Why dont they make a gas 2 stroke engine work like a diesel engine or vica versa?


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dvalued6 years ago
Because diesel and gasoline have significantly different properties, the engines designed to burn the fuels have to be different as well.

Gasoline is extremely volatile. It releases fumes easily, and those fumes are easily ignited by a spark. The addition of the spark makes gasoline engines operate at a higher speed and can start much more easily than a comparable diesel engine.

Diesel, on the other hand, is heavier and more stable. Because of this stability, it does not take to a spark too easily. The engines don't use a spark, just compression. This makes the engine slower, and harder to start manually. (If it's too cold, for example, a diesel won't start at all without an additional input of heat - that's what glow plugs are for.) Also, diesels have a phenomenon named (appropriately) dieseling, which is a condition where the engine does not stop when you want it to, only when it runs out of fuel or oxygen, which is potentially dangerous (and quite annoying). While most automobiles, for example, have ways of reducing the risk of dieseling, it still is possible for it to happen.

Each engine has its uses. Gas engines are faster and more responsive, diesels are more efficient and provide higher torques.
Hey man, you seem to know a lot about engines, do you think it's possible to make a nice gas engine out of simple parts from a hardware store?
Let's think about this in a different way.

You want to know if, using off-the-shelf parts not designed for this purpose, you can contain 1600 degree explosions conducted hundreds of times a minute. Not only that, but these explosions occur in a precisely choreographed sequence.

In short: not bloody likely. Won't say it's impossible - hell, a 14 year old kid created his own fusion reactor! - but it's damned tricky.,
well... then... it might be possible if you have heavy duty stuff like; thick, short pipes able to withstand 3-4 thousand pounds per square inch (p.s.i,) oh and metal to, as well as an engine control unit (e.c.u.) and fuel mixture, spark plugs, egnition and kill switch, a sparker for the spark plug. I could go on but the time I am in while writing this is 1:46 a.m. so, I'm out.
Re-design7 years ago
A gas 2 stroke in diesel mode would be inefficient since the gas would ignite too early. Using a spark lets them time the ignition to provide the most power.

A car that is over heated or with dirty plugs will diesel but runs very badly.

It's very difficult if not impossible to ignite diesel fuel with a spark.
Acepilot42 (author)  Re-design7 years ago
well what if the compression ratio was reduced to a normal gas engine but still used valves and a blower like a 2 stroke diesel?
Here's the fundamental problem: the fuels' characteristics dictate the engine characteristics.

Typical gas engines have a compression ratio of somewhere between 8:1 and 12:1. (Higher numbers tend to be in fuel-injected performance engines, where it's possible to more accurately meter fuel flow.) Typical diesel compression ratios start at 16:1 and go up.

Spark-ignition engines don't require as high a ratio because it's the spark that causes the explosion which powers the engine. (It's also why a spark-iginiton engine can be easily modified to run on any fuel which either has - or can be modified to have - the volatility required. Methane and hydrogen are gaseous in normal weather, so by definition they have full volatility and have the most ability to interact with gaseous O2. Lighter alcohols can easily aerosolize, like gasoline does, and has sufficient volatility to ignite with a spark.)

Fun fact: early spark engines were designed to run on alcohol, as alcohol could be acquired nearly anywhere and can be made by nearly anyone, and gasoline was an industrial waste product that was too dangerous to transport safely!

Compression-ignition requires higher ratios because, well, the fuel/air mix ignites when pressure is applied; the higher the pressure, the biggest bang for the buck. Such engines can also take a variety of fuels, though if you want, say, coal dust to ignite you need to modify the engine for it. (And yes, coal dust can be used in a compression engine, as can vegetable oil, heavier fractions of crude, anything combustible that isn't too volatile as the volatility would cause premature detonation.)
countable7 years ago
Just get a 2 stroke diesel engine....
Acepilot42 (author)  countable7 years ago
give me the money then
no
I've seen it done with nitro RC engines, because Nitro fuel has similar compression to diesel.
Acepilot42 (author)  TheFoofinator7 years ago
i know i have 2 nitro rc trucks myself
lemonie7 years ago
What exactly are you asking?
There are gasoline 2 strokes, diesel 2 strokes, and other compression-ignition engines. Which part / function are you interested in?

L
Acepilot42 (author)  lemonie7 years ago
is it possible to make a gas 2 stroke work like a diesel 2 stroke, you know by using valves and a blower

Not without a fuel-pump and injector(s) and even then your compression-ratio would be wrong.
Why?

L
Acepilot42 (author)  lemonie7 years ago
whatev
If the compression ratio was reduced, it wouldn't work, that's an intrinsic part of diesel operation.