The Turbo on Your 300ZX

300ZX Turbochargers

Stock boost spec: 6.7 psi

The turbos on 84 300ZXs do not have water cooling, cooling was added in 85. If you have an 84 turbo, drive easily for the last mile or two before you turn the engine off. For a rebuilt stock turbo you should expect to pay about $300-500. If your 300ZX turbo seems a little more sluggish than you think it should be, try measuring the peak boost level, it's probably fallen a bit from its original level due to wear, espically in the wastegate.

There are two important things to remember when modifying your 300ZX turbo:

The boost level is completely mechanically controlled
The pop-off valve opens at about 8 psig

The first thing you need to do is to take care of the pop-off valve. Most companies who sell any type of turbo modification will have these. Don't simply remove it, should something break(wastegate diaphram, wastegate solenoid, etc.) and allow too much boost you'll feel really stupid when your engine explodes. This, of course, is bad.
Since the boost pressure is mechanically controlled, the computer won't attempt to limit fuel, ignition, boost, or anything else if things go wacky, it just accomodates the extra air going in with extra fuel and appropriate timing changes. You have been given enough rope to tie your own noose now, be carefull with it! You should throughly read the turbo faq before you turn one bolt on your car.

You know you're using your turbo when you open the hood and see this.

There are many companies that sell a wide array of turbo accessories. The most common(and best for the money) is a "boost controller" and does nothing more than enable your turbo to make more off-peak boost with varying amounts of peak boost increase by altering the pressure to the wastegate. This sounds unimpressive, but mid-range power is increased to the "Oh my god, we're going 80mph in my driveway" range. The single best boost controller out there is a hallman style unit. It is a poppet valve dealie, and can be ordered from Buschur Racing (www.buschurracing.com) for $90. Look here for a fairly comprehensive explanation of the theory behind boost controllers.