Pinning Irons And Extra Dowels...
12-15-2004, 08:02 AM
#1
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Thread Starter
Join Date: Dec 2002
Location: Bayou-self Louisiana
Posts: 947
I assume its the set screw on the bearing. If so Id rather save my motor than lose it all if the OE tag snaps.
But a if its not that, what is the techique and ...could you talk about how people go about extra dowling the motor?
Also... how do you run an SS oil from the rear to front housing to by pass the OE design which eliminates the oil passage crack at the dowel near it.
I know that all drag rotaries were being done like this. Any pics?
But a if its not that, what is the techique and ...could you talk about how people go about extra dowling the motor?
Also... how do you run an SS oil from the rear to front housing to by pass the OE design which eliminates the oil passage crack at the dowel near it.
I know that all drag rotaries were being done like this. Any pics?
12-17-2004, 08:30 AM
#2
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Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
l8t apex,Dec 15 2004, 06:02 AM
I assume its the set screw on the bearing. If so Id rather save my motor than lose it all if the OE tag snaps.
But a if its not that, what is the techique and ...could you talk about how people go about extra dowling the motor?
Also... how do you run an SS oil from the rear to front housing to by pass the OE design which eliminates the oil passage crack at the dowel near it.
I know that all drag rotaries were being done like this. Any pics?
I have no idea what pinning is. The dowels are additional connections between the rear iron and the rear rotor housing, and in some casses between the rear rotor housing and the center iron. The Engman picture show the rear iron bored out to fit an additional stock dowel. I am guessing here.
The huge HP numbers from turbo engines bring along a problem or two. To make HP the rotor is being forced in one direction by the combustion process and the rotor housing is forced in the opposite direction (Newton) with exactly the same amount of torque. The rear rotor housing must convey the torque from the front and rear rotor housings into the rear iron that is being held from turning by the bell housing. HP=Torque X RPM/5252
In some cases the interface of the rear iron and the rear rotor housing cannot remain indexed with only two dowel tubes. Usually the upper dowel hole fails as a result of the oil passage drillings, making it a bit less stiff than the lower dowel area. It is hard to imagine the rear iron flexing to any great degree, but it does, and the iron failes through the dowel hole.
How many additional dowels are added and where I don't know. The mod is reserved for very high output engines.
I remove the tang from rotor bearings. There is no index requirement in the rotor, and it is just anothere failure mode, when pressing in the bearing. Some builders get extra bearing clearance by honing out the bore in the rotor and that looses some of the press fit of the bearing. In those cases there will be a few very small set screws holding the bearing in place. These will be through the face of the bearing, not that "end on" deal the factory used to do.
If you fear the bearing coming loose use red Locktite. Warm the rotor and chill the bearing before pressing. Do it quickly and have a shoulder on your pressing tool so it stops at full depth, and you don't push it in too far.
The extra oil line is installed to provide an extra path for oil in addition to the top dowel run to the front main bearing. The latteral drilling to the front main bearing is opened up and tapped for a dash 10 by boss fitting. The oil filter adaptor is discarded and an aluminum block is added that has ports for oil pressure, temperature, the dash 10 fitting to supply the front, and if you are running an external pump, oil in from the pump. In those cases the outer gallery that connects the banjo fitting and the outer gallery at the filter adapter is not used, and is plugged.
The picture is this adaptor block. Only the inner gallery to the rear main and dowel run is used. The big hose is from a cooler and dual filters in a remote installation. It is a dash 12 Aeroquip. The other connections are a dash 4 to the oil pressure gage and a oil temp gage bulb. The fitting that takes oil to the front bearing is not visible in this picture.
Lynn E. Hanover
I assume its the set screw on the bearing. If so Id rather save my motor than lose it all if the OE tag snaps.
But a if its not that, what is the techique and ...could you talk about how people go about extra dowling the motor?
Also... how do you run an SS oil from the rear to front housing to by pass the OE design which eliminates the oil passage crack at the dowel near it.
I know that all drag rotaries were being done like this. Any pics?
I have no idea what pinning is. The dowels are additional connections between the rear iron and the rear rotor housing, and in some casses between the rear rotor housing and the center iron. The Engman picture show the rear iron bored out to fit an additional stock dowel. I am guessing here.
The huge HP numbers from turbo engines bring along a problem or two. To make HP the rotor is being forced in one direction by the combustion process and the rotor housing is forced in the opposite direction (Newton) with exactly the same amount of torque. The rear rotor housing must convey the torque from the front and rear rotor housings into the rear iron that is being held from turning by the bell housing. HP=Torque X RPM/5252
In some cases the interface of the rear iron and the rear rotor housing cannot remain indexed with only two dowel tubes. Usually the upper dowel hole fails as a result of the oil passage drillings, making it a bit less stiff than the lower dowel area. It is hard to imagine the rear iron flexing to any great degree, but it does, and the iron failes through the dowel hole.
How many additional dowels are added and where I don't know. The mod is reserved for very high output engines.
I remove the tang from rotor bearings. There is no index requirement in the rotor, and it is just anothere failure mode, when pressing in the bearing. Some builders get extra bearing clearance by honing out the bore in the rotor and that looses some of the press fit of the bearing. In those cases there will be a few very small set screws holding the bearing in place. These will be through the face of the bearing, not that "end on" deal the factory used to do.
If you fear the bearing coming loose use red Locktite. Warm the rotor and chill the bearing before pressing. Do it quickly and have a shoulder on your pressing tool so it stops at full depth, and you don't push it in too far.
The extra oil line is installed to provide an extra path for oil in addition to the top dowel run to the front main bearing. The latteral drilling to the front main bearing is opened up and tapped for a dash 10 by boss fitting. The oil filter adaptor is discarded and an aluminum block is added that has ports for oil pressure, temperature, the dash 10 fitting to supply the front, and if you are running an external pump, oil in from the pump. In those cases the outer gallery that connects the banjo fitting and the outer gallery at the filter adapter is not used, and is plugged.
The picture is this adaptor block. Only the inner gallery to the rear main and dowel run is used. The big hose is from a cooler and dual filters in a remote installation. It is a dash 12 Aeroquip. The other connections are a dash 4 to the oil pressure gage and a oil temp gage bulb. The fitting that takes oil to the front bearing is not visible in this picture.
Lynn E. Hanover
12-17-2004, 10:05 AM
#4
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Join Date: Feb 2003
Posts: 240
Originally Posted by Lynn E. Hanover' date='Dec 17 2004, 06:29 AM
The picture is this adaptor block. Only the inner gallery to the rear main and dowel run is used. The big hose is from a cooler and dual filters in a remote installation. It is a dash 12 Aeroquip. The other connections are a dash 4 to the oil pressure gage and a oil temp gage bulb. The fitting that takes oil to the front bearing is not visible in this picture.
Lynn E. Hanover
Lynn E. Hanover
wouldn't that bypass your secondary oil pressure regulator?
12-17-2004, 03:32 PM
#5
Senior Member
Join Date: Feb 2003
Posts: 240
because so many of you have asked, this is where you typically place dowels.
there is a bit of confusion about dowel pinning, and what problems it attempts to address. If you take a typical two rotor application, the engine is built sort of like books stacked on a shelf....this "stack" is dynamic in that, without the dowel pins, the pieces could move individually of each other about 2-4mm in either direction (clockwise/counterclockwise) based on several factors, including the tension bolts, and the eccentric shaft (the pure geometry of the engine)
However, when the motor is fully stacked/assembled, the engine is held in place by several factors in the following order:
a.) the dowel pins, one set is filled with oil and used as a "go between" or a "galley" from the front to the rear of the motor, the other set is a dummy set of dowel pins, used strictly for reinforcement of the stack.
b.) tension bolts essentially do just that, they provide the necessary "tension" to the stack, that is all they do
c.) the oil pan, this provides limited structural support, but in essence, it is tied to all of the "books" in the "stack" so it can be a functional structural entity
now, the confusion arises between all of these when several methods of "fixing" this solution are proposed, one of which being- studs.
This method works by two principles, it fills the entire cavity that the OEM tension bolts normally do not fill, thus it can offer a bit of added rigidity and strength to the stack. the downside is that it bypasses all of the engineering and research Mazda has placed in the thermal expansion and overall material design aspects of dealing with aluminum and iron.
To use the stud method basically disregards the science of pressurizing an aluminum/iron stack and then placing internal stress on these components through combustion heat/expansion. With the amount of heat cycles and varying environments of pressure/abuse that a street motor will see versus the consistancy of a road racing/lemans/competition system, studs are not the solution for a street machine, it will ultimately result in "shrinking" the width of the rotor housings, resulting in failure or poor performance. If you don't think so, try it, and report back
The oil pan method works on the theory of providing structural strength to the "stack", it certainly does not hurt to do so, but it does not address the relevant issue with a 2 rotor. In a 4 rotor application and in some 3 rotor applications, the amount of "torque" being transmitted through the chassis/drivetrain relative to the amount of rigidity of the chassis itself can be a determining factor in the overall structural integrity that the engine will receive. Thus, a "flex plate" or larger oil pan (or simply a replacement for the oil pan in dry sump applications) can be implemented to facilitate the strength of the stack, but it is by no means the integral functional component of the unit. Almost all competition engines are ALSO dowel pinned.
Which brings us to the best solution, which is adding additional dowel pins, as they seem to be the only mechanism that truely addresses the main issue of rotor housing "warpage" under the extreme stress of combustion/power/torque
I am attaching a picture that shows the common points for dowel pinning, you want to dowel pin in these areas because it is where the rotor housing see the most amount of "coersion" to warp or deform.
Then I am attaching a pic that has the rotor housing "hot spot" and the typical warp path (red normal, blue after warping) to show how placing dowel pins will facilitate the structural integrity of the unit.
there is a bit of confusion about dowel pinning, and what problems it attempts to address. If you take a typical two rotor application, the engine is built sort of like books stacked on a shelf....this "stack" is dynamic in that, without the dowel pins, the pieces could move individually of each other about 2-4mm in either direction (clockwise/counterclockwise) based on several factors, including the tension bolts, and the eccentric shaft (the pure geometry of the engine)
However, when the motor is fully stacked/assembled, the engine is held in place by several factors in the following order:
a.) the dowel pins, one set is filled with oil and used as a "go between" or a "galley" from the front to the rear of the motor, the other set is a dummy set of dowel pins, used strictly for reinforcement of the stack.
b.) tension bolts essentially do just that, they provide the necessary "tension" to the stack, that is all they do
c.) the oil pan, this provides limited structural support, but in essence, it is tied to all of the "books" in the "stack" so it can be a functional structural entity
now, the confusion arises between all of these when several methods of "fixing" this solution are proposed, one of which being- studs.
This method works by two principles, it fills the entire cavity that the OEM tension bolts normally do not fill, thus it can offer a bit of added rigidity and strength to the stack. the downside is that it bypasses all of the engineering and research Mazda has placed in the thermal expansion and overall material design aspects of dealing with aluminum and iron.
To use the stud method basically disregards the science of pressurizing an aluminum/iron stack and then placing internal stress on these components through combustion heat/expansion. With the amount of heat cycles and varying environments of pressure/abuse that a street motor will see versus the consistancy of a road racing/lemans/competition system, studs are not the solution for a street machine, it will ultimately result in "shrinking" the width of the rotor housings, resulting in failure or poor performance. If you don't think so, try it, and report back
The oil pan method works on the theory of providing structural strength to the "stack", it certainly does not hurt to do so, but it does not address the relevant issue with a 2 rotor. In a 4 rotor application and in some 3 rotor applications, the amount of "torque" being transmitted through the chassis/drivetrain relative to the amount of rigidity of the chassis itself can be a determining factor in the overall structural integrity that the engine will receive. Thus, a "flex plate" or larger oil pan (or simply a replacement for the oil pan in dry sump applications) can be implemented to facilitate the strength of the stack, but it is by no means the integral functional component of the unit. Almost all competition engines are ALSO dowel pinned.
Which brings us to the best solution, which is adding additional dowel pins, as they seem to be the only mechanism that truely addresses the main issue of rotor housing "warpage" under the extreme stress of combustion/power/torque
I am attaching a picture that shows the common points for dowel pinning, you want to dowel pin in these areas because it is where the rotor housing see the most amount of "coersion" to warp or deform.
Then I am attaching a pic that has the rotor housing "hot spot" and the typical warp path (red normal, blue after warping) to show how placing dowel pins will facilitate the structural integrity of the unit.
12-17-2004, 03:37 PM
#8
Senior Member
Join Date: Feb 2003
Posts: 240
Originally Posted by 93BlackFD' date='Dec 17 2004, 01:32 PM
Then I am attaching a pic that has the rotor housing "hot spot" and the typical warp path (red normal, blue after warping) to show how placing dowel pins will facilitate the structural integrity of the unit.
the orange would be the rotor face, and no this is all chicken scratch MS paint level drawings, but you get the idea...essentially the pressure warps the rotor housing outward
rick engman has confirmed that this will occur around 18-19psi on a typical "large" turbo application
i.e, 400-420rwhp
12-17-2004, 04:09 PM
#10
Senior Member
Join Date: Feb 2003
Posts: 240
Originally Posted by Lynn E. Hanover' date='Dec 17 2004, 06:29 AM
If you fear the bearing coming loose use red Locktite. Warm the rotor and chill the bearing before pressing. Do it quickly and have a shoulder on your pressing tool so it stops at full depth, and you don't push it in too far.
this is actually frowned upon by most major engine builders, the concept behind loctite is that it is an anaerobic process by which the fluid begins to harden the minute it lacks oxygen, thus the process can be similar to pressing the bearing in with "shrapnel" behind the bearing between the rotor or gear and the bearing itself, this shrapnel can press through the bearing material as it is soft and pregnable, so the result is a compromised bearing surface
now, this may not be an issue for some because it relies on the loctite instantly or near instantly hardening, as some weaker and less commercial strengths tend to take longer as they aren't as pure or "exact" of a mixture
however, the "susbtance" is behind the bearing from day one until the bearing is removed, so whether or not you see these impressions immediately, or you notice them after a few thousand miles, a compromising element within your bearing does exist...
again, i would stick to using a press lubricant only (and perhaps freezing/heating), but no loctite- these are also issues that will come out of a motor that is built and then subjected to stress, so that could explain why some of you are able to get away with this- but i would think the purpose of using loctite is in anticipation of stress situations