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Hellcat Swap Fuel System Setup in Your Classic Mopar

We know you're questioning how to get your Hellcrate, Redeye, Hellephant, or even just your Gen III Hemi up and running. All this talk about kPa, PSI, LPH, have you confused? Keep reading. 

Hopefully you've got the wiring harness & computer situated already. 

In this post, we will help you understand your fuel system requirements. 

If you do not know what an AN fitting is, check out our other post here, first!


Fuel Pump: 

The Hellcat crate engine (Hellcrate), Redeye, Hellephant, and theyr computer system requires a PWM pump. PWM stands for pulse width modulation. This is a feature of a fuel pump that is the ability to turn on and off thousands of times per second; which in turn will alter the pressure output of the fuel pump. The engine computer and/or FPCM (fuel pump control module) senses the fuel pressure demand and commands the pulses, or changes in pressure, via PWM. 

A typical 255lph fuel pump that most of us know is not typically PWM compatible. 

Most higher output fuel pumps now days are PWM compatible, but you need to check the specs just in case! 

Mopar states that the Hellcrate needs a fuel pump with 300lph (liters per hour) at 80psi. The pump pressure (PSI) is important here! An Aeromotive or Walbro 340lph pump is enough, right? NOPE! 
The advertised flow is 40-43.5 psi. The higher PSI you go, the lower the flow. 

OK, so what do I need???

Walbro released a 450lph fuel pump that is called a Hellcat pump since it is capable of supporting a Hellcat engine. This is the pump we recommend for the Hellcrate. It flows approximately 360lph at 80psi. 

Do you have modifications done to your Hellcat engine? Maybe a pulley? You should still be OK. 

IF YOU HAVE A REDEYE engine, or a Hellcat with bigger injectors and other modifications, you'll need to step up to the Demon 525lph pump (Also called the Hellcat 525). My rule of thumb is up to 850 flywheel HP for this pump.

If you have more substantial upgrades and are running over 850 flywheel horsepower, then you need MORE FUEL! 

You will need to run 2 pumps. The factory FPCM is not an option for running multiple pumps. 
The 1000hp Hellephant requires a minimum fuel flow of 630lph. That's a lot of fuel. 

Running a twin 525 pump system will give your modified Hellcat/Redeye or Hellephant plenty of hydration. 

The most effective and efficient way to run twin pumps is by using a Vaporworx PWM controller. This will increase the life of your pumps and help the fuel flow. The controller and pumps will run you around $1000, plus a fuel tank. 
The pump controller turns on the second pump depending on the MAP sensor readings (aka if it senses boost it will turn the 2nd one on). 

 If you're swapping it into an older Mopar, chances are we can put together a nice stainless steel fuel tank and twin pump system. Pretty much plug and play. 

Planning on running E85 fuel? You may need even more. Contact us for more info, and provide us with details on your build. 



Fuel Lines

Okay now that you have a bunch of pump on tap, how are you going to get it to the engine? 

Since the fuel pressure is controlled by a control module, there is only one line from the pump to the fuel rail. 

If you have a stock Hellcat engine, a 3/8" or 6AN line is plenty. 

You'll want to step up to an 8AN feed line if you are 800-1200hp. We've run 1000hp on 6AN and I'm sure others have run more, but this isn't something you should risk, or skimp on. There's no excuse to run a smaller line. If you do hard lines, 1/2" OD line would be the closest to 8AN. 

The Hellcat engine, Redeye, and Hellephant all have a 1/2" quick disconnect fitting on the fuel rail. We have special adapters for 10AN and 8AN connections. The fuel inlet is on the RH side of the engine and it is not reversible. We do offer a set of billet fuel rails which would allow a different inlet position, however.

Planning on E85? Make sure you run a PTFE lined hose such as Fragola series 6000. 



Fuel filter

Don't forget about filtration! You should always run a 10-micron inline filter even if the factory did not. We only use Aeromotive fuel filters in supercharged and E85 applications. The filter media called Microglass is E85 safe. Make sure the ends are the same size as your line (8AN, 10AN, etc).
The position of the fuel filter does not matter. Just don't have it too close to your headers or exhaust. 



If you have any further questions or need additional help with setting up your fuel system, please give us a call or send an email!