Intake mod with bigger throttle bodies

[swimshark]

So I picked up another upper plenum off a J30 at a junk yard. In the picture below are 3 sets of throttle bodies. Right is stock, middle is the Z1 upgraded tb and left is Nissan Stanza throttle bodies.


For now i am going to shave and sand the current upper plenum and install the Z1 throttle bodies and see if i can dyno to show power increase. Pretty much shaving off the random mount points i do not use and cleaning up the casting to smooth it out. Then sanding it smooth and getting it powdercoated.The stanza throttle bodies take a little bit more work and don't have proper work environment.
http://www.twinturbo.net/nissan/300zx/f ... -pics.html

Here is a size comparison between the throttle plates (stock is 50mm and stanza is 60mm)


air in to the motor will flow better and see maybe a ~5whp increase.

[jdurrty]

Have you considered doing an internal port/polish job on any part of the intake, rather than just smoothing the outside? I've almost considered designing a single intake upper plenum with internal velocity stacks, but the issue of too much time, effort, money, and lack of flow-testing computer software have prevented me from doing such a project. Is there already such a thing in the Z world? I'd figure you'd know best

[yodawill2000]

With your Intake those would make an awesome sound up there !

[GerryO]

Random thoughts; have read that the optimum air/fuel ratio to maintain is 14.7 to 1. Don't know if bigger injectors will also be required, along with some sort of ECM/MAF related recalibration or if all things are automatically compensated for up to a point. Imagine that any gains are at very high engine rpms or wide open throttle conditions, when things may get starved for air, fuel or both. Z1 must have some recommendations and data, since they sell the upgraded TBs.

[swimshark]

So finally got on the grind today and started shaving plenum and mock up the 60mm throttle bodies.

stock throttle body off and stanza throttle body mounted to mark where it needs to be ported


porting done


have to get the lower mounting holes welded up and then add weld to re-drill new holes and tap them to secure the throttle body


roughly done for now (bottom view). deleting pcv valves and egr ports and trimming up a lot of casting and unneeded mounts.