i am wondering whats the difference in the pr3 and the pr4? all i know is that both of them are put on diffent year civic? do they both create same power? can anyone tell me if theres a difference, because i have no clue? any info would help alot... thanks

 

what parts are you asking about? pr4 is non vtec b18, and pr3 is vtec b16.

 

pr3 is a crx/civic ecu (jdm b16)
pr4 is a 90-93 integra ecu

pr3 is vtec and the pr4 is non vtec

 

Pr3 has a small dome piston
Pr4 has a small dish piston
Both are 81mm

Someone keep it going