Hit and Miss Engine 2

[wayneoz]

Hi everyone,

I wish to convert a 4 stroke engine into a hit and miss engine - or something similar.

I have made a flux generator that is powered by the small (Carburetor) 4 stroke using a flywheel. I wish now to make the engine more fuel efficient.

My plan is to use an Arduino and solenoid to shut the fuel and spark on & off so it fires once every 2-3 seconds.

I am a bit green with 4 stroke engines and would love to hear any suggestions.

Thank you

 

[LittleInch]

More efficient??. Looks to me like you just mean used less fuel but this will be accompanied by less power out.

What is this thing powering?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

Buy a smaller engine - more fuel efficient.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[IFRs]

Couple a flux capacitor to the flux generator - use the stored flux to add efficiency.

 

[dgallup]

Carbureted hit an miss engines have very low efficiency. All those revolutions sucking in air and fuel without producing work are just about the worst thing you can do for efficiency.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[berkshire]

Hit and miss engines were a way of regulating engine Rpms with the primitive carburetors available in the early days of engine manufacture. R.A. Lister used this system on their early engines, which had massive flywheels to compensate for the engine inefficiency. Are you sure you want to go this route?
B.E.

You are judged not by what you know, but by what you can do.

 

[MikeHalloran]

They do have low efficiency, but they don't suck in air and fuel on every rotation; automatic intake valves (check valves) only open when there's a vacuum in the cylinder, which only happens on firing cycles because the governor holds the exhaust valve open otherwise.

see 'how hit-and-miss-engines work' in

https://en.wikipedia.org/wiki/Hit-and-miss_engine

Fifty plus years ago, I saw 'Rumely Oil Pull' engines running at Henry Ford Museum. I think they worked by exploding kerosene and air in a large external combustion chamber, and expanding the hot gas through what was mechanically a steam engine. The sound was essentially the same as that produced by a regular h+m engine.




Mike Halloran
Pembroke Pines, FL, USA

 

[Artisi]

OK I'll ask the obvious - - WHY?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Lou Scannon]

Sounds cool... even cooler than a Harley?

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[GregLocock]

My favorite uni lab experiment, plotting performance curves for a heavy hit and miss natural gas stationary engine. I think it might have made 10 hp, and was as big as a car.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[itsmoked]

We had one of those monster single lunger H&M engines in our power mechanics class in high school. You could start it with a bar in a hole in the flywheel. It was crazy. The flywheel was about 4 feet in diameter and had monster spokes. The flywheel probably weighed a thousand pounds.

It was salvaged after a fishing boat that is was the motive power for sank, in the harbor. Seems the starting bar got jammed in the starter bar hole in the flywheel on starting. The bar went around with the flywheel and plowed a huge smile in the lowest point of the hull. The boat sank fast.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LittleInch]

wayneoz - the issue you will face is that carburetors don't like having fuel turned on and off. They usually have some sort of float system and bowl which holds enough fuel for a few seconds, so turning the inlet fuel on and off won't make any difference to the fuel out, but can affect the re-start as the bowl fills up again.

Also systems like this actually lightly coat the inlet chamber in a thin film of petrol. If you manage to cut off the fuel, this film dries out, but then on re-start the engine coughs a lot. I remember on a car some time ago where they used carbs and tried to cut off fuel on the overrun, they found when you put your foot on the accelerator it wouldn't go properly so had to actually cycle the fuel on and off when on overrun.

Fuel injection now, especially electronic FI, is a different thing.

All up no one can work out why you're trying to make your engine less efficient than it is at present....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[berkshire]

Little inch,
What is that carb ? It looks a bit like a Stromberg.
B.E.

You are judged not by what you know, but by what you can do.

 

[BrianPetersen]

Very typical constant-velocity motorcycle carburetor. They're all like that.

 

[LittleInch]

Be. Dunno. Just the nicest picture I could find to demonstrate that turning the fuel off on a carb won't end the fuel supply for several seconds.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Lou Scannon]

In our mech eng power lab, we had a very tired National Gas engine, I think the data plate was dated 1915. Four men cranking on the flywheel with a crank handle for all their worth to get it started. The experiment was to adjust the compression ratio via shims in the conrod to find the highest output and efficiency. Blowby was so bad on that tired old beast that MBT compression ratio came and went pretty quick with more shims. Flyball governor cut the ignition when governed speed was reached, classic H&M governing. For fun I held the governer down for a few seconds and let the engine accelerate, but I quickly lost my nerve.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[JStephen]

I'm thinking I've heard pumpjack engines that were hit-and-miss, but no idea how old they were. Heard them in recent years, I mean.

 

[waross]

Every time you cycle off, you will waste most of the fuel in the carburetor bowl. When you cycle on you will will have to wait for the bowl to fill enough to supply a fuel mixture.
There are after market kits that add fuel injection to small gasoline engines. You can then simply cycle the injection off and on.
The big question is "WHY?"
Most small engines have a serviceable governor.
If your engine does not have a governor, you can probably make one with a flapper that the cooling air blows against. The faster the engine the more force on the flap. Use a spring to hold the throttle open. Use linkage from the flap to close the throttle at the speed that you want.
It will take some cut-and-try and trial-and-error to get it right but there have been many small engines governed in this fashion.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

The emissions/pollution profile of any H&M would likely prevent it's commercial application.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[gruntguru]

Skipping firing events (provided the fuel is shut off as well as ignition) is a more efficient method of reducing engine load than throttling.

je suis charlie