Most WRX and STI fuel system upgrades start with an in-tank pump, and for good reason, they are simpler to install and cover a wide range of power goals. The AEM 380LPH Inline Fuel Pump exists for builds that have moved past that range. It is an external, high flow pump built for setups where a single in-tank unit can no longer keep up with fuel demand, whether that is from a big turbo, E85, or both.
What the AEM 380LPH Pump Actually Delivers
This pump uses the industry standard “044 style” envelope with a -10 AN female inlet and a -6 AN female outlet, built for either external mounting or in-tank installation with separate hardware. It flows 380 lph at 43 PSI, 340 lph at 73 PSI, and 270 lph at 120 PSI, numbers that hold up well into boosted fuel pressure rather than dropping off the way smaller pumps do under load.
That flow curve is what makes it relevant for serious builds. AEM rates it to support over 1,200 horsepower naturally aspirated and roughly 860 horsepower at 30 psi of boost. Few WRX or STI builds actually need that much capacity, but the ones running a big single turbo or E85 at high boost are exactly the builds where an in-tank pump starts running out of headroom.
Gasoline, E85, or Both
The pump is compatible with flex fuel setups running E85 or E90 as well as standard gasoline. Running 100 percent alcohol fuels shortens pump life, so most builds run it on a gasoline or E85 blend rather than pure alcohol. For STI and WRX owners weighing whether to make the switch, the post on E85 vs pump gas on WRX and STI covers what actually changes in the fuel system once ethanol enters the picture, and why pump capacity becomes a bigger factor once it does.
External Pump vs In-Tank: Which One a Build Actually Needs
Not every fueling upgrade calls for an external pump like this one. For builds staying within a more moderate power range, an in-tank solution is simpler to install and easier to package. The AEM 340LPH 65mm fuel pump kit for WRX and STI covers that in-tank option and where it fits.
The 380LPH external pump becomes the right call once fuel demand outpaces what an in-tank pump can flow reliably, typically once injector size, boost, and fuel type all push toward the upper end of what the platform can support. The post on when bigger injectors actually become necessary and fuel pumps vs injectors, which upgrade matters more both help frame where pump capacity fits into that decision.
Where This Fits in a Fuel System Build
A pump this capable is rarely the only fuel system upgrade a serious build needs. Rails, lines, and a pressure regulator built to handle the same flow and pressure round out the system rather than leaving a factory component as the weak point. WRX fuel system upgrades and STI fuel system upgrades cover how pump capacity fits alongside the rest of the fuel delivery path.
Frequently Asked Questions
Does the AEM 380LPH pump fit inside a WRX or STI fuel tank?
It can be installed in-tank with separate mounting hardware, or run externally. It does not come as a drop-in replacement the way some in-tank kits do, so installation typically requires more planning than a direct-fit pump.
Is this pump overkill for a moderately built WRX or STI?
For most bolt-on or stage 2 level builds, yes. It is built for setups pushing well past what a stock or mildly upgraded fuel system can support, closer to big turbo or high boost E85 territory.
Can this pump run E85?
Yes, it is compatible with E85 and E90 as well as gasoline. Running 100 percent alcohol fuels reduces pump life over time.
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