RX-8 Hydrogen RE a Dual Fuel Car

greekgod8591 writes "Japan's Mazda Motor Corp. said on Wednesday it will begin leasing a dual-fuel car that can run on both hydrogen and gasoline in the auto industry's latest effort to reduce oil consumption in vehicles. Mazda said the RX-8 Hydrogen RE, based on its popular RX-8 sports car, gets around these problems by running on gasoline in the absence of a hydrogen fuelling station, and using existing engine parts and production facilities to lower costs."

Re:Rotary

[mashade]

All of the RX- line are rotaries, IIRC.
The RX-7 was very popular for a time, competing with Nissan's Z series.
The two cars were styled similarly.

Re:Rotary

[berboot]

Mazda has been the main user of the rotary engine for the past decade or so. Both their RX-7 (which ended it's lifespan in 1995, IIRC) and the current RX-8 are rotary engine designs.

From the reading car enthusiast forums that I frequent, both are seen as great cars, but have their share of oil leaks. Additionally, it's rather difficult to find a mechanic that is willing to work on rotary engines, so most cars are maintained by shade-tree mechanics.

Re:Rotary

[Bullfish]

You may be thinking of a radial engine which was (and still is) used to many power prop driven aircraft. Mazda used to use rotary engines in the 70's, stopped for a while and re-introduced them in the RX-8. Mercedes tried them out too.

Thirsty Wankels...

[Rdickinson]

I ran an RX8 (hi-powered, UK) for two years, 30,000 miles. It drinks like a fish.

Hydrogen , whilst its a nice step forward isnt going to help much overall, and 62miles is ok if you live very close to where you fill up. As for 340miles out of the gas tank, forget it, most mine did was 275, typicaly 200-220.

Stunning cars though, balance, power and practicality, tho the Hydrogen cycle runs at 50% power and thats with a turbo.

mazda have had a demo/development duel fuel RX8 for a number of years.

For more info from the experts....

[NevarMore]

...on the RX-series as well as the wankel-style rotary engine check out the following:

http://rx7club.com/ [rx7club.com]
http://fc3s.org/ [fc3s.org]
http://www.mazdatrix.com/ [mazdatrix.com]
http://rx7.org/ [rx7.org]

and if you live in or near Ohio:

http://www.ohiorotaries.com/ [ohiorotaries.com]

These are some of the better sites/forums maintained and populated with rotorheads.

Its a two way exchange too, if you know anything about multi-fuel or new fuel vehicles we would like to hear from you as well.

Re:Rotary

[scotch]

Fortunately, not much goes wrong with wankel engines. Very few moving parts. Biggest problem is the seals wearing out, iirc, but the rx-7 i had in the 80s ran over 100k miles without any engine work, and didn't leak oil noticibly between oil changes, either.

Re:What about the sealing problems?

[Rdickinson]

No there using it as fuel in the wankel, no fuel cell here.

The wankel rotary is pretty good at using hydrogen, far better than a piston engine.

Oh and the seal problem was solved a long time ago, RX7's had an overheating problem on part of the apex seals made out of a rubber, that part is cast iron on the renesis in the RX8.

Radial != rotary

[AJWM]

Some posters seem to be confusing radial piston engines with rotary engines. While radial engines were common on many piston aircraft (some of which are still around), the pistons themselves still moved in a back and forth motion within the cylinders. In a rotary engine, specifically the Wankel used in the Mazda, the "pistons" are roughly triangular in shape and rotate (not oscillate) within an oval housing (the "cylinder" equivalent). The varying shape and volume of the space between the triangular center piece and the oval housing provides the compression and expansion provided by the oscillation of the piston in the cylinder of a more conventional engine.

Radial engines were so designed to provide adequate cooling airflow to all the cylinders, since all cylinders were at the front of the engine (or for some engines, in the space between two cylinders in front). Aircraft engines are usually air-cooled, for a variety of reasons (weight, reliability, etc).

As far as WW1 or WW2 engines, the required machining precision and seals technology to make something like a Wankel rotary was just not available. Cylindrical pistons and bores with circular seals are much simpler.

Re:Rotary

[RyMon]

That's one of the huge cases for them; no valves, valve springs, cam shafts, pistons or rods to deal with. They are commonly used in planes due to their small size and light weight per horsepower they can produce. Specifically, my RX-7 runs 400 horsepower out of a 2 rotor 1.1 liter 350lb engine... Granted it's race only, because the intake ports are huge; it doesn't start making power until around 9000 RPM, but maintains it until around 14,000 RPM. (That's the other thing; since the rotors themselves are only spinning at 1/3 rotation per crank rotation, you can get them to rev all to high hell.) Their negatives are that they tend towards low gas milage, because of the long narrow combustion chamber (hence why then generally run with two spark plugs per rotor).

Re:Rotary

[Uncle Rummy]

They don't leak oil, as such, they consume it. The design of the engine requires that oil be injected into the combustion chamber to lubricate the apex seals. Of course, the net effect to the owner is the same - you have to keep an eye on your oil level, but the consumption is really pretty slight in the RX-8 engine - I check my oil every 1,000-1,500 miles and need to top off about half of those times. After 26,000 miles, I've added a total of less than 2 quarts between scheduled oil changes.

Re:RX-8?

[TooMuchToDo]

Not really. A rotary engine isolates the combustion process better then a standard ICE, which enables it to be Gas/Hydrogen FlexFuel stock. A standard ICE can't do this (currently).

Naysayers

[Frogbert]

Whenever there is an artical posted about any type of alternative energy there are about 400 trolls complaining that X energy isn't a good enough and that it is a complete waste of time and money to even try.

Here's the thing, if someone doesn't start the ball rolling it never will start, so its great that Mazda has done this, perhaps it will be a failure, perhaps it will do better then they expected but mainly this is planting seeds.

The first company to bring out competitive alternative energy cars is going to be in an excellent market position, the only way to do this is to actually start bringing out the cars once they see what works and what doesn't they will be miles ahead of the competition.

Re:Rotary

[modecx]

The Sopwith's engine wasn't a rotary engine like a wankel (which uses a rotor, not pistons), but it was called a radial rotary engine because the crankshaft was in fact fixed, and the cylinders, pistons, heads, manifolds, propeller--everything rotated around the crankshaft. As a matter of fact, the propeller was mounted to the engine itself!

In effect, the rest of the engine became the flywheel. Because it didn't need an external flywheel, these engines had better power to weight ratios, which is obviously very important in WWI biplanes. There was also a French airplane, which, IIRC made dual use of the crankshaft as a gun barrel... So bullets fired straight through the center of the engine, and the barrel was very effectively oil cooled if you can imagine!

They're wrong, however, saying that Mazda makes the only Wankel engine, because of course, Moller international also makes them, and they're going to be used in their much anticipated VTOL Skycar.

already dual fuel vehicles

[Doppler00]

There are already a lot of duel fuel propane/LNG/gasoline trucks out there. Most of the places I've seen them though only fill them up with gasoline. Also, the tank for the LNG fills up about a quarter of the truck bed in the back. Same problem, although worse with hydrogen. Since hydrogen naturally doesn't have as much energy densities at similar pressure you have two choices: Make the tank even bigger, or compress the gas to a ridiculusly high pressure. Both choices have their own associated problems.

Mazda is Ford

[minus_273]

For those who aren't in the know, Mazda is a division of Ford [ford.com]. Many of the cars use the same components and sometimes they are the same cars with different model names. People looking for a "japanese" car often buy Mazda not knowing they are buying a Ford. Go to the mazda site and compare some of the models to the ford site, the resemblance is uncanny ;)

The real issue with hydrogen

[Belseth]

Alcohol engines are a better solution in the short term. Everyone assumes that the hydrogen is going to be produced by electricity but that simply isn't true. Most hydrogen is extracted from fossil fuels, I believe primarily natural gas at the moment. The reason for the big push on hydrogen is Bush is trying to lock us into a oil based hydrogen economy. Most of the investment is in a petroleum/hydrogen based infastructure to make sure we are still oil dependent. Alcohol can run existing cars with minor modifications. It doesn't require the storage systems or distribution systems hydrogen does and can get similar mileage to gasoline, not as much but far better than hydrogen. As for the extra carbon it's carbon active within the environment so it's a wash and doesn't add to the overall carbon. All petroleum products add carbon that has been stored. Alcohol can potentially be extracted from farm waste, plant stalks and such. At worst it comes from corn and the like, even plants like Agave. It'll probably never be a 100% solution but can help as a transitional fuel. An ideal combination would but alcohol hybrides that can be wall recharged and have limited solar cells for helping to top the car when sitting in an outdoor parking space. Given the fact if you were primarily commuting you'd only have to fill it a few times a year the savings would be huge even if alcohol ran 2X what current gas prices are. That's based on the results an engineer got when he simply added more batteries to his hybrid and charged it from the wall at night. The recharging was cheap and he was getting over 200 miles on a tank since he rarely went off batteries. Adding minimal solar cells would drastically reduce gas useage even if it just added 10% to the range. The extra batteries only added a few grand to the cost which would be quickly paid back in savings. Solar cells would add a few grand more but would reduce the alcohol engine to an emergency back. It would only be needed on long hauls and during bad weather.

Re:Mazda is Ford

[drhamad]

Someone should have modded that comment up. I would if I had points at the moment.

Anyway, you're right, Mazda is Ford. To be specific, Ford owns a controlling interest in them of approx 1/3. They use the same engines (Duratec/MZR 23 (I4), Duratec/MZR 30 (V6), though sometimes tuned differently),
same platforms: (CD3/etc (they use different names) is the Mazda6, Ford Fusion, Mercury Milan, Lincoln Zephyr)
the Euro Focus (not yet the American), Volvo S40, and Mazda3

That being said, the RX-8 does not share its platform with anything else, though I'm sure many of the components inside are the same.

The Mazda6 is even made in Flat Rock, MI alongside, if I remember correctly, the Mustang (and in the factory that previously made the Mazda MX-6 and Ford Probe).

Mazda is definitely Ford, and it has never been doing better.

Re:Rotary

[Enigma Deadsouls]

Rotax may have at some point or another in their 80+ year history built a rotary engine (none come to mind, but I could be wrong), they however do not build any currently.

As an owner of two Aprilia (a 2001 RSV Mille [charter.net] and a 1999 RS250 [charter.net]), I can tell you the Rotax built V990 (998cc 60deg V-Twin) in my RSV is not a Rotary engine. RS250 doesn't matter as it uses a Suzuki VJ22 (250cc 90deg two-stroke V-Twin) engine.

That said there are motorcycle that were built using rotary engines [millville.org].

Re:RX-8?

[StikyPad]

It's about alternative energy, not fuel conservation. The RX-8 actually gets pretty crappy mileage, especially if you drive it like a sports car. Also, the RX-8 is the only vehicle Mazda sells (in the US?) with a rotary engine, and the rotary engine is what makes it easier to swap fuels. The biggest advantage is that the rotary engine can't backfire. Backfiring is caused by undetonated fuel being expelled to the exhaust pipe, then ignited on the subsequent cylinder firing. Since the rotary engine intakes at, say 0 degrees, then rotates to 120 degrees to fire, then rotates to 240 degrees and expels the exhaust, backfire conditions are never met. (I just made up those numbers; I don't know what the actual angles are). It's a bad thing in a reciprocating engine because the piston is trying to move up to expel the exhaust, and the detonation from the exhaust pipes pushes it down.

So basically, it makes perfect sense to use the RX-8.

Re:Rotary

[TheNetAvenger]

Mazda has been the main user of the rotary engine for the past decade or so. Both their RX-7 (which ended it's lifespan in 1995, IIRC) and the current RX-8 are rotary engine designs.

From the reading car enthusiast forums that I frequent, both are seen as great cars, but have their share of oil leaks. Additionally, it's rather difficult to find a mechanic that is willing to work on rotary engines, so most cars are maintained by shade-tree mechanics.

The Oil leaks are not leaks, the nature of the lubrication system of the rotary design intentionally burns a small amount of oil during operation as a part of the lubrication process. However it is only like a 1/2qt every 3000-4000 miles.

The older RX3 and RX5 vehicles made by Mazda in the 70s DID have oil leaks, but this was due to a faulty seal design that was overcome with the 12A Rotory engine introduced in the new 1979 RX7. The engine's size was increased and refined again in 1985 with the GXL-SE RX7, and this engine, the 13B, then became the standard engine of the new body style that ran from 1986.

Mazada redesigned the RX7 again in 1992, and it still holds as one of the top sports cars ever produced, with under 5sec 0-60sec times, over 1g skipad, etc. However the engine in the 1992 RX7 Was the same basic 13B engine introduced in 1985, but with an improved twin turbo system, giving this simple engine amazing horsepower and the lower end torque to move.

The RX8 is a new revision to the Rotary engine, giving it more horsepower without the need for turbo. (However if the earlier Twin-Turbo was added to this engine, it would be in the ranks of the fastest cars ever made, a decision I think Mazda skipped on due to the market of the RX8(too much power for the average buyer); however, rumors of it or a new RX7 with twin-turbo are going around.

As for working on the rotary engine, it is out of ingornance if mechanics won't work on them, they are a very simple design, much simplier than the more complex piston based combustion engine.

The biggest failure in RX7s were the transmissions, as the rotary engine normally runs at a higher RPM than other engines, as it just keeps spinning and doesn't have to reverse direction. So a 9K redline is nothing, in fact many street racers and modders in the late 80s early 90s used RX7s in racing because the standard engine could still perform reasonably well in the 15,000-18,000 rpm range, it was the transmission to hold up to this amount of speed and power that was the trick.

Rotary engines are quite interesting and surprising that they have not caught on more in the market. They can be more fuel efficient, and emmissions are often better as the engine does a more complete burn process of the fuel. They are also surpsingly small, and lightweight. An average person can lift the engine. Which is kind of cool seeing a tiny engine that back in 1992 and 1993 was basically a 2 cylinder engine and could out perform even the Corvette ZR1 at the time.

The light weight nature of the engine and lack of vibration were also benefits to the performance of the car, as the engine could be mounted futher back in the car giving the car a 50/50 weight distribution for great cornering, and unlike other cars in its class, no vibration problems that other companies like Nissan were plaqued with when they tried to compete with their 6cylinder engines of the time.

Another footnote on the Mazda/Rotary engine is that in the racing circuit, Mazda for years has used a 3cylinder version of the rotary engine in its racing cars, and unline competitors like GM/Corvette, Porche, Ferrari, etc - the Mazda team uses the SAME engine throughout the racing season because of its high durability, where the other competitors usually replace engines between each race.

I am somewhat of a car enthusiast, and have owned all 3 variations of the RX7. I actually miss them, they were fast, nimble cars that were easy to do things well in them.

In contrast to the Corvettes and other performance cars I ha

Re:Rotary

[Anonymous Coward]

RX-7 owner here. No, you're thinking of a radial engine. Those have pistons radiating from the crankshaft. Very common in aircraft designs. Mazda licensed and refined Dr. Wankel's design, which uses two sorta triangular-shaped rotors that both orbit and revolve inside an oval chamber that's a little pinched at the sides. Those turn the eccentric shaft, which then turns the transmission. There are no pistons, camshafts, valves, or anything else you're used to hearing about. Really only three moving parts, and because it doesn't reciprocate (think of the piston going back and forth, stopping at each end then going the other way) it'll turn a whole mess of revolutions and develops more and more power as it spins faster. Whoever said they were noisy and sluggish is dead wrong. Even at 120+ MPH (and believe me, I've run mine at 100+ for hours out on lonely desert roads) they're vibration-free and eerily quiet. A little slow off the line, but comes alive around 3000RPM. At freeway speeds, I regularly smoke Corvettes and Porsches. The other benefit is that they develop a lot of power in a small package. Because of this, Mazda put the rotary behind the front axle on the RX-7, making it a true mid-engine car with 50:50 weight distribution. Totally neutral handling and fantastic speed. If you ever want to know what a supercar is like on the cheap, buy one. Mine's been bulletproof, too. Just regular maintenance.

Rotary engine is an excellent hydrogen engine

[Brett Johnson]

Because a Wankel Rotary Engine has no valves it makes an excellent hydrogen combustion engine. [The high temperature of hydrogen combustion tends to burn valves in piston engines.] The effect is improved by burning a mixture of hydrogen, air (oxygen), and aerosolized water. The high combustion temps vaporize the water, increasing the expansion pressure. [Note that a hydrogen combustion engine is different than a hydrogen fuel cell engine].

Wankel rotary engines are underutilized today because of the bad rep they got in the 70's. Their horsepower-to-weight ratio makes them an excellent performance engine for light vehicles (like the Rx7, portable generators, and airplanes). They tend to be weak on the torque side, however. [Performance piston engines often can built with 1-1 horsepower to torque ratios.]

The lightweight, simple, valve-less structure of rotary engines make them good candidates for alternative fuels. However, current rotary engine designs require injections of small amounts of oil to lubricate the apex seals. This oil is combusted with the fuel and expelled. [Typical oil consumption on a 13B engine is about 1/2 quart per 1500 miles.] Unfortunately, even when burning hydrogen, this tiny amount of burned hydrocarbons disqualifies the engine as a "zero emissions" vehicle - no research grants - no subsidies - no ZEV tax credits.

http://www.millville.org/Workshops_f/kess_mech/too ls/1tools/hydrogen.html [millville.org]

Re:Rotary

[TheNetAvenger]

Nope, sorry. "Wankel engines are criticized for poor fuel efficiency and exhaust emissions."

"Just as the shape of the Wankel combustion chamber prevents preignition, it also leads to incomplete combustion of the air-fuel charge, with the remaining unburned hydrocarbons released into the exhaust."

"A related cause for unexpectedly poor fuel economy involves an inherent weakness of the Wankel rotor design when used with conventional fuels. Some studies have indicated that at high speeds, the rate at which the volume of the combustion chamber increases in the moments after ignition actually outpaces the expansion of the burning fuel. The result is that, at high speeds, less useful energy is extracted from the same volume of fuel"

http://en.wikipedia.org/wiki/Wankel_rotary [wikipedia.org]

Nope sorry...

You need to rely on more than wikipedia my friend. Originally the Wankel design was less efficient at both the full usage of the fuel, resulting in lower fuel efficiency and extra pollution.

However if you would have looked up some of the Work Mazda specifically did with the design, these concerns were virtually gone at the 12A engine, and with the 13B engine were better than a comperable performing regular cylinder engine.

Remember you have to contrast the performance of the Engine. A 1987 (13B) Mazda RX7's fuel efficiency was better than a 6 Cylinder Nissan, yet the Mazda produced more horsepower.

Additionally, with the Mazda designs, the combustion chamber DOES Burn the fuel more completely, and there are considerable less emmissions when comparing the engine to the same performing engine.

Here is where people get confused. The Mazda Rotary engines were 'classified as 4cylinder engines because they had 4 spark plugs - lead and trail on each of the two chambers'. However the engine is in the performance class of V6 and V8 engines.

So yes, if you were to compare a 2 chamber Rotary engine with an average 4 cylinder engine, the fuel economy looked bad. However, when compared to the same performance level 6 cylinder engine, the rotary was far ahead of it.

So these are false stats, as you can't truly call the Mazda Rotary a 4 cylinder engine, when it outperforms 6 cylinder engines. (And technically it is a two chamber engine.)

Even look at the new rotary in the RX8, it is technically classified as a 4 cylinder engine for insurance purposes or in common car classifications; however, it outperforms the Mitsubishi Eclipse 6 cylinder engine, and gets the same or better fuel efficiency. So in terms of power, it is a 6 or 8 cylinder engine.

Here think about it like this, a 1985 Corvette had 230hp, with the new tuned port V8, and yet the new Mazda RX8 has better horsepower and better fuel efficiency.

If you want to call the 2 chamber rotary a 4 cylinder engine, and try to compare it to an engine that produces about 1/2 the HP, then sure, the fuel efficiency doesn't look so great.

But doing so would be a bit 'insane'...

PS WikiPedia is only as good as the person that felt like an expert the day before you looked up the article, do some real research next time.

I may not do cars for a living, but I know my way around them, owned every type of RX7 and many other sports cars, outside of computers, it is my passion. I also did an engineering paper on the Wankel when I was in University, so I have did a bit more than just drive and work on them.

Re:Naysayers

[red_dragon]

Does this mean you have to top up the oil at the same time as the fuel (or indeed, mix oil in with the fuel) as with a 2-stroke?

No, the rotary engine is planted firmly in four-stroke land. What the Mazda 13B does is inject a small amount of oil onto the apex seals of the rotors via a port on the inside of the rotor housing. It's really sort of a controlled drip instead of a squirt, so that when the seals go over the oil port, they literally "squeegee" the oil around the interior surfaces of the engine. The oil is sourced from the regular supply of oil used to lubricate the rest of the engine. Yes, it needs to be topped off regularly, but it's on the order of 1L/2000km for an engine in good condition, which is not much different from many reciprocating engines. Take a look at this page [rotaryengi...trated.com] for an illustration.