Against All Odds and a Monster Awakens

Jon’s Z story is sadly alot like the other doom and gloom stories.  Thankfully after much love and a heavy therapy session at Specialty-Z there are no longer clouds looming over this Z.

Mods are as follows:

  • Built Engine
  • JWT 400 Cams
  • HKS Turbos (unknown size, possibly 2530s)
  • Tubular Exhaust Manifolds (mid-length)
  • ASH 2.5″ IC Piping & Massives
  • Larger Throttle Bodies
  • ASH Inlet Pipe Kit
  • Border 850cc Fuel Kit
  • SZ modified 2.5″ SS Downpipes
  • Custom 3″ Test Pipes & Catback
  • Twin Disc Clutch

After fixing the tremendous amount of issues we began to tackle this Z on the dyno for some data logging and tuning.   After a few pulls we uncovered more issues that needed addressing.  The Z came us with solid intake cam gears.  We installed a set of BDE Intake Cam Gears to revive Nissan’s VTC system.  Unfortunately we found that the VTCs were still not working.  We pulled the valve covers and found that the check valves were not installed in the back of the cams.  Adding the much needed check valves did the trick.  We also found that the fuel pressure was abnormal, very abnormal.  It was causing tuning grief and running too lean at 3300 RPM up until 4200 RPM.  This was remedied by untangling old bad work.

Fuel pressure reading on the lowest graph.  You can see how its running base fuel pressure up until 4200+RPM.  This is not good as you can see how lean it gets.  You can also see how it hurts power causing a nice dip.

Here is the graph (red run) after we fixed the fuel pressure issues.  The old bad run (blue) is displayed to show the obvious differences.  35 torque and 35 whp gain.

This graph shows the dramatic difference that a working VTC system can make.  The blue run was prior to fixing the VTCs.  Red is after with the VTC system working.  75 torque and 57 whp gain!!!!!!  Look at how the turbos react (boost curve).

The most impressive thing about this Z is its ability to make power on 91 octane and its strength against the evil California fuel.  You can’t hold it back.  It will go all the way.

If you can’t see it clearly enough, that graph says 564 whp & 501 torque.  It also says peak boost pressure of 20 psi.  All this on 91 octane.  A freak, an anomaly, a monster.  This Z gets to have its cake and eat it too.  It also takes other people’s cakes and eats it too!  It has amazing low end response, top end power, and makes a shit load of safe reliable power on 91 octane.  So much power that Jon declined to make any higher octane tuning.  Really?  Too much for you eh, Jon?

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Comments (4)

  1. Mark Holtzman (Louisiana)

    Seb, any idea what internals is he running in order to be able to run 20 psi with no knock?? And on 91 octane?!?!? I am wishing he didn’t decline the higher octane run probably would have been crazy..

    Good job Jon your car sounds awesome!

    Keep up the good work Seb I really enjoy reading the articles!

  2. Hi Mark
    There are many factors that affect knock thresholds. Back-pressures, octane of fuel, inlet air temps, compressor efficiency, cam timing, supporting modifications,etc….
    The actual internals as far as pistons go can only have an affect if the pistons have lower compression. So it is very possible Jon may have lower compression pistons. The actual make or type very rarely has an effect.

    Thank you for the support and thanks for continuing to enjoy the blog!

  3. William V

    Any more info on the exhaust manifolds? “Tubular mid-length”? Is it the old Inconels or a custom setup?

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