How to Swap an Electric Water Pump onto your Honda (K series, F series, etc...)

(Note: this isn't meant as a step-by-step guide but rather as a general set of recommendations for all Honda engines, chassis, etc.)

Over the last four years we have had quite a few of our Honda customers (especially the owners of K24-swapped racecars) ask us if it's worth it to swap in an electric water pump and our answers is always "NOPE".  Unless you are at the top 5% of drag racers out there really is no need for an electric water pump: the Honda water pump barely wastes any horsepower (1WHP maybe 2WHP max) and the added complexity of having to deal with the wiring, mounting, and plumbing of an electric water pump is not ideal.

That being said we have a few stubborn customers who don't care about the cost or complexity - they way want to make the most horsepower possible.  If you are also one of those people then you are in the right place!

What is needed

• water pump/housing block off plate
  • the water pump sits inside of the water pump housing which is attached to the lower right side of the block (if you're facing the timing cover) and the alternator
  • (red circle for the water pump housing, blue circle for the water pump/pulley)
  • e.g. for K series engines - https://dragcartel.com/products/water-block-off-plate-race-only
• alternative mounting solution for your alternator (or don't run an alternator!)
  • if you still need to mount your alternator in the OE location we recommend using the TracTuff Water Pump Housing Delete (With Alternator Mount Kit)
• an electric water pump with electrical connector i.e. one of the Pierburg water pumps
  • Pierburg CWA50 Water Pump
    • VW OE Part numbers - 7P0965567 / 8K0965567B
  • Pierburg CWA100-2 Water Pump
    • Ford OE Part number - DR3V 8K232 AA / DR3Z 8501 A
  • Pierburg CWA100-3 Water Pump
    • VAG OE Part number - 4N0965567
  • Pierburg CWA150 Water Pump
    • VAG OE Part number - 4KE965567B
• a bracket or mount for installing the electric water pump i.e. the Walshmo Racing Pierburg Water Pump Bracket
• any hoses, AN lines, fittings, etc. needed to plumb your block off plate to your electric water pump to your intake manifold coolant port (or engine head coolant port)

Electric Water Pump Recommendation

If you are unsure about what electric water pump to use we recommend using a Pierburg electric water pump.  The main reasons we recommend these water pumps are the wiring is extremely simple and they are used on OE cars so you know they have been tested and are extremely reliable.  Lastly the pumps are reasonably priced and available straight from the manufacturer so sourcing one is never an issue!

The only problem we have run into during these swaps was mounting the Pierburg water pumps - we decided to solve this problem by creating a two piece bracket that allows you to mount the pump virtually anywhere:

(Pierburg CWA100-3 pictured with the Walshmo Racing bracket)

Pierburg Water Pump Wiring

Wiring for the Pierburg water pumps is extremely simple.  You can find for the corresponding data sheet for the pump you decide to use on the water pump product pages linked above.  In that datasheet it will give you the pinout diagram for the water pump, here's the diagram for the CWA100-3:

The pump has three wiring inputs: ground, power (12v), and signal.  The signal here can be a PWM signal if you want to modulate the operating speed of the water pump.  Most users are simply looking to have the water pump turn on and operate whenever the engine runs (just like the physical water pump did) so in order to do that we just need to wire our constant 12v to the signal.  When the water pump sees a constant 12v for the signal input it runs it at 95% speed which should be more than enough.

Note if you are looking to have more granular control over the water pump using the PWM interface you can refer to the PWM info PDF on the water pump product page linked above.

Water Pump Plumbing

We are leaving this part a little bit vague because this part is going to depend on which block off plate you're using as well as your return coolant port location.  The Pierburg water pumps have provisions for standard rubber hoses  (with hose clamps) which should be more than sufficient for the coolant pressure any Honda should expect to run.

Feedback / Questions

Please reach out to us on Instagram @walshmo_racing or via email (orders@walshmo.com) if you have any questions about this article or about our Pierburg Water Pump Bracket.