Huskyfan23

I know that rotary engines are completely different in terms of break down and design than piston engines, but I also know it takes a much higher RPM to go the same speeds in a rotary than it does in a piston.

In my old Eclipse, at 85 - 90 MPH the tach always read about 3600 - 3800 RPM. In the RX8, at the same speed the tach is right around the 4700 RPM mark.

The question is, if you were to constantly drive at about 85 MPH, would it be damaging to the engine? 4700 RPM's sems extremely high, especially on a consistent basis.

P.S., responses to the question asked only! I have previously posted about going 90 MPH (and how smooth it felt), and I got a ton of responses back like "Why do you drive so fast? I hate fast drivers like you". I understand that some people like to go the speed limit, but some people like to have fun.

Rootski

iTrader: (1)

No. Rotaries are not 'damaged' by revs like piston engines are, because their mass is rotating and not reciprocating. Theoretically you could drive around at redline all the time (after warming it up, of course) and the engine would be no worse for wear.

mtrevino

Without having any knowledge in the engineering aspect of the engine, it's always been my assumption the that Rotary likes the higher RPM's more. I don't think it would be damaging by keeping the tach at around 4700, considering it's only halfway to the redline.

Now if you were to ask, is it damaging keeping the tach at 8700, that would be a different story. Since the renisis engine is used a lot in racing apps, I'd think the only thing you'd have to worry about with the RPM's that high is keeping the engine and/or oil cooler than normal.

my two, uneducated cents,
michael

9291150

Why do you drive so fast? I hate fast drivers like you.

Rhawb

I thought I heard somewhere that the redline in our cars is determined by the transmission not being able to (reliably) take the revs, rather than high RPMs being a danger to the engine itself. The only problem I could foresee for the engine at high revs would be excessive heat generation - then again, I honestly barely know anything about engines in general. I'm just kind of talking about what I think might be an issue based on what makes sense to me.

ZoomZoomH

iTrader: (1)

3000-5000rpm is the cruising 'sweet spot' for the Renesis, you can tell by the sound and feel of the engine; it's not under-revved and struggling to turn over yet not over-revved and wasting unused power.

davidh

read this and draw your own conclusions as to wheather it can last at 80-90mph
http://geo.channel4.com/4car/news/ne...20&ref=archive
and
http://www.gcorbett-motors.com/mazda/news3.html

mysql101

Your transmission is spinning at 4700 rpm. Your engine is not. Your rotors would be spinning at 1/3rd that rate, or 1500 rpm. That's why generally speaking, rotaries can have less wear - they spin slower, and move in a smoother fashion.

Spin9k

You can run the engine at high revs (4500) for a long long time, that's just normal interstate running speed in 6th. Heck running it at or near readline doesn't seem to do anything bad either. I'd say the things that get difficult esp at or near redline are the cavitition possible in the water pump (cooling issues), the possible heat damage to the cat, (esp. if the mixture is leaned out by a 3rd party ECU mod for extra power), and the need to maintain oil level as it goes thru it (injecting it into the engine) fairly rapidly at those rpms.

beside it SOUNDS so nice to do this regularly!!

Huskyfan23

Thanks for the responses....it's good to hear that constant driving at 4700 RPM is not damaging the engine at all. I don't think I'll feel so bad taking it up to redline on a "multiple times a day" basis either.

You state that it's the transmission spinning at 4700 RPM, not the engine. If the transmission is doing all the work, could a higher RPM range be damaging the transmission?

I really am a newbie when it comes to this stuff. Thanks for the responses.

Huskyfan23

Could modding the ECU affect anything mechanically? I was thinking about doing it, but I heard (like turbo'ing) it can lead to damage....

nycgps

iTrader: (1)

Yep So in the other words when you see the 9K rpm on your Tach, your engine is actually spinning at 3k RPM smoothly.

Rotary should be able to *roll* much faster than 3K, but the problem is that the eccenrtic shaft cant handle the speed. Its going to twist and break.

So in short, You can keep your 9K without the fear of engine breakdown.

nycgps

iTrader: (1)

Turboing wouldnt damage your engine unless you gone crazy about it. Crappy Engine managament does

nycgps

iTrader: (1)

Well this manual tranny can handle it without problem. Auto tranny's limitation is in the Torque converter. It might explode if its constantly going above 8K rpm, and its not going to be funny (when it explodes)

Huskyfan23

Great answer! I always wondered why the Auto version of the RX8 redlined at
7500 RPM and the manual was 9000 RPM. It just became a lot clearer.

Thanks!

silverwolf

uh boy i gonna get flamed for this if i cant find it... about 5 months ago someone asked this and another responded with a video of him running his 8 at nothing below 8700 rpm for
6 min and 45 seconds...... do that with a piston and youll be dissappointed. you wont have much of a engine left. put a piston through your header maybe... or just blow up.

nycgps

iTrader: (1)

How many *regular street use* piston engine actually has higher than 8K redline ?

Huskyfan23

Doesn't the S2000?

Huskyfan23

I hope you can find it......I'd love to see it.

Rootski

iTrader: (1)

I think it's 8k, not over.

dmorales

I remember reading somewhere that the 787b that won the 24 hour le mans in 93 had it's engine disassembled after, and they claimed the enigne was in such good shape they felt the car could have run the race again.

Rotary engines are hardcore...until they blow.
________
ECIGARETTE FORUM

Huskyfan23

lol. I was about to say, if they are so great at running 24 hour stretches and maintaining high RPM Revs for hours on end, why is the reliability of the RX8 always in question?

Rhawb

IIRC (and, as usual, I could be wrong) it used to be 8500, but in more recent models they dropped it to 8000 after tinkering with the engine.

dmc27

Mostly b/c there are so few over 100k for the answer to be apparent. That, and the whole engine replacement/mutliple engines w/less than 20k thing. Oh, and that pesky mulligan incident. Add "whiners club" to those issues, too.

Rhawb

Yeah, like people say - you don't get on an internet forum to let people know that everything is rainbows and puppy dogs.