TomCat39

I've been searching and coming up fairly dry.

I've only barely caught wind that the 307-05-600 K Ultra Street Intake Manifold (IM) can be made to fit the K20Z3 8th gen civic head with some modification.

I have not been able to find out what modification is required or what the challenge is.

Plenty of Pro IM's out there that are specifically for the K20Z3 but it seems the Ultra series is left out for this head. I am really looking towards the ITB velocity stack design of the Ultra series in a plenum that has modular spacer capability.

I ham however running into brick wall when trying to figure out what the challenge is with these manifolds on this particular engine head.

Anyone able to provide some insight?

DaIll1

This is from 8th gen

TomCat39

At first I didn't understand why you posted that post.

But then it all sunk in. Honda tuned the RBC intake manifold for the K20Z3.

Speculating here but..... Skunk2 Racing found that their design didn't improve anything over the stock RBC IM Honda designed so the support just isn't there.

So really, the only reason one might even go with the Skunk2 Ultra series is if they were doing a cam upgrade. Then the tune of the RBC is now off as it was designed around the stock Si cam profiles.

Thank you for that post. It makes sense now why I could find very little information and why skunk2 doesn't have an ultra for the 8th gen Si motor. I'm not quite sure why they would have a pro series IM though, the Ultra is a much better design overall I would think. Sure does improve on the K20A motors.

DaIll1

Yeah, sometimes answers are clear as mud. Glad I could help

TomCat39

Adding a touch of info to this thread for future reference.

Stock RBC IM has a coolant tube at the base of the TB connection flange of the IM:



Not found on the Ultra K IM:




But is on the Pro series IM:

JRCivic1

TomCat39, that isn't a coolant port. It is actually the MAP port or Purge Control port. The coolant circuit/port is the end of the intake manifold flange in your LOWER photo. If you look closely at your top photo, the end of the intake manifold flange is just past the #4 runner opening with no provision for the coolant passage found on the cylinder head of the Z3 (or similar). One would have to use some type of coolant passage adapter like one from K-Tuned.

TomCat39

Ahhh thank you, so the metal pipe on the top picture is actually a vacuum line, not a fluid line?

I just got the car so am just beginning to learn about the K20Z3 engine.

I did notice a couple of adapters but wasn't too sure if they would be applicable:





I did bounce into hondapartsnow and tried piecing together the coolant lines between the IM, TB and main pipe.

I really need to get the FSM and begin studying it.