Jman
Site Developer
As most of you may have heard Mazda is coming out with a new generation of engine to power their new RX-8. It's called the Renesis and it has some significant differences over the 13b. I've been doing some reading and came across some interesting information.
1. Mazda claims that the Renesis engine is 12% lighter and slightly more compact than the 13b. The published numbers are 304 lbs for the Renesis compared to 344 for the 13b. How much of that weight savings will be realized on a conversion still remains to be seen. From those numbers it sounds like Mazda is including all of the accessories which may or may not be used in a conversion. If most of the weight loss is in the basic components then that would be good news indeed. Mazda also claims that the Renesis rotors weigh in at 8.2 lbs each which is 14% lighter than the 13b rotors.
2. The official Horsepower numbers are 250 HP at 8500 RPM. Peak torque happens at 5500 RPM at 159 lb-ft. The very interesting thing about this to me is that it is normally aspirated. Although there is not a turbo version yet, the moment the RX-8 hits the street you can bet there will be turbos installed. As to whether or not Mazda will offer a stock turbo anytime soon, that is still up in the air. Personally, I like the idea of a turbo. Not necessarily for an increase in output, but to keep full power at cruising altitude and high density altitude airports.
3. The fuel efficiency is said to be much better than the 13b. The RX-8 is expected to get 18-19 mpg city and 23-24 mpg on the highway. The mileage specified for the 1995 RX-7 which uses the 13b is 14 MPG. Mazda also claims that the Renesis burns 40% less fuel than the 13b at idle (not sure if this is a useful number). This better mileage is attributed to the engines ability to scavenge un-burnt fuel from the exhaust cycle into the intake cycle. The good thing is that this scavenging takes place because the exhaust ports have moved from the periphery to the sides like the intake ports. See picture for details. Incidentally the intake port area has increased by 30% and the exhaust port area has increased by 100%.
There is one thing about the engine that is giving me some pause however. Below is a quote from a Mazda press release.
Photos:
External View
External Veiw2
Internal Veiw3
Internal Veiw4
Intake Drawing
Old and new Ports Drawing
Ports Drawing
Side Seals Drawing
Unburned Fuel Drawing
Anyway, I just thought I would share the info I came up with. I'm still quite a ways away from needing an engine, but it's an interesting subject for me none the less. Anyone else looking at this engine as a possible conversion?
1. Mazda claims that the Renesis engine is 12% lighter and slightly more compact than the 13b. The published numbers are 304 lbs for the Renesis compared to 344 for the 13b. How much of that weight savings will be realized on a conversion still remains to be seen. From those numbers it sounds like Mazda is including all of the accessories which may or may not be used in a conversion. If most of the weight loss is in the basic components then that would be good news indeed. Mazda also claims that the Renesis rotors weigh in at 8.2 lbs each which is 14% lighter than the 13b rotors.
2. The official Horsepower numbers are 250 HP at 8500 RPM. Peak torque happens at 5500 RPM at 159 lb-ft. The very interesting thing about this to me is that it is normally aspirated. Although there is not a turbo version yet, the moment the RX-8 hits the street you can bet there will be turbos installed. As to whether or not Mazda will offer a stock turbo anytime soon, that is still up in the air. Personally, I like the idea of a turbo. Not necessarily for an increase in output, but to keep full power at cruising altitude and high density altitude airports.
3. The fuel efficiency is said to be much better than the 13b. The RX-8 is expected to get 18-19 mpg city and 23-24 mpg on the highway. The mileage specified for the 1995 RX-7 which uses the 13b is 14 MPG. Mazda also claims that the Renesis burns 40% less fuel than the 13b at idle (not sure if this is a useful number). This better mileage is attributed to the engines ability to scavenge un-burnt fuel from the exhaust cycle into the intake cycle. The good thing is that this scavenging takes place because the exhaust ports have moved from the periphery to the sides like the intake ports. See picture for details. Incidentally the intake port area has increased by 30% and the exhaust port area has increased by 100%.
There is one thing about the engine that is giving me some pause however. Below is a quote from a Mazda press release.
One of the things that has attracted me to the Rotary is its reliability based on fewer moving parts. If I understand the above quote, a new level of complexity has been added that may or may not decrease reliability.
Photos:
External View
External Veiw2
Internal Veiw3
Internal Veiw4
Intake Drawing
Old and new Ports Drawing
Ports Drawing
Side Seals Drawing
Unburned Fuel Drawing
Anyway, I just thought I would share the info I came up with. I'm still quite a ways away from needing an engine, but it's an interesting subject for me none the less. Anyone else looking at this engine as a possible conversion?
