ROTARY HISTORY 8
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*Reprinted on http://rotarywiki.com with consent of the author.
- Part 1:The Smallest Wankel Of Them All
- Part 2: The Smallest Production Aviation Wankel
- Part 3: Biggest of Them All
- Part 4: The Citroen Connection
- Part 5: Russian Rotaries
- Part 6: The Orphan Mazdas
- Part 7: The One that Won in '91
- Part 8: Chinese Experiments
ROTARY HISTORY 8: CHINESE EXPERIMENTS
This column has discussed rotary development in Russia. It shouldn't be surprising, then, that such work has also taken place in the People's Republic of China, particularly at the South China Institute of Technology at Guangzhou. But this rotary program is even more mysterious than the Russians', and my primary source for it is a US Society of Automotive Engineers (SAE) paper, no. 880628 of 1988, by Chen Teluan of the institute. The paper cites a few other sources, all Chinese. My letters to Mr. Chen for an update and technical information have so far gone unanswered.
Wankel research began in China back in early 1960 (!); the paper reports a claim that over 150 "factories and research institutes" were involved with the engine in the '60s. Testing was rather extensive, including engines of 1 to 3 rotors, "water and air cooled, compression- and spark-ignition, with a displacement per rotor ranging from 150 to 1500 c.c." In the early '70s "common technical key difficulties" led most researchers to end their work. Chen's institute and a few others concentrated on solving these and had done so by the early '80s. The emphasis was mostly on vehicle use.
Two water-cooled 2-rotor gasoline engines believed suitable for production by the time of the SAE paper were the GZ2-900 with 900 cc per rotor, a 9.5:1 compression ratio, 120 hp at 3600 rpm and a weight of 454 lb; and the JZ211B with 1094 cc per rotor, 8.5:1 compression ratio, 158 hp at 4000 rpm, and weight 573 lb. The rotor dimensions were not given, though curiously the overall engine dimensions were: the GZ2-900, 23.9 in long; the JZ211B, 36.2 in.
These engines are clearly on the large side. Their state of technology can be gauged by the use of alloy cast iron with (apparently) NO coating for the rotor housings and, at first, steel apex seals! Newer apex seals are ceramic, and the paper implies but does not explicitly say that the housing material is now different.
Manufacturing economy has obviously been emphasized as much as improving fuel efficiency. Longetivity compared to, say, a Mazda rotary has been secondary. Tests in trucks and buses in the mid-'80s showed that the JZ211B could typically go for 60,000 km (37,000 mi) before overhaul, though one made over double that. According to cost analyses based on fleet use in rugged Chinese conditions compared with piston engines, the rotary was more economical because of its much lower overhaul cost. Its fuel cost was quite comparable and in certain applications even lower. By 1988 endurance tests of 1,000 hours were about to begin.
Tests of compound-induction and multi-fuel stratified-charge versions were also occurring and showed much promise. Multifuel capability would include safer, cheaper diesel fuel, and this rotary would have "the advantage over a reciprocating diesel engine in specific weight and specific volume, and over [a] small gas turbine [!] in fuel consumption rate, air consumption and production costs". Aside from the trucks, buses, "high-speed boats", small hovercraft, and generator sets the conventional versions have been tested in, multifuel versions "will play an important role" in "special-purpose vehicle[s] as well as military applications". Note that comment.
All this research is meant to benefit the Chinese military in the long run. It probably explains the relative lack of specific engineering details in this paper. If the US ever faces war with China, their troops just might be using rotary-powered vehicles!
POSTSCRIPT FOR INTERNET: Since writing this, I have found that a number of books and papers were published in China about the engine in the '70s-early '80s. Most were of course in Chinese; a few were in English. After that, except for this 1988 SAE paper, nothing surfaces. A Chinese paper published in 1987 does discuss multifuel rotary engines, giving an idea of development trends.
In 2000 SAE published a comprehensive guide to engine manufacturers in China. None were listed as making rotaries. I have since contacted the editor asking about the status of rotary engine manufacturing there. He knew of none being made but intended to have his colleague in China look into it. For now, it appears that rotary research there has either largely ended or been driven underground. I doubt it has ended. And if it has indeed gone underground, that has obvious implications.
The fly in the ointment is that though China has impressive research and manufacturing capabilities, the technological level and execution are less than ideal (though this is changing). Compare Japanese tractors to Chinese tractors as an example. Both by various manufacturers have been sold in numbers in the US. From numerous accounts, the Chinese tractors produce less power and are heavier, more trouble prone, and less durable and reliable. Much the same issues plagued Russian equipment. If China is to produce rotary engines in any number, perhaps it will have to do as VAZ in Russia did (see Rotary History 5): build copies of Mazda engines. But what has happened since 1988? Please e-mail at email@example.com me if you have any information.