Challenger Fuel Pump Upgrade: When and What to Install
A stock fuel pump limits how much power you can make. Here's when you need an upgrade and what options exist.
Stock Fuel Pump Flow Rates
| Model | Fuel Pump | Approximate Max Support |
|---|---|---|
| 5.7L R/T | ~90 L/hr | ~450 whp |
| 6.4L Scat Pack | ~95 L/hr | ~550 whp |
| 6.2L Hellcat | ~145 L/hr | ~750 whp |
| 6.2L Redeye | ~180 L/hr | ~900 whp |
When a build exceeds these thresholds, the fuel pump runs at maximum duty cycle and can't maintain fuel pressure under WOT. The result: lean condition, detonation, and engine damage.
Symptoms of Insufficient Fuel Pump
- Fuel pressure drops under WOT (requires a fuel pressure gauge or data logger to confirm)
- Power drops off in the top end of a pull
- Lean spikes on wideband O2 (if monitored)
- Engine pulls timing from knock sensor response
Upgrade Options
In-Tank Pump Replacement (R/T, Scat Pack):
Drop-in high-flow pumps (Walbro, Deatschwerks, Aeromotive):
- 450 L/hr pump: Supports 600–700 whp on E85
- 525 L/hr pump: Supports 800+ whp
These install in the factory fuel pump module, preserving the factory sending unit.
Hellcat Redeye Fuel System Swap:
The most popular upgrade path for Hellcat owners pushing past 750 whp is swapping in the Hellcat Redeye's larger fuel pump and module assembly. This is a direct swap and plug-and-play with a tune.
Dual Pump Setups:
For high-power builds (900+ whp), some builders add a second in-tank pump or an external lift pump feeding a surge tank.
Fuel Lines
At extreme power levels, the factory fuel lines (3/8" on most models) can restrict flow. Upgrading to -6AN or -8AN lines increases capacity for builds over 800 whp.
E85 and Fuel Pump Demands
E85 requires approximately 30% more fuel volume than gasoline for the same power output. A pump adequate for 600 whp on 93 octane is only adequate for ~460 whp on E85. Factor this in when sizing your fuel system.
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