MTFCA Forum

Have any tests been made to determine if there is a difference in HP running without magnets on the flywheel.
You would have a reduction of weight on the flywheel which would also include a reduction in enertia.
Most are using 12 volt and a distributor. Also doesn't a magneto and 4 coils give better performance than a dributor as the RPM increases giving higher voltage to the coils and a more intense spark causing better combustion.
Just wondering, Henry designed it to run on mag and you sure can crank all day and get nowhere with a dead battery and a distributor.

Hey Dennis, i am not aware of any tests done but guys running without magnets report a somewhat 'snappier' engine (i.e. quicker responding to the throttle) but a loss of smoothness pulling away from standstill and/or transition from low to high gear.
All of which is easily explained by the removal of the considerable weight of the magnets from the flywheel.
The discussion between 'magnet 'n coils' and 'dizzy' is a can of worms equal to what oil to use or waterpumps

Dennis_Brown wrote: ↑

Tue Mar 05, 2024 9:30 pm

Have any tests been made to determine if there is a difference in HP running without magnets on the flywheel.
You would have a reduction of weight on the flywheel which would also include a reduction in enertia.
Most are using 12 volt and a distributor. Also doesn't a magneto and 4 coils give better performance than a dributor as the RPM increases giving higher voltage to the coils and a more intense spark causing better combustion.
Just wondering, Henry designed it to run on mag and you sure can crank all day and get nowhere with a dead battery and a distributor.

There will not be any horsepower difference running with or without magnets if the same ignition system is used in both tests. Reduction in weight of rotating mass does NOT increase/decrease horsepower numbers.

Interesting question. I believe Brent is correct, the horsepower output of the engine does not change. The question is, does the weight of the magnets rob horsepower, or merely store it? And if so, how much?

A heavier T flywheel assembly will give much smoother operation and more available low speed torque. I don't think HP would be much affected at higher speeds, other than less parasitic loss due to the turbine effect of magnets in the oil.

A 4-cylinder engine delivers 2 power impulses per revolution, so for a substantial portion of each revolution, no power, or very little power, is being produced, and thus no power can be delivered, EXCEPT for power stored in the rotating parts of the engine, including the flywheel assembly. A heaver flywheel will reduce torque peaks that occur during each revolution, and will continue to deliver torque during those portions of each revolution during which the engine is not producing any power, or very little power. A single cylinder engine would be useless without a heavy flywheel, and many have two heavy flywheels. As the number of cylinders increases, the need for a heavy flywheel diminishes.

The weight (mass) of the flywheel assembly stores torque, with very little, if any loss. The flywheel mass collects power from the crankshaft whenever the shaft accelerates, and releases it back to the crankshaft any time it decelerates.

If a flywheel was mounted on perfectly frictionless bearings in a perfect vacuum and spun up, it would continue to rotate for a very long time, maybe forever, assuming it was made of a non-magnetic material. If any part of the assembly was iron or steel or any material affected by magnetism, it would slow down and stop eventually due to interaction with the Earth's magnetic field, or any other magnetic field.

As I understand ( the Montana 500 guys will disagree because they work super hard to make sure their coils are all equally matched) stock coils
don't fire all the same & as the engine speed gets faster the accuracy of the ignition starts to break down. This limits the RPM the engine will
achieve. & that is why the racers went to using single point ignition distributers & racing magnetos. For normal everyday use I would not think a distributer would give a lot of noticeable HP improvement. In my own defense I run dizzys because I have had the misfortune to find cares &
engines with out mags or with damaged coils. As far as for racing the lighter the flywheel is the faster the RPM will increase & decrease which
is an advantage over a heavy one.
Craig.

I agree completely with Pat. The engine without magnets might be a bit faster starting out and run fairly smooth on level or nearly level ground, however it would need to be revved up a bit more when hill climbing because would not be as smooth at lower speeds.
It is interesting that although the Model A had a distributor ignition, it had a heavier flywheel than the Model T.
Norm

The Model A flywheel weighs 65 pounds, maybe more with the clutch installed.The A crankshaft is also heavier than a T. The Model A flywheel is not a flat disk...it's more like a brake drum with a a very heavy rim. This arrangement gives the engine very good low speed torque and fairly smooth operation for a 4 cylinder with a non-counterbalanced crankshaft.

I have a 4-cycle, single cylinder engine that is rated 35 horsepower at 190 RPM. It has a 14 1/2" bore and a 22" stroke. That works out to somewhere in the 800 to 1100 ft lbs of torque range. It has two heavy flywheels about 6 feet in diameter that weigh around 1350 lbs each. Without the flywheels in place, it could not run at all. With them in place, it can run at 30 to 40 RPM.

Dennis,
I have performed power measurements to determine the power it takes to run the magneto and the power to spin oil with the flywheel/magnet assembly. Those results were published in the May/June, 2022, issue of the Vintage Ford (Vol.57, no.3). Although I cannot answer your specific question the power measurements can help. Note that there is a typo on page 30 under SET'UP. For the oil drag measurements the magneto / magnet spaced was set to 0.200 inch, NOT 0.020 inch. With very thin oil (0W-20) it takes nearly 1 hp (at 1700 rpm) to circulate the oil with the flywheel and magnets with only 3 qts of oil in the system. The power requirements drop quickly as one reduces quantity of oil but there is an obvious potential catastrophe if one reduces the oil too much! I would guess that removal of the magnets would make a few tenths of a hp difference at high speed, remembering you would have to replace the magnets with paddles or something to maintain oil flow to the front of the engine. If you wish I can email you the original data and analysis that I performed. Just send me an email at dribblebit@comcast.net .
Larry Azevedo

Improving Acceleration
Vehicle Weight And Rotating Mass
Objects that are lightweight will move faster than ones that are heavy. When owners try to make their vehicles as light as possible, it will increase acceleration. It is possible to identify the heavier parts of a vehicle and replace them with lighter car performance parts. Some car owners replace their factory brakes. They install lighter two-piece rotors that are lighter and provide better performance. Doing this can also provide a significant reduction in weight. Others decrease their vehicle’s weight-to-power ratio by removing the factory flywheel and replacing it with a lighter version. A heavy stock flywheel needs more HP to get going than a lighter version. Some vehicle owners also install a lighter battery. Others change the heavy factory wheels that came with their vehicle with ones made with a lightweight alloy. A lighter crankshaft and drive shaft will also help increase acceleration

Anything on an accelerating vehicle that rotates has to be accelerated forward with the vehicle, AND "revved up". All of the engine's rotating mass, including accessories, as well as wheels, tires, brakes, etc have to gain both rotational speed and forward motion. That said, piston engines require enough rotating mass to absorb power impulses to keep the engine rotating between power impulses. Limiting rotating mass in the engine and the vehicle to what is necessary gives better acceleration in at least two ways.

I have a hill on the way to my house which I can climb in high gear when I am alone in the car, however if I add passengers I need to use Ruckstell. I can also tell the difference between my 2 Roadsters and my Touring. The Roadsters with only me in the car will climb the hill a bit faster than the touring.
I remember my dad and uncle telling about a trip to Yosemite in a Model T. They had 2 adults and 3 boys along with their camping equipment. When grandpa came to a hill the boys would hop out and push while he drove up in Low Low. That is Ruckstell Low and Low Pedal.
Norm

Norm,
Fun story but today your granddad & uncle would be arrested for child endangerment & the three boys would be in custody of CPS. The car
would be impounded & sold @ auction.
As far as the performance issue see Newtons second law of motion.
Craig.