I have a base model rsx i purchesed a k20a3 from a civic s1 05. is there any difrences in motors? i noticed the intake manifold was difrent.... is there anything i need to change? can i use the same ecu?
The motors are pretty much the same. If you got the 2nd motor because you damaged the 1st all you would need to do is transfer everything from the RSX motor over to the Si motor, well anything that is different. Do some research you may find one mani is better than the other and will work. The RBC mani is the best stock mani for sure though. If you are building a 2nd motor for more power then just save up for a K20A2 or K20Z1. Better yet build K24/Z1 hybrid, they can do 300+whp NA.