Rotary engines uses "rotaries" instead of pistons. This triangular shaped disc is very unique since it doesn't have any pistons in the engine. The rotary is quite unique since it spins to combust the fuel inside the chambers. It puts out better performance and reliability and fuel economy is quite low. Unlike pistons where you replace them after 110,000+ miles when cracked, the rotaries have tiny blades on the three points. These blades actually slides against the chamber walls causing friction and eventually wearing out the blades which in total doesn't create a tight seal when combusting fuel. THese are actually required to be changed every 30,000 miles or so. Mazda is known today as the only manufacturer to use the rotary engines on their performance model lineup, the RXs. RX-1 to RX-8. Also the Eunos Cosmo also sported a two rotary wankel engine back in early 90s.

i have to correct you here, since you are quite wrong in a few places.

first - the apex seals on the 12a and 13b rotary motors(both are n/a) the apex seals will last WELL over 100k miles. my 1985 GSL-SE had over 200k on the original seals, and finally died. the 13BT(single turbo) generally needs a rebuild between 60k and 100k...depending on the driver. the 13BTT(twin turbo) goes up quickly, if driven hard. these CAN die every 30k or so. fuel economy is low, as you said, but they do tend to be quite quick IF modified. stock rotaries are pretty slow...stock NA rotaries are EXTREMELY slow. if not driven hard at least once a week, the second rotor can lock up.

there were quite a few rotary powered vehicles in the Mazda family...and not all had RX in their moniker. see the Mazda history link below for more info.

they're much easier motors to rebuild than any piston motor...the only downside is getting the apex seals the perfect size before putting them back in the rotors.

if anyone wants to read more about the rotary, and kill any further misconceptions about the motor, please feel free to visit these sites(at least one of them has an animated picture of the rotory in action):
http://www.mazda.com/history/rotary/
http://en.wikipedia.org/wiki/Wankel_engine
http://auto.howstuffworks.com/rotary-engine.htm

 

I wouldn't necessarily say rotary engines have a power advantage. You can make impressive horsepower for the overall displacement, but torque is virtually nill.

Also, inline engines can actually be quite large depending on application. Finally, V-engines can be 60 degrees or 90 degrees.

 

wanna point out whats a "VR-4" "W8" ? (Mitsi & Audi I believe respectively)

 

W8 came from VW Taureg. And there is a successful V4 engine. Its developed by Ford. Not to mention the various number of Motorcycle companies. I understand what the W8 is but I sure as hell couldn't explain it.:lol:

 

I have heard of a W12 in the Bentley Continental GT it is two V6s side by side. I think the VR-4 is just a model name. But i could be wrong

 

wanna point out whats a "VR-4" "W8" ? (Mitsi & Audi I believe respectively)

VR-4 is just a Mitsubishi trim level for the Galant, 3000GT, among others


Volkswagen's "VR6" is essentially a 15-degree V6 as opposed to the typical 60, basically half I6, half V6. A V6 is not always 60 degrees, as V6 blocks based on V8 designs (V8 is typically 90 degrees?!) can carry 90 degree "vees" as well: case in point, the GM 3800 and 4.3L motors. Smoothness can be negatively affected, and this was the case in the 70's and early 80's with these motors. GM eventually figured out a sucessful firing order and introduced a balance shaft in the 1988 3800. Vibration difference between a 60 degree V6 was reduced to virtually nil, speaking from my experiences.

The W8, W12, and W16 designs are literally just two V4, V6, and V8 (respectively) blocks that are staggered, here's a W12:

Every design has its advantages and disadvantages - inline-six and boxer (think 180 degree "vee") engines are noted for being naturally balanced, but advances in V6 balancing technology and NVH control have made the race pretty close.

The I4 will always be unbalanced.




I had a really good tech article link on this kind of thing once, I don't know what I did with it :

 

A "W" Engine is basically two "V" engines together as one. A W8 engine is actually two "V4" engines with different degrees. Hence the "W" So a "W12" is basically two V6s' together.

 

Why would a I4 always be unbalanced? To me they should be the most balanced, I could be wrong. If you think of the 4 stroke cycle and 4 cylinders it works perfectly. One cylinder is always on power stroke. Unlike an I6 1 or 2 cylinders could be on power stroke it will not alway be the same number, and so on with different amounts of cylinders. Thats why i believe the I4 is the most balanced. "V" motors would be the most unbalanced because each cylinder cant cancel out one another to smooth the engine out, because the cylinders go up and down on an angle. "I" and flat motors should be the most balanced for that reason of canceling out each other. I cant really talk about "W" or rotories because i dont really know them that well. I dont really know if i explained this properly, but i hope you understand.

 

Why would a I4 always be unbalanced? To me they should be the most balanced, I could be wrong. If you think of the 4 stroke cycle and 4 cylinders it works perfectly. One cylinder is always on power stroke. Unlike an I6 1 or 2 cylinders could be on power stroke it will not alway be the same number, and so on with different amounts of cylinders. Thats why i believe the I4 is the most balanced. "V" motors would be the most unbalanced because each cylinder cant cancel out one another to smooth the engine out, because the cylinders go up and down on an angle. "I" and flat motors should be the most balanced for that reason of canceling out each other. I cant really talk about "W" or rotories because i dont really know them that well. I dont really know if i explained this properly, but i hope you understand.

Hop into an inline-four powered car.

Hop into an inline-six powered car. You'll see.

I've yet to encounter an I4 engine that's remotely as smooth as an I6, or even a well-tuned V6.





To illustrate, here's a video of the Toyota 1G-GTE (2.0L twin turbo I6), with a coin on top, revving:





(apparently the 1G was Toyota's smoothest engine before the 1UZ V8 came about)

 

HAHA was I proven wrong or whatwnedsmas

 

The only reason you think the I-4 is smooth is due to the balance shaft technology they use now. Even then they are not very smoot. SIt in a 5s camry and then compare it to a 1mz camry

 

What would you consider a Previa engine to be? It's a 4 cylinder inline, but sideways like a pancake engine.

 

What would you consider a Previa engine to be? It's a 4 cylinder inline, but sideways like a pancake engine.

It is still an inline engine. doesnt matter what side it is laying n the cylinders are still "inline".


Also I seem to rememebr Honda testing a V4 for something like a Civic many many years ago. Anyone rememebr anything about that or ever heard. THis was probably 15 years ago or more. It never made it here to the US but I thought I read it somewhere when I was in high school.

 

Air cooled V-4 engine was used on 55 Fiat 600.

 

what about 2 strokes, 4 strokes, and 6 strokes?

 

what about 2 strokes, 4 strokes, and 6 strokes?

Well, those refer to compression/combustion cycles, not engine configuration -- which is what this thread was about. Might be a good subject for another thread, though!

 

THese are actually required to be changed every 30,000 miles or so. Also the Eunos Cosmo also sported a two rotary wankel engine back in early 90s.

xpeed, great initial post, very informative thread, should help clear up a lot of misconceptions. A few minor oversights, mostly cleared up.

As to Wankel rotaries, falnfenix knows a lot more than I do. What you posted (above) as to apex seals failing by 30 K miles was, I believe, quite true in the early models, but has long since been resolved.

Also, without researching it, I believe the Cosmo was a four-rotor. Most (if not all) other production Mazdas used twin-rotors -- including their small pickup from the late Seventies or early Eighties. What the heck was that called?

V-engines can be 60 degrees or 90 degrees

While these are by far the most common configurations, others exist. As an example, Ferrari is currently using 65 degree V12 engines in production cars.

 

including their small pickup from the late Seventies or early Eighties. What the heck was that called?

the name can be found in the history of subaru link i posted.

 

the vr6 has all 6 cylinders under 1 head.

 

the name can be found in the history of subaru link i posted.

My bad : with my slow dialup, I had not yet checked the links... good stuff! :thumbup:

 

My bad : with my slow dialup, I had not yet checked the links... good stuff! :thumbup:

damn...i'm a dork. i thought i typed history of MAZDA...can you tell where my mind was last night? :lol: :lol: :lol:

 

xpeed, great initial post, very informative thread, should help clear up a lot of misconceptions. A few minor oversights, mostly cleared up.

As to Wankel rotaries, falnfenix knows a lot more than I do. What you posted (above) as to apex seals failing by 30 K miles was, I believe, quite true in the early models, but has long since been resolved.

Also, without researching it, I believe the Cosmo was a four-rotor. Most (if not all) other production Mazdas used twin-rotors -- including their small pickup from the late Seventies or early Eighties. What the heck was that called?


While these are by far the most common configurations, others exist. As an example, Ferrari is currently using 65 degree V12 engines in production cars.

That's why it's good to research it because the Cosmo's Wankel is a twin-rotor. The only quad-rotor (that I know of) was in the Mazda 787 LeMans Group C prototype of the early 1980's.
Regarding apex seals, replacing stock ones with ceramic tips will increase longevity and can withstand more abuse, but comes with a price (typically anyway).

In terms of V-engine angles configuration, it depends on the number of cylinders, as well as other factors such as room that the engine compartment allows for, and centre of gravity. The Porsche Carrera GT for example is a V-10 of 68 degrees, a weird number but one that works well with the design (and the fact that Porsche engineers know what they're doing), as opposed to the Dodge Viper V-10 of 90 degrees, simply because Dodge's too lazy to engineer a new V-10 block on a clean sheet of paper, so they just simply "welded" 2 extra cylinders to their existing 90 degrees pushrod V-8 engine design. That engine's cheap for a reason

 

I wouldn't necessarily say rotary engines have a power advantage. You can make impressive horsepower for the overall displacement, but torque is virtually nill.

Also, inline engines can actually be quite large depending on application. Finally, V-engines can be 60 degrees or 90 degrees.

Depends on the application. Obviously low and mid-range torque isn't any of the Wankel engine's forte, but that's because the rotory is all about top-end due to the fact that it quickly spins up to the maximum of it's rev-range. Much like sportsbike engines that has little torque but awesome top-end, you'll not see a car that weighs a lot that'll utilize a rotory engine. That engine's power delivery can only be complimented by a lightweight vehicle. Plus the rotary design allows for lower centre of gravity and better 50/50 weight distribution, so obviously it's not gonna win on any drag strip, but can easily out-corner many other cars that're more powerful but heavier.

 

Air cooled V-4 engine was used on 55 Fiat 600.

Also in a few old rare Saabs as well.

 

the vr6 has all 6 cylinders under 1 head.

Yup, it's 15 degrees between the two "banks" I believe.