RX-3 Questions.

[yetterben]

Note of concern: The fact you cracked the keg at 180,xxx and did not change the seals or housings for that matter tells me that keg did not have that many miles on it. In all of the engines i have done or custom built over 50 i have never seen one that high that did not have housing chattering or plating chipping off around the edges if not more severally. Seals can be re used sure sure. Apex seals sure sure side seals? Corner seals? Side seals are just as important as apex seals my man and i hope you got new ones and etched them down and dropped them in. Not turning this into a pissing match its good there is a fellow rotard here.

 

When you stated research i hope you don' think i am a internet warrior as this comes from years of my own experience.

 

Rotaries fail at high rpms due to bearing walk and stationery gear cracking and e shaft flex. Also because the oiling is not there threw the shaft. Torsion bolts flex in the middle iron and the whole keg stretches and allows coolant seals to shatter. When i do custom builds i have a billet sleeve that inserts threw the middle iron so the torsion bolt cant flex it has a home so to speak instead of passing threw the iron.

 

Ceramic seals are not the answer to anything neither are the unbreakable ones. They just chatter and cause massive housing wear. Its like buying life time brake pads and running regular rotors.

 

Brittle injection line where mentioned but on any rotary i have ever had its just not to be trusted non of them even the cpu controlled ones from the s5 on up. The pumps themselves made buy mikuni are just junk and fail. The older 12a are simple to rebuild sure just a few o rings. But the later ones are bad bad bad. I would think anyone could see oil oozing from a cracked nylon hose for supply.

 

Is premix the answer no but its a important key when looking at a rotary does the owner have a clue what you're talking about when you ask him if he premixes? If not well your call. Some people ran those apex's dry took off the pump after it barfed and never ran it again.......SCARY! anyway its time for breakfast.

Edited March 23, 2010 by yetterben

[spensaur]

Mmm.. So much information. Thank you guys! I learned quite a bit, i'm glad I made this thread and I'm thankful you guys are taking time out of your day to help me and post your thoughts and information you've learned over the years. Time for work

[yetterben]

Glad we could help. Old rx's are like Jaguars and Z's better to find a good chassis and a ok/bad motor than one that runs great and is rusted out. These old jap tin cars are getting hard to find parts for a rx2 or 3 is so hard to say find a good fender or whatever. Let alone floor stuff which would all need to be custom. Hell i would trade my zed right now for a decent rx3-sp. They do not exist in the midwest.

[spensaur]

Yeah, I've found three rx3's here in socal and one is stripped and one has a decent amount of rust. So we'll see what happens when I get my tax return ^^ haha. I would love an SP but I doubt I could find one here so a normal rx3 will do for me. I'm excited to get it underway with hopefully some more time on my hands with summer coming up. I'm going to meet up with my friend that has a a few donor rx7's at his house and see if I can grab some of the engines/transmissions any other parts to put into my rx3. Thanks again guys. I hope you get that rx3 yetterben. If I ever see one out here in socal and you're interested in transporting it I'll let you know.

[Guest Laocoon]

Yeah, of course, Yetterben, I love talking rotaries. I am really grateful to have a friend around here with a t2 that has been fully built uhhhh 10ish times now??? I rode with him once 0-170mph in under a mile (he let off early but said he had hit 180 with just him in the car, and would have been real close with me in the car). He has too much knowledge about just about anything... lol BlueTII on rx7club or nopistons..

 

I was on a budget when I rebuilt my engine but the rest of the seals/springs were new just apex seals were reused, and it was the first rebuild I had attempted, but it has lasted over a year of really hard driving so far. The friend I bought the car knew the history of the car, and it was the original engine, never rebuilt. But yes the engine blew about a 1" chunk out of the coolant seal under the spark plugs and just dumped the coolant out the exhaust. A 1.5hr (50min with my driving ) trip took me 5.5hrs to limp the car back without continuing to overheat...

 

I am not in the mood for a pissing contest lol You made alot of good points up there. Not every engine is the same for sure, but I had excellent luck with mine, and I wanted to show a N/A 13B could be cheap and provide more than enough power to make an RX-3 fun (wait... sporting a stock RX-3 would be fun... haha).

[zgeezer]

Not saying that you are completely wrong. You seem to have done a bit more research than anyone else in this thread, however... I disagree with your reasoning on why the rotary engine fails at high rpms...

 

Apex seals while they are metal, still flex minimal amounts just like anything. It's this flex that ends up putting the middle of the apex seal ever so slightly into the peripheral exhaust port on rotation. Notice on every engine pulled open the scaring above the exhaust port as the apex seal is forced back in from it's flex. I have not done any research on the renesis engine wearing, however the exhaust port is no longer a p-port, and rather a side port like a stock intake port. I am sure this helps the stability of the apex seal a bunch (thus the ability for mazda to release a reliable engine turning 9k... ).

 

You are right about requiring some oil flow modifications to turn higher rpms. And yes these are not all able to be solved using premix (thus the modifications)... The problem is not with the oil pump is not the failing point, but rather the brittle oil injection lines that need replacement like vacuum lines. The lack of oil in the engine causes the metal seals on the metal housings to create friction/heat. This heat will warp the housing causing points where the metal can catch on like the apex seal in the exhaust port.

 

Also at extended high rpm's the water in the water pump cavitates causing the water to not circulate correctly. Or the belt on the water pump slips causing the water pump to not turn at all which again, no circulation. If the water in the engine can't cool the engine, expansion takes place. The engine is a combination of aluminum and steel which expand at different rates causing the same issue as not letting the car warm up before getting on the throttle. This can be fixed with an electric water pump though.

 

Even with all this fixed and running an apex seal which doesn't flex as much (ceramic... less weight which means less centrifugal force causing the seal to flex). High rpms will destroy a rotary engine due to the e-shaft (basically a crankshaft for the rest of you) being pulled around as it rotates and flexes in the middle. Imagine looking at the rotor from the side and adding and subtracting camber as the center of the e-shaft flexes. You can see how the seals would not keep a perfectly even surface anywhere... However the good news is the Australians developed a center bearing which supports the middle of the e-shaft allowing tons of rpms!

 

Last thing to think about for high rpms (besides hardening of gears/lightening and balancing of rotors and e-shaft because all these forces mentioned above don't disappear, but instead get minimized by the fixes, oh and fuel delivery/spark ect...) is the drivetrain. Most flywheels can't handle over 10,500rpms. Anything that turns 9k+ rpms is required to have a scatter-shield installed around the transmission through the NHRA. Also, the balancing and protection of the "3" moving parts in the engine is nothing compared to what you would have to do to the transmission. Instead you would have to have a gear reduction to the transmission. Say a 2:1::Engine:Transmission... Build and engine that can push 18k rpms, idles at 2k... Transmission would seed 1k idle and a 9k rev limiter.

 

The rotary engine is full of rumors and superstition, mainly because if a mechanic at a shop doesn't understand what is going on, he tells his client what he thinks, and they tell someone else and they tell someone else..... and another mechanic hears about it and sees something similiar and decides it's the same thing as he has heard about... I have talked with even the rx8 mechanic at the mazdaspeed dealer close by here and couldn't hold a legitimate conversation with him cause he didn't know 1/2 of what I was talking about... I have put in YEARS of research to get rid of the rumors/superstition and get down to plain old fact... But I can't tell you much of anything about a piston engine! lol

 

Oh, how I love this site. Back in the day, I purchased a Mazda R=100 with a very small rotary that had, hold your breath for it, blew its seals. Next purchase same day at the JY next door was a13B with 5 speed out of as sedan... Rx-4, I believe. Racing Beat Holly, front caster blocks, custom header (simple two tubes out 24 inches to a collector) MSD box , Allison LED ignition and exhaust plugs. Nothing more. I beat the living crap out of that car: drove from the "House of the Rising Sun" at Ash Creek, though Beatty, and over to Tonopah (Nevada) in third gear all the way at 8000 rpm before I realized that I had two other gears..... . No torque; just RPM in numbers I'd never seen before. Smooth. Almost no vibration. Loud as hell without mufflers and a nice rasp through a muffler. I drove that car for 2.5 years and a little over 50,000 miles before it gave up. Not seals. Just a "click" one morning and it froze, piece of aluminum in the pan.

 

Now for the banker's rap. If you have access to a good clean Rx3 for the "right" price, buy it, play with the 13B Turbo II, and when you are through, put all the original running gear back in, polish the stock body, and sell it for a bunch of money to finance your next Toy. Do a google search for Mazda Rx3 for sale and spot how many clean stockers with nice paint (survivors) are selling for 4-11 thousand . Think hard about that figure and then go to Hybridz's for sale forum and see what thrills 6 or 7 thou will buy you here. Other than Porsche, there are few marks around that one can buy, drive, keep clean, beat, and then sell at anywhere near purchase price. Your Rx3 may be one of those. By the way, remember where 5th gear is and keep the rpm down to 7,000 or so and have a great time.

 

Yes, my DD is a Mazda...Speed that is as Mx5 Mazda Speed. I wish it were my old R100.

 

 

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[spensaur]

I'm so excited to pick one up. I hope my tax return makes a quick appearance haha. I'm so glad that everyone posting has taken their time to help me understand that rotaries are great engines. I will definitely admit that all I hear about them is bad things. The only time I ever heard a good thing about them was when my dad talked about my aunt's rx7 that she loved. I looked around for pricing on rx3's that are in good condition / restored and i've only found a few so far and they were listed around 10k-20k. I'm not sure what the future would hold for myself and my rx3 but I would love to keep it with me til i could pass it down to a family member. Thanks for the wealth of great information. I knew hybridz would be the best place to ask. In the short few months I was browsing this forum i learned more than I'd ever have. My friend's and peers aren't ones who share the same interest and passion as I do so I resort to countless hours reading forums like this haha.

 

So I guess the idea I'm generally getting from everyone is to get a roller rx3 or something in ok condition with no rust. Drop a 13b rebuild it, drop it in, and have fun.