Gasoline engine without spark plug

[Christophe]

Methanol or nitromethane are not gasoline ... CQFD ...

When I tested 10% (or 20% reminds me more) of nitro in my mbk51 mob, the slowdown was much higher but the identical performance ... Must say that the mob was no longer entirely original ...

I think it is the nitomethane which acts as a "virtual candle" since methanol has a very high octane number (greater than 130 I think)

[chatelot16]

lubrication is not a problem: even if petrol is injected into the cylinder it does not prevent the oil from being swallowed by the intake

the French company tractors are indeed 2-stroke precompression in the crankcase: diesel when it is hot, and gasoline injection to start: the oil pump injects not even by the intake, but by the crankshaft bearings and a point on the passage of the segment: even no need for special 2-stroke oil: it eats ordinary mineral oil

Uh, the tractor system must be ultra polluting: don't even bother to think about it: you have to remember that at the time, people didn't give a damn about the environment, besides there very commonly had 4-stroke engines with lost-oil lubrication, especially in the distribution, and in the days of the Soviet Union, the many cars with 2-stroke engines made the roads slippery so much there was oil on the road. ..

not foreclosure so polluting as that: you must have used a real French company tractor to realize this: it is a large cylinder: you only lubricate the surface, not the volume: it consumes very little oil: even if the oil is lost in principle, it is not a consumption greater than what loses a normal old 4-stroke

moreover in a diesel, most of the lost oil burns with compression

it is not at all the same thing as the 2-stroke petrol or the lubricating oil comes out through the exhaust

[chatelot16]

the glow plug spark plug of the reduced model engine is not only used for starting

it is supplied with electricity only at start-up to make a hot spot, then in normal operation it remains the hot spot essential for ignition: I am not even sure that it remains hot only by the heat of the explosion, but also by combustion catalytic on its surface since it is a platinum filament

the adjustment of the carburetor is not done to have the best mixture, but to have the right spark plug temperature and the right ignition, tanpis if you need an excessively rich mixture which wastes fuel ...

[Christophe]

It's very fair chatelot but there is nevertheless more ignition controlled (i.e. ordered at the right time).

I wonder what the size limits of an uncontrolled spark plug engine are ...

Some "ultimate" motocross (ice racing) use methanol as fuel but they keep a spark ignition engine well ...

[chatelot16]

the only interest of the glow plug is the simplicity: but considering the waste of fuel that it produces, if someone knew how to make a good spark ignition for small engine, all the model makers would be happy

alas, there is not much to do to reduce the size of a spark plug or the ignition coil: for a 3cm3 engine the spark ignition would be heavier than the engine

as soon as we reach 20cm3 the spark ignition is acceptable and we are happy to forget the glow plug

[oiseautempete]

The timing of ignition has a great influence on the efficiency and quality of combustion, an incandescent ignition is therefore absolutely not suitable except mini engines ...

[ggdorm]

Indeed, consumption is excessive ... For a 7.5 cc it is around 300 ml / 10 minutes. The exhaust gases contain many small drops. I still learned a lot thanks to you. This forum is a real mine of information ...

[Christophe]

The timing of ignition has a great influence on the efficiency and quality of combustion, an incandescent ignition is therefore absolutely not suitable except mini engines ...

Well even on the operation: if you do not have the advance it takes your engine will not start anymore ...

It would be interesting to test a mob with a glow plug

For a 7.5 cc it is around 300 ml / 10 minutes

And that means what order of magnitude level of performance?

[chatelot16]

7.5cm3 can be 1kw

300ml / 10 mins
0.3lx 60/10 = 1.8l / h

1.8l / h / 1kw = 1.8l / kwh

a good gasoline engine can do 300g / hp

300g / cvh / 0.735 = 408g / kwh

gasoline density about 0.7
0.408kg / kwh / 0.7 = 0.58l / kwh

the reduced model motor consumes just 3 times more, and my power of 1kw can be optimistic: it will be worse if it does less

this consumption is not due to poor ignition: thermodynamics is very unfavorable to too small engine

[Flytox]

the reduced model motor consumes just 3 times more, and my power of 1kw can be optimistic: it will be worse if it does less

this consumption is not due to poor ignition: thermodynamics is very unfavorable to too small engine

Indeed almost all the energy goes into the cooling and the exhaust . About advance and compression, on a very small model (0.8 cm3) mounted on a circular flight, I realized that it worked much, much better by inserting a piece of tape between the propeller and the cylinder / cylinder head to limit cooling. The temperature climbed significantly more and the fuel became adjustable Engine temperature control thus became a means of changing the advance The mill withstood the joke very well ... he died for having a bad encounter with the planet