Well I here a lot of stories about rotary engines but the most is that there is no real readline. I was just looking for some answers to this. thank you

 

Absolutely...they can easily rev to over 200k RPMS.



-Joe

 

One way or another, there is a redline. I know for sure that the ECU can't keep up AT LEAST after 16k RPM(might be lower, probably is) and that the fuel injectors will hit max duty cycle before too long... but as far as just the engine goes? yes there is a redline there as well. apex seals will start to chatter and the ecc. shaft will start to flex... so no you can't take your car to 10 kajillion rpm's.

 

thank you. And is it better to have a larger fuel pump even with stock injectors.

 

That sounds like a challenge

 

So I can probly hit 10.000 to 12.000 safely?

 

NO, the redline on the car is what is safe.

Anything past that and you run the risks of blowing the motor, or even worse the flywheel.

I have seen S4 flywheels come apart at 8500.

And further more the stock ignition system, as well as the ECU have trouble at 8000 RPM, well alone higher. Just put a scope on the ignition and watch the spark break up past 7000, well alone past 8000.

Then you have the problem that the intake starts running out of room at 6500 (7000 on a 89-91 non turbo), so you have breathing problems.

So, unless the motor is custom built, with a custom flywheel, with custom aftermarket ECU, do not exceed the factory redline for any length of time.

And for the rest of the answers in this thread:

Several posts in this thread have sarcastic replies, that will only confuse people. Please don't post such replies... find some other outlet for this like on AIM or some other service

 

dear god what is peoples obsession with redlines, shift where the factory tells you too, there is no reason to go past the stock redline...no more power, no neat noise, no cool factor. unless you have put 5 grand into the engine your not doing anything above 8000rpms and even if you had put serious money into it you still wouldnt be getting much past 9000k on a streetable car.

 

So is there any danger in using stock flywheels (mine's S5) @ autoxs & open lapping about 2-3 times a month?

and do you have any suggestions for an upgraded flywheel that will be durable for high rpms & not ridiculously light for daily driving?

 

A truism and a question:

Everything that rotates has a limit as to it's maximum safe rotational speed, that's why safe redline rpm specifications are published, choose to ignore them and you're asking for trouble. You may get away with the occasional foray into the twilight zone, but why take the risk?

If you want it to be safe at higher RPM's you need to buy a flywheel certified for such uses or have your flywheel balanced by a shop that specializes in this service. Remember that all rotating parts within the engine should be treated with the same respect for RPM limits.

Now for my question, why isn't 7 or 8,000 RPM enough for your application?

 

ACT makes a lightened flywheel for the S5 N/A, it's not cheap though, if memory serves it was in the $500 range...I'm not sure of the RPM spec though. You might like to check out their website for more information.

 

I forget which forum I was on, but I stumbled on a thread somewhere about some Aussie drag racers who took their engines up to 14k rpm. The were using two piece e-shafts, lightened rotors, and customs intake manifolds. Very expensive.

I think a company called GURU motorsports supplies their e-shafts.

 

Suddenly it's the cool thing to REV to 10k, I think we can thank the Idiots at Honda.net Anyhow, if you want to rev your engine to whatever stratospheric number, then go ahead. But heed this. People have lost their LEGS when flywheels & clutches have let go. THEY LOST THEIR LEGS! Go get ballistic blanket, or some scatter shield.

 

If mazda states that the redline is 7000 there must be a reason for it . If they thought It could safely do 8 or 9 or 10,000 rpm I am sure thats where the redline would be !

 

I know taking a piston up the redline and the hard acceleration kills piston engines after time, does the same hold true for rotaries? Since the action is much smoother, are they less likely to take damage from running them at higher revs?

 

the rotary engine likes to be reved up. I know a guy that has had if car for like 7years or so since he got it he always shifted at over 5-6. Also took it to redline alot when he was driving it and never had any problems. I think reving them up is good because it keeps them clean.

 

revs are the new horsepower, the higher you can rev the faster you can go, dont you guys learn anything on those honda forums? here's a reality check though the tach says 8,000rpms on a s5 the engine rotors are only moving at 1/3 that speed, the eccentric shaft is moving at 8000rpms, so see its not as cool as you thought.

 

Haha, that's laughable. Guess what? My engine continues to pull hard up to 7500 (7k redline on my s4 n/a). Wanna know what I had to do to do that? Removed the 5th and 6th port actuators/sleeves/etc, TB mod, and ported intake manifolds. I did all those at the same time and suddenly I had all the power I could want up till 7500. Cost? Not 5 grand, thats for sure... Probably more like $20.

 

Like said above.

There is no real reason to rev higher than stock settings.

All your power drops off by that point unless your ported.

The guys which do go that high have race built engines.

They do stuff like extra oil passages or somehting to help with high rev oil flow(can starve the rotors/E shaft)
They get everything lightened and balanced. They usually have a huge port which idles at 2-3k and doesn't top out until high rpms.

Basically your exceeding the stock rotational balance. Mazda only made them to rev so high.

The S5 NA's can go an extra 1k more because the rotors are lighter than S4's

So... If you went to Racing beat or who ever and got Aluminum/lightened rotors and made a Jport/P port engine tyhen you would actually use those rpms.

Dub.
All you've just shifted your power band a little higher. You've removed low end power for top end.

You may have a bit more flow due to TB mod and ports but nothing still warranting going past redline.
7500 is still pretty safe.

They say 5k because for actual power up there you usually need to do engine porting.

I remember hitting the end of the tach a few times while doing some drifting. Scary stuff to hear the engine whine that high.

 

talk to the Formula Mazda engineers i don't know what exactly the redline was on those engines, i think around 14k or so...

and there is some truth in revs = power. there's a reason F1 cars go to 18000 RPM...it's weird, F1 cars are everything that big domestics oppose, low displacement, high revs...gotta love it, lol

 

I know what you mean. I try not to go past 7500, but twice I have made mistakes. On the day I did my 15.3 1/4mile run, I was burning out for so long I didnt notice the revs, burning out stopped, looked at the tach and I saw about 7800 rpms, imediately I shifted freaked out, but then I ended up with a 15.3, beats me =|

The other time it was wet and my tires were spinning, stereo high, wasn't paying attention, and I hit 7900 according to my safc, freaked me out tons. I actually was hoping nothing bad happened from that, and so far everything seems fine. When I go back to the track this Friday my times will tell me if anything broke/got fucked

 

You got to have a reason to be that high.... I remember when I was about 17 I was doing donuts on my vert and I kept doing them and the needly stayed at 8k constantly.... I wasnt really thinking about what coold happen, but after I saw direct freaks clutch explode through his hood and through his bell housing and know I think twice, so a scatter shield is next up for me...but yea I think everything should be safe from 8k-8.5k.. since thats wat mazda posts on the tach... but you can actually feel the car slow down at that engine speed so there is no need to be up there...unless of course you are modded.. but I took a **** when I saw this guys **** explode and imagine your flywheel and clutch flying in through the floor board....dont risk yourself or your motor for some dumb ****...

 

Apart from the fact that this is complete nonsense from an engineering point of view, if there really was no redline, then Mazda wouldn't have printed one on the tacho. It's not just there for decoration...

What's laughable is that you're stating this as fact when it sounds like your car's never actually seen a dyno. Don't confuse "pulling hard" with "making a lot of noise". Your relatively minor mods are not going to have moved peak power up to 7500rpm, and neither have they made it any safer to do so.

Back on redlines, the safe rev limit of flywheels has been mentioned several times, but you must also consider the safe rev limit of clutch cover plate. I've witnessed both flywheels and clutch cover plates fail due to over-revving, and the result is pretty much the same (i.e. massive destruction). Keep that in mind when buying performance clutches if you plan on exceeding redline by much.

 

I thought their was a fuel cut to the rear rotor?

 

on the piston engines, the low displacement is usually combined with small rod movement, which inturn makes little oposing intertia on the piston returning for the next stroke. The main reason even piston engines can rev so high is because of the very short crank/rod movement.