Mazda's strange engine
- Thread starter sagaper
- 12 comments
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Rotary Junkie
Premium
- 9,810
- Canton, MI
- RJs_RX-7
It's "better" in some ways but lacking in others... Mainly lack of development.
Anyway, @ OP: If you want to experience the true strength of the rotary, buy a 787B. If you'd prefer a road car, look no further than the 2002 RX-7 Spirit R.
Anyway, @ OP: If you want to experience the true strength of the rotary, buy a 787B. If you'd prefer a road car, look no further than the 2002 RX-7 Spirit R.
- 10,557
- Columbia, MD.
- Parnelli_Bones
One of the ways the rotary seems "better" than ordinary combustion engines with pistons is power per liter. Here we have a 1.3 liter engine putting out over 150 hp per liter in many RX-7s. Most naturally-aspirated engines range from 50 to 80 hp per liter (not including certain cars like Hondas with VTEC valvetrains), and most turbocharged engines put out just over 100 hp per liter and up. The rotary's specific output is therefore pretty high.
I'm not sure how big the 787B's engine is, though. I've never driven or studied one over all these years.
I'm not sure how big the 787B's engine is, though. I've never driven or studied one over all these years.
BobK
Premium
- 7,020
- Massachusetts, USA
The 787B had a 4-rotor 2.6 liter normally aspirated engine that could put out about 900 hp. The GT4 Mazda dealer lists the HP as 690 but my black 787B currently is listed as 763 (dunno if it could use an oil change or not right now).
The Wankels don't drive all that different in GT4, but they certainly do sound different!
The Wankel does have a higher specific output, partly (mostly?) because it makes three power pulses per revolution per rotor, as opposed to a normal 4-stroke which makes one power pulse per cylinder every other revolution. Also, because it doesn't have any reciprocating parts, the Wankel runs much more smoothly (less vibration).
One problem with the Wankel is it doesn't have great fuel efficiency. Another is that it's difficult to maintail a good seal between the rotor and the housing. This means, along with poorer fuel economy, the engine generates more emissions as well. Mazda has come a long way towards solving this, but it's still a problem.
An interesting sidenote: The Chevrolet Monza was originally designed to use a Wankel engine, and the engine bay was designed with this physically small engine in mind. But the fuel economy and emissions problems led to the cancellation of the engine project, which was replaced by (among other options) the Chevy smallblock V8. This engine was much larger than the Wankel. The net result was that you had to unbolt the engine and jack it up a few inches to get enough clearance to change one of the sparkplugs!
The Wankels don't drive all that different in GT4, but they certainly do sound different!
The Wankel does have a higher specific output, partly (mostly?) because it makes three power pulses per revolution per rotor, as opposed to a normal 4-stroke which makes one power pulse per cylinder every other revolution. Also, because it doesn't have any reciprocating parts, the Wankel runs much more smoothly (less vibration).
One problem with the Wankel is it doesn't have great fuel efficiency. Another is that it's difficult to maintail a good seal between the rotor and the housing. This means, along with poorer fuel economy, the engine generates more emissions as well. Mazda has come a long way towards solving this, but it's still a problem.
An interesting sidenote: The Chevrolet Monza was originally designed to use a Wankel engine, and the engine bay was designed with this physically small engine in mind. But the fuel economy and emissions problems led to the cancellation of the engine project, which was replaced by (among other options) the Chevy smallblock V8. This engine was much larger than the Wankel. The net result was that you had to unbolt the engine and jack it up a few inches to get enough clearance to change one of the sparkplugs!
- 2,529
- Alton, Illinois
- big_noobowski924
^ You know that is neat to find out about the monza's since I always thought they looked a bit like early RX-7's. Don't ask why I was 7-8 when I first saw one which was also around the same time I was loving the RX-7 in GT1
- 10,557
- Columbia, MD.
- Parnelli_Bones
From what i understand, a lot of cars were experimenting or about to experiment with rotaries, actually. Mazda is the only one that took the plunge and spent the time and money to get them right. I imagine during the '70s, Mazda execs must have been worried daily whether the rotary would tank their company if it failed in the long run. Fortunately it didn't.
Mercedes was the earliest I believe to put a rotary in a concept car. The NSU Ro80 was the first mass-produced rotary powered car, but it had tons of probs, as Bob K noted. I think NSU went out of business sometime during the '70s. I lived in Germany for a year when I was a kid in 1977-78, I remember plenty of NSUs around and about back then, but apparently NSU didn't last.
Mercedes was the earliest I believe to put a rotary in a concept car. The NSU Ro80 was the first mass-produced rotary powered car, but it had tons of probs, as Bob K noted. I think NSU went out of business sometime during the '70s. I lived in Germany for a year when I was a kid in 1977-78, I remember plenty of NSUs around and about back then, but apparently NSU didn't last.
- 1,426
- Burammm
NSU merged with Auto Union and became AUDI. So they are alive and kicking!
- 10,557
- Columbia, MD.
- Parnelli_Bones
