What's so bad about rotary engine?

[daatguy]

I've been looking at couple rx7 & rx8s and i love it.
But whenever I see reviews about the cars, or ask my friends, they say rotary engines suck.
I asked everyone's best friend, google, about it but the answers I have found is very confusing to me.

Can you guys help me why rotary engines 'suck so much'?

[spikerS]

on paper, they are the cat's ass. On paper they are awesome compared to the standard engine, even of today.

In reality, they are notoriously un-reliable, and a PITA to fix.

[ryanallan]

the problem is that people dont know what they are talking about

[daatguy]

how does rotary engine work ??

[B4tMan]

it works in an unreliable, expensive to maintain fashion

[Graham_A_M]

The apex seals can't typically handle boost. Very very few people know those (grenade fragile) engines well.. those that do have great experience and great things to say about them, but unfortunately that said group of people happens to be very small in numbers, much unlike the people that own them.


Originally posted by daatguy
how does rotary engine work ??

With this comment, I strongly suggest you steer clear of these engines, since I feel you'll be one of these guys that doesn't know how to take care of them: and will be part of the majority that has incredible amounts of problems with these cars in general.

[revelations]

Rotarys are like turbo-engines - people should be educated before they drive em.

[Ekliptix]

Originally posted by revelations
Rotarys are like turbo-engines - people should be educated before they drive em.
:werd: like a jetta, I can't believe VW lets people drive those things without schooling.

[B4tMan]

a jetta, can't believe VW lets people drive those things without schooling.

it's ok, some of us can't believe people willingly choose to drive them


jokes aside, why do you say that ? how's it different from most turbos

[whiskas]

Originally posted by daatguy
how does rotary engine work ??

triangles... spinning

[Ekliptix]

Originally posted by B4tMan


it's ok, some of us can't believe people willingly choose to drive them


jokes aside, why do you say that ? how's it different from most turbos
me? From everything I've heard, they're unreliable, terrible on gas, and don't have greater performance to vehicles of similar cost.

[Kloubek]

ok... I've owned a few of these. Even had one blow on me. Here's the TRUE goods:

The Rotary is a FINE engine. The size/hp ratio can't be beat. The inherent nature of their mechanics make them exceptionally smooth. They sound neat too - as they make a slightly different note than a piston engine. Also, they handle boost just fine. If they didn't, then turbo models would never have been made. They are also lighter and smaller - which is especially positive for a small car like the RX7.

The only real negatives to a rotary are fuel and oil consumption, which are excessive for the size of engine. Still, not ridiculously so.

And the last negative - maintenance. These are fragile engines. The seals will fail if the engine is not meticulously maintained. This means oil changes EXACTLY as required; even more than normal if you want to be safe. It means not letting them overheat; not even once.

A properly maintained engine will technically last longer than many piston engines, due to MUCH fewer moving parts. But again - if they are not properly maintained, they will blow withoput much warning, and are super expensive to fix.

For more on how the rotary works, click here:
http://www.youtube.com/watch?v=oGrD7FTFLJc

This is just the first one I found. There is plenty of info on the 'net if you know how to use Google.


Originally posted by Weapon_R


Everything.

See - it's blanket statements like that which people see online which gives them a false opinion of the engine.

[Weapon_R]

Originally posted by daatguy
What's so bad about rotary engine?

Everything.

[RX_EVOLV]

I hope everyone who replies to this thread actually have real life experience driving/working with Rotary engines.. otherwise it's all just :bullshit:

I do agree that the biggest problem is the buyer doesn't know what a rotary engine is before buying it, and therefore cannot maintain it properly. If you buy a Rx8 then bitch about the bad mileage (for example), you are one of those ppl....and to be honest it's not as bad as ppl make it out to be. Instead of getting like ~12L/100km out of a 350z or sti or whatever, you are probably going to get ~13-14L/100km. Of course then they are going to say it doesnt have the straight line speed/power of a 350z or a STi. A rotary fanboy will reply by telling you to go buy a Mustang if you want speed. blah blah .. it will go on and on and on...

regardless. Maintenance wise, 3 years and not a single problem so far.. *knock on wood*

[SRT10Killer]

you can find good condition rx7's both rhd and lhd for low-ish price with a rebuilt engine, just try to find once with 3 MM apex seals, mostly stock, and a complete engine rebuild

[Kloubek]

See - that is the biggest problem. Nobody knows how well the previous owner maintained it, so it could potentially be due for a rebuild at any time. And even if it was recently rebuilt, it is tough to know if it was done properly. (Though it usually is, since most shops will not touch a rotary... so the only place to get it done is a place like RX7 specialties...)

In the end, I have decided to stay away from used rotarys for the reliability/maintenence issue. (Plus the fact that the RX8's don't have *quite* the power I am looking for. Shame they never made a turbo version.)

[Ashkente]

Originally posted by ryanallan
the problem is that people dont know what they are talking about

QFT :werd:

[hampstor]

Originally posted by Weapon_R


Everything.

Diagram of the problem:

http://lolinter.net/apexseals.gif

[dj_honda]

After working on a friends RX7, I have to say I kind of I don't mind them so much. If you are mechanically inclined I think they are interesting engines and should consider owning one. They sound pretty cool, are light and can make decent power. The thing is, for major work there is no one local (Except rx7 specialties....I've heard both good and bad about them).

I think if well taken care of from the beginning they would be a decent car to own. THere are a lot of annoyances with them though such as for instance, how easy they are to flood, even bone stock. I can only imagine what it would be like if they had upgraded injectors LOL.

I would definitely consider a LHD rx7 turbo now, probably mess around with the rotary until it blows, and replace it with an LS6 or something :P

[ShermanEF9]

Originally posted by hampstor


Diagram of the problem:

http://lolinter.net/apexseals.gif

this :rofl:

But yeah, the biggest things is the apex seals... they like to blow and cause all sorts of issues... if you're looking for reliable fun, steer clear...

[Deetz]

I had fun driving the rx7 i used to have, but they sure are hard on gas, and some times like to flood for no reason.

[soobad]

I daily drove a big-single-turbo FD Rx7 with a 13b rotary every day for almost 2 summers. It was a PITA, always having to put oil in it, waiting for the engine to cool down when parking (before I got a turbo-timer) etc.

It wasn't particularly good on gas, etc. But I can't fault the reliability when it was taken care of.

I'm now putting a 2004 LS1 into that same car, if that tells you anything...

The main problem is that all the people that could fix a rotary engine for you which is a very small #, are vastly more likely to screw you over, and it's just generally scary and annoying to own a rotary engine. It's much less stressful and there is no reason not to just get a "regular" car.

[Kloubek]

Originally posted by Deetz
I had fun driving the rx7 i used to have, but they sure are hard on gas, and some times like to flood for no reason.

Actually - this is a good point. The 2nd gen (86+) liked to flood, which gets really annoying and kinda scary when you can't get your car running.

If you do buy one, I suggest getting a kill switch for the fuel pump, and use that to turn off your engine before the ignition switch. That way, there is no excess fuel that can flood the engine on next startup. Kinda a Mickey-Mouse kind of fix, but it works.

Don't let the fuel consumption deter you. They aren't the most efficient engines in the world, but they are not nearly as bad on gas as people here are making them out to be.


Originally posted by Infinity888
I own a RX8... And flooding (i actually just had this happen to me for the first time last week) if you turn the engine off when its still cold there is a chance it will happen, i drove about 30ft, rookie mistake.

I thought this flooding issue was fixed in the Renesis engine. Guess not. That's pretty sad actually - I'm sure the Mazda engineers could have figured out a way to keep it from happening again....

[Infinity888]

I own a RX8, downsides would be fuel and oil consumption. i get ~18mpg but the 350z (closest comparable car imo) gets ~19mpg so no big difference there. occasionally have to add oil (the rotary uses it in the engine to lubricate) every 2-3 fill ups usually. And flooding (i actually just had this happen to me for the first time last week) if you turn the engine off when its still cold there is a chance it will happen, i drove about 30ft, rookie mistake.

[Trini]

Originally posted by hampstor


Diagram of the problem:

http://lolinter.net/apexseals.gif


:rofl: :rofl: :rofl:


I'll admit I love the sound of a rotary engine,such a distinctive sound.

[tentacles]

A rotary isn't just a car, it's a LIFESTYLE.

[Sugarphreak]

....

[gcoap]

The other issue you might run into is the fact that the RHD RX-7's are dam small inside. Make sure you fit inside before you even think of buying one.

[Tomaz]

Originally posted by gcoap
The other issue you might run into is the fact that the RHD RX-7's are dam small inside. Make sure you fit inside before you even think of buying one.

Quoted for truth!

I am 6'2" and can't even wedge myself into the passenger side of a JDM RX-7. Those cars are not "white-man friendly".

[jjmac]

Originally posted by tentacles
A rotary isn't just a car, it's a LIFESTYLE.

:rofl:

[snoop101]

I heard that theres something inside the engine that if it breaks you cant repair it and you need to throw out the engine. It was that or when they do break that it costs to much to repair the insides because its not like a conventional engine.

But they are amazing engines. My dad used to race a NSU spider with a wankel motor. It was before my time, but he said that he used to take off on all the american cars in the hill climb's. Very high rpm.

[bourge73]

well when the coolant seals (internal) go thats it time for a rebuild...

[Cos]

http://dclips.fundraw.com/zobo500dir/liftarn_Hand_grenade.jpg

[DonJuan]

http://www.theburningbiscuit.com/Pictures%20for%20site/Demotivational%20Posters/UserCreated%20-%20ALL/rotary-400.jpg

LOL

[RX_EVOLV]

FYI if you are planning to buy a RX8, they all (03+) come with 8years/160k warranty on the engine standard.

[Doozer]

Originally posted by daatguy
how does rotary engine work ??
Normal engine:
http://rapidforceexhaust.com/images/cylinder_animation.gif


Rotary engine:
http://www.rmutphysics.com/charud/invention/invention2/rotary-engine/RotaryEngineAnimation.gif

[Tomaz]

^^^ No matter how many diagrams I see, it still confuses the crap out of me. :(

[Xtrema]

Originally posted by tentacles
A rotary isn't just a car, it's a LIFESTYLE.

One that keep you in the garage every weekend (which can be a pro or con)

[heavyD]

Originally posted by Tomaz
^^^ No matter how many diagrams I see, it still confuses the crap out of me. :(

Really? One has a piston going up and down in four cycles, the other shows a lobe (rotor) rotating. It's pretty obvious from the depiction that everything hinges on the condition of the apex seals for the rotary to work which is the major weakness of the design.

The Wankel engine is a really interesting concept. In reality not so good at providing reliable transportation for the average commuter under varying loads/speeds and extreme elements that are placed on automobiles. If you know what you are getting into and have a mechanic that knows rotarys you can have alot of fun. Otherwise best left to the people that actually think it's a good idea.

[craigcd]

I have had 3 RX-7's 2 were low KM and the other rather high . I did nothing besides standard maintenance and didnt ever have a problem. Great cars IMO the biggest issue is the lack of information.

[Kloubek]

Originally posted by RX_EVOLV
FYI if you are planning to buy a RX8, they all (03+) come with 8years/160k warranty on the engine standard.

Does this apply in the US too? (Wondering if a US import would also have this warranty...)

[01RedDX]

.

[soobad]

Originally posted by Tomaz


Quoted for truth!

I am 6'2" and can't even wedge myself into the passenger side of a JDM RX-7. Those cars are not "white-man friendly".

I'm 6'4 and 195lbs, and I fit just fine into my LHD 93' FD-RX7, granted, I have a momo race steering wheel and that helps a LOT. With a regular wheel it would be hard to angle myself under it and fit comfortably I imagine.

Really looking forward to enjoying the car once it has it's new LS1 V8 in it... :bigpimp: :angel:

[B4tMan]

Originally posted by Infinity888
the 350z (closest comparable car imo) gets ~19mpg so no big difference there [...]

unless you're from ponoka, the ~50% more power does create quite an advantage

[epp01]

I swapped in a 5L 302 with a 600 carb it got BETTER fuel economy then my 13B ever did haha. This was in an FC.

[Akagi Redsuns]

Originally posted by SRT10Killer
you can find good condition rx7's both rhd and lhd for low-ish price with a rebuilt engine, just try to find once with 3 MM apex seals, mostly stock, and a complete engine rebuild

3mm? Why would you want to use what are usually out-of-spec rotors with the hardend edges machined off and adding 50% more friction area to boot? Anyways, you know where I stand on the 2mm vs 3mm debate :)



Originally posted by soobad


I'm 6'4 and 195lbs, and I fit just fine into my LHD 93' FD-RX7, granted, I have a momo race steering wheel and that helps a LOT. With a regular wheel it would be hard to angle myself under it and fit comfortably I imagine.

Really looking forward to enjoying the car once it has it's new LS1 V8 in it... :bigpimp: :angel:

JDM in the last post = RHD. I'm 6'1 and could not cram myself into a RHD but have no problems with LHD versions. They made the seat tracks way shorter for some reason, maybe because of the rear seats. Have the same issue with the FC.

[Crymson]

Originally posted by Akagi Redsuns


3mm? Why would you want to use what are usually out-of-spec rotors with the hardend edges machined off and adding 50% more friction area to boot? Anyways, you know where I stand on the 2mm vs 3mm debate :)

Agreed! The only reason we use 3mm seals here is because it's cheaper to mill a rotor than get a new one. 3mm = crap, nothing like a brand new rebuild that makes 80 psi because the seals "seal better at high rpms"



Originally posted by Akagi Redsuns


JDM in the last post = RHD. I'm 6'1 and could not cram myself into a RHD but have no problems with LHD versions. They made the seat tracks way shorter for some reason, maybe because of the rear seats. Have the same issue with the FC.

Exactly. I'm 6'2 200 lbs, and had no problems what so ever with my LHD fd, but couldn't even get into a RHD drivers seat. The seat rails seem to be about 3 inches shorter due to the rear seats.

I loved my FD, coolest, most fun car i've ever owned. And it was reliable. It had over 125,000 km's on the orginal twin turbo motor and it was strong, clean, and fun to drive. No problems so long as their not ridden hard and put away wet.

[ThatRx7Guy]

I loved my FC. But like most have mentioned, the apex seals went. A quote comes to mind with the rotary engine: Works 60% of the time all the time.

[Consumer beware]

I am wondering if someone can help me. Purchased a 2004 Rx8 in May/09. Obtained service records. Previous ownwer in Calgary had car for one year. First owner out of Edmonton and service records/hisistory done on vehicle. Engine failed one month ago. Service Mgr. indicated warranty extended to 8 years but needed to prove all oil changes. Have retrieved 7. Car has 81000 kms. Previous owner in Edmonton had work done at Abbey Road Automotive (now out of business)..tracked the previous employee of Abbey Road Automotive and he will not help me in obtaining records. Then found out he himself is the Service Mgr at Jarmin Mazda....and owned 40 percent share in Abbey Road Automotive. Mazda is denying the warranty saying that I do not have sufficient oil change receipts. Lack of oil was/is not a problem with this car. It was always well maintained and seviced. Cost to replace engine 5700. 00 PLUS they are charging me 300.00 to diagnose the problem. Blown Apex seal or hole in rotor they say?
Can anyone help me? I am having a helluva time even getting contact info. Both the Regional Service Rep and Customer Relations are basically regurgitating the local Service manager's position that even though I have records for 7, they say that in order for them to put work under warranty, I require 6 more receipts. I am interested in obtaining some concrete assistance. Please forego the shoulda known better remarks...believe me, harder on myself than you anyone of you could be.

[shizzay]

you know how you know that these engines suck?!?! because if it was such great technology and an efficient engine other car companies would have started to use it. and mazda would put it in all it's vehicles. the fact is that your better off with traditional combustion. personal opinion.

[Hamann]

Rotary Engines are alot like Communism... Both work great in Theory, but they seem to fail in practice

[psycoticclown]

Haha, I love all those rotary quotes.

How much does it cost to swap in a LS1 anyways.

[g-m]

less than $5700. I was looking at sbcs with my buddy for swapping into his 240Z and it looked like if you looked around you can get an engine+tranny for 2500-3000$

[bourge73]

believe that the OP would be looking for a dealer installed engine and 5000+ seems legit. I ve owned one (FC) and had the seals go on it and wont be owning another one. Wish you the best man, would try to track down what you can for receipts as Mazda seems to be holding firm on that position. Guess there is something to be said about getting oil changes from the dealer on new (er) cars as doing it "yourself" may cause future owners major headaches.

[revelations]

Originally posted by Consumer beware
I am wondering if someone can help me. Purchased a 2004 Rx8 in May/09. Obtained service records. Previous ownwer in Calgary had car for one year. First owner out of Edmonton and service records/hisistory done on vehicle. Engine failed one month ago. Service Mgr. indicated warranty extended to 8 years but needed to prove all oil changes. Have retrieved 7. Car has 81000 kms. Previous owner in Edmonton had work done at Abbey Road Automotive (now out of business)..tracked the previous employee of Abbey Road Automotive and he will not help me in obtaining records. Then found out he himself is the Service Mgr at Jarmin Mazda....and owned 40 percent share in Abbey Road Automotive. Mazda is denying the warranty saying that I do not have sufficient oil change receipts. Lack of oil was/is not a problem with this car. It was always well maintained and seviced. Cost to replace engine 5700. 00 PLUS they are charging me 300.00 to diagnose the problem. Blown Apex seal or hole in rotor they say?
Can anyone help me? I am having a helluva time even getting contact info. Both the Regional Service Rep and Customer Relations are basically regurgitating the local Service manager's position that even though I have records for 7, they say that in order for them to put work under warranty, I require 6 more receipts. I am interested in obtaining some concrete assistance. Please forego the shoulda known better remarks...believe me, harder on myself than you anyone of you could be.

Not sure how we could help :dunno:

The RX8 warranty policy requires logged, explicit procedures to be completed because, as mentioned in this thread before, even missing out on one oil change can kill a rotary.

If you were missing one receipt, probably not a huge deal, but 6 is a lot in this case.

[revelations]

Originally posted by shizzay
you know how you know that these engines suck?!?! because if it was such great technology and an efficient engine other car companies would have started to use it. and mazda would put it in all it's vehicles. the fact is that your better off with traditional combustion. personal opinion.

Its problematic because most people who own rotaries treat them like other vehicles and thus, get lazy when it comes to regular maintenance. Rotaries are even more maintenance intensive than turbo engines.

Thats why they arent offered in other vehicles - owner apathy.

[Maxt]

Its not really a maintenance thing, and every year of rotary has had its own unique issues, which some were not directly to do with the engine design, you can't generalize like that.
I drove the piss out of my FC on the track and the street this year, on the same plugs on oil all year long. On that particular car all I have done on the engine is change the plugs and oil every spring and thats it. And every shift at lapping days was on the limiter at 10,200 rpm, on all stock engine internals.
Once you get them dialed in , they are pretty robust power makers.