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Question:
I have a '93 Dodge 250 with an automatic transmission. I plan on putting 60hp injectors and Rocken-Tech's 14mm head and 4mm cam plate in the injection pump with other add-ons, but I was reading your "First-Gen Performance" article in the Feb. '09 issue, and it says that if I use the Rocken-Tech parts, I need a high-flow lift pump. Problem is, I can't seem to find one for the first-gen Cummins. I would appreciate it if you could help in finding one.
Zach Hickman
Via email
For big horsepower applications,...
For big horsepower applications, a high-pressure, high-flow lift pump such as this Aeromotive A1000 is highly recommended.
Answer:
There are a few solutions for your lift pump dilemma. First off, the stock lift pump can't support the kind of fuel you will need to be flowing, so don't even try it. There are conversion kits for low-pressure piston-style lift pumps, but we'd stay away from these if you're shooting for more than 400 hp, or running a 14mm head instead of the stock 12mm version. The 14mm/4mm cam plate is probably a combination to stay away from-it seems that the larger pump head combined with more lift is just too taxing on the design of the Bosch VE pump. There was one combination that we're aware of where the 14mm head combined with the big cam plate worked, and the results were impressive: 501 rear-wheel horsepower with a 62mm-inducer turbo. However, this truck only lasted 400 street miles and a few dyno pulls before it ran away on the dyno and the pump seized. So if you're going to try the 14mm/4mm combo, know there are big risks. Instead of 60hp injectors, we'd try to get a set of 6x.016 injectors made for your truck. Places like Scheid Diesel, Buddha Power, and New Era Diesel can custom make injectors that will help just as much as a 14mm head will. With a good size turbo (62 to 64mm-diameter inducer) 450 hp at the wheels is achievable with a 12mm pump, large injectors, and a good fuel system.
A stock Dodge piston lift pump found on '94 to '98 Cummins engines flows about 48 gallons per hour (gph) of fuel at about 15 psi, and first-gen Dodge rotary lift pumps flow even less than that. For a hopped-up VE pump, you're looking for a lift pump that will flow 100 gph or more. While made for gasoline applications, Holley and Carter both make race pumps that will flow in the 120- to 140-gph range and seem compatible in diesel applications. Besides flow, pressure is another thing to worry about. You want at least 10 to 15 psi of pressure to keep the VE pump happy, but no more than about 20 psi or else you are at risk of blowing out the front pump seal and filling the crankcase with diesel. Adding some Loctite to the front pump seal, or making a retainer are fixes for this problem, but at 400 to 500 hp, just make sure you don't exceed 20 psi and you'll probably be fine. In addition to the pump, the stock tank pickup and filter are also restrictions. Bypassing the stock filter and installing a larger version, and installing an aftermarket sump or a draw tube in the fuel tank will take you a long way toward maintaining fuel pressure. If you're looking for an all-in-one solution, a complete fuel system from FASS or AirDog will solve both your filter and pump problems and will be 100 percent compatible with diesel fuel.