Navigator water pump

The popular "Cobra R" water pump (actually just a Mustang water pump, part # YR3Z-8501-AB) has smaller impeller blades and does not have the fan attachment.  According to the designer of the pump, it adds 4-5 crank hp over a 7-bladed stock Lightning pump (later trucks) and 6-7 crank hp over an 8-bladed lightning pump (earlier trucks).  On the other hand, I know of two people who have done before-and-after dynos and found that the "Cobra" pump lost a few rwHP.

That Ford engineer also explained that the Cobra pump adds power only because it flows less (taking less drive HP) -- which means that it cools less!   He specifically states that he would not use the "Cobra" pump.

One "Cobra" pump user reported the following:

With a 70/30 coolant mix and a jacked up idle in gear to curb the Eaton cavitation sound, I had no problem keeping the coolant temp below 200 degrees while idling for extended periods of time in 90 degree ambient temps with the Cobra pump.

With a 50/50 coolant mix and stock idle rpm in gear the coolant temp goes up to 208 degrees. Before putting it in gear the temp was 194 degrees in Park after idling for 10 minutes. That's how on the edge the Cobra pump is.

The Ford engineer adds:

Even though the coolant temp measured in the head is reading "normal". The increased diameter of the truck pump/impeller makes the coolant flow at a higher velocity. This will more effectively sweep the gasses formed on the cylinder walls and head to the degas bottle. The end result being more effective cooling *and* a more consistent temp from spot to spot to spot to spot within the engine.

• 1999-2000 Lightning: cast iron housing, heavy duty design (8-bladed impeller with no shroud ring), extended shaft for mechanical fan (8 lbs)

• 2001-02 Lightning: Like the 99-00, except standard duty design 7-bladed impeller with no shroud ring)

• 2003-04 Lightning: Like the 01-02, but with shrouded impeller for better flow (the 5.4 block is slightly conical, so the shroud straightens the flow)

• Navigator: Like the 03-04 Lightning pump, but with aluminum body (3 lbs) and no extended shaft for the mechanical fan

• "Cobra": Aluminum body, no mechanical fan shaft, substantially smaller diameter shrouded impeller

The Navigator pump is the best bet.  For 99-02 trucks, it provides better flow.  For 03-04s, it's just a cosmetic thing.

The 2004 Navigator water pump is part #3L3Z8501CA.  $116 from fordpartsonline.

After installing an electric fan and the Navigator pump, at least one user reported significantly higher ET and trap speed:

Before 12.68 @ 108

After: 12.46 @ 109