I have a rotor housing theory question for you: One of my own 12A rotaries had the typical rear-rotor lost-compression failures, ie: the engine was barely able to run, and only on the front rotor. Limped home thinking my apex seals had failed like last time, but inspection found all six seals intact and not stuck in their grooves. Teardown revealed that the rear rotor housing had exactly the catastrophic chrome flaking as that shown in the above video, with most of the chrome from the spark plug areas to and beyond the exhaust port missing. A little history on this engine: This car, a bone stock '85 RX7 GSL 12A was purchased used with about 100,000 miles on it. I replaced the bee hive oil cooler with an under-rad unit from a series 2 RX7, and installed a Richard Sohn-designed oil metering pump adapter with a gravity-fed 2-cycle oil reservoir, using a block-off plate at the OMP so that the system fed only 2-cycle oil from the reservoir rather than pulling in dirty 4-stroke oil from the sump. Talking to another rotary guru about the cause of the chrome flaking, he suggested that the minor flaking at the edges of the rear housing gave this 2-cycle oil (which mixed with the fuel in the 4-barrel carb fuel bowls) a place to work its way under the edges of the flaking chrome, causing scads of it to depart. Does this make sense as a contributing factor? Heat certainly played a part considering the location of the flaking, but the housing was not showing any of the expected warpage and coolant seal deterioration that I'd have expected from excessive heat. Thoughts?
@@RotaryEngineRebuilds How degrees can you advance the ignition timing at idle before you start to run into problems? My prototype reduces engine knock and I what to see if A rotary engine is worth modifying with it. I have A video of it being used in A piston engine so far.
@@787brx8 Sorry, I do not know the answer to the question. Rob Golden would have. I helped create the videos but Rob was the Mazda rotary engine expert who has passed away :(.
You like a pretty smart guy, I thought I would shoot this idea past you. I used to have a Suzuki motorcycle I also used to have a few rx-7s. I never came up with this idea in till just recently as a truck driver I became interested in the RX-9. What if the RX-motors didn't have side ports? What if the RX motor had the same size port as the exhaust port or slightly longer or taller just above the exhaust where the intake is now but at 10 or 2 o'clock depending on what side you look at. It would get a great deal more air than it does now. As the rotor pulls away it would suck in more air than the side port. Also a reed valve would be just inside the intake port to prevent any exhaust gas from going back through the intake port on the exhaust stroke of the rotor... It would be basically be like a two stroke motor in a rotary design instead of a piston design, the best of both worlds... I think it would work? Of course the that whole side of that motor would have to be redesigned, but think of the power. It could change it's fuel wastfulness problem...
This might be a dumb question but say you have used housing that look pretty good .. deff usable is there anything you have to do to the surface to "prepare" it for a rebuild/to be used . or just put in the new seals and such as normal?
I have a rotor housing theory question for you:
One of my own 12A rotaries had the typical rear-rotor lost-compression failures, ie: the engine was barely able to run, and only on the front rotor. Limped home thinking my apex seals had failed like last time, but inspection found all six seals intact and not stuck in their grooves.
Teardown revealed that the rear rotor housing had exactly the catastrophic chrome flaking as that shown in the above video, with most of the chrome from the spark plug areas to and beyond the exhaust port missing.
A little history on this engine: This car, a bone stock '85 RX7 GSL 12A was purchased used with about 100,000 miles on it. I replaced the bee hive oil cooler with an under-rad unit from a series 2 RX7, and installed a Richard Sohn-designed oil metering pump adapter with a gravity-fed 2-cycle oil reservoir, using a block-off plate at the OMP so that the system fed only 2-cycle oil from the reservoir rather than pulling in dirty 4-stroke oil from the sump.
Talking to another rotary guru about the cause of the chrome flaking, he suggested that the minor flaking at the edges of the rear housing gave this 2-cycle oil (which mixed with the fuel in the 4-barrel carb fuel bowls) a place to work its way under the edges of the flaking chrome, causing scads of it to depart.
Does this make sense as a contributing factor? Heat certainly played a part considering the location of the flaking, but the housing was not showing any of the expected warpage and coolant seal deterioration that I'd have expected from excessive heat. Thoughts?
Not at all, the issue lies at the feet of the quality of electroplating of the chrome period, the adhesion of the Cr to Fe is factory issue.
This video looks like it was filmed in 1976.
2006
@@RotaryEngineRebuilds How degrees can you advance the ignition timing at idle before you start to run into problems?
My prototype reduces engine knock and I what to see if A rotary engine is worth modifying with it.
I have A video of it being used in A piston engine so far.
Great year.
@@787brx8 Sorry, I do not know the answer to the question. Rob Golden would have. I helped create the videos but Rob was the Mazda rotary engine expert who has passed away :(.
Excellent video. Thanks 😊
You like a pretty smart guy, I thought I would shoot this idea past you. I used to have a Suzuki motorcycle I also used to have a few rx-7s. I never came up with this idea in till just recently as a truck driver I became interested in the RX-9. What if the RX-motors didn't have side ports? What if the RX motor had the same size port as the exhaust port or slightly longer or taller just above the exhaust where the intake is now but at 10 or 2 o'clock depending on what side you look at. It would get a great deal more air than it does now. As the rotor pulls away it would suck in more air than the side port. Also a reed valve would be just inside the intake port to prevent any exhaust gas from going back through the intake port on the exhaust stroke of the rotor... It would be basically be like a two stroke motor in a rotary design instead of a piston design, the best of both worlds... I think it would work? Of course the that whole side of that motor would have to be redesigned, but think of the power. It could change it's fuel wastfulness problem...
Paul Bickley bit late but you've descibed almost word for word a peripheral ported engine haha
Thx for the video...
This might be a dumb question but say you have used housing that look pretty good .. deff usable is there anything you have to do to the surface to "prepare" it for a rebuild/to be used . or just put in the new seals and such as normal?