What is a Diesel Engine ?

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How industrious and intelligent they were at the turn of the century with what they had to work with!
The Engineering of fuels has come a very long way too.... I have no idea how chemists work their magic.... breaking down crude fuels into building blocks that are then recombined to make the petroleum we use in spark ignition engines.. just Magic! Kerosene and Diesel fuel oil - and many other things down to the tar on roads - are really just by-products from extracting the best bits for petroleum for spark engines, and feed stocks for plastics etc.
Or so I was told by the man (Doctor Chemist) at Texaco...
When cars owners were sold the idea that diesel was 10% less cost than petrol, and went 10% further, they thought a 20% fuel saving was a benefit to out-weigh the higher initial cost for the car. Then governments and oil companies realised the petrol - diesel production (a natural fractional balance based on the chemistry mixture in crude oil) was out of balance with the added need for diesel for cars that were not using petrol.... so they increased the price and taxation on diesel fuel to compensate... according to an accountant fron an oil company! That, plus emissions limit tinkering, restored consumption balance to the natural oil production fractional balance.
Big Brother rules!
Fine, you got me, but only because most of the work is already done, and all the stuff I have to do on the steam engine project has to be done at home. I'll make another attempt.

I'll be using this engine:

It's an old 12hp? briggs flathead. It's what powers my old mowercycle project. It's 500-something cc displacement I think. It has points without wasted spark, which makes things easier for me. All I have to do is put the hot bulb on, and wire the injector board to the points instead of the coil.

This is the hot bulb I made for the weed whacker engine. It seems that I had issues with leaks. I think I originally tried to use an aluminum foil gasket, but ended up just covering it with braze.

I found the cad model of the bulb. Fusion says it's 2.1CC volume including the tube. Looks like I turned it down on the lathe to reduce heat conduction.
Screenshot 2024-07-09 093214.png

I whipped up this driver board. This particular valve requires higher than normal voltage to fire, more like 15-20V, so I had to add a boost converter. It's triggered by the points, however those fire near TDC, so it has to calculate the cycle time so it can fire during the intake stroke.

The solenoid valve itself was a left over prototype from a canceled project at work. It takes 8ms to open and 2ms to close at 24 volts. Much faster than your average solenoid valve, and everything is silicone or stainless. I used an RV water pump to build fuel pressure. It has a built in pressure switch, so it would turn on for a fraction of a second every few cycles. I'll probably add a long coil of plastic tubing between the pump and the valve to create more of a "bladder tank" and smooth out the pressure.