Alternative motorcar engines
Posted 12 February 2007 - 01:49 PM
The Wankel engine was heralded as the engine of the future in the late 1960's. Some brands only had experimental cars with them, but NSU commercialized the Ro80, and Mazda had the RX-7 and RX-8. The Ro80 disappeared shortly after NSU became part of the Volkswagen-Audi-Group, and as far as I know Mazda does not market Wankel-driven cars any more.
There were also two types of motorbikes : one by Suzuki (chain driven and with the rotor axis transversal) and another by Hercules (shaft driven and with the rotor axis lenghtwise). They are both becoming collector's items I'm affraid
I remember also a gasturbine driven racing car participating in Le Mans and making the full 24 hours. (I checked, it was in 1963) But the only occasions where you see vehicles with gasturbines nowadays are tractor pulling events. Of course, noise may be part of the problem here.
Anyone around who can provide extra info on either of this ? (And I don't mean wikipedia)
Posted 12 February 2007 - 03:34 PM
Last I checked, you can still buy 2007 Mazda RX-8, available only with a 2-rotor Wankel engine. Evertime I think of getting a car, a Mazda RX is high on my list, not because its engine is unusual, but because it revs uncomplainingly to over 8,000 RPM, with a steady increase in power. Though RXs don’t have a lot of power by modern sports car standards, it’s very usable power.
… as far as I know Mazda does not market Wankel-driven cars any more.
The basic problem with the Wankel was and, unfortunately, remains that it’s rotors seal far less well than a conventional piston engine, causing it to have excessive unburned fuel and other dirty stuff in its exhaust. Fuel efficiency and environmental friendliness suffer. They’re also less durable, their rotor seals getting progressively leakier as they age, making them among the few modern engines that an enthusiastic owner is likely to need to overhaul in the life of the vehicle.
It’s worth mentioning that the Moller Skycar uses 8 wankel engines to provide about 750kW (1000 HP) to its 4 ducted fans.
I wasn’t aware of a turbine racing at Le Mans in the 1960s – thanks for the info. I think you’re referring to http://en.wikipedia....erimental_cars'>Rover-BRM turbine (what’s wrong with wiki links, eh?!).
I remember also a gasturbine driven racing car participating in Le Mans and making the full 24 hours. (I checked, it was in 1963)
At least one other turbine car was designed for, and may have actually practiced at Le Mans, the Chrysler Patriot, ca. 1995. This car suffered, in the opinion of most, from being too innovative, having a compact gas turbine/generator, electric drive motors, an, most controversial of all, a ceramic energy storage turbine intended to provide the system with incredible momentary power. Legend holds that, after seeing videos of explosive failures of the flywheel (with lots of waist-height shrapnel), drivers refused to share a track with it. An awesome, if ultimately unsuccessful, design, IMHO.
I’d say the most famous turbine race car in history is the Lotus 56, which qualified first and had an uncatchable lead in the 1968 Indy 500 when its engine failed a few laps from finishing. Fearing that the sport would become a 4WD turbine “arms race”, USAC, the sanctioning body for the Indy 500, made turbines and 4WD illegal in 1969.
To my knowledge, there hasn’t been a production turbine car for sale in the US since the 1963 http://www.turbinecar.com/top.swf'>Chrysler Turbine Car (of which only 55 were made).
But the only occasions where you see vehicles with gasturbines nowadays are tractor pulling events. Of course, noise may be part of the problem here.
I believe you can, for US$150,000, buy (that is, have built for you) a MTT Turbine Superbike – basically a large sportbike with a 240kW (320hp) helicopter motor.
Posted 13 February 2007 - 12:04 AM
Funny enough, however, it seems as if Wankel rotors still have an application in the auto industry. Volkswagen have introduced their next line of cars with self-tightening seatbelts. It works in the same principle as airbags, where a decelormeter measures constantly if there's an impact. If there is, it fires off explosive charges in the seatbelt coil, the center of which contains a tiny Wankel rotor. The gas from the explosion escapes through the Wankel rotor, turning it at one helluva speed, and through a little step-down gearbox it tightens the seatbelt in a very small part of a second before you've even hit the airbag.
Wankels are cool.
Posted 13 February 2007 - 07:17 AM
I have hear that electric engines are far more efficient and reliable than internal combustion engines (leading to far fewer repairs). With the advance of electric engines from a number of manufacturers, is anyone aware of any downfalls to the engines? I am sure there are some, just wondering what to watch out for.
Posted 13 February 2007 - 07:41 AM
The problem has been, and still is, the size of the batteries you need to lug along to provide anough juice to make it worthwhile. Hydrogen fuel cells are making inroads into this issue, but I think its still a long way off before they can compare to internal combustion engines for performance and ease of use.
Think about it, you have an engine weighing, say, a hundred kilos, plus another 60 litres of fuel. That'll give you approx 150kgs of fuel and engine to take you roughly 1,000 kms. Try it with an electrical motor that gives the same performance, and you'll end up with an engine of, say, 20 kilos, but you'll need about a ton of battery to take you 1,000 kms with the same performance the petrol engine gave you.
We're still a way off, but we're definitely getting there, in my opinion. If you made the same comparison ten years ago, you'd have had to lug along two tons of battery, today its half that. So, yeah - its pretty cool and very promising, but I reckon its about another decade or two away before the weight/performance issues will be sorted out. And NOT the weight of the motor, mind you, electrics have already surpassed petrol engines in that department. The obstacle is solely fuel (battery) weight and supply.
Posted 09 April 2007 - 02:00 AM
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DMFC proves more reliable than liquid hydrogen fuel cells The Direct Methanol Fuel Cell (DMFC) technology developed under the supervision of Dr. Rao Surumpudi supervisor of the Jet Propulsion Laboratory at the California Institute of Technology's electrochemical-technology group is the basis for the patents and license for which DTI Energy has control. Dr Surumpudi's revolutionary thinking in this process was that a fuel cell that converts methanol directly into electrictiy (Direct Methanol Fuel Cells) without a reformer, would be simpler, cheaper and more reliable than liquid hydrogen or methanol and reformer based fuel cells
Posted 09 April 2007 - 03:33 AM
--it's all good and well to valve a four stroke, but with todays quick acting solenoids, and computer testing you could whip up a two stroke which would/could well and truly outperform a 4 on both petrol consumption and power issues (including environmental burning of feul issues)
--the two stroke can also be manuipulated much more easily, and could also serve well to burning several types of fuel much more easily.... maybe even in concert - eg 1 piston for cooking oil 1 for gasoline 1 hydrogen.
--it's lighter - and stroke lengths could be made adjustable much more easily.... maybe even a variable stroke 2 stroke could curb petrol usahe by half just by adjusting length for rev.
then thier is the possibility of mixing electrical movement into the petrol mechanism... eg. soleniod action to assist drive.
--The 2 stroke has always been more efficient --just harder to get the 'right revs' out of it.... but with electronics could be alleviated.
- silverslith likes this
Posted 09 April 2007 - 06:17 AM
Sarich aka orbital engines and lotus both did them with plain bearing oil fed crankcases, air going in thru a single head valve and normal exhaust ports. They had a stratified injection system that didn't put fuel in until some air went first-so none was lost thru the tuned chamber supercharging. Far better weight, size emissions and fuel consumption than 4 stroke. a 1200cc sarich weighed 40kg and was about 18" cube. The injection tech evolved into a low volume 80-120psi air assited job on the mercury and tohatsu outboards. They still pump air thru the crankcase but with no fuel its much better. Especially the merc with its pressure oil fed needle bearings. they have 1500cc triples, 2L 4cyl and the bodacious 3.2L v6. All incredibly compact. I was looking at a 2L for a sportscar. potential of 500 hp from a 50kg motor. Much better economy than 4 stroke and lower emissions- but they've gone and banned them most places and they'll be gone soon in favor of the stupid supercharged 4 strokes with far higher loadings and 4 times the size.
That hafnium tho, million miles on one kg. And then you get it recharged. Not even radioactive when its flat. Give me a closed cycle steam turbine driving superconducting electrics!
Posted 09 April 2007 - 08:25 PM
--aswer ... communist block actually did make 2 strokes, sadly the opinion was that they were pretty darn bad (anyone heard of the Trabant) --the petrol tank was under the bonnet.
--I would like to see a simple 2 cylider 2 strok for small cars... design:
2 cyliders on the one cracnk inline, set with another V-ed smaller stroke cylinder for 'volatile denotation'....
the 2 cylinders would use either diesel/heavy unclean oils, with a recycling plant feeding 'lighter elements' to the small stroke piston.... you could incorptorate three tanks in the system.... oils, petroleum, hydrogen/actylene/methane(whaever is going goo)
--with computer control and gas sensors of today, you could control what piston gets what - the long stroke pair for heavy 'burning' material (one of which would be able to switch between diesel compression and petroleum detonation)
--with some even more work, you could incorporate a tuubine into the crank, maybe ommiting the third short stroke piston.
--you should be able to switch the action of the pistons into compressors for air, eg. no hydrogen intank? use the short stroke as an air compressor to help burn the diesel.
--and because this engine is so light and scmall --design the vehicle with centre engine and CVtrans, completly computer controlled, and if people later want to upgrade, they can replace thier wheels with 'electric wheels' ... giving rolling charging to produce hydrogen via electrolysis... only needing minimal storage..
--I wreckon you could, if you really tried get a car down to 500ml per 100km with some of these principals. (you could eveen incorporate a steam engine, fired from the heat of the engine!)
Posted 10 April 2007 - 03:06 PM
The best thing about strokers is their simplicity. Diesels work fine. The world record for economy is over 5000km from a gallon, using diesels aroun 10cc.
Posted 18 April 2007 - 07:02 PM
Compressed Air Motor
Somewhere around 80% of the energy in the fuel burned in a combustion engine is lost to heat.
The friction heat generated by a compressed air motor could be used to heat the incoming air to expand it resulting in higher pressures and more efficient use of the compressed air by the motor.
No extra equipment would be needed to have regenerative braking.
simply pump the exhaust back to the compressed air tank when the exhaust pressures are higher than the tank pressure.
Compressed air can be generated by many sources.