in my infinite quest to design and build the best rotary yet in an rx7 i'm tryign to go through every area of the engine and see what alternatives can be done to eliminate weight, increase power, or reliability, or all of the above. so my next question is has anyone manufactured rotors yet out of other lighter materials? what about hollow rotors? ideas? suggestions? links?

What are the ones on the renesis made out of? I like the way you're thinking https://www.nopistons.com/forums/pub...IR#>/bigok.gif



Mark

titanium?

The rotors are already hollow. https://www.nopistons.com/forums/pub...1047683664.gif





-Ted

not true... the rotors are yes open in the center but not "hollow." by hollow i mean the useless area between the apex and the center hole. thats alot of unnecessary weigth in that cast iron. now i know a certain degree of thickness is required to and the pressure but i believe that the right fabricator could actually use titanium plates or maybe inconel or even other light materials and cnc weld or laser weld the unit together incredibly reducing mass. The unit is already triangulated and anyone who knows anything knows that triangles are extremely strong designs so i dont see why a hollow core rotor would fail. probably wouldnt be good for drag racers who need that inertial energy to launch the car but for the road racers its perfect. I honestly think you could save a very meaniful level of weight which could really help these things spin up faster and higher... i mean hell they already spin high enough but a lighter rotor wouldnt have as much to worry about the g's tossing as much weight around and also hopefully avoid that dreaded dragging on the sideplates. From my rotary knowledge the only part of the rotor that touches metal(besides the gear on the inside) is the apex and oil seals correct? because titanium doesnt do well with direct metal to metal contact. I dunno maybe im just dreaming but I am an engineer and i was going through some of the machinery at a power plant im working at and it just got me thinking...

how about the traditional rotor lightenning technique of shaving weight from the outside, within the oil/side seals. this allows you to minimize the wall thickness without drastically modifying the rotor. i have a rotor next to me right now and im examining it and it seems like its almost impossible to remove material within the rotor without cutting the rotor in half or using surgical tools.



im not sure of the architecture within the rotor itself, but maybe you can just cut out the whole corner section and cast it with a lighter metal... dunno, sounds costly. or maybe find a way to effectively use renesis rotors in a 13b-rew and trim it before putting it in the engine..... should save a lot of weight.



just so you know, titanium is not recommended material for temps over 1600deg F ...... meaning it will not work for a rotary engine. maybe inconnel would be a better material if you're eventaully going to do a cut and replace type project within the motor. or near the motor's exhaust.

I have a friend in Australia who made rotors out of aluminum. he said that the Apex seal groove would wear very fast, so he made the groove larger and put a steel insert in the groove for the Apex seal to sit in. He told me it worked awesome, but was very expensive to manufacture. I remember him telling me it has to be a certain grade of aluminum, something about expansion rates. I don't remember since this was a while back.

nick (apex13b) his boss races a 3-rotor turbo that has rotors that were privately cast. and an e-shaft and turbos and so on.

1) Expansion is a major problem.



2) You can go only so light before the bearings take a beating.



3) The Mazda OEM rotors work very well.



Only NA racers might find lightened rotors worth the cost and hassle.

If it's forced induction, I doubt you'd see significant gains.



If you're going to volunteer to run experiemental rotors, by all means, GO FOR IT!





-Ted

what do you mean if the rotors are too light the bearings are gonna take a beatng? wouldnt less weight help the bearings? and yes i know they work well.. everyone works "well" but everything can also be improved on... ughh people come on... not many people leave the "box" when it comes to building their rx-7's