Do a search for quasiturbine engine. For some reason rotary and turbine type
engines call out to me. If you have never driven a rotary powered car, Go for
a test drive in a Rx-7 and rev it out to 7000 rpm or so in second gear and
hold on!! They are effecient since they don't have to change reciprocating
motion to rotary motion and they don't have a valvetrain that adds extra drag
onto the motor and ends up taking away power(hence MPG) The power to
weight ratio of the motor and the cubic inch to hp ratio really are reasons the
motor should be looked into and with modern ceramics, alloys and lubricants
can be used to make it create more power and to make them last longer.
OF course the QT motor needs more development but if it can get over the
apex seal problems that traditional rotaries have it is worth someone to make
it work and even to power a high frequency high power generator could make
a high powered hybrid!!

 

Why bother with a rotary, when turbine systems are more practical every year? I'd rather hae a non-wearing blanket of cooling air than apex seals any day, and turbines are simple and versatile. That's probably why no one is pushing rotaries hard any more.

http://www.baesystems.com/ProductsSe...ybridrive.html

 

This can be considered a variation of the Wankel engine that wasn't exactly a commercial success, though it actually made into a few production cars. There are several other rotary engines that 'on paper' can look really good and revolutionary, but I'm not holding my breath. Here's a a short, and more or less objective writeup on such engines: http://en.wikipedia.org/wiki/Pistonless_rotary_engine

 

Turbines and rotary engines are very inefficient, which is why we dont have many of them today. Chrysler made a succession of turbine car prototypes in the 1950's and 1960's, including 50 handed out to the public for "real world" testing. Both GM and Ford built turbine heavy trucks for evaluation. I actually got to see (and hear) the Ford. Fuel mileage was horrible. I took a thermodynamics class and we had a turboshaft engine in the lab, along with a Mazda rotary and Ford straight six. The Ford piston engine was by far the most efficient. We later used the Ford for alternate fuel conversion projects.

The big problem with the rotary is geometry, that is, poor combustion chamber shape, along with poor control of intake and exhaust port flow and timing. While there is no internal friction from valve gear, apex and side seals have more friction than modern piston rings in a conventional setup. Frictional losses are in single digits as far as the percentage of fuel burn, while thermodynamic differences in basic engine designs can easily reach 30 or even 40 percent.

Jim

 

Old turbines were inefficient, but turbine hybrids (for example) where the turbine can run at ideal speed can work very well.

http://www.capstoneturbine.com/prods...ucts/index.asp

http://biz.yahoo.com/bw/080306/20080306005585.html?.v=1

 

The wankle is very efficent and they is proved by the power that it make with only
being a 2 cylinder!! OF course it is too easy to getinto it and open the carb up and
suck down some fuel, But if you short shift and don't get the rpms up to 8000 you
can get a good mpg numbers and still make power. I had one and I got good mpg
alot of that was because the power to weight ratio. Of course if I beat on it and
brought it up 9000rpm that thing would move and suck down a bit more fuel, But it
was worth it and nice to have we you needed it. They are easy to replace apex
seals but the new ones will last forever as long as you don't overheat the thing if
you do the thing gets warped!! Mazda has been making the Rx-7 for along time and
overseas they have more models running them and some are 3 and there are some 4
cylinder models, They put that 3 cylinder into the Miatas over there!! That thing must
book.

 

Because of the way Wankel works, direct comparison between cylinders and displacement is meaningless.

I looked up mpg numbers on the RX7 and RX8, and they weren't any better than comparable cars' mpg.

The fact that many car companies tried it, yet only a handful of models available with it, should speak for itself -- ultimately, it's the market that decides what's good, and what's not so good.

 

A 1.3 liter engine is a displacing the same amount of liters and if it is a
2 stroke, 4 stroke, gas, diesel, turbine the horsepower and torque it makes can
be compared.
OF course you are comparing a high performance motor of a certain
displacement with a motor in a car that was designed for efficency of the same size,
so how can that even be considered a comparison of the MPG. Compare the fuel usage
on a per horsepower basis and get back to me.
A piston motor is still based on the same principle as a cannon and the loss from
up and down to rotational is something that will never be engineered away and will
always take power away(and gas mileage)
The whole reason for this exercise(posting) is to get into different types of motors and
of course noone wants to change, but the thing is everything changes and look at all
the people that are still mesmerized by the changeover to EFI and it is still a dogma of
many people "I wish cars were like they used to be, they were so easy to work on!!"
and more trusty/releable.
I call BS on that and one look on to the side of the highway will prove that since the
amount of vehicles broke down due to mechanical issues has dropped and if you do see
a car pulled over it is for a flat/ overheat/ cell phone call I hope. I would like to see a
points car let you limp home(let's say for the average housewife without sandpaper and
a feeler gauge!!) Not to mention the fuel system issues with carbs.
It amuses me to no end when that dogma gets repeated by young guys who never have
even rebuilt a carb let alone set points, Just because they heard it and that is a
excuse for not knowing a thing about a ICE. The sensors and computer just allow a
engine to do the same thing that a cannon does(except without sending the piston out)
And really nothing has changed and if you understood them bitd, then just a bit more
knowledge about electronics and how they function will let you understand a efi motor
and you can even diagnose it without a scan tool. I don't own one and have never
brought a vehicle to a shop!!

 

The Wankel has been given a fair trial, plenty of initial good press, and has found its niche market. If it were uniformly superior to the piston engine Mazda would have run with it and displaced piston powerplants throughout their line, making lots of money thereby! We aren't seeing rotary trucks or econo-boxes. Wonder why? There was no lack of desire (and hype!) when the first Mazda Wankels came out.

"look at all the people that are still mesmerized by the changeover to EFI and it is still a dogma of many people "I wish cars were like they used to be, they were so easy to work on!!"
and more trusty/releable."

Those folks can be ignored (except for specialty applications where carbs are more maintainable in primitive conditions with awful fuel, etc) as many of them choose to be tech-illiterate. People who stop learning get no sympathy from me. It's all technology and everyone who is a mechanic should be comfortable with the whole spectrum from carbs to EFI.

As for turbines and hybrid electric drive systems, the mover may well be the Army Future Combat System program. The extreme pressure to save fuel, plus the benefits of stealth loiter (no engine running, just lurk on battery power) and running weapon systems that need serious juice is driving research into practical (= "G.I. resistant") powerplants. So far the contenders are turbines and piston diesels. The characteristics of the gear would allow it to scale down to truck and automobile size, and Uncle Sam can risk research capital more easily than a civilian company.