Miata Injector Sizing Guide
Quick answer: for most NA/NB Miata builds the FF640 (640cc NA / 725cc NB) is the right injector and supports about 300 to 350 hp on a turbo setup. Step up to the FF960 only when your target goes beyond what 640cc can feed, into the 500+ whp range. NC owners run the NC 640cc kit, and ND2/ND3 owners run the ND2/ND3 Stage 1 kit. NA/NB injector kits require standalone engine management.
How to think about injector size
Injectors are sized to your power target, fuel and fuel pressure, not to your car alone. Bigger is not automatically better. Oversized injectors on a small four-cylinder can hurt idle quality and low-load drivability if they aren't well matched. FlowForce matches every set within +/-1% at idle and wide-open throttle specifically to keep big injectors drivable. Pick the smallest injector that comfortably covers your power goal with headroom, then let your tuner do the rest.
By platform and goal (NA/NB)
| Your build | Recommended kit | Flow (NA / NB) | Supports | Price |
|---|---|---|---|---|
| Entry level, mild builds | FF380 | 380cc | to about 200 whp | $279 |
| Stock-ish to mild turbo, street and track | FF640 | 640cc / 725cc | ~300-350 hp turbo | $329 |
| Big turbo, high boost, race | FF960 | 960cc / 1100cc | 500+ whp | $449 |
All NA/NB kits are plug and play for 1990-2005 and require standalone engine management. Any of them can be bundled with a DeatschWerks DW200 fuel pump, the right pump for most cars since it uses stock wiring and needs no tune changes.
Other platforms
NC (2006-2015): the FlowForce NC 640cc kit, $299. Bosch EV14, matched +/-1%, E85 compatible. Tuning required.
ND2 (2019-2022) and ND3 (2023+): the FlowForce ND2/ND3 Stage 1 kit, $499. Adds 18% flow over stock with OEM-like drivability. On the ND, the factory injectors are usually the first real fueling limit.
Don't forget the fuel pump
Injectors can only flow what the pump feeds them. The DW200 covers most NA/NB builds and can nearly max out even the FF960. If you're targeting very high power or E85, plan your pump and fuel system alongside your injectors.
Frequently asked
What size injectors do I need for a turbo Miata?
For most turbo NA/NB builds the FF640 (640/725cc) covers about 300 to 350 hp. Go FF960 for 500+ whp.
Are bigger injectors always better?
No. Oversized, poorly matched injectors hurt idle and drivability. Match the injector to your power goal. Matched sets like FlowForce's keep large injectors drivable.
Do FlowForce NA/NB injectors need a standalone ECU?
Yes. NA/NB kits require standalone engine management and tuning. If you need one, the AMP Plug-and-Play ECU is a direct swap.
Will these work on E85?
The NC kit is E85 compatible and the ND2/ND3 supports ethanol blends with the right tune and fuel system. For NA/NB, your fuel system and tune determine E85 capability.
Still not sure?
Email team@goflowforce.com with your platform, power target and fuel (pump gas vs E85) and we'll point you to the right kit. Final sizing is always your call and your tuner's.
Dead times, flow data and install steps for every kit live on the injector instructions page and the injector data page.