Engine Advancement--Hit and Miss

[chrisski]

 

That is a 5 HP Hit and miss engine.  I first learned about them when someone posted that what was found in a wash was probably a hit and miss engine.  In theory, I thought something like this where you only use gas when needed would be a novel concept, and could be used today.  I had forgotten how much engines had advanced.  This chest high hit and miss engine has the same power as a backyard 5 HP lawnmower.  I'm just amazed at how advanced engines had gotten.  I'd actually leaned that once before but forgotten.  I thought it would be great to make a car today that you could crank start, like the model T.  I learned the old engines used a 1:4 or less compression ratio so anyone could crank start one, but a modern vehicle can use a 10:1 compression ratio with much more volume, as much as 6 or 7 liters, so no one could crank start that.  

I've been told the internal combustion engine is about as efficient as it will get, but I wander what our engines will look like in a hundred years.  In the last hundred years, a chest sized engine was shrunk into a boot sized engine.

If it were the zombie apocalypse, getting the hit and miss to run would probably be easier then a modern super machined engine.

[clay]

There is more to a motor than horsepower. The 5 hp hit and miss generates about 45 pounds of torque at about 600 rpm. The 5 horsepower lawnmower generates about 7 pounds of torque at about 3500 rpm.

If you want to mow a small lawn the lawnmower gas engine is going to do a much better job and be a lot easier to move. The hit and miss would do the same job with a lot of gearing and a much bigger cutting blade (a thresher is a very large mowing machine).

If you want to run a large threshing machine, a crusher or a big heavy platen press the hit and miss will do the trick. The lawnmower engine could do the job but you would need a huge transmission.

I've worked quite a bit with old flywheel engines and they do have their advantages particularly in agriculture and heavy industry. Hit and miss and the next generation carbureted flywheel engines were very fuel efficient compared to a modern gas engine with the same torque but you will pay in time. Everything is slower with a high torque low horsepower engine.

Modern diesel and electric motors are what replaced high torque gas flywheel engines. Gas engines have had many advancements but are still pretty fuel inefficient in high torque situations - about 15% efficient. That's why tractors and industrial torque engines still use larger heavier flywheels and lower rotational speeds and why gas engines use low mass flywheels and higher rotational speeds.

Different motors for different jobs.

Edited July 29, 2018 by clay

[chrisski]

Thanks Clay.  I'm still a novice at engines.  I did not realize there could be such a difference between torque and horsepower.

I never really wanted to learn how to fix any of them or learn how they operate until around when I was 40 and got sent to Korea. The American car I brought with me broke down, and the mechanic there said bring the parts and we'll fix it for you.  That started me learning the basics.  I got a diesel when I got back to the states, and knowing how those work is very important if it needs to get fixed.