Where should I install the oil temperature, oil pressure, water temperature, and boost pressure sensors on a Mazda RX-7 FD?

Installing aftermarket sensors on an FD RX-7 is a great way to accurately monitor engine health, especially if you plan to track the car. Below are the most proven locations for each sensor based on standard practices for the 13B-REW.

Difficulty Rating: Moderate This requires draining fluids, routing wiring, and potentially tapping metal components depending on the methods you choose.

Boost Pressure

• Upper Intake Manifold (UIM): The easiest and most accurate location is to connect the sender line to any extra, unused vacuum nipple on the UIM ¹.

Water Temperature

For the most accurate readings, the sensor must be placed where it can measure the coolant before or as it exits the engine block. Avoid installing the sensor in the lower radiator hose, as the gauge will not read accurately until the thermostat opens ¹.

• Throttle Body (TB) Coolant Hose: This is a very popular, easily reversible option. You can cut the TB coolant line and install an inline hose adapter (like a 38mm Greddy adapter or a custom brass T-fitting) ³.
• Water Pump Housing / Thermostat Cover: You can drill and tap the back of the water pump housing or the thermostat cover. Ensure you tap behind the thermostat so the sensor receives an accurate reading of the block temperature before the thermostat opens ¹.
• Rear Iron: Another option is tapping the coolant line coming off the top of the rear iron ¹.

Oil Pressure

• Aftermarket Oil Filter Pedestal: The cleanest and easiest method is replacing the factory oil filter pedestal with an aftermarket billet CNC pedestal (such as the SakeBomb Garage unit). These typically include pre-tapped 1/8" NPT ports for both your oil pressure and oil temperature sensors ¹.
• Factory Block Location: You can remove the stock oil pressure sender located on the block under the oil filter and use that port ¹. Note: Mazda uses an international 1/8 PT (BSPT) thread pitch. Most aftermarket sensors (like Autometer) use 1/8" NPT. Do not force an NPT sensor into the BSPT block; you will need a 1/8 BSPT to 1/8 NPT adapter or a Y-adapter ¹.
• Sandwich Plate: You can install an oil filter sandwich plate (a Honda B-Series plate uses the same thread pitch). However, this pushes the oil filter higher, severely reducing clearance to the throttle position sensor (TPS) wiring. You will likely need to run a shorter oil filter to prevent cracking the TPS during engine movement ⁵.

Oil Temperature

• Aftermarket Oil Filter Pedestal: As mentioned above, a billet pedestal is the most ideal location to run both the temperature and pressure sensors in one place without clearance issues ¹.
• Oil Pan Drain Plug: You can use a drain plug adapter (M14x1.5 to 1/8" NPT) to place the temperature sender directly in the oil pan. This is an extremely simple install and gives a reliable reading of the resting oil temperature ⁵.
• Banjo Bolt: You can tap the banjo bolt on the line coming from the engine block to the oil coolers. This measures the oil at its absolute hottest right after it exits the engine, though care must be taken to ensure the sensor tip does not restrict oil flow through the bolt ¹. Ensure you use liquid Teflon or sealant on the sensor threads to prevent leaks.