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Some people have been wondering if the pumps were the same or different, i'll grab some pics later tonight (at work), but they are infact different, the actuall size of the k20a2 water pump is smaller by about 2-3mm on the pulley itself., i'll mesure them exactly and post pics. so the k20a2 water pump is underdrived from the TSX/k20a3's and k24a1/3/4's counter part. I noticed this and was quite intrigued. (if the waterpump system) does cavitate at highrpm, if you used the same crank pulley one could use this water pump and plug the cooler port.

the ECT question people had, you have to understand when you underdrive you are doing it to all the accessories. waterpump also. less rotation on the pump will draw less power, but less flow aswell.

something i'll test for certain on the dyno! mesurable hp if any.

so a k20a2 water pump, and crankpulley is a "factory" underdrived unit compared to a k24a2 engine. Also you if you use a k20a2 crank pulley when doing the tensioner bypass, you will need the aem pulley and might need to shim it greater because of the shorter radius, thus affecting belt clearances.
 

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good info. i can tell you for sure the new 06 SI (k20z) motors water pump will not bolt up to a k20A2 block. bolt pattern is different.
 

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i realized that. the water pump that came off of my donor car's k had a bent pulley, so my friend had an k24a3 waterpump.the housing and all is the same... but yea the pulley size is slightly different.

measureable HP?? maybe... significant? we'll see. then again, every ounce counts!
 

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you should mesure the Z1 pump, take a mesuring tape, and mesure the whole diameter of the pump so we can compare.
 

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Interesting. I'm using a k20a3 crank pulley, a k20a2 water pump pulley, and all accessories from a k20a3 (civic si). I guess I didn't notice the 2-3mm of difference because it didn't affect how the k20a3 belt I was using went on.
 

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so using the k20a2 waterpump will gain more hp and have better flow?

and all i have to do is plug the cooler hole?
 

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HotWheelz said:
Some people have been wondering if the pumps were the same or different, i'll grab some pics later tonight (at work), but they are infact different, the actuall size of the k20a2 water pump is smaller by about 2-3mm on the pulley itself., i'll mesure them exactly and post pics.
I just measure my K24A1 and my K20A2 water pump pulleys and they're both 128mm.
 

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You sure about the base model K24s not already being pre-tapped? I just went and looked at a K24A1 we have and Justin's K24A2, the place for the oil cooler looked to be exactly the same on both motors.
 

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is there any difference on the placement of the pcv valve on the k20 water pump, ive got a custom intake for my k20 that the bottom of it is hitting the pcv valve on the water pump assembly and im wondering if the k24 pump is different
 
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