The 'Stealth' Z - Part 7

by Steve 'Stealth' Webb

As promised weíll go through some of the gauges available on the market. For oil pressure, water temp, and voltage I am using Autometerís new Lightweight Aluminum series of gauges in place of the normal gauges in the dash. These match the interior of my ëZí perfectly, are direct reading for accuracy (I highly recommend direct reading oil and temperature gauges due to their accuracy, reliability and quick reading abilities), and are relatively inexpensive (around $40 - $70 each). For boost I am currently using a Cartech gauge, although I donít think these things are available anymore.

The least expensive boost gauge that I would even consider using is the Autometer one. It is fairly accurate and can usually be found for under $50 to $60 bucks. The down side is it is a plain looking gauge and has terrible illumination during nighttime viewing.

In my opinion, the Greddy boost pressure gauge is one of the best looking and easiest to read (especially at night) gauges on the market. For those that donít know, Greddy (also known as Trust) is the second largest manufacturer of aftermarket parts in the world for Japanese vehicles. The gauge comes in 52mm and 60mm, in black face and white face. The disadvantage of the Greddy boost gauge is it is graduated in bar, and even after lots of exposure, reading in bar for me is still not very natural. It is also moderately expensive (list is $139). Another excellent boost gauge is a model made by SPI (Sharp Precision Instruments). It comes in white and black face and does read in PSI (up to 30psi) instead of bar. I donít know, but it just seems more impressive to run 15 lbs of boost instead of running just one bar (1 bar = 14.7 PSI). The other clever thing abut the PSI gauge is you can choose the color of the lighting (red or green) by simply choosing the wire you run to the power source. It is priced in between the Autometer and the Greddy at around $109.

I lived with several VDO boost gauges for years, and although they are cosmetically decent looking, they all had a bad tendency to intermittently not return to "0" when the engine was shut off. That just doesnít give me a good feeling about accuracy or dependability.

HKS just released a new series of gauges last month. I havenít had an opportunity to see any of these new units, although they are still graduated in bar and come in an off-size 46mm and the ëstandardí oversize 60mm. Although HKS use to be the standard in the market only a few years ago, their current availability and customer service have been far from outstanding.

Now to specialty gauges. For any turbocharged car I would highly recommend an EGT (Exhaust Gas Temperature) gauge. This gauge uses a thermocouple to read the temperature of the exhaust at the inlet of the turbo. This is important for two reasons. One is to keep from ëovertempingí the turbo. In other words, running at a temperature that would be damaging to the turbo components, reducing the life of the turbo. 1650deg F (or 900deg C for those of us with Greddy gauges) is the generally accepted max continuous reading. Transitional peaks above these reading are ëOKí and can be normal depending on the vehicle, up to 1800deg F (1000deg C), as long as it is transitional and only lasts for 1 - 2 seconds max. The second advantage is in monitoring the operation of your vehicle. Any changes to these temps could alert you to a new or potential problem before it becomes serious, and is also very helpful in troubleshooting. Again, I think the Greddy line is hard to beat in terns of accuracy, looks and design. In addition to the standard gauge, they have a line of "Peak Hold Warning" gauges that have a adjustable warning light that will illuminate if the setting is exceeded. You can also ërecallí the highest reading for viewing since the last time the reset button was pushed. This is very convenient in situations where you donít have time to monitor all the gauges during a run and would like to review the readings.

HKS also has a similar line of high quality Peak Hold Warning gauges, although my above statement still holds true, especially with new items.

Another gauge I would recommend having, especially in a force fed car, is an oil temperature gauge. Turbos are hard on oil and this would be a very important item to monitor. There are all kinds of ideas of what optimum and max temps should be, but I would be concerned if temps were consistently above 220deg F.

More for curiosity, I installed a sensors to monitor transmission and diff temps. It is switchable so one gauge can be used for both. Also out of curiosity I will be monitoring intercooler inlet and outlet temps, to measure the efficiency of the unit.

One last thought on gauges is where to mount them. For the 300ZXTT there is an ëAí pillar mount that looks great and keeps the gauges in view without obstruction vision. In the earlier cars we are stuck with mounting them on the steering column and center console (as I have). I might get ambitious and fiberglass an entire ëAí pillar to mount boost and EGT on, but that will realistically be down the road a bit as it will take some time to make it look right and cover it with material to match the interior... and I just have all this extra time on my hands... yea right!!...

Well, I did sneak in one more dyno session last week after getting the J&S Safeguard ignition unit back from reprogramming. It seems that John at J&S did a good job of designing the program in the first place as I made exactly the same HP as before. Although now I can dial it back to minimum sensitivity and just start to hear the onset of detonation. I was really hoping to find a couple more HP there, but the J&S is doing its job perfectly. Especially since I am running my timing at 14deg BTDC, which is very aggressive for a turbo motor, but gives outstanding response.

The next addition will be a three inch exhaust with a newly acquired carbon fiber muffler from B&B Fabrications. This muffler is an all stainless inlet and outlet straight through design with a carbon fiber center section. It is ultra light weight, ultra compact (only 6" OD) and ultra high flow. B&B is one of the highest quality exhaust manufactures on the market and offers dyno tuned, full polished (the entire exhaust is polished) stainless steel exhaust systems for many cars including the 300ZXTT, as well as stainless and carbon fiber mufflers in any size or configuration (Alamo Autosports is now a Authorized Dealer for the central US for B&B).

Ok, we didnít get to the wiring or insulation yet. After gathering together all my info for these subjects, it became clear that to cover each of these items properly would require at least a separate article apiece. So next month will be some interesting wiring mods. And maybe a look at the completed exhaust...

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