On our Project GD STI we upgraded the fuel system using a Radium Engineering fuel hanger and a single large Walbro TIA450 fuel pump. However, we found that Subaru wiring experts iWire do not recommend a single large Walbro pump, in particular the higher flowing versions of this pump like the 525 Hellcat pump. This is because they cause fuel pump controller and wiring issues and tend to heat up and burn out. Doing some further research we found that this pump is designed to run at 18 volts and some of the issues are due to it running at lower voltages. The 450 pump does not have as serious issues thank god but iWire still doesn’t feel that this is the best setup.
iWire thus recommends two smaller pumps over a single big pump and that this is more reliable than a single big pump in the case of Subarus. Therefore on Project WRX we are going to go this route. We will show how a double pump is set up.
Here is the Radium hanger, if you want to read all the details on it, check out this article that we did previously. For our fuel pumps, we chose a pair of DeatschWerks DW300 pumps. The DW300 flows 340 LPH at 40 psi. It has carbon brushes and a totally encapsulated armature for full E85 compatibility. The DW300 can be safely run at 6 to 18 volts and is capable of pulse width modulation control. We have had very good results with DeatschWerks pumps and the long-term use of E85. Although it’s a subjective thing, Deatschwerks pumps seem to be quieter than other brands, especially with E85,
The OEM hanger has a siphon jet pump to get fuel out of the other side of the saddle tank. This can often be a flow restriction and a cause of fuel starvation.
The Radium siphon pump is much higher flowing and will keep the fuel flowing from the other side of the side saddle tank.
The Radium hanger has a manifold that handles the return fuel and the fuel coming out of the dual pumps.