Why Do Rotaries Suck?

[Sydneykid]

If you read my post again, I did not say that rotaries were unknown in the 80's or that they weren't attracting any type of following by enthusiasts. Having been involved in the rotary scene through the late 80's & then 90's, it's my impression (and it's been written before elsewhere by others) that the rotary following really took off in the early to mid 90's.

To further emphasize this point, show me early 80's car magazines that regularly featured on the front cover a hot rotary? Sure, you may be able to point out one or two (I don't know of any personally), but through the 90's newsagancies were exploding with magazines specifically targetting rotary enthusiasts (Hot4, Fast 4's, Tuffest rotaries, How to build a rotary engine etc etc).

How many rotary engine vehicle events were held anywhere in Australia in the early 80's? My guess, probably very few, if anything at all. Nothing like the 4 & rotary Jamboree which started in the 90's and still in existence today. Go on rotary cruise in the 80's and you were going with a handful of cars. I have video from the 90's on a cruise with literally hundreds of rotaries & enthusiasts.

Even in the late 80's, performance parts seemed few and far between, finding a rotary specific workshop was hard as there wasn't very many, and bumping into another car enthusiast who hadn't even heard of a rotary was common. I could go on and on, but I probably have bored you already!

I guess its subjective, but having been there, it's my opinion that rotaries really become popular through the 90's, not before.

Thanks.

You're both Johnny come latelies, it was the early '70's. Check out your history, 1971 Bathurst Hardie Ferodo 500 first in Class C Mazda RX2.

The revival in the late 80's early 90's was due to turbo chargers and the realisation that at 3.9 litres a 13B made a good turbo engine with it's low compression ratio. Hence overcoming one the rotary engine major drawbacks, the inability to achive high compression ratios.

Cheers

Gary

[ylwgtr2]

You're both Johnny come latelies, it was the early '70's. Check out your history, 1971 Bathurst Hardie Ferodo 500 first in Class C Mazda RX2.

The revival in the late 80's early 90's was due to turbo chargers and the realisation that at 3.9 litres a 13B made a good turbo engine with it's low compression ratio. Hence overcoming one the rotary engine major drawbacks, the inability to achive high compression ratios.

Cheers

Gary

Im sure it was....i do get the point by the other guy about the hype...but i think its more to do with the average guy (no so much the guy that does his own engines/spannering ect) jumping on the rotary bandwagon....further more....he asked for my own experience....i wasnt at bathurst in 71....Its my memory of the early eighties,that they were quite fast after a bit of porting and the power to weight ratio of those paticular cars at that time were very impressive

[bozodos]

lol interesting reading apart from the tl;dr posts about physics etc. Most of the rotor forum invaders have done nothing to help their cause, they are nearly as bad as the muzza's from Calais Turbo lol.

IMO rotaries suck pure and simply because they are impractical as a street car or a daily in any form. That and the insane fuel consumption.

[warps]

So, Rice and SydneyKid both agree that in a full cycle, a 13B is a 3.9 litre (2 stroke vs 4 stroke aside)

Why the angst?

Rice, I think you should research your adversaries a bit more before resorting to name calling and personal insults. Gary was building race cars (including rotaries) when you were still playing with toy trucks in your sandbox. Hell, you're probably using parts Gary himself developed in your all conquering uber SP.

And as far as starting a credentials war - hoo boy did you pick the wrong fight there

Now, you obviously have something intelligent to say. How about keeping it on topic, and try to resist your typical urge to insult anyone whose opinion differs from your own.

Despite what you might think - I didn't see very much rotary hate in this thread at all (and I came into this thread as a rotary defender). In fact, the hate only started after you made an appearance. Not that different to Ausrotary, really.

I too have had differences of opinion with Gary, and every time I have challenged him he has responded professionally and backed up his arguments with technical merit. Yes, I did get an honours degree in Mech eng, (and did exctemely well at thermodynamics and fluid mechanics btw) so have a grasp of the concepts being discussed. I would hardly claim that any of that makes me an expert in engine design, and I think that anyone trying to show off because hey have the same qualifications is a bit of a fool.

Edited September 21, 2009 by warps

[rxnomore]

Im sure it was....i do get the point by the other guy about the hype...but i think its more to do with the average guy (no so much the guy that does his own engines/spannering ect) jumping on the rotary bandwagon....

Yes, that's kinda what I meant.

Cheers

[martyt]

lol interesting reading apart from the tl;dr posts about physics etc. Most of the rotor forum invaders have done nothing to help their cause, they are nearly as bad as the muzza's from Calais Turbo lol.

IMO rotaries suck pure and simply because they are impractical as a street car or a daily in any form. That and the insane fuel consumption.

This is the sort of rubbish i keep reading in this post. The question was why do rotaries suck. 2 points were put forward. Fuel consumption, and, reliability.

Lets look at the B.S comments such as above. "insane fuel consumption" etc.

Do a quick search on the Commonwealth government database, yes the official one that has verified proven statistics on most cars under exact same test conditions. this is what we get:

Vehicle Year / Model CityConsumption(L/100km) Highway Consumption(L/100km) Engine Size(Litres )

1996 Mazda *RX-7 Man Coupe 2dr 13 7.6 1.3

1995 Nissan 300ZX Man. Coupe 2dr 12 7.6 3

1996 Mazda MX-6 Man Coupe 2dr 10.5 8 2.5

1996 Holden VS Commodore Executive Man Sedan 4dr 10.5 6.8 3.8

1996 Holden VS Commodore Executive Man Sedan 4dr 14 8.5 5

1996 Nissan 200SX Man Coupe 2dr 10 7 2

2002 Nissan S15 200SX Man coupe 2dr 10 7.2 2

1996 Subaru Impreza WRX 10.5 7 2

2003 Subaru Impreza WRX Man sedan 4dr 11 8 2

1996 BMW M3 Man Coupe 2dr 12 6.6 3.2

A few points. The fuel consuption will be less than almost any V8 motor, remember this list has the 96 5L for comparrison. newer 5.7L engines will use more than 13B.

While "City" driving shows consumption of some 23% more than the equivalent model WRX or 200sx, highway driving is more or less the same. the 2003 model WRX uses more fuel for highway driving!!

The same year 96 model mazda mx6 cant match the cruising efficiency of the 13B, infact its consuption almost matches the 5L V8.

No stats are available for Skylines but you would have to be kidding to beleive they would be any less than the 2L turbo cars. In fact it would be similar to the 300ZX in consumption. And the 300ZX is marginal, if any, in fuel savings.

So lets see.. a GTR would undoubtedely use MORE fuel than the RX7, and would be just as fast.

Everthing else is slower and uses a little less fuel. to bring another car up to similar performance would increase consumption to roughly the same.

So WTF is the argument about FUEL CONSUMPTION????

Now, point 2 why rotaries suck... maintenance.

As I said before. The rotary engine will last as long as the warranty states it will if you do the maintenance that is outlined in the service book/owners manual. There seems to be a lot of "they are hard to service" or "keep breaking" or too many probs" sort of comments. It seems that many people have a very low intellectual capacity if you can not understand how to take your car to the dealer at the correct prescribed KM or month interval. By the same logic, ferrari's, porsches, f1 cars are all "cars that suck" because they are hard to maintain or require regular maintenance. Up until 2 years ago, F1 engines only had to last the race because team were allowed new engines every race and after every qualifying run.

And another thing, I need to service my SR20DET every 5000km or six months, maybe sooner if i feel the oil has degraded, fluids low. I do this because i want it to last and want it to make its full potential. Im certain the stock rotary engine can live with that maintenance or maybe better.

oh, and i know the debate did move to a bit off the topic, but i just wanted to add my 2 cents as to why i think they dont suck.

please feel free to point out anything i missed or got incorrect.

Have fun.

[Birds]

Good points martyt.

The consumption is not that bad in these cars and like any car it depends how you drive the thing more than the engine it is equipped with. Perhaps alot of people poorly assume that the 1.3 rotary will give them fuel consumption similar to that of a 1.3 litre 4 stroke piston engine? I would say it's about on par with a GTR Skyline, and they both have similar performance too. I always matched the late model RX7s well to the GTR.

[jase-r34]

Ok, a very quick search and I found -

Nissan R35 GT-R

3.8L 6cyl (T), Auto 6 speed

Coupe, 4 seats, 4WD Combined Fuel Consumption 12.4l/100km

360 kW @ 6400 rpm

580 N-m torque

Mazda RX-8

1.3L Rotary, Man 6 speed

Sedan, 4 seats, 2WD Combined Fuel consumption 12.9l/100km

170 kW @ 8,200 rpm

211 Nm @ 5,500 rpm

Mazda RX-8

1.3L Rotary, Auto 6 speed

Sedan, 4 seats, 2WD Combined Fuel Consumption 12.1l/100km

158 kW @ 7,500 rpm

211 Nm @ 5,500 rpm

This paints a slightly different picture yeah?

[Birds]

Just gonna throw it out there and say f*** cars altogether, motorbikes ftw

[GT-R32]

marty I don't care what they say there, I've owned both and a FD RX7 will use 17/18L/100kms around town. While a GTR will use 10-15% less in the same situation. Highway is comparable, however.

[jase-r34]

Just gonna throw it out there and say f*** cars altogether, motorbikes ftw

+1 hahaha

[mad082]

the problem with factory quoted fuel consumption is that they seem to find the most economical old granny they can to drive the car while they do the test. the economy never really equates to the average joe driving around. especially when it's a sports car. they don't take into account that they will be driven spiritedly. and that is when the rotary's consumption goes out the window. honestly who gives a crap about highway economy. they are all pretty close on that. but round town even the figures martyt quoted show the fuel economy of the rx7 being higher round town than a 300zx, which is a 3.0L v6 and weighs a few hundred kg's more. hell, even a 3.8L commodore beats it on both highway and city. for the city driving it spanks it, with the mazda using nearly 25% more fuel.

and if you compare it to something similar in weight, like the 200sx, the rx7 uses 30% more fuel round town, yet it is supposed to be 700cc smaller in capacity.

[GT-R32]

It's actually 30% greater capacity, comparatively (as the 200SX is a 4 stroke).

Oh, did I go there again?

[martyt]

ok, Firstly to Jase.

where did you get those figures from? mine are from official lab test by the government to test vehicle under the same conditions

www.environment.gov.au/settlements/transport/fuelguide/

Secondly, what a douchebag you are. Why put the RX8 n/a power and torque fiqures? the FD has a 13B twin, which uses only slightly more fuel but makes almost double the power.

even then you are comapring an engine design that is over 25 years newer. yes the rotary is pretty crap compared to the R35. why dont you compare the R35 against your 34. you got a hero R34 that makes what 200ish KW?? and you probably burn just as much as the R35 or more?

Has nissan got a magical way to create power with less fuel? Almost everyone in this forum would agree that the figures i presented were roughly in the ballpark. i was giving comparisons.

and to GT-R32; I was quoting official stats. all those cars were tested under the same conditions. thats what the test proved. But hey, don't let FACTS get in the way, just quote your own guestimates...

I am not saying the rotary is high efficiency. By the stats you can tell that stop start really effects the fuel consumption, more so than anything bar modified turbo cars or V8s, which by comparing it to will show that the difference is minimal. Nothing to make thes B.S. statements like "insane fuel consumption" hold any water whatsoever. that was my point.

it is most definately people assuming the 1.3L rotary is similar to 1.3 Inline 4. but then Mazda never ever hid the fact it was a rotary.

Edited September 21, 2009 by martyt

[GTR-32U]

I think when people mention fuel consumption and noise they immediately think of the old school rotors. The RX3's with the 13B Bridgeport and 4 barrel Carbs.( Brap--Brap--Brap--Brap )...Yes these things were a fuel guzzling nightmare and noisy as all hell to boot.Add the mandatory warm up and your neighbours would wish death onto you every morning. However technology has done a lot with the rotor.Keep the ports mild as possible and rely on good ole Boost and they dont have to be as nasty and loud. Change oil very regularly,let it warm up correctly and they are very reliable. An engine builder I used to know once told me he could build a 500 hp Rotary cheaper and more reliable than a 500 hp 351 clevo....

[GT-R32]

I've owned rotaries for 9 years and still do. The figure I quoted is from my 'real world' experience, where around town a FD with an average speed of about 30km/h, will see 350kms before the fuel light goes on and ~62L of fuel goes in again.

An exceptionally tuned 13B bridgeport in a light RX3 or something can get closeish to the stock FD figures! Most people run them as absolute cops and way too rich, which makes for sweet flames, LOL. This will make them use like 22L/100km.

My 20B Cosmo would do the same thing except it would only do 300km and need more fuel.

Most of those figures to me are fairly acceptable for modified performance cars. The Cosmo being the exception, LOL.

[bozodos]

just FYI fuel consumption above 15L/100km is shithouse.

Funny how everyone I know with rotary powered cars never seems to have them on the road for more than a month or two at a time, and are getting fuel consumption skywards of 15L/100km. (AFAIK the R32 GT-R is quoted at around 16L/100, and GTS-T at 10L) Thats why I mentioned reliability, and fuel consumption, from my own experiences. The OP asked why they suck (and if they were any good they would be in mainstream use), and apart form epic thread diversions and invasions from RX-7 owners, is being told opinions why.

[martyt]

so bozodos, to sum up.

your friends have modified rotary cars. they get the consumption of a modified car, whis is STILL less than a 32GTR. They complain about this fuel consumption. You say that all rotary's have the consumption of a modified car. regardless of if it is stock or not.

Mate, you need to do some basic research. mybe find out what the fuel economy was on hardcore 240Z's back in the day.

do you know the km/L on a full house 2JZ, what about drag GTR engines? stroked 2.2L SR20 with 1000cc injectors.

We should just look at the stock car, which, while consumption is not low, it aint bad for a car that was a match for GTR in performance.

who said rotaries were not mainstream? this may have more to do with expense design for the other manufacturers who need to catch up on 20 years of mazda developement. the market would probably be hard to capture for the newcomer.

as far as i have come across, stock and mild modified rotaries seem to need no more maitenance then any other "sports" car. but if it is your experience, yeah fair enough but let ppl know your talkin about modded engines.

[jase-r34]

Again with the insults? Say what you want I really don't care.

We were comparing the fuel economy of rotaries vs piston engines were we not?

They are both new cars. The power and torque figures are there so you can see how much fuel the rotary uses to make its 170kw vs the R35 making 360.

And yeah, my 11 year old 200ish rwkw R34 will still use less fuel than them both. I consistently get 10-11L/100km average when I fill up. If I drive harder of course it goes up, but as mad082 said, all the figures we have both quoted for all those cars are done using a granny driver getting the most out of every drop of fuel possible.

Consumption figures from here

But again, bikes FTW! oh and they have piston engines too!

[SimonR32]

That's what I said 20 pages back and you pulled out the insults and said I didn't know what I was talking about. Since you now agree with me on the capacity, let's move on to the 2 stroke/cycle discussion.

You are still following the same Mazda lies as on the true capacity, you are looking at only one side of the rotor and saying it's a 4 stroke/cycle engine. That would be like looking at the piston crown in a 2 stroke/cycle piston engine and saying it's a 4 stroke/cycle engine. For the very same reasons it's illogical to only look at only one side of the rotor, when the undeniable fact is another side is inletting while the side you are looking at is combusting. That's a 2 stroke/cycle at work. Now the non thinking rotary supporters point at the fact that a rotor has 3 sides, which of course is true, but it's irrelevant when determining the difference between 2 stroke/cycle and 4 stroke/cycle. The fact remains that a 4 stroke/cycle engine does one of the 4 things at a time and a rotary doesn't, so it can't be a 4 stroke/cycle engine. A rotor does multiple parts of the combustion cycle at the same time, hence it's a 2 stroke/cycle engine.

For the others, go back and look at what I have posted and you will find nowhere have I knocked the rotary engine itself. What I have a problem with is Mazdas 40 years of lying on capacity, rpm and 2 stroke/cycle. The engine itself is fine and I would have no objection if the truth of 3.9 litres (using a 13B example), 2 stroke and 3,000 rpm had been revealed from the start. So do rotors suck, no they don't, but Mazda does.

Cheers

Gary

Ok Gary,

Firstly engine RPM is exactly that, the amount of revs per minute the engine is outputting... Not the piston strokes or rotor cycles, you can't say that a rotor's rpm is what is takes for one rotation of the rotor, otherwise you would have to judge a piston engine on piston speed and then the RPM of a 2-stroke would only be half the speed of a 4-stroke!!! But they are not, the engine RPM is based on crank speed.

It's not a 2-stroke, its not a 4-stroke... It's a rotary!!! Granted it's got more in common to a 2-stroke engine, but it's not because it does not have pistons... therefore it doesn't have a piston stroke.

I'm sorry but your a little wrong with your displacement comparison as well. You can not compare them as they are not the same, a piston engine does not carry potenial energy of more than one combustion cycle in a single cylnder, but a rotary engine carrys not only one combustion process but the potential energy of 2 other combustion processes.

It can't be compared to a 1.3L piston engine as much as it can't be compared with a 3.9L. It's a 1.3L engine per combustion process with 2.6L of potential energy in reserve, a piston engine is a 1.3L per combustion process with no potential energy in reserve!!!

Cheers

Simon