. This action makes a lot of exhaust noise and heat on the valve and exhaust.
I am looking to try this on a small engine, maybe a briggs 5hp.