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Hey my fellow Honda friends! So I知 new here and I am hoping to find some knowledge! I have an 05 civic si hatchback and I知 looking to swap the k20a3 with a k20z3! Can anyone help with a list of parts or accessories I will need to make this happen? Please!!! Thank you in advance!!

 
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K to K?
drop it in there.
Contact Hondata to see if tuning ECU needed

 
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Yes a k20a3 to a k20z3

 
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You will need an ECU and wiring harness (the A3 has intake side VTEC and the Z3 has both). The rest should be fine as-is.

 
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Thank you! So that will be all I need is an ecu and harness? Can someone tell me where and what ecu I need or should get?

 
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An ECU from a later model RSX Type-S would be ideal as that痴 what the engine痴 from. I値l see if I can get the code for it at some point today. Junkyard/Facebook marketplace should have something.

 
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You could also use your stock ECU but get it Kpro'd, stock harness should work then as well. Kpro costs around $700 but then you have full tuning capability. There may be some sensor changes I can't remember but that would be it.

 
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Ok so another question! What would you do in this case?

 
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I guess it depends on what you want. If you池e going to swap, chances are you値l want more power in the future, so K-Pro would be the way to go. If you just want a fun car and not modify any further, ECU and harness should be around half what K-Pro is.

 
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Sounds good! If I did k-pro and didn稚 do any mods in the future is it a waste of money? Technically the same as a stock ecu at that point?

 
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You would load a stock cal for the z3 onto your ECU and just run that. You could consider it a waste of money if you don't do any more upgrades in the future.

 
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Forgot the Z3 came in the Civic Si as well.

https://www.ebay.com/itm/31363173254...sAAOSwXylhBW46

https://www.ebay.com/itm/254453566948

This should be all you need, assuming the K20Z3 is complete.

 
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Would also need an adapter harness or some custom wiring for the body connections. z3 had a 6 speed with reverse lockout and the high frequency VSS, your EP3 doesn't have either. May see faults for reverse lockout, would need some sort of VSS converter. Or were you taking the 6 speed transmission too?

 
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I was gonna keep my 5 speed for now

 
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I can just buy adapter harness? Would k-pro eliminate the need for all that?

 
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The z3 is complete

 
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call them
they handle more cars than any of us
share results for the community later on

 
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I値l give them a call! Stay tuned!!

 
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I was also going to suggest contacting Kpro (Hondata). I believe once your stock ECU is Kpro'd you keep the original engine harness and transfer to the new engine. No additional wiring is needed unless some of the sensors need swapped or rewired. You can also ask if there's a stock z3 calibration available in the Kmanager software for your stock ECU.