[AJAcosta23]

Hello, my dad is about to hand me down his 2008 350z that has a DE engine in it, and it is due for a new engine soon. I wanted to put a HR engine in since I heard they are more powerful. I was just wondering if I will pass smog If I engine swap to a HR engine.

 

[dkmura]

Welcome, but please explain why your Z needs a new engine? Not sure why an '08 Z has a DE in the first place, but whether it is a VQ35DE or HR, these engines last for hundreds of thousands of miles with proper maintenance. If your Z came with a DE in it, the ECM will NOT run a HR adequately without throwing a lot of codes and CELs. This is certainly not anything that will help you pass an emissions test.

 

[MicVelo]

That’s the big question….. why in earth does this ‘08 have a DE engine when all ‘08s in USDM have VQ35HR?

If you were going from DE to HR, you could get it passed via referee (CA) as long as everything was moved from the donor car including harness, ECM, etc. to bring the car up to the engine’s year. Doesn’t sound like this is the case though.