NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   Rotary Engine Building, Porting & Swaps (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/)
-   -   Question About Rotor Bearings (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/question-about-rotor-bearings-51802/)

Mr. Midas 08-11-2005 12:56 AM

Would it be good to use them for a stock-like setup which would get autoxed now and then. Would I need to do any oil mods to keep idle pressures normal?

I've read Mr. Hannover's threads on oil related mods and definitely plan on instaling a baffle plate and modifiyng the pickup tube.

I need some professional opinions before I make up my mind weather or not to use compition bearings though. (My car is an '88 NA)







Thanks, New

Mr. Midas 08-12-2005 09:50 AM

Were is everyone? Almost three days and no replies? Pease help. I realy need some advice from experienced people, as this is my first build and I want to do it right.



Please. Pretty please? https://www.nopistons.com/forums/pub..._DIR#>/sad.png



New

treceb 08-12-2005 10:29 AM

3 days?? it hasnt even been 12 hours...



if your car will see high rpms repeatedly and/or you can afford them then go for it. dont see any harm in getting them for normal driving.

Mr. Midas 08-13-2005 09:54 AM

Thanks!

I wish I could find some good text books on rotary engine tuning and modification techniques/dynamics. Then I wouldn't have to ask such simple questions. https://www.nopistons.com/forums/pub...1047683664.gif

rfreeman27 08-13-2005 01:01 PM

normal bearings are fine. Competition ones are a little looser for cars running consistantly high oil pressure.

Mr. Midas 08-14-2005 09:00 PM

[quote name='rfreeman27' date='Aug 13 2005, 11:01 AM']normal bearings are fine. Competition ones are a little looser for cars running consistantly high oil pressure.

[snapback]748203[/snapback]

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Could I get consistantly higher oil pressures by using a turbo oil pump?

Would I need to get the high performance rear regulator as well?

I've only done a little reading here on this subject. I've heard so many people say the front regulator spring needs to be shimed as well. Isn't the front regulator like an over-pressure relief valve? Its set to keep the system from exceeding the maximum design pressure right? Or am I wrong?

So many questions.



I need to get educated...

Lynn E. Hanover 08-16-2005 09:14 AM

[quote name='Newguy707' date='Aug 14 2005, 06:00 PM']Could I get consistantly higher oil pressures by using a turbo oil pump?

Would I need to get the high performance rear regulator as well?

I've only done a little reading here on this subject. I've heard so many people say the front regulator spring needs to be shimed as well. Isn't the front regulator like an over-pressure relief valve? Its set to keep the system from exceeding the maximum design pressure right? Or am I wrong?

So many questions.



I need to get educated...

[snapback]748520[/snapback]

[/quote]





The object of increased oil pressure is to move heated oil off of the bearing to keep bearing overlay below its failure temperature. The oil in the bearing interface is heated by the imense pressure of the load, and comes off of the baring at about 1 1/2 times the oil temp you read on the gage.



The bearings are made of a tin like material or lead/indium.



So soft that you can carve grooves in them with your finger nail.



This material has a low melting temperature. Before it melts, it looses strength, and under heavy load may begin to move out of the interface area. So the bearing that has a grey dull apperance when installed may now have a shiny surface. At the edges, there may be very tiny flakes extruding and falling off and may be found in the filter. The oil may take on a silvery look from flakes too small for the filter to remove. (under 16 microns).



There is no need to improve on the stock oil system for the limited loads that autocross or similar use may imply. Observe the stock redline (or close to it) to limit bearing loads, and keep oil temps as low as possible during the competition day. Don't run for Wendy's between passes. The plate between the engine and sump is good to keep the pickup submerged.



Daryl Drummond says 160 degrees is the point where added oil temp starts to cut down power dramatically. Rotor face temps are controlled by the oil temp. The hotter the rotor gets, the smaller the amount of fuel/air that can be inducted.



Simple. Obvious.



Lower coolant temps, same thing. Warmed up just a bit. Then 150 degrees is plenty of coolant temp once the engine is broken in.



Between runs, pop the hood. Run the heater blower with the heater controls on high heat for a few minutes. Get there early. Pop the hood and let it cool. The lower the underhood temps the more power it can make.



If you will be above the redline repeatedly, modify the pickup end and throw the bug screen away.





Lynn E. Hanover

Mr. Midas 08-16-2005 11:29 PM

Very good info. You allways have something good to say. https://www.nopistons.com/forums/pub...#>/biggrin.png






Originally Posted by Lynn E. Hanover' date='Aug 16 2005, 07:14 AM
The object of increased oil pressure is to move heated oil off of the bearing to keep bearing overlay below its failure temperature. The oil in the bearing interface is heated by the imense pressure of the load, and comes off of the baring at about 1 1/2 times the oil temp you read on the gage...



...There is no need to improve on the stock oil system for the limited loads that autocross or similar use may imply. Observe the stock redline (or close to it) to limit bearing loads, and keep oil temps as low as possible during the competition day. Don't run for Wendy's between passes. The plate between the engine and sump is good to keep the pickup submerged.



Daryl Drummond says 160 degrees is the point where added oil temp starts to cut down power dramatically. Rotor face temps are controlled by the oil temp. The hotter the rotor gets, the smaller the amount of fuel/air that can be inducted.



Simple. Obvious...





This is where I'm concerned because all the housings in the motor are cermet coated.(I should have said so sooner. I appologize.) Cemets are good at repelling heat. The cermet coating on the rotor housings has been show to reduce water cooling loads by 25% alone. Some of that reflected heat is going to get into the rotors.

It looks like I was getting ready to go a little too far to compensate.

Since its going to kept below red-line, the bearings aren't realy going to get above-stock loading. But, because of the cermet coating, the rotor faces will probably see slightly hotter-than-stock temperatures. I'm thinking that all I need now is the high perf 80-85 psi regulator to provide a little more flow of oil to the rotor faces at higher rpms.



What do you think?



One other question. At what rpm or pressure do the oil-jets open. I know I've read about it somewhere before. I just cant remember what it was that opened them. https://www.nopistons.com/forums/pub...1047683561.gif





Thanks again for all the info, everyone included.


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