Why Do Rotaries Suck?

[Sydneykid]

sure a rotor isn't as small as an inline 4 to be used in fwd, but a 3.8L v6 isn't as small as an inline 4, yet mitsubishi used them in the 380. also didn't stop pontiac putting a 5.3L v8 in the grand prix gxp (also the chevy impala SS) and it's also fwd. then there is the host of fwd v8's that cadillac has made over the years. but then they did have massive bonnets. but the new impallas, etc, don't have massively huge bonnets to fit the v8's in, so i'm sure that it wouldn't be that hard to shoehorn a rotary into a fwd.

True, but (there is always a but), Mazda have dug their own grave. By claiming 1.3 litres for a 13B they are automatically competing against 4 cylinder engines on capacity. Any decent inline 4 cylinder engine pisses all over a 13B for packaging, not to mention fuel economy. So the 13B loses out to the 4 cylinders every time.

But (yes, another one) if they told the truth about 3.9 litres then they would get destroyed in any comparison to other 3.9 litre engines on power and torque. Lately the 13B would even lose out on economy to the current generation of V6's. As a 2 stroke, I'll leave out emissions as it's an obvious problem.

Rock and a hard place, 1.3 or 3.9 Mazda lose either way, that's why they gave up and used a 2.3 litre 4 inline 4 cylinder in the 6 and 3 ranges.

Cheers

Gary

[mad082]

Nice try at muddying the water, the fact is turbocharged or not the capacity of the engine is still the capacity of the engine and a 13B is 3.9 litres. It's an invalid comparison anyway, nobody hides the fact that it's a 2 litre turbocharged engine, but Mazda lie and call a 3. 9 litre engine a 1.3 litre. There is no comparison, next you will be saying just because a 6.2 Chrysler Hemi can switch off 4 cylinders at any one time that it's really a 3.1 litre. The fact remains it's still a 6.2 litre, just like a 13B is 3.9 litres.

I don't know about you, by my tacho reads ignition pulses, it doesn't actually count the crankshaft revolutions. Tacho's are very simple devices, for a 2 stroke they count how many combuston events per minute and divide it by the number of combustion chambers and that = rpm. Very simple, now do it for a rotary engine and you end up at 3,000 rpm. It's not that hard to understand.

Cheers

Gary

the point he is making though, is that you don't compare a 2L turbo to a 2L NA. who gives a flying f**k if mazda lied or not about the 787. the point you are making about the capacity is pretty much the same as every v8 owner makes when talking to a turbo import owner. it's pointless. they are 2 totally different things.

but at the end of the day, it is still pointless. sure the rotary might be underpowered and very low on torque for a 3.9L engine, but it still works well as a race car. and to compare it is also stupid. why not compare the power output of the 3.6L boxer engine from a gt2 and the 4.0L engine from an xr6t and say that it is crap because it makes 150kw less despite having 400cc more. hell you could even compare the beloved vg38 from the r35 and motor from the GT2. the porsche motor os 200cc smaller yet puts out 30kw more and 92Nm more torque, and doesn't need to be serviced as often.

my point is, you can't just simply compare 2 motors and say 1 is shit and 1 is good just because you happen to like 1 more than the other.

[warps]

What? The current lap record holder at Mallala, Sandown and Winton actually is an RX3 powered by 1.8 litre Mazda 4 Cylinder turbocharged engine with a restrictor. He took a rotary engine out of that car and then started winning and setting lap records.

What? a turbo piston engine was faster than a NA rotary? Stop the Press!!! You and I both know that the IPRA restrictors hardly strangle a 1.8 litre engine. What they may lose in top end they will more than make up with a fatter torque curve. I certainly won't start one of those arguments here.

What about other tracks?

What about race results?

All those RX7's out there must be running piston engines as well then, hey?

Interesting history there. Phil Irving OBE, Repco Brabham designer, author of many books, actually did a study on rotary engine capacity in the '70's. Based on sound automotive principles he arrived at a capacity of ~3.2 litres for a 12A. This was submitted to CAMS but was rejected by the then CAMS President John Large. As most people know the Large one was the man most responsible for allowing a Sports Car (Mazda RX7) to race in the Australian Touring Car Championship at the behest of one Allan Moffat. Hence perpetuating an almost bigger lie than 1.3 litres and 9,000 rpm, that being an RX7 is a Touring Car.

Yeah, yeah, more sour grapes. It's all a conspiracy

[joeyjoejoejuniorshabadoo]

srsly... who cares about marketing lies?

mazda told a few lies about capacity, holden lie every time they put a pretty number on the back of a car to impress the morons, japanese companies lied when they produced 84billion different models with 206kw, hummer lied when they said the h3 is actually a motor vehicle as opposed to a giant billboard saying how much of a wanker the driver is...

WELCOME TO MARKETING

the real point is this:

i'm not a huge rotary fan and hence i own a skyline, but i'd be MORE than happy to have DCUPS sitting in my garage...

[Sydneykid]

the point he is making though, is that you don't compare a 2L turbo to a 2L NA. who gives a flying f**k if mazda lied or not about the 787.

I sure as hell don't, but someone raised it (being chucked out of LM) as proof of rotary engine superiority, when in fact is was proof of cheating.

the point you are making about the capacity is pretty much the same as every v8 owner makes when talking to a turbo import owner. it's pointless. they are 2 totally different things.

No it's not, far from it in fact. There is no forced induction at work here, it's straight N/A capacity versus N/A capacity.

but at the end of the day, it is still pointless. sure the rotary might be underpowered and very low on torque for a 3.9L engine,

Glad you agree.

but it still works well as a race car

Not if it had to compete against other 3.9 litres engines.

. and to compare it is also stupid. why not compare the power output of the 3.6L boxer engine from a gt2 and the 4.0L engine from an xr6t and say that it is crap because it makes 150kw less despite having 400cc more. hell you could even compare the beloved vg38 from the r35 and motor from the GT2. the porsche motor os 200cc smaller yet puts out 30kw more and 92Nm more torque, and doesn't need to be serviced as often.

Irrelevant, as none of them are claiming 1.3 litres for a 3.9 litre engine and none of them are tripling their true rpm.

my point is, you can't just simply compare 2 motors and say 1 is shit and 1 is good just because you happen to like 1 more than the other.

Who says I like one more than the other? Not me, my points are simply cheating for 40 years about rotaries true capacity and lying about their rpm. Good vesus bad, never in my argument.

Cheers

Gary

[Sydneykid]

What? a turbo piston engine was faster than a NA rotary? Stop the Press!!! You and I both know that the IPRA restrictors hardly strangle a 1.8 litre engine. What they may lose in top end they will more than make up with a fatter torque curve. I certainly won't start one of those arguments here.

What about other tracks?

What about race results?

All those RX7's out there must be running piston engines as well then, hey?

Yeah, yeah, more sour grapes. It's all a conspiracy

Actually it was a conspiracy, the Large one wanted Moffat in the Australian Touring Car Championship and the only way was to let RX7's, an FIA Homologated Sports Car, race in a Touring Car category. IP Racing still suffers as a result of that breaking of the rules of homologation, the undeniable fact is RX7's are Sports Cars and they shouldn't be allowed to run in a Touring Car category.

Meaningless diversion anyway, that's a car and we are talking engines here, rotary ones in fact, so let's get on with it

Cheers

Garty

[jase-r34]

Quick question about rotaries vs piston engines....

I have a few years of experience working on and around many piston engines, but next to none with rotaries. I understand how they work, I just haven't spent the time actually hands on. So basically my dislike of rotaries is mainly due to the horrible noise they make lol.

Anyway, the question is - Think of the worlds elite motorsport categories. Formula 1, A1GP, Nascar, Top fuel drag racing, the list continues.... All of these categories use piston engines. If the rotary is (as it seems to be some people's opinion) a better race engine, why is it not used in any of these race categories?

This is a serious question, I'm not trying to be a smartass!

[scathing]

One of the reasons would be that homologation rules requires a piston engine for those categories, I'd say. It might have something to do with the teams, and in some cases fans.

Can you imagine your average gap-toothed redneck tolerating a rotary powered Nascar racer? Or anything that didn't have a V8?

[jase-r34]

Granted, some of those categories are going to be governed to some extent by what the fans want, but do you really think that is the case for F1? I don't. If that was the case then bernie and max would have been gone long ago

I honestly think it comes down to what works better and gives the best results. Or am I wrong??

[Streeter]

^^probably the same reason as the crap in this thread. The engines are different. Comparing them and trying to say it = XX cc is just retarded.

This means making an even playing field extremely difficult as you really cant compare them.

they were banned from Lemans cause they won, if they were so shit, no one would have kicked up a stink and they wouldnt have been knocked out. This is pretty standard for any piece of engineering that works. Would have thought someone as involved in motorsport as SyndeyKid would have clued onto that? maybe Im giving too much credit here?

Just to stir, wouldnt a 3.9 litre V6 at 3000 rpm have alot of trouble making the same power as a 13b? just some food for thought and more of wakeup call of comparing pistons and rotors on RPM and size as being pretty retarded.

[aDrew_C]

First of all, I don't see how it matters as far as comparisons go if they state 1/3rd the capacity and then 3x the rpm. The two cancel each other out... sure for motorsport things are a bit different, but surely the low rpm has to be taken into account. I don't see why they should say "well it's your fault your engine doesn't rev, not ours, change the design so that it does rev", because that seems to be what is being proposed here.

If they'd made a 3.9L V6 that couldn't rev for shit and wanted it to compete against lower capacity engines then that would be different. This is not what's happening, the design of the engine lends it to be strong in one aspect but adversely weak in another that just happens to directly correlate with the aforementioned strong aspect. I don't see how the hell it matters! It's just twice as much half as often.

[aDrew_C]

Just to stir, wouldnt a 3.9 litre V6 at 3000 rpm have alot of trouble making the same power as a 13b? just some food for thought and more of wakeup call of comparing pistons and rotors on RPM and size as being pretty retarded.

Yes a 4 stroke would, but not a 2 stroke. Also remember the two stroke would also be significantly lighter and smaller than a 4 stroke, maybe even weighing less than a 13B.

[Streeter]

Yes a 4 stroke would, but not a 2 stroke. Also remember the two stroke would also be significantly lighter and smaller than a 4 stroke, maybe even weighing less than a 13B.

and thats why you see those 3.9 litre 2 strokes in sports cars!! what was I thinking

I don't know about you, by my tacho reads ignition pulses, it doesn't actually count the crankshaft revolutions. Tacho's are very simple devices, for a 2 stroke they count how many combuston events per minute and divide it by the number of combustion chambers and that = rpm. Very simple, now do it for a rotary engine and you end up at 3,000 rpm. It's not that hard to understand.

Cheers

Gary

Actually thats how the tacho works but not what its supposed to be measuring. Sort of like saying that the speed of your tail shaft is what you should be caring about not actually how fast you are going. It's not that hard to understand.

Like I keep repeating. Arguing about terminology is retarded, yet here I am... oh dear.

Edited September 17, 2009 by Streeter

[aDrew_C]

and thats why you see those 3.9 litre 2 strokes in sports cars!! what was I thinking

Obviously there are other reasons why you don't see such engines used in motorsport...

Actually thats how the tacho works but not what its supposed to be measuring. Sort of like saying that the speed of your tail shaft is what you should be caring about not actually how fast you are going. It's not that hard to understand.

Like I keep repeating. Arguing about terminology is retarded, yet here I am... oh dear.

The point is that how the ignition affects the drive shaft is what's important. In the case of a rotor the rotor itself ingites 3 times per revolution but the eccentric shaft is only rotated by one of these ignitions for it's revolution. The exact same effect as a two-stroke. This is what mazda seem to have based their definition of a 1.3ltr high revving engine on. I somewhat agree with their definition because the driveline is what affects how the power is output, the fact that the rotor spins three times slower can either be viewed as being similar to having more pistons or as mazda would like to see it, the same "pistons" on their next cycle.

You're right though, comparisons to piston engines don't really mean anything... unless you're trying to figure out what category rotarys should be lumped into for motorsport.

[Streeter]

Obviously there are other reasons why you don't see such engines used in motorsport...

The point is that how the ignition affects the drive shaft is what's important. In the case of a rotor the rotor itself ingites 3 times per revolution but the eccentric shaft is only rotated by one of these ignitions for it's revolution. The exact same effect as a two-stroke. This is what mazda seem to have based their definition of a 1.3ltr high revving engine on. I somewhat agree with their definition because the driveline is what affects how the power is output, the fact that the rotor spins three times slower can either be viewed as being similar to having more pistons or as mazda would like to see it, the same "pistons" on their next cycle.

You're right though, comparisons to piston engines don't really mean anything... unless you're trying to figure out what category rotarys should be lumped into for motorsport.

I just find it weird that ppl get so upset with mazda calling it a 1.3 litre. In my opinion if someone told me it was a 3.9 litre and was that size, I would be MORE impressed. And making that much power at 3000rpm?? how good is that! glad you can see my point about definitions and terminology. A rotor is a rotor, piston engine is a piston engine. Trying to compare them like that is stupid.

Only ppl to get shitty with the size classifications are either retards (cause what difference does it make?? call the thing a 50 litre engine, still performs exactly the same!) or ppl getting spanked by them on the track and crying about it being unfair LOL

[Granthem]

Sadly, all friends etc with rotors have quickly killed them. This has scared me from owning one.

Fresh Dyson builds, Maxfix builds etc have all bitten the dust in no time.

I know there will be reasons, but when compared with normal piston engines, the failure rate that I personally have witnessed is far far far too large.

Gary (sydneykid) for PM!

Edited September 18, 2009 by Granthem

[mad082]

if you look at the 2 stroke aspect of things and take it into account (where at 3000rpm it is effectively firing the as many times per minute as a 4 stroke at 6000rpm) the power they put out isn't so amazing. it still isn't bad, but it isn't anything spectacular as it is lower than a same year model ford or commodore (when comparing NA to NA or turbo to turbo)

but in the cars that they are in they perform well.

[Birds]

The biggest problem here is that Sydneykid is enginist. He feels that all engines should conform and assimilate to the white man's piston engine. No rotary should be allowed to compete with pistons in motorsport because they are not the same, they are not equal. All rotaries do is influence our children through their terrible exhaust note that can hardly be called music. They should all move out of the Mazda wreckers and get real jobs like driving trucks, just like piston engines. Piston power, piston power!

As I said before, if it is true about Mazda "lying" (which it isn't, because it has been pointed out numerous times in this thread that comparing rotary engines to piston engines based on the characteristics of a piston engine is nothing short of ridiculous), the only people who would give a shit about this are involved in motorsport. The only thing that matters in the real world (i.e. consumer markets) is the perceived value of the engine. For an engine only produced by one manufacturer in one model at a time there sure are alot of rotaries still around.

[nerm]

if piston and rotary engines are so different and comparing them is stupid, why are they allowed to compete against each other in motorsport? shouldnt they have their own catagory?

i think it is perfectly valid to compare rotaries to piston engines. the both do the same job (granted in different ways) and therefor should be compared. its like comparing a boat to a plane, one will get you there quicker and one will get you there in more comfort, they both still get you there in the end.

i also think their design is quite remarkable. its not the most efficient design with regaurds to reliability and fuel consumption. its another take on the old combustion engine, that Felix Wankel must have been a pretty smart guy. Also when the engine was designed im pretty sure that fuel economy wasnt that important (late 50s early 60s), any they probably were just as reliable as the piston engines of the time.

as its been stated eleventybillion times (this number has been proved to be just under a bajillion) its horses for courses. i personally dont have anything aginst rotaries i just hate it when their owners bag out piston engines.

and i agree, the above rx7 (dcups i think?) is fkn hot..

Edited September 18, 2009 by nerm

[Streeter]

if piston and rotary engines are so different and comparing them is stupid, why are they allowed to compete against each other in motorsport? shouldnt they have their own catagory?

i think it is perfectly valid to compare rotaries to piston engines. the both do the same job (granted in different ways) and therefor should be compared. its like comparing a boat to a plane, one will get you there quicker and one will get you there in more comfort, they both still get you there in the end.

The size, centre of gravity and power make them a pretty good performance engine. And same as turbos etc it makes it difficult to put them in a class where its totally fair with restrictors etc as there will always be ppl saying that how its figured out isnt right.

Just look at ANY class where they are allowed and you will find ppl like Sydney kid whinging about how the size/class is calculated.

And thats the reason in most motorsport categories they ARENT allowed, pretty much the same as turbo/supercharging cause its too hard to make a level playing field where everyone is happy.