So I've had my Z for about a year now and I just noticed this while I was changing my spark plugs. It looks as if the previous owner of the z installed a Plenum Spacer. I'm curious as in if it's an aftermarket one or oem one that comes with the 03 performance model Z. I haven't heard of any plenum spacer's coming straight out of the factory already installed on the Z so it might be an aftermarket one. It's not as big as a motordyne one I was looking into but then again it's still a spacer. One less bolt-on I have to buy ig even tho I'll buy the Motordyne 5/16" Iso Thermal Spacer later on lol. What do ya think, I might get flamed on this thread but screw it

 

Every Z in '03 (and pretty much every other year) had identical engine/drivetrains regardless of trim from Base to Track.

Therefore: aftermarket plenum spacer.

 

for the Z, all plenum spacers are aftermarket. if it was up to the Nissan engineers they wouldn't add a spacer, they would of just mad the top plenum taller to accommodate more air flow

 

And to add to your idea of buying the thermal spacer:

Your strut tower is going to have issues clearing the upper plenum if you install it along with the spacer you already have.

Hope this helps. Good luck!

 

^^^^you don't want TWO spacers, period. And for what they give you in gains, just stick with the one already on there. Not worth the time/expense for another 5 HP.

 

This may be a dumb question, but are the spacers even worth it ?

 

Hotly debated but in my opinion yes. It has been pretty much shown that airflow to the back cylinders is not ideal with the OEM plenum only. And, it is not expensive nor labor intensive.

 

since we are all talking about the plenum spacer , i don't mean to thread jack but don't want to start another.. can they be reused? as in i have to replace my valve cover gasket and have to remove it..

 

Yes you can re-use it, deff not a problem... People even sell used ones... The real question is why are you changing your valve cover gaskets?

And OP..... Come on

 

What thickness is the better option? I have seen 5/16, 1/2, and 5/8. I understand that raising the upper plenum with the spacer, that the cross member height will have to be adjusted. I am wanting to do this upgrade, but trying to evaluate which thickness is the better option without deleting the cross member.

 

To the above. 5/16 hands down is the best plenum for daily driver and performance. It's been debated in the past and that size became the majority winner.

To the one replacing the valve cover gaskets. If you are going with a spacer It's best to go ahead and do the plenum while your whole intake is out of the car anyway if budget allows. I decided to do a full wire tuck when I did my gaskets and clean the engine real good. My 03's engine looks like it came off the assembly line a year ago now.