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Zachr20
03-30-2014, 11:44 AM
This may be a stupid question, but I see a lot of people recommending to change the stock k20a3 oil pump to a different pump. Can someone explain to me why I would want to do this?

usedep3
03-30-2014, 12:07 PM
Most will upgrade the oil pump to reduce the risks of oil cavitation at higher rpms.

Zachr20
03-30-2014, 07:12 PM
O ok, so an "upgraded" oil pump just outputs more oil as compared to the stock one then. Cool, thanks for the response.

Deadphishy
04-13-2014, 08:18 AM
O ok, so an "upgraded" oil pump just outputs more oil as compared to the stock one then. Cool, thanks for the response.

This is not correct.

The pump most people use is a k20a2 Oil pump out of the Type S RSX. This pump has two things that make it better for performance then our stock oil pump.


1st, the stock oil pump has two very large balance shafts built into it. These heavy weighs spin with the pump, and help balance the natural vibration of a 4 cylinder motor. This makes for a smooth feeling motor, however it's take power to spin these weight.

2nd important feature of the RSX type S pump is the gear ratio. Because the stock oil pump has the balance shafts it must spin at a 1 crank rotation to 2 oil pump rotations ratio. This keeps the weighted balance shafts in sync with the motors vibration. The Type S oil pump does not have the shafts so it's ratio can be different. The Type S pump spins at 1:1.7. That is slower then our stock oil pump. But what that means is at very high RPM the pump won't be spinning too fast. A pump that spins to fast will cavitate and your oil pressure will drop and the motor will lose lubrication.



Other options are the oil pump out of a 06-11 civic Si. This has balance shafts and spins at 1:2 ratio however it has an improved pump design that allows it to spin faster and not lose pressure.

Zachr20
04-13-2014, 10:30 PM
Thank you! That was an awesome answer and led me to a great Wiki post on balance shafts and now things are clicking a little more.

So to make sure I understand correctly, the type s pump has lighter balance shafts to decrease its strain on the engine, and also has a lower gear ratio that supplies the engine with more oil at higher rpm's. Is that correct?