Hit and miss engine?

[akumabito]

What do you guys think about a modern take on the hit and miss engine? I was just thinking you could engage the hit/miss mode electronically by cutting power to fuel injection and ignition. It would probably work best with engines with a heavy flywheel and coupled to a CVT.. To maintain an average of 2,000 rpm, you accelerate to 2,200 or so, cut fuel and ignition until RPM's fall to 1,800, then reengage and let the RPM's climb back up. would there be any fuel savings at all, or would you spend more fuel accelerating than you'd safe during the 'misses'?

[ConnClark]

Wouldn't this be the same as whats his name was talking about with doing variable displacement without shutting down the valves to the deactivated cylinders?


I pretty sure it wouldn't be good for the O2 sensor or the Cat.

[Diesel_Dave]

They have it--it's called cylinder deactivation

I'm familiar with hit and miss engines. I have a 1927 IHC Type M I'm restoring in the garage (which, technically, is throttle governed not hit and miss, but similar style).

The hit and miss concept was for the purpose of governing speed, not for efficiency. Which, by the way was absolutely awful in those days--as was power density. My IHC weighs ~400 lbs and is only 1.5 hp. It's compression ratio is 3.5 to 1. That should tell you something about the efficiency.

[jakobnev]

You can test this by just flooring the throttle and turning the ignition key on and off! (I assume EFI)

[stillsearching]

Reviving the dead but it was a thread of high interest to me and I was about to post on it until I found something called a "Search" button finally. ^O_o^ ^o_O^

Actually I for one am very interested, I think the concept has alot of potential. However I think one version of the modern form is "pulse and glide" driving, by what I understand you accelerate up then turn ignition/fuel off and coast for a bit. Instead of storing energy in a flywheel the car itself stores energy by accelerating/adding momentum then coasting down.

Another version is the hybrid car - when the engine is on it works harder storing energy, then it can turn off for a bit (properly designed) at least at lower speeds and put energy back in. Thus power pulses from the engine are used when it's more efficient to do so (higher loads = more efficient use). In a way the battery is the flywheel storage.

Trying to do the same with a literal hit and miss engine with a heavy flywheel would be extremely difficult - the flywheel cant store enough energy to be useful (they had like a 6hp engine with like a 100lb flywheel, can you scale that up ten times?), in other words you'd be hitting so often the misses are almost irrelevant. The only real time it would show advantages are at idle and near idle speeds - which is almost better taken care of by some form of hybridization (pneumatic or electric). Under any kind of load you'd have a smoother engine relying upon cylinder deactivation at the lowest speeds and loads.


Oh and dont knock those early engines. You cant compare a hit/miss engine to a modern one and say that was their power level, the normal engines with a governer were about the same. Things ran 600rpm at those times. And economy was not necessarily abysmal either - things like the Lister diesel were typically quoted as 255 to 268g/kwh which AFAIK is pretty comparable to modern stuff in that size range, except the Lister also was known for running 50,000-100,000 hours without a rebuild. That's 12 YEARS NONSTOP. That's why there's century old engines still running today in Alaska. Try that on your Honda.

[user removed]

People who forget the lessons of history are doomed to repeat them. I got interested in the early rotary aircraft engines 12 years ago. They were marvels of engineering and produced almost unbelievable power to weight ratios when carburetors and cooling systems were in their infancy.
I always thought you could combine the mechanical design of the rotary with all of the improvements made over the last 100 years, and end up with one heck of a powerplant when you consider the rotary is the only piston in cylinder IC engine that has no reciprocating parts.
My first design was a version that would eliminate the stroke of the pistons and act as a flywheel instead of an engine. To this day I think few people understand the potential, of recovering a 60-0 stop's energy and reapplying it for acceleration. Even fewer understand the concept of incorporation of P&G into the vehicle itself.

regards
Mech

[arcosine]

I wonder how much energy could be sorted in a flywheel of 220 lbs, the weight of my engine., E= 1/2 J omega squared.

Diameter .5 meter

J = mr^2 = 100*.25^2= 6.25 kg m^2

omega = 4000 rpm = 4000/60*2pi = 419 radians/sec

E = 1/2*6.25*419^2 = 548 MJ

Which would accelerate my 2300 lb sc1 car to:

V = sqr(2E/M)

M = 2300/2.2= 1045 kg

V = sqr(548*2/1045)= 32 m/s =52 mph (if I did the math correctly)

[stillsearching]

Originally Posted by arcosine

I wonder how much energy could be sorted in a flywheel of 220 lbs, the weight of my engine., E= 1/2 J omega squared.


V = sqr(548*2/1045)= 32 m/s =52 mph (if I did the math correctly)

I can't speak about the math, but I can say that all other experiments with flywheel based storage border on safety hazards... special substances are needed that get spun up to _25,000rpm_ to store enough energy for even short bursts of energy. RPM beats weight, even if you use weight you have to have something that will take the rpm. A 220lb flywheel would fly apart at any substantial RPM. That much mass accelerating and decelerating would probably be felt jerking the car around... and I wouldn't want a crash with a 220lb flywheel spinning thousands of RPM coming through the back seat if I could help it.

[user removed]

http://www.youtube.com/watch?v=2BQwBGKxShk&feature=plcp

FLYWHEEL BATTERIES

regards
Mech

[arcosine]

Originally Posted by stillsearching

I can't speak about the math, but I can say that all other experiments with flywheel based storage border on safety hazards... special substances are needed that get spun up to _25,000rpm_ to store enough energy for even short bursts of energy. RPM beats weight, even if you use weight you have to have something that will take the rpm. A 220lb flywheel would fly apart at any substantial RPM. That much mass accelerating and decelerating would probably be felt jerking the car around... and I wouldn't want a crash with a 220lb flywheel spinning thousands of RPM coming through the back seat if I could help it.

...You missed the point (no pun intended) if the 220 lb radial engine were a flywheel...