Nice sarcasm. I'm no noob sir.

Why not worry about balancing the motor to withstand 10-12K redline? Balance the rotors for that targeted RPM. It's the floating and chattering of the rotors/flywheel/counterweight that will cause the seals to shatter. Not E-Shaft Flex. Use racing seals also. Racing seals can take a beating.

This is quoted off the mazdatrix site:

Balancing of the rotating engine assembly parts is usually only necessary for high RPM race engines, or when mixing rotors, counterweights, flywheel, or using lightened rotors. Please call for specifics before sending in your engine parts.

I don't see anything about E-Shaft flex. The E-Shaft is pretty damn strong to begin with.

or

Lighten the rotors if you are worried about E-Shaft flex. But Put Racing Seals in there for the high RPM! <--*stressing*

 

THANK YOU
I got sick of talking about the e-shaft because of those myths you mention; people who thought they knew it all and had never even seen one besides in pictures.

 

LOL,

this is hilarious, the problems with shaft flex come after ~10.5K the weight of the rotors causes the shaft to flex and the sides and tips of the rotors smack the rotor housings. there are ways to prevent this but it is difficult to get much over 12K on stock rotors.

"Balancing the rotors" 1) they are balanced 2) they are always off center so what does it matter if they are balanced.

the rotors weight 9.5 to 10.5#'s and this may not seem like a lot but then fill it with oil and see what you have. the way to get extreme RPMs from a rotary (other than porting) would be to do extreme lightening of the rotors, this is costly and takes its toll on rotors. aluminum rotors would make for incredible rpms due to the light weight. if "dry" rotors could be made out of aluminum with possible ceramic to shed heat, who knows the possibilites. maybe a siamesed 6 port would become the racing engine of choice.

but then when you get into those rpms you have to have a F1 tranny so it doesnt blow up and kill you at 17K.

there are all kinds of limitations to the rotary other than the ecc shaft, and it cant solely be blamed for high rpm flex, it is extremely strong. and the 20B has three bearings on the e shaft. that is why it cant do that. the 26B has one between every rotor i believe.

BUT Eshaft flex is not a myth, it just has more to do with rotating velocity rather than HP. with all of the oiling mods done correctly and a well built engine, your tension bolts will break LONG before the Ecc shaft

dman that was wordy
Jsutin

 

^^true^^ But E-Shaft flex still isn't a problem. The seals and heavy rotors are, which I am agreeing with you. High RPM balancing as well. Like 11K+.

 

^^^^^ E shaft Flex IS a problem, but only because of the heavy rotors. the shaft is very strong, but not invincible. fact is it wont be the first thing to break in your engine so by the time anyone is reaching a point where it will break, they already fully understand its limits and how to fix them. very small percentage of people on this forum will EVER have to worry about the eshaft, unless they run their car w/o oil

Justin

 

^^I hope you have torn down and rebuilt a rotary engine before^^

You are not convincing me. It has to do with balance. Poor balancing gives you chatter. Chatter destroys the sidehousings and seals very quickly @ high RPM.

 

i did not broke it, bougt car with it broken already...

 

^^ That sucks. But That is not from EShaft Flex.

 

isn't that from oil failure or something. I read the post those pics where first in. didnt one of the rotors seized up?

 

Ok, whatever. You know what's right, and everyone else is wrong.

To state that the e-shaft does not flex is a physical impossibility.

Yes, poor balancing gives you chatter, but balancing alone does not mean you can rev the engine sky-high. The weight of the rotors at high rpms causes force to be exerted on the eccentric shaft.

We can prove this to be correct with Mazda's engineering. The S4 NA cars had a stock 7000 rpm redline. The S5 NA cars, who's rotors were lighter by one pound, had an extra 1000 rpm before redline.
Both series of rotors recieved the same balancing method, so it is obvious that even MAZDA thinks that it is rotor mass, and not balancing, that causes problems at higher rpms.

So, continue to argue. Just let me know when the engineers behind the rotary design agree with you, and when the laws of physics on earth no longer apply.

*Yes, I have rebuilt a rotary. In fact, I have rebuilt a few. In fact, I am beginning on another one this weekend. In fact, I am building a 20B for my own car.
Have you ever rebuilt an over-revved engine? I have.*

 

I'll disagree with you there. Poorly balanced rotors put stress on everything. Yes, lightness will help, but the seals are what give out first.

I never read anything in the Mazda Manuals, other manuals, etc... that said, you can't rev pasy 7K on a Series 4 due to the fact that the rotors are too heavy.

And please keep the sarcasm down a bit.

ALSO: Those pictures above of that broken EShaft are probably from somebody dumping the clutch at a stoplight or a nice powershift. TORQUE is what most likely killed that EShaft, with the help of it being defective probably.

 

Actually, oil system failure killed that eshaft, and the bearing siezed, causing the e-shaft to spin off.

 

Ouch. So the pics are unrelated to this thread.

 

couldn't another reason behind the redline be powerband?

remember the s4 without the VDI setup the torque curve starts to fall off

but on a s5 the VDI opens up and lets the motor breath a little better

 

actually yeah i have torn down and rebuilt a couple before.

balance and weight of the rotors are two different causes and effects entirely, it doesnt matter how well you balance your rotors because as long as it is a rotary THE ROTORS WILL BE OFFCENTER. yes having out of balance rotors causes chatter, but not eshaft flex.

i dont care if i am convincing you or not, i know what i am talking about.

"And please keep the sarcasm down a bit" stop your whining, nobody likes a whiner

he said that balanced rotors alone wouldnt allow you to rev sky high and you disagreed with something he NEVER SAID. do you even know where you are??? why would mazda manuals say anything about revving above the redline??? that is why they put the little buzzer in, so it would be out of the question.

fact is a S4 motor is limited to 7000 due to the powerband more than the rotors. with the right mods you can take a stock S4 eshaft and rotors to 10.5K

The LARGEST effect on eshaft flex is the weight of the rotors, it is simple physics

Justin

 

Ok RX-7Impreza. How am I whining? I am disagreeing and creating an argument to defend my "so called" opinion, even though I am posting facts of my opinion that are all over the internet. I am grabbing my proof off of FACTS. Show me some liturature and proof to defend your staments.

How is this whining? I really don't get it. People always warned me about the "RX7forum" and how argumentive people are here with no backup for their opinions.

Please keep your namecalling/flaming to yourself, because it will get thrown right back at you.

 

dude can you even hold a simple conversation??? you have taken everything said on here out of context....

you are ridiculous. i dont need literature to know this, its common sense/knowledge, more than enough people on here have and will back me up on this. Where do you get your so called "FACTS"??? back up my information??? why?? last time i checked i am not applying for a patent... all of this is common sense, take it or leave it, worst you could do is go pay ridiculous amounts to get your rotors balanced and have the same thing you had before... oh and Mazda balances them in the factory

oh and your argument is whining at all, in fact i enjoy the challenge but this "And please keep the sarcasm down a bit. " and this Please keep your namecalling/flaming to yourself, because it will get thrown right back at you.

please do your worst, namecall away, fortunately for me i dont give a rats *** what you say about me

if you cant understand simple english in simple sentences how can you have a conversation on the internet. i am here to dispell rumors and misinformation are you here just to argue???

Justin

 

Thank you for confirming that I am arguing, not whining. And why don’t you take some grammar classes before you insult someone's English. If I remember correctly, sentences begin with a capital letter.

Why should I call you names? That would just put me at your low level.

That's right. E-Shaft flex is a Myth. Not a fact, under the conditions we provided. No proof proves it.

 

Sorry, ReZ311, but I am going to go with the knowledge of a well-known RX-7 engine builder and racer over what little proof you have provided.

You can continue to argue when you are running as fast as crispeed is with a 2 rotor engine.

 

In fact, ReZ311, after just re-reading through all of your posts in this thread, not once have you given any kind of rational explanation for why the e-shaft would not flex.

Let's look at some facts then.
1. Unless the laws of physics on earth no longer apply, any object, including diamond, will flew when any force is applies to it.
2. Unless the laws of physics on earth no longer apply, offset reciprocating motion creates lateral force.
3. Unless the laws of physics on earth no longer apply, this force increases as revolution rate increases.

So please explain to me why the e-shaft would not flex, using rational physics-based explanations. Also, please explain that to racer's such as crispeed, the crew at racing beat, and guru motorsports.

 

What in the hell are you talking about?

 

Crispeed is running 9.20 in the 1/4 mile with a turbo 2 rotor. His knowledge of building rotaries far exceeds both yours and mine. He says the e-shaft flexes.

If you read the above quote in my post, you would have realised that.

Convenient you play dumb instead af coming up with a rational explanation...

 

Why don't you guys talk abotu a 787B? Then you might see some EShaft flex.

 

Unfortunately, no, since the R26B 4 rotor motor runs 3 intermediate bearings, one in between every rotor housing.

Again, avoiding the topic. Got any proof?

Besides, this thread topic is talking about STOCK 2 rotor e-shafts. The same ones I, crispeed, Impreza, etc are referring to.
I am OWNING you right now.

 

How are you owning me? Are you 12 years old? Because you sould like it.

Proof? Ok. Then explain to me first, why does the E-Shaft flex?!

Does everybody make sure your E-Shaft isn't bent everytime you do a rebuild????