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Location:
Sydney
Registered:
May 2002
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Sun, 11 August 2002 11:40
 
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I've heard rotaries use quite a bit more fuel. Like reading various sites about S6 RX7's and the guys car would average around 20l/100km when being driven around the streets, hard, but not always caning it.
An equivalent piston engine (S15 Silvia Jap Spec) I'd imagine would use much less fuel than that.
Having said that, Mazda are supposed to have gone back to the drawing board and totally changed the ports on the RX8's engine so things could start to even out.
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Location:
sydney
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Sun, 11 August 2002 22:18
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Don't be fooled rota's chew the juice when driven hard,and they go through a bit just cruising but I wouldn't go any other way they ROCK
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Location:
Adelaide
Registered:
June 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Sun, 11 August 2002 22:59
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Yeah, rotors are less efficient by virtue if their basic design. You can prettymuch equate them with two stroke piston motors. (ie power hit for every rev of the crank/eccentric shaft for each cylinder/chamber) Also, they tend to waste a lot of energy and fuel out the exaust-hence the very hot exhaust on most rotors-however, this drawback is also one of the reasons they respond soooo well to turbos.
Beautiful bit of machinery once you learn to sort out the the bullshit about them from the facts.
Sean
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Location:
Brisbane - Chapel Hill
Registered:
June 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Sun, 11 August 2002 23:45
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Yup, that is correct, rotaries to expend a lot of heat energy out through the exhaust.
However, when it comes down to fuel economy, it all comes down to the fuel management system. eg. A badly tuned carby can waste just as much fuel on both design designs.
Also, one must remember, that a rotray is really a performance engine, (Well, at least in my opinion) and as such, is usualy tuned for performance hence trading fuel efficiency for power.
I dont have any figures, but I suspect an economy tuned turbocharged rotary and an economy tuned piston of equivalent capacity (I'm not opening that can of worms) both running a low boost, would achieve very similar fuel economy.
I say low boost, since a lot of vehicles used in the comparisons we see, are running insane boost levels, with huge spool-up time, and extremely rich mixtures to avoid detonation.
Another factor, is driving style with a rotary. They only start to sing above 3-4 grand, and keep on singing until 8+ grand, however dont tend to have as much torque down low (tho this can be fixed by manifold design of course) which shifts the drivers ger changes up higher in the rev-range, requiring more fuel for an equivalent distance.
Still, I know which I'd rather 
Re Rensesis: I think it's still a 6-PI N/A with revised port timings, but the major difference is the exhaust is no longer peripheral. Perhaps this will address some of the above-mentioned exhaust heat-loss issues. I cant wait to see one!!
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 12 August 2002 01:34
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Hmm... I can't wait for the Renesis either.
Should be good. Although they're not claiming 206kW any more...
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Location:
Sydney
Registered:
May 2002
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Location:
Brisbane
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 12 August 2002 08:45
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It's hard to compare rotary engines to piston engines, since only one major manufacturer actually makes rotary engines! Mazda has always used the rotary engine as its performance flagship, so you wouldn't expect it to be tuned for maximum efficiency. If you think of it as a highly-strung 2.6 litre engine, its fuel economy actually looks pretty much normal.
As for the advantages of a rotary engine - they're very compact and are capable of awesome power output with relatively minor mods. There are lots of people these days who know how to extract BIG numbers out of a 13B.
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 12 August 2002 09:09
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Mazda scrapped the 206kW version of the RENESIS because it was going to be too difficult to mass produce, especially when they are trying to keep the car in the S2000 bracket. Still, I think the 187kW version is still going to be awesome.
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Location:
North Sydney
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 12 August 2002 10:52
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I think one of the greatest advantages of the RE is the weight of the engine and it's size. Equivalent to a 20 gallon drum in your engine bay which is great for keeping lightweight package.
My best mate had an RX2 with a race-prepped 4port 13B. Removed the engine and sent the car to the panel beater but he went broke and took the car. He still has the awesome engine which has only done 3000kms! Revs to 9&3/4 and has a delorto carby.
We've got sound file of it revving easily over 9 grand.
PM me if your interested in buying it, was built by a guy who races 20b's round oran park and is very reknown.
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Location:
sydney
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 12 August 2002 11:18
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When I first got my 23 it was stock and used about 3/4 of a tank to go from inner Sydney to Mudgee.With the 13b in it the first few times driving it easy it used about the same.Now that I know and trust it it gets driven a bit harder and uses a bit more but it's not getting any newer and it was 5 or so years ago that this engine was doing it and it has only ever been serviced in that time NOT rebuilt.
To answer the question better from someone who has been there drive an 18rc or 13b(mildport) steady and they about the same.drive a twin carbed 18rg hard and a 13b(mildport)hard and the 18rg would use more (it did in my brothers Hilux).The piont is that it is hard to say work out what sort of hp you want then work out how you want to get it.
Remember horsepower is not cheap,the rest is up to you
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Location:
Tasmania
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 12 August 2002 12:35
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I think a small engine running at high rpm will use more fuel than a bigger engine running at a slower rpm, both producing the same power. Just my thought.
And a 13B is the equivelent of a 1.3 litre motor right? Often compared to 2 litre motors making the same power at lower revs?
My standard 2TG is getting about 11.7 litres/ 100km at the moment, on carbies. Depends on driving style. And if I drive hard, its not that much different, maybe 12.1 litres. If you drive a rotary hard, it will use double that fuel.
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Location:
Sydney
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Tue, 13 August 2002 05:52
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Hmmm...interesting
Well so far the only major downfall is chugg factor which is not much of a hassle
ta for the reply's
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Tue, 13 August 2002 08:08
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sorry to come in with late information... part of the reason for chuggine fuel is the rotary's huge requirement to consume air!!! for a given power output, a same size piston engine will consume less air. so to keep the engine happy, it needs to have an appropriate air/fuel ratio... more air, more fuel!!!
rotaries are often avoided in racing situations where intake restrictors are used. this is simply because fo a given amount of air consumption, a piston engine makes more power!!!
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Location:
A.C.T
Registered:
July 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 05:04
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Hey Manipulate, I have 9 words for you mate;
"If It Ain't A Rotor, It Ain't A Motor!" 
(of course there are a select few exceptions, but i prefer to keep with the above motto.) 
André
ps. If anyone is going to write-in and try to complain about what i have just written, yes your engine is one of the "Select few"
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 06:28
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Man, if you are going to make that quote, you have to put it in the dodgy Japanese accent of the dude who first said it 
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Location:
A.C.T
Registered:
July 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 06:50
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haha, yeah well. It's good to see that no wanker has decided to just jump into this convo and knock rotors. I hate people that just think that thay can say what they want and that their opinion is the be all and end all. Especially cunts that go around knocking rotors. My previous quote was just a saying i like to use because it's pretty hectic, i was obviously joking about the piston thing. There are heaps and heaps of awesome piston engines around, and if for some (highly unlikely) reason i decide that i don't want to put a rotor back in my Celica, my next choice will definately be a piston engine of some decription...lol jokes.
André
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 06:53
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Rotors are real cool, no denying that...there is only one thing I've never heard sounding right...the noise 
From the mild, to a PP one...all blat blat...
Hopefully the different way Mazda made the RENESIS will change the acoustics 
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Location:
A.C.T
Registered:
July 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 07:33
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I'm assuming you've never heard a 3 rotor 20B then! The 20B is un-denieably the best sounding engine in the world in my books, and i'm sure even some of the most die-hard V8 lovers will agree that they are an awesome sounding engine. I admit that a non-turbo ported 20B can slightly resemble it's twin rotor sisters, however only slightly and this is more than adequately made up for by it's sheer roar from all 3 rotors under full throttle. Twin rotors bark or yell, tripple rotors ROAR! I suggest you seriously try to download some video clips of ROTORMASTER's 20B powered R100 doing a half-track burnout, the sound is unbeleivable! As for the usual twin rotor sound, it's all just personal opinion. Most people say they sound crap simply because they are different. They don't sound conventional so people like to pay them out. "ohh they sound like chickens on steroids" and crap like that. Personally i think the majority of them sound awesome. I used to hate Rotors with a passion when i was younger, but that was because i just went with the flow. But once i came to experience them first hand, i realised how awesome they really were and never looked back, now i can't get enough of them! Yes i agree that some of them really sound sickening, like tired 12A's and little 10A's with bad exhausts and the like. They sound really tinnie and aweful. However i love the deep bruuup bruuup bruuup from a fresh 13B peripheral port running injection and a deep, yet not too obtrusive exhaust. And of course you cant go past the smooth injected turbo 13B's in cars like FREAKY and AXX-13B. The mixture of the turbo spooling up and the Rotarie's exauhst note are simply meant to be!
André
Ps. Make sure you get videos of ROTORMASTER's old R100 at full noise!
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 07:39
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Maybe its just the little buggers...I dunno, the 20B's I'd heard hadn't been "that" great...
The only awesome one was the R26B from the 787B Le Mans car...that sounds pretty cool!
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Location:
A.C.T
Registered:
July 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Thu, 15 August 2002 07:59
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go to 3rotor.com and go to the HB audio clips down the left-hand side of the page. Then just click on the first one at the top. It's not the best 20B i've heard, but it sure as hell shows that they are not the same sounding engine as the 2 rotors. Try to find on the site a video clip of the ROTORMASTER R100 doing the burnout.
Also i doubt that the new renesis engine will sound all that much different from the old design. Yes the exhaust is no longer of a peripheral port design, this may make a slight difference, however it is not likely to make all that much difference once you fit a fat exhaust and port the thing!
André
Go the Rotors!
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Location:
Perth
Registered:
August 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Fri, 16 August 2002 00:58
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*WARNING* TRIVIAL INFORMATION POST! *WARNING*
For what it's worth. Norton have made at least 2 different Rotary engined bikes, and nissan(!!?!?!?) apparently did a run of rotary silvias, however these are quite old definitely s10 thru s12 somewhere.
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Location:
Sydney, Australia
Registered:
May 2002
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Location:
gold coast
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 19 August 2002 12:03
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Nice Premmie!! All it needs is a 20B
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Mon, 19 August 2002 15:45
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if you get a 12a, then it doesn't "blat blat" (as someone said) ... it sounds more like a normal engine.
a 13B peripheral port blats with the best of them at idle.... but tends to scream higher up.
I'm with toyrota here though, the 20B is an amazing sounding engine (plus I've seen the vid of a sprinter with a 20B turbo in it... 650bhp.. you'll never bad a rotor again when you see that thing drag from 100km/hr)
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Location:
Face down in a ditch
Registered:
May 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Tue, 20 August 2002 03:53
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I just thought I'd throw my 2 cents worth into the thread because I've owned a couple of Rotaries.
First of all, the biggest consideration is not the juice they chew, but when they break, you are up for alot of money to get them fixed. Destroy one apex seal and you are up for a $2k+ rebuild. That said, if you use top quality oil, warm the car up completely and let it warm down after being thrashed, you should have no problems.
Dunno if this was mentioned, but the reason they use more petrol when thrashed is because for each turn of the crank (eccentric shaft), they make 6 power strokes. As I'm sure you know a 4 stroke motor only makes 2 power strokes for each turn of the crank.
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Location:
A.C.T
Registered:
July 2002
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Re: Fuel Efficiency Between Rotaries and Pistons ..???...
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Tue, 20 August 2002 04:00
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Yeah thanks Draven, good to see you're on the goodies side! If anyone wants to see that insane 20B powered Trueno then go to http://www.3rotor.com and then go to "3rotor speed kings" on the left hand side menu, then go down to the 20B sprinter bit and load it! Still can't remmember where i got the video of Rotormaster's R100 doing a half-track burnout but when i do i'll let everybody know, it's the best 20B you'll ever hear. Also go to http://www.geocities.com/cd23c/hydrogen.html for some interesting info on the hydrogen adaption to the rotary engine that we were discussing in a previose thread.
André
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