This is a generalized write-up of information pertaining to the wide range of injectors used on Mazda’s RX-7’s. This information will hopefully come in handy for those looking for higher-flow injectors for cheap upgrades
First Generation RX-7 (FB)
1985 RX-7 GSL-SE
This car was the last year of the first generation RX-7 body style (FB). This particular trim featured a 135hp Fuel Injected 13B. All previous cars had been carbureted. This car has two 680cc, low impedance, Hitachi-type, square plug injectors. Originally they have a black body, those this paint may be rusted away. Plastic tops are Orange/Tan in color. The serial number on them is: 195500-0900.
Ways to spot this car:
Fuel injection manifold with air cleaner assembly.
14 inch alloy wheels, in a “phone-dial” pattern.
4x114mm bolt pattern. All other FB’s have a rarer 4×110 bolt pattern.
Second Generation RX-7 (FC)
The second generation of the RX-7 was sold in the US from 1986-1991. They are commonly identified as looking like 80’s Porsche 924/944’s. They were offered in the US market in turbo and non-turbo charged models in a coupe and convertible form. All US market convertibles are non-turbocharged.
These cars are somewhat divided by a mid design overhaul. Cars from 86-88 are called Series 4 cars, or S4 for short. 89-91 cars are called Series 5 or S5. The difference between the two is somewhat important, as you will read later.
For now, let me list some easily discernible differences between the two cars.
– S4 cars have black colored body trim, S5 cars have body color trim.
– S4 cars have standard manual seat belts, S5 cars have automatic/electric seat belts.
– S4 cars have squared off, 4 block tail-lights. S5 cars have dark tail-lights with three circles inside, resembling an 80’s Thunderbird or Nissan Skyline.
Series 4 notes:
Naturally aspirated car’s came with 460cc injectors. Turbo cars came with 550cc injectors. All of them are a Hitachi type, square plug injector. HOWEVER, 1986 and early 1987 cars came with LOW IMPEDENCE injectors. Late (most) 1987 cars and all 1988 cars came high impedance injectors. To easily discern the two, refer to the VIN and build date. The switch over was made in June of 1987. All cars with a VIN ending in 7601 and higher are HIGH IMPEDANCE. All cars with a VIN lower than 7601 are LOW IMPEDENCE. Another way to tell the difference is to remove the stock airbox. For low impedance cars, there will be a resistor box located under the airbox assembly.
86-87 NA RX-7 w/ VIN before an ending of 7601 = 460cc low impedance. (((I HAVE NEVER SEEN ON OF THESE BEFORE IN REAL LIFE)))
87 Turbo RX-7 w/VIN before an ending of 7601 = 550cc low impedance. Black body, tan colored top. Serial # – (((I NEED TO LOOK THIS UP)))
87-88 NA RX-7 w/VIN of or after 7601 = 460cc high impedance. Black body, red top. Serial # – 195500-1350
87-88 Turbo RX-7 w/VIN of or after 7601 = 550cc high impedance. Black body, red top. Serial # – (((INSERT HERE LEX)))
Series 5 notes:
Again, NA cars came with 460cc injectors. Turbo cars came with 550cc injectors. All of them are high impedance. HOWEVER, Mazda changed the wiring harness (and the injectors) on the cars for the S5 upgrade. As such, while these are still standard Hitachi-type injectors, they do have an oval connection plug instead. To use them, simply acquire new injector plugs (dealership, junkyard, etc.) and solder them into your wiring harness.
These injectors all have a silver, unpainted body. On the 460cc injectors, the tops are a purple-red in color. The serial number is: 195500-2020. The 550cc injectors have a slightly more red top. It is best to check they serial number to differentiate. That serial number is: 195500-2010
By: Jayson West