Dark Horse Studio
Page5SF
As the car had the original 12A Wankel engine, another dilemma arose. Should the engine be upgraded or replaced entirely by one with larger displacement? After much thought and consideration, I decided to replace the factory unit with a turbocharged 13B from a second-generation Turbo II. However, that quickly changed when Luis informed me of a spare 12A project he had for sale. The engine was from a 1985 RX-7 and outfitted with an aggressively large street port and a Camden supercharger at 10psi.
The engine underwent a complete overhaul by Luis with the inclusion of many internal components from a 13B turbo. Turbo II apex seals, gaskets, and a water pump were added to ensure lower compression and proper heat tolerance. Unfortunately, upon road testing the completed engine, it was discovered that the Camden supercharger unit was not capable of withstanding the extremely high rpm rate of the built engine as it would lock up after 8000 rpm's. The decision was made to retain the built engine but to remove the supercharger and install a high performance Holley quad barrel carburetor from Racing Beat. A ported Racing Beat intake manifold was also added to provide maximum air flow. The loss of power was evident in the lower rpm's but noticeably higher in the upper range.
A problem then arose with belt slippage in the higher rpm's. The OEM spec belt would sometimes completely remove itself from the drive even with a dual-groove pulley setup. An idea came to me when a friend of mine from Jamaica reminded me of an Australian-made synchronic Gilmer Drive System similar to that used by high horsepower V8's. It consisted of a toothed cog pulley and synchronous belt system that completely eliminated belt slippage even in the highest rpm range. After a few overseas phone calls, a unit was finally found and shipped to me from Australia. Due to the larger water pump, the entire pulley setup had to be custom tailored and machined to fit the engine and alternator. With the complete setup installed, I was very impressed with the stability it provided to the engine and the signature whine the belt drive produced. It has since gained the title of “Solid Synchronous System”. At its current status, the engine is at the beginning levels of Stage 2, with further plans to increase it's performance and cooling system. It has been dubbed “12B” due to the merger of the different 12A and 13B components to achieve a hybrid rotary engine.
...Continued on Page 6...
Page5SF
As the car had the original 12A Wankel engine, another dilemma arose. Should the engine be upgraded or replaced entirely by one with larger displacement? After much thought and consideration, I decided to replace the factory unit with a turbocharged 13B from a second-generation Turbo II. However, that quickly changed when Luis informed me of a spare 12A project he had for sale. The engine was from a 1985 RX-7 and outfitted with an aggressively large street port and a Camden supercharger at 10psi.
The engine underwent a complete overhaul by Luis with the inclusion of many internal components from a 13B turbo. Turbo II apex seals, gaskets, and a water pump were added to ensure lower compression and proper heat tolerance. Unfortunately, upon road testing the completed engine, it was discovered that the Camden supercharger unit was not capable of withstanding the extremely high rpm rate of the built engine as it would lock up after 8000 rpm's. The decision was made to retain the built engine but to remove the supercharger and install a high performance Holley quad barrel carburetor from Racing Beat. A ported Racing Beat intake manifold was also added to provide maximum air flow. The loss of power was evident in the lower rpm's but noticeably higher in the upper range.
A problem then arose with belt slippage in the higher rpm's. The OEM spec belt would sometimes completely remove itself from the drive even with a dual-groove pulley setup. An idea came to me when a friend of mine from Jamaica reminded me of an Australian-made synchronic Gilmer Drive System similar to that used by high horsepower V8's. It consisted of a toothed cog pulley and synchronous belt system that completely eliminated belt slippage even in the highest rpm range. After a few overseas phone calls, a unit was finally found and shipped to me from Australia. Due to the larger water pump, the entire pulley setup had to be custom tailored and machined to fit the engine and alternator. With the complete setup installed, I was very impressed with the stability it provided to the engine and the signature whine the belt drive produced. It has since gained the title of “Solid Synchronous System”. At its current status, the engine is at the beginning levels of Stage 2, with further plans to increase it's performance and cooling system. It has been dubbed “12B” due to the merger of the different 12A and 13B components to achieve a hybrid rotary engine.
...Continued on Page 6...