Rotating engine design

Hi
We have been working on a Mazda RX-7 and converting one housing and rotor
into a engine similar to the first Wankel engine that was successfully
tested in November of 1957.This engine had a stationary eccentric and a
rotor rotating at two thirds the revolutions of the housing in the same
direction.
In reading a Hanes Repair manual it says to check the compression take the
stopper from the gauge and the needle should bounce to 85 psi at each
surface when turning at 250 rpm.
As a young guy back in 1962 I rebuilt a 1955 Pontiac engine and wrongly put
1950 chev rings into it. All this engine had was 85 lb.psi pressure. It
would not start unless it was given a push start and then it was hidden by a
cloud of blue smoke.
Therefore the Mazda engine requires a duel ignition to start it the first
ignition creates sufficient pressure and blows the fuel over to the leading
edge spark plug to be ignited slightly later.
We have installed a duel point and condenser ignition we have side mounted
spark plugs, (thought was that surface plugs will fill with oil etc with the
centrifugal force of the spinning housing) The spark plug wires are
connected to two independent circular metal bands that have a sliding
contact from the coil.
Problem poor spark or no spark.
Is there an added problem by having the 45 degree dwell for two ignition
systems connected to one 12 volt battery.
The engine has a normal ground when stationary but appears to lose it when
it is spinning as sparks jump everywhere except in the spark plug when it is
spinning.
Any suggestions
Thank you
.
Ken McKenzie
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Reply to
Kenneth McKenzie
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As it was explained to me some decades ago, if an engine is set up for best performance with either one of two redundant ignition systems working, then running with both systems on effectively advances the timing, perhaps enough to be detrimental.
Conversely, if an engine is set up for best performance with both systems on, then turning one off effectively retards the timing, causing performance to fall off.
On the third hand, the microprocessor was invented in those intervening decades, so a smart person could program an engine control system to let the engine decide what is best for it, in real time, continuously.
-Mike-
Reply to
Mike Halloran
*Could* decide ignition timing in real time? That's the purpose of the ping sensor to an ECS - to keep the ignition advanced, but not so much as to provoke ping.
Brian W
Reply to
Brian Whatcott
Depends on the strategy in the ECS program.
When ping sensors first appeared, triggering them would just crank in a _lot_ of retard to prevent detonation and engine damage. Modern ECS systems are more subtle, but most of which I'm aware won't _advance_ timing beyond the default curve.
I've seen reports that an LT1's ECS _will_ take advantage of better fuel at least up to 106 Octane, when the tester couldn't find better fuel.
The ping sensor is not the only way to detect when an engine is happy. Harmon Electronics had a patented system that (mechanically) dithered the timing continuously, and used a high resolution incremental encoder (flywheel ring gear teeth and a reluctor) to measure the engine's response (delta rpm). It worked okay, but the (nearly stock) advance mechanism had durability problems because it wasn't designed for the high cycle rate. The "Optimizer" became obsolete when microprocessors got fast enough to do per-spark computations, and its simple optimization algorithm may not have been compatible with catalytic converters. The related SAE papers are interesting reading nonetheless.
-Mike-
Reply to
Mike Halloran
I have repeated all the information from the first post to keep the topic intact.
Hi We have been working on a Mazda RX-7 and converting one housing and rotor into a engine similar to the first Wankel engine that was successfully tested in November of 1957. This engine had a stationary eccentric and a rotor rotating at two thirds the revolutions of the housing in the same direction.
In reading a Hanes Repair manual it says to check the compression take the stopper from the gauge and the needle should bounce to 85 psi at each surface when turning at 250 rpm.
As a young guy back in 1962 I rebuilt a 1955 Pontiac engine and wrongly put 1950 Chev rings into it. All this engine had was 85 lb. psi pressure. It would not start unless it was given a push start and then it was hidden by a cloud of blue smoke.
Therefore the Mazda engine requires a duel ignition to start it the first ignition creates sufficient pressure and blows the fuel over to the leading edge spark plug to be ignited slightly later.
We have installed a duel point and condenser ignition we have side mounted spark plugs, (thought was that surface plugs will fill with oil etc with the centrifugal force of the spinning housing) The spark plug wires are connected to two independent circular metal bands that have a sliding contact from the coil.
Problem poor spark or no spark.
Is there an added problem by having the 45 degree dwell for two ignition systems connected to one 12 volt battery.
The engine has a normal ground when stationary but appears to lose it when it is spinning as sparks jump everywhere except in the spark plug when it is spinning.
Any suggestions
Thank you Ken . Ken
...
Thanks Mike
Actually We have already put a brass strap as a brush from the vehicle frame to a flat circular spinning surface at the front of the engine. We now are now thinking that it is too wide and could be insulating itself from the surface with oil and grit.
We have left the thing alone for the last week as we were concentrating on making a machine to cut the nine sided rotor chamber. This is done. This afternoon we purchased a 2.75 inch by 10 inch diameter steel disk to cut the chamber profile out of. This will take a lot of time as we plan to take a quarter inch deep cut from the surface every eight hours.
If all goes well tomorrow we will get back to the Mazda rotary.
The Wankel engine derives all of its power from turning a crankshaft with less than a 5/8 inch throw. and sadly even the top dead center of this throw follows the working piston surface for the first thirty degrees of piston travel.
One would think it absurd to direct the water flow at the two foot diameter of a six foot diameter water wheel.
We see a huge leverage advantage to utilizing the rotating housing to obtain power.
The perplexity that we now face is that the simplicity of the Starnine design makes the rotating housing Mazda obsolete.
Is there problems with having two ignition systems operating simultaneously?
Thanks again
As it was explained to me some decades ago, if an engine is set up for best performance with either one of two redundant ignition systems working, then running with both systems on effectively advances the timing, perhaps enough to be detrimental.
Conversely, if an engine is set up for best performance with both systems on, then turning one off effectively retards the timing, causing performance to fall off.
On the third hand, the microprocessor was invented in those intervening decades, so a smart person could program an engine control system to let the engine decide what is best for it, in real time, continuously.
-Mike- *Could* decide ignition timing in real time? That's the purpose of the ping sensor to an ECS - to keep the ignition advanced, but not so much as to provoke ping.
Brian W
Thanks Mike and Brian.
I earlier said that the Mazda engine only creates about 85 Lbs. per sq. inch when turned by the starter. Therefore the Mazda engine requires a duel ignition to start it the first ignition creates sufficient pressure and blows the fuel over to the leading edge spark plug to be ignited slightly later.
Another problem is the trailing apex seal sweeps the liquid fuel ahead of it in the cold engine so the fuel is confined to the trailing edge of the rotor.
Another problem is that the fuel combustion takes place where it is ignited and advancing the rotor past the center axis does not stop the rotor from wanting to spin backwards when the ignition is on the trailing edge.
The first rotary engines had to be rotated at 2000 rpm to start them.
We believe that the solution found by the rotary engine developers was to provide a duel ignition the first would be a poor one but sufficient to raise the internal pressures and blow the fuel to the leading edge of the rotor for the second spark to ignite and apply substantial pressure on the leading side of the rotor surface..
I am not aware of spark advancement on the Mazda rotary but I could be wrong. I will look in the manual tomorrow.
In every conventional point and condenser automobile ignition the 12 volts is only used when the starter is turning and a resistor reduces the voltage to six volts when the engine is running.
In our Starnine engine we are contemplating using pressure switches in place of the conventional points. As the engine is in the compression stroke it will close the circuit through the coil when the apex seal sweeps past the holes the pressure will be gone and the circuit will remain open during the intake stroke.
This is a simple way to time the non rotating Wankel rotary engine also.
If we have missed something regarding the pressure switches let me know.
My plan is to use two batteries and have the two sets of points work independent of each other so we can start the rotating Mazda engine.
I have also noted that one of our sliding contacts is to short and we are going to remedy that.
Thanks again
Reply to
Kenneth McKenzie

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