Case Studies – Upgrading injectors in a VQ35


We will be upgrading the injectors on a 350Z drift missle for the upcoming Open Track event, and slapping in a set of 600cc Deatschwerks injectors. These injectors are a direct fit, and as they are customized for each car there is no need to fiddle with inline resistors for those wanting to move from high or low impedence.

The part number in question is 21S-05-0600-6and you will need an adjustible fuel pressure regulator if you don’t want to trip the good ‘ol P0175 OBDII System Too Rich check engine light.

To begin, remove your stock intake snorkel and disconnect all electrical sensors from the intake plenum and throttle body area

Now remove the lower 10mm bolts that hold the upper half of the intake manifold in place, and undo the 10mm bolts that hold the upper plenum to the lower half.

Make sure to use the sequence in the diagram below whenever removing or putting the stock intake manifold back in place

With the intake manifold removed, you can now access the fuel rail and injectors. Open your gas cap and undo the factory gas cap to relieve any pressure from the system. Disconnect your battery, as gas and gas fumes will be prevalent and then undo your factory fuel return.

Undo the clips to the injectors, and pull gently to remove the entire fuel rail assembly. The picture above shows that I have not clogged the intake ports to the engine, because I am incredibly overconfident in myself. In reality however, it’s a prudent idea to block these intake ports as you don’t want any isolators or nuts falling into your motor.

With the factory rail removed, you can now install the upgraded units with relative ease. Make sure not to rip or tear the oring isolators, and make sure not to lose any of the isolators that space out the rail from the heads.

Now may be a good time to install a intake manifold spacer, like this BLOX one. This car will be getting a new intake manifold in anticipation of….

BOOST!!!!

Next up, mocking up the turbo manifolds and wastegate locales before deciding on what engine management.

Happy boosting!

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3 thoughts on “Case Studies – Upgrading injectors in a VQ35

  1. Be careful of those Deatschwerks injectors, I’ve heard nothing but horror stories with them on the VG (Z32 forums mostly) as they make them by enlarging factory injectors by drilling the orifices. This leads to wildly different flow rates between injectors and irregular spray patterns. Not sure if this carries over to the VQ, but figured I’d mention it!

    • wow I’ve never heard of that drilling out the stock injector stuff, I’ll definitely have to ask Dean about it. Have you experienced problems firsthand? what happens? leaking or a general failure?

      • Basically the stock injectors were never meant to be redriled, so this leads to wildly different flow rates compared to what they’re supposed to flow (as the flow to duty cycle rate changes).

        It makes the car incredibly hard to tune as you have some cyl’s running lean and some running rich. Obviously besides the tuning issues, you can also damage the motor with the lean/rich conditions.

        There was a set of “redrilled” injectors in the white Z when I first got it, and I’m sure that lead to the motor’s demise. They were supposed to be redrilled to 550cc specs, but consistently ran pig rich and varied from Cyl to Cyl. The car would load up bad in around town driving which I’m sure washed down the Cyl’s.

        I’ve heard that they now “flow match” the redrilled injectors to help ileviate the issues, but the flow/DC is still off and not linear.

        I have also read that somehow the redrilled holes can elongate over time.

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