Which oil modifications
11-21-15, 10:50 PM
#1
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Which oil modifications
I am rebuilding a 12A and was wondering what I need to do to the oiling system?
I have seen the oil pressure regulator mod where you press the regulator down on a press to get 80-90 psi. Is there anything else I should do? Oil pump, etc?
Thanks
I have seen the oil pressure regulator mod where you press the regulator down on a press to get 80-90 psi. Is there anything else I should do? Oil pump, etc?
Thanks
11-22-15, 12:00 AM
#2
You will need to shim the oil pressure bypass on the front cover with a couple of washers after modifying the oil pressure regulator. And depending on what year engine you have you can also upgrade to a 83-85 oil pump. And leave the oil jets, check ball and spring inside the eccentric shaft alone , modifying it with a weber jet or Mazdatrix "racing " jet is just going to give you all sorts of problems if your planning on driving on the street.
Last edited by heynoman; 11-22-15 at 12:11 AM.
11-22-15, 07:19 AM
#4
Old [Sch|F]ool
DON'T use a bigger oil pump. All that does is cost energy and heat the oil up even more.
DO use an RX-8 front cover gasket. You can either cut the water pump housing portion off or use it as-is. When you use this gasket, there is no O-ring to fail.
DO port the sharp edges out of the pump's inlet and outlet on the front side housing. The plan isn't "bigger" so much as it is "smoother".
You could mess with teardropping the oil holes in the eccentric shaft, but a 12A isn't going to rev high enough to need that without a lot of other changes so I wouldn't bother.
The critical thing is, the oil pump design sucks and cavitates easily. The larger pumps are deeper, which makes cavitation MORE likely. If you make it easier for the oil to get in, the pump will cavitate less.
DO use an RX-8 front cover gasket. You can either cut the water pump housing portion off or use it as-is. When you use this gasket, there is no O-ring to fail.
DO port the sharp edges out of the pump's inlet and outlet on the front side housing. The plan isn't "bigger" so much as it is "smoother".
You could mess with teardropping the oil holes in the eccentric shaft, but a 12A isn't going to rev high enough to need that without a lot of other changes so I wouldn't bother.
The critical thing is, the oil pump design sucks and cavitates easily. The larger pumps are deeper, which makes cavitation MORE likely. If you make it easier for the oil to get in, the pump will cavitate less.
Last edited by peejay; 11-22-15 at 07:21 AM.
11-22-15, 11:35 AM
#5
The 83-85 12As and 84-85 13Bs came with a 17mm oil pump. It's the biggest pump you can get for the 1st gen. It is a good upgrade for 82 and older engines.
While I can understand why peejay would recommend against the 17mm pump for the reason he stated, I don't recommend it at all. The reasons are:
1) it was stock on some years so going smaller would be a downgrade
2) the thread starter didn't state what his engine would be used for whether some kind of racing or street, and at what RPM the engine would spend the majority of its time
3) 12mm oil pump engines have more wear compared to 17mm engines
I've torn down enough engines to see a clear difference in condition of all parts in contact with oil. From pitted worn thrust assembly parts to bearing condition and even oil seal wear, regardless of what the engine was used for, the 12mm oil pump engines always have far more wear. This wear is usually absent or far less on 17mm engines.
The 17mm oil pump is the clear winner here.
While I can understand why peejay would recommend against the 17mm pump for the reason he stated, I don't recommend it at all. The reasons are:
1) it was stock on some years so going smaller would be a downgrade
2) the thread starter didn't state what his engine would be used for whether some kind of racing or street, and at what RPM the engine would spend the majority of its time
3) 12mm oil pump engines have more wear compared to 17mm engines
I've torn down enough engines to see a clear difference in condition of all parts in contact with oil. From pitted worn thrust assembly parts to bearing condition and even oil seal wear, regardless of what the engine was used for, the 12mm oil pump engines always have far more wear. This wear is usually absent or far less on 17mm engines.
The 17mm oil pump is the clear winner here.
11-22-15, 12:25 PM
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if you're going to port the oil pump land on the front iron, i would suggest
A. just radius the curves/sharp edges.
B. find an Rx8 front iron and copy that, its the best one.
for oil pressure, the stock 71psi is totally fine, unless you're trying to spin it higher than 8000rpm for longer periods of time. the S1 Rx8's only run 71psi, with 5-20w oil and fuel cut @9300rpm.
A. just radius the curves/sharp edges.
B. find an Rx8 front iron and copy that, its the best one.
for oil pressure, the stock 71psi is totally fine, unless you're trying to spin it higher than 8000rpm for longer periods of time. the S1 Rx8's only run 71psi, with 5-20w oil and fuel cut @9300rpm.
11-22-15, 01:09 PM
#7
Old [Sch|F]ool
The 83-85 12As and 84-85 13Bs came with a 17mm oil pump. It's the biggest pump you can get for the 1st gen. It is a good upgrade for 82 and older engines.
While I can understand why peejay would recommend against the 17mm pump for the reason he stated, I don't recommend it at all. The reasons are:
1) it was stock on some years so going smaller would be a downgrade
2) the thread starter didn't state what his engine would be used for whether some kind of racing or street, and at what RPM the engine would spend the majority of its time
3) 12mm oil pump engines have more wear compared to 17mm engines
I've torn down enough engines to see a clear difference in condition of all parts in contact with oil. From pitted worn thrust assembly parts to bearing condition and even oil seal wear, regardless of what the engine was used for, the 12mm oil pump engines always have far more wear. This wear is usually absent or far less on 17mm engines.
The 17mm oil pump is the clear winner here.
While I can understand why peejay would recommend against the 17mm pump for the reason he stated, I don't recommend it at all. The reasons are:
1) it was stock on some years so going smaller would be a downgrade
2) the thread starter didn't state what his engine would be used for whether some kind of racing or street, and at what RPM the engine would spend the majority of its time
3) 12mm oil pump engines have more wear compared to 17mm engines
I've torn down enough engines to see a clear difference in condition of all parts in contact with oil. From pitted worn thrust assembly parts to bearing condition and even oil seal wear, regardless of what the engine was used for, the 12mm oil pump engines always have far more wear. This wear is usually absent or far less on 17mm engines.
The 17mm oil pump is the clear winner here.
The bigger pumps are needed for turbo engines (more things to oil) but mainly they are a crutch for the pressure drops involved with the tortuous oil passages going into and out of the pump, and in some respects they are a step backwards.
That's my theory and I'm sticking to it, and building my engines to that paradigm.
Last edited by peejay; 11-22-15 at 01:11 PM.
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11-22-15, 01:35 PM
#8
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Street engine, street ported with weber carb and header with RB exhaust. Nothing super high powered or fancy just really my first rebuild.
Some additional questions:
Do I need to super glue the apex seals together and install as one piece or leave as 2?
Also, I needed new rotor bearings and was wondering if there is any "play" on pressing them in or if they have to be pressed in exact? By that I mean depth, can you screw this up?
Finally, what should the bearing diameter be in relation to the e shaft diameter? What is clearance there?
Thanks
Some additional questions:
Do I need to super glue the apex seals together and install as one piece or leave as 2?
Also, I needed new rotor bearings and was wondering if there is any "play" on pressing them in or if they have to be pressed in exact? By that I mean depth, can you screw this up?
Finally, what should the bearing diameter be in relation to the e shaft diameter? What is clearance there?
Thanks
11-22-15, 01:37 PM
#9
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You will need to shim the oil pressure bypass on the front cover with a couple of washers after modifying the oil pressure regulator. And depending on what year engine you have you can also upgrade to a 83-85 oil pump. And leave the oil jets, check ball and spring inside the eccentric shaft alone , modifying it with a weber jet or Mazdatrix "racing " jet is just going to give you all sorts of problems if your planning on driving on the street.
Thanks
11-22-15, 04:42 PM
#10
(2) 1/16 x 7/16 washers .... You can glue the side apex seals together no problem just don't go crazy on the glue and make sure it does not come out of the sides ...........
For the e-shaft to rotor bearing you will need about .003" of clearance .
You shouldn't have any problem with installation and long as the bearing tool you are using has a stop ring installed on it. Remember to heat the rotor and cool the bearing and use loctite .
For the e-shaft to rotor bearing you will need about .003" of clearance .
You shouldn't have any problem with installation and long as the bearing tool you are using has a stop ring installed on it. Remember to heat the rotor and cool the bearing and use loctite .
11-22-15, 06:41 PM
#11
Originally Posted by peejay
I have the "small" pump in my 13B. It makes 80psi by 4000rpm and holds it out to 10k, with no pressure drop-off that other people note as "normal". I cut open my oil filters and haven't found any debris in there yet...
The bigger pumps are needed for turbo engines (more things to oil) but mainly they are a crutch for the pressure drops involved with the tortuous oil passages going into and out of the pump, and in some respects they are a step backwards.
That's my theory and I'm sticking to it, and building my engines to that paradigm.
The bigger pumps are needed for turbo engines (more things to oil) but mainly they are a crutch for the pressure drops involved with the tortuous oil passages going into and out of the pump, and in some respects they are a step backwards.
That's my theory and I'm sticking to it, and building my engines to that paradigm.
11-23-15, 04:59 AM
#12
Old [Sch|F]ool
For the application, the big pump won't hurt, but I wouldn't go out of my way to locate one, you know?
No matter what pump goes in, i definitely would blueprint it - get out the feeler gauges and straightedge and make sure the end clearance isn't huge. The spec is in the service manual, I think .004". I also put a very - VERY - thin smear of Right Stuff on the pump where it meets the side housing.
For installing rotor bearings, I made a tool on the lathe (brake lathe
) out of an old front pulley hub. I can never get the tang lined up correctly so I just grind it off before installing the bearing. The crush fit is what holds the bearing in place. If something grabs the bearing and tries to spin it in the rotor, the tang isn't going to stop anything, and would actually make things a lot worse.
No matter what pump goes in, i definitely would blueprint it - get out the feeler gauges and straightedge and make sure the end clearance isn't huge. The spec is in the service manual, I think .004". I also put a very - VERY - thin smear of Right Stuff on the pump where it meets the side housing.
For installing rotor bearings, I made a tool on the lathe (brake lathe
) out of an old front pulley hub. I can never get the tang lined up correctly so I just grind it off before installing the bearing. The crush fit is what holds the bearing in place. If something grabs the bearing and tries to spin it in the rotor, the tang isn't going to stop anything, and would actually make things a lot worse.
11-23-15, 09:33 AM
#13
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I made my own tool out of some 4" aluminum I had. I did not make a stop ring and just kind of looked at the other rotor to gauge depth. I think I'm good but I want to make sure there is at least some room for error. I'll make a stop ring for the other one.
As for the use of Locktite, is that really important? I did on the first one but I also know that Loctite melts with heat so not sure if it is really a worthwhile effort.
Thanks
As for the use of Locktite, is that really important? I did on the first one but I also know that Loctite melts with heat so not sure if it is really a worthwhile effort.
Thanks
11-23-15, 04:53 PM
#14
Old [Sch|F]ool
Well.... Mr. Hanover used it for years, and he had been building and racing rotaries *literally* since around the time I was born (I'm 37, I'm not old!) so I defer to his judgement on matters like this.
If nothing else, it acts as a hard-setting lubricant when pressing in and helps to transfer heat from the bearing to the rotor. i haven't had one walk, or crush from heat expansion, and the bearing is DEFINITELY difficult to press out after it sets compared to an OE bearing.
If nothing else, it acts as a hard-setting lubricant when pressing in and helps to transfer heat from the bearing to the rotor. i haven't had one walk, or crush from heat expansion, and the bearing is DEFINITELY difficult to press out after it sets compared to an OE bearing.
11-23-15, 07:37 PM
#16
Old [Sch|F]ool
Disclaimer: We have a 250ml bottle of Loctite 262 at work. I use it on all flywheel/flexplate bolts and torque converter and clutch bolts, as well as anywhere else red Loctite is specified (not often, the blue is usually spec'ed). I also used it on my rotor bearings when I did them. I always preferred to use seasoned (used) bearings, but my last set of good S4 rotors had some seriously roached bearings after a front cover O-ring loss incident, over .007" clearance, so I had to change them.
My boss got that bottle for free at a drag race from a Loctite rep. I have been working for him since 2004. It was half empty back then, it's maybe 7/8ths empty now... I think the bottle is 25 years old! Price out how much the BIG bottle costs... and they gave it away for free. They lost 25 years worth of sales that day
If you are replacing bearings, bear in mind that the breakin period goes up dramatically. With used bearings, you are pretty much good to go as soon as you know that the cooling system is purged free of air (two or three heat/cool cycles). With new bearings, you need to run at least 1000mi before you really lean on the engine or run at high RPM. There is a lot of chance that the bearing goes in crooked or gets warped on installation.
My boss got that bottle for free at a drag race from a Loctite rep. I have been working for him since 2004. It was half empty back then, it's maybe 7/8ths empty now... I think the bottle is 25 years old! Price out how much the BIG bottle costs... and they gave it away for free. They lost 25 years worth of sales that day
If you are replacing bearings, bear in mind that the breakin period goes up dramatically. With used bearings, you are pretty much good to go as soon as you know that the cooling system is purged free of air (two or three heat/cool cycles). With new bearings, you need to run at least 1000mi before you really lean on the engine or run at high RPM. There is a lot of chance that the bearing goes in crooked or gets warped on installation.
Last edited by peejay; 11-23-15 at 07:44 PM.
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