This is something that I find very interesting, and am wanting to get an engine fully balanced, but need to know when doing the balancing what allowances need to be made for simulation the weight of the oil in the rotors and eccentric shaft, along with any other weights that may need to be taking into account?



Does anyone have any experience with engine balancing and what tips can you give?



The engine in question is a 12A from a1984/85 SIII RX-7 (1st gen) which will be bridge ported.



Thanks for any info you might be able to share.

 

well thats the tricky part, you can assume that the eshaft is gonna be full but the rotors are a big question mark.



you may be able to get a rough estimate of it by looking at the oil level when its running at various rpms

 

It needs to be measured much closer than that, down to a few grams really if the balancing is to be accurate and worth the effort.

 

Is there nobody who knows anythng about this at all?



Or do they just not want to share it

 

The Mazda Motorsports catalogue (I believe you can view it on the web) gives a balancing procedure with weights of various rotors, bob weight values, how much to offset the bob weight, and how much extra to add for oil in the rotor.

 

Where's Dazz from. U.S or AUS.

 

I'm in Australia.



Thanks for the pointer The Kid.

 

"When the oil level insid the rotor is higher that the outer diamer of the stationary draining vane, the surplus oil is drained through radial and axial passages which are interconnected. This maintains constant oil level, and thereby eliminates engine vibration due to changes of oil quantity in the rotor." - Kenichi Yamamoto in his 1971 book 'ROTARY ENGINE' Published by Toyo Kogyo

 

i was wondering if they took the from pulley into consideration when balancign the motor and i guess they do after i foudn these holes drilled in there...

 

There should be a good understating on what you want ?

Oil volume or oil pressure?



Oil passages should always be size matched..Stay as close to oem as possible..then use royal purple oil (viscosity is key)



And yes to properly balance an engine you should balance everyhting that is on the E-shaft.



Clutch, pplate, flywheel, rotors, front weight, front pulley,



You would be surprised if you knew what 1 gram of exes or off weight is at 10000 RPM....



The blancing art is best defined on the Rx8's...a buddy of mine just picked one up the otther day, we poped his hood in my driveway and fired the engine up...

It was unbelevable to see the engine hardly move...the only thing that gave it away was the alt belt..the the precision balancing that the mazda engineers did on the RX8 is awsome...and also as it was reved.