FD3S Methanol Injection Tank: Fitment and Setup Guide

By Garage Alpha: Titanium Hood Props, Carbon Fiber Door Sills ... | Published: 2026-10-15

Category: How-to Guides

A step-by-step guide to planning, mounting, and plumbing a methanol injection tank in your FD3S engine bay, including fitment checks and common mistakes to avoid.

Quick answer

Mount the tank on a rigid, isolated surface in the rear of the FD3S engine bay, away from direct heat and moving parts. Use the factory rear wiper tank location as a reference if you want a clean, integrated look. Plan the full plumbing route before drilling any holes, and pressure-test the system before adding methanol.

Why the tank location matters on an FD3S

The FD3S engine bay is tight and runs hot, so the tank cannot simply go wherever it fits. Methanol is flammable and corrosive, and the tank needs to stay cool enough to avoid vapor lock while remaining accessible for filling and level checks. The rear wiper tank area, used on some international market cars, is a proven reference point because it keeps the tank away from the exhaust manifold and turbocharger while staying within easy reach of the firewall. If you plan to run a front-mount intercooler or a larger radiator, confirm the tank does not block airflow or interfere with the bumper support.

Planning the plumbing route before you drill

Map the entire path from the tank outlet to the pump and then to the intake charge pipe. Keep the line away from exhaust components and any sharp edges, and use a heat sleeve where it passes near the downpipe or manifold. The pump should be mounted lower than the tank outlet so it gravity-feeds and does not run dry. If you are using a progressive controller, decide where the controller and wiring will live before you commit to a tank position. A common mistake is mounting the tank first and then discovering the pump location forces a long, uphill suction line that causes cavitation.

Mounting the tank securely

Use a bracket that spreads the load across the tank body rather than a single strap that can crush or fatigue the plastic. Rubber isolators between the bracket and the chassis reduce vibration and prevent stress cracks over time. If you are using a purpose-built tank, check whether it reuses factory mounting points; if it does not, measure twice and use a backing plate on the other side of any sheet metal you drill. Torque fasteners to the tank manufacturer's specification if one is provided, and check clearance to the hood and any strut tower bar after the hood closes.

Wiring, testing, and first fill

Wire the pump through a relay and an ignition-switched source so it cannot run with the engine off. Test the system with distilled water first to confirm the pump primes, the lines hold pressure, and there are no leaks at the nozzles or fittings. Only after a successful water test should you introduce methanol. Start with a conservative mixture and a low boost threshold, then datalog intake air temperatures and knock before increasing flow. If you are running a stock ECU, confirm it can accommodate the tuning changes; if not, plan for a standalone or piggyback before you rely on methanol for knock suppression.

Step-by-step FD3S methanol tank setup

Choose and verify the tank location: Position the tank in the rear wiper tank area or another rigid, cool spot. Check clearance to the hood, strut bar, and any intercooler piping with the hood closed. Common mistake: mounting too close to the turbo or manifold, which heats the methanol and causes vapor lock. Checkpoint: with the hood closed, there should be at least a finger's width of clearance above the tank.
Mount the tank with isolated brackets: Use a bracket that supports the tank body evenly and rubber isolators to reduce vibration. If reusing factory points, confirm thread condition; if drilling, use a backing plate. Common mistake: overtightening straps until the tank deforms. Checkpoint: the tank should not move when you push it firmly by hand.
Route and secure the suction line: Run line from the tank outlet to the pump, keeping it downhill and away from heat. Use heat sleeve near exhaust parts and secure it every 6–8 inches with cushioned clamps. Common mistake: uphill suction runs that cause the pump to cavitate. Checkpoint: the pump inlet should be the lowest point in the suction path.
Mount the pump and wire the relay: Mount the pump below the tank outlet and wire it through a relay triggered by ignition power. Use a fused circuit and weatherproof connectors. Common mistake: wiring the pump to a constant live so it can run with the engine off. Checkpoint: with the key on but engine off, the pump should not run until the controller commands it.
Pressure-test with water, then add methanol: Fill with distilled water and run the system to check for leaks at every fitting and nozzle. Fix any weep before switching to methanol. Common mistake: skipping the water test and discovering a leak with methanol in the system. Checkpoint: hold system pressure for at least 10 minutes with no visible drips.
Tune and datalog before relying on methanol: Start with a conservative mixture and low boost threshold, then datalog intake air temps and knock. Increase flow only if the logs support it. Common mistake: assuming methanol alone will fix a lean condition or detonation without tuning. Checkpoint: confirm your ECU strategy can pull fuel or add timing safely before you push boost.

Product facts

Mazda RX-7 [FD3S] SakeBomb Methanol Injection Tank: Inspired by the Euro Spec rear wiper tanks from select international markets, this purpose-built water/alcohol injection tank for the FD3S aims to add a seamless water/meth injection solution to all FD's with the reliability and integrated design as Mazda would have done from the factory. Currently out of stock; this is a pre-order for the next group-buy. If you want a factory-style integrated location without fabricating your own brackets, this tank is designed for that. Because it is a pre-order, confirm timing before you plan your install date.
Mazda RX-7 [FD3S] LHD SakeBomb Passenger Foot Rest: The SakeBomb Garage passenger footrest is constructed from aluminum with a semi-rough finish and provides support for the passenger's feet while adding a stylish touch to the interior. The design was based off the OEM Spirit R footrests found on right-hand drive RX-7's. If you are pulling interior panels or running lines through the cabin, this footrest is a simple interior upgrade that does not affect methanol system function. It is not part of the injection system itself.