about what hp is the stock fuel system good for and what would be the first performance replacements you would start with? ohh and does a fass system replace anything?

 

I am about the 400hp mark on stock fuel system and at WOT it was starving the injection pupm im sure. Plus 2 days ago my lift pup took a big crap on me and is about gone. So now comes the FASS either sometime this week or weekend.

Go with guages first and then i would get a FASS before anything else IMO.

 

The fuel system on the 24 valve ISB Dodge is only capable of supporting about 300 HP. It all comes down to, “How low a pressure are you comfortable with?”

Cummins wrote in an email:
The lift pump pressure is only one parameter pertaining to fuel system
operation/diagnostics, and as long as you have positive pressure to the VP-44 at
adequate flow, your engine should run fine. "Adequate" means normal performance,
starting and smoke levels. Any issues with the engine running outside of the
below listed pressures being in their respective proper ranges should be addressed.

Idle speed: 700-1000 rpm
Maximum fuel inlet restriction to lift pump: 6 in Hg
Maximum Fuel Pressure at Fuel Filter Outlet (engine cranking): 4 - 8 psi
Minimum Fuel Pressure at Fuel Filter Inlet (engine running): 8 - 17 psi
Fuel Drain Line Maximum Restriction: 10 psi
Fuel Inlet Maximum Temperature: 165 deg. F
Engine Minimum Cranking Speed: 150 rpm

The above email was copied from one of the forums, but I don’t remember which one.

The VP44 on my 5 speed, 1998 ETC engine in stock form burns 0.393 lb/BHP-HR at 3200 RPM (TDR issue 29, pp 48) and is making 225 BHP. Multiplying 0.393 x 225 = 88.43 lb/HR of fuel burned. Diesel at 7 lbs / gallon, is 12.63 gallons per hour when making this BHP. The fuel flow back to the tank is 30 gph at 3100 RPM, for a total of 42.63 gallons per hour required by the lift pump. The Carter lift pump delivers 60 gallons per hour at 8.5 psi and 40 gallons per hour at 12 psi. These numbers are what I have measured from a good lift pump. Someone wrote that the filter assembly will only allow about 45 gph flow, enough for a stock engine but not enough if you bomb. If you do the math, that leaves only 2.6 gph available for bombing, or about 50 BHP before the pressure falls below the magic 8 psi.

Now if you do add horsepower by bombing, you will need an extra 5.61-gallons per hour for each 100 BHP. The efficiency of the ISB will not remain constant as BHP is increased. Instead of the calculated value of 5.61 gallons per hour for each 100 BHP added, a safer number might be 10 gallons per hour.

Using 10 gph per 100 BHP, to make 300 BHP the lift pump and lines, fittings, and filter the lift pump should supply 50 gph. At 350 BHP you need 55 gph and at 400 BHP you will need a lift pump that supplies 60 gph.

These numbers are just best guesses based on my research over the years reading these forums. I always try to err on the safe side of things. You may not need an additional 10 gallons per hour for each 100 HP increase but more is better than not enough.