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This is a compilation I have produced in which ANYONE comtemplating or performing any upgrades on their car should perform. These preliminary tests will ensure that your car is prepared to safely meet the demands your upgrades are going to demand of it. Overlooking these tests is a sure fire way to destroy your engine and be left with nothing but thousands of dollars in repair costs, perhaps only to go out and just do it all over again. These tests are not only beneficial for those who plan to upgrade, but should be a battery of tests that one continually abides to performing. 3000 mile oil changes are a MUST with these vehicles and I would suggest the same mileage interval to test these specifics I am about to detail. This document primarily caters to the twinturbo guys, however, I will point out the differences for the non-turbo guys along the way. As always, I am open to any input on this or any constructive criticism that benefits the forum and its members. I look forward to hearing from you! Now, without further adeu.... The primary concerns one should have when they begin modifying the original design parameters of their vehicle is simple. 1) Is it getting enough fuel
2) Is it getting proper ignition
3) Is it getting proper air These three components are what enable your engine to effectively and safely produce power. With only one of these components missing, the engine will not run at all. With any one of these improperly 'configured', it could mean poor gas mileage, poor drivability, or much worse - catastrophic engine failure. The tests you are about to perform will ensure that these three components are properly working and configured for producing high output.
Introducing: The Weapons of War:
These are the required components to effectively perform the tests outlined in this document. Starting at upper left is a timing light (the thing that looks like a gun)
Immediately to the right of the timing light is a pressure guage. I acquired this from Autozone for about $20. It is used for oil pressure testing, but that's inconsequential - it tests up to 100psi with 5psi increments. Perfectly suited for testing fuel pressure too. I acquired a "T" connector for 8mm (5/16") to allow easy "T-ing" into the fuel line. I simply soldered the "T" connector to the end of the pressure testers fitting and used a 4" piece of hose and a hose clamp to secure everything together. Immediately to the right of the pressure guage is a 10mm socket on a 3/8" ratchet wrench. This will be used to loosen the bolts on the CAS to allow for you to adjust the base timing. We'll get to that in a few. Immediately to the right of that is a compression tester. This is used to determine the condition of the combustion chamber and its ability to compress the air and fuel that enters into it. A brand new engine will produce 170psi whereas a worn, tired engine will produce 120psi or less. Just below the wrench is my pressure tester. It is actually a speaker magnet that I drilled a hole through the center of and simply inserted a wheel valvestem to allow me to pump air into the intake system. You can get creative here as well and build your own, but I believe there is also a member here that produces a pressure testing kit that you can purchase inexpensively. This will allow you to easily isolate any intake tract leaks and fix them. At the very bottom is a 'feeler guage'. This tool is simply an assortment of metal strips of various thickness. Each one is labeled as to its thickness and we will be using it to guage the gap of the spark plug.
Test #1: IGNITION TIMING
Ignition timing is essentially telling you when the spark plug is being fired in relation to the position of the piston and crankshaft. The value you are used to seeing is a value in degrees. This is angular degrees, not thermal degrees. In the VG30, the base timing (or the timing reference at idle) is 15 degrees. This means the ECU is making the engine fire at 15 degrees BTDC, or Before Top Dead Center (now you may see why I stated "...relation to the position of the piston and crankshaft.") BTDC means that as the piston is in its upward motion on the compression stroke, the plug is being fired when the crankshaft is 15 degrees before the piston reaches top dead center of the cylinder. The object here in setting base timing is to make the ECU and the timing mark on the pulley agree with each other.
Typical timing lights use an inductive pickup to detect when the plug is being fired and when it detects this, it causes a strobe light to fire off. This basic principle allows us to see exactly when the plug is being fired off in relation to the crankshaft position. On the front of the engine is a timing indicator which shows a range of degrees on what looks like a ruler. The values go from 0 to 30, from left to right. On the pulley is a mark that indicates the position of cylinder #1. When the mark is lined up to "0" on the indicator, this means the piston is all the way at the top of the cylinder. Timing lights also require power in order to fire that strobe light off so be sure to connect the power leads as such.
 The inductive pickup:
 NOTE:! Using this point as the pickup I have found to be the quickest, most accurate method of hooking up the timing light. There is also a black loop on the PTU harness that is supposed to be used for this, however, I have on a nuimber of occasions seen vary peculiar results - sometimes getting two points of indication on the pulley and sometimes it being so far off you can't even see it. I DO NOT RECOMMEND using the inductive pickup loop on the PTU harness. Try this method first and if it doesn't work at first, wiggle the pickup around a little on the wire. You should get a pulse. If it still doesn't want to behave, you should pull the coil pack out and use a plugwire extension and put the inductive pickup on the high voltage line going to the plug. I simply have seen the inductive loop do way too many weird things to really trust it with something like ignition timing. Once you have everything properly hooked up, point the light at the pulley and observe. This is what you should see.
 
NISSAN FACTORY BASE TIMING IS 15 DEGREES BTDC. They also say +/- 2 degrees, but its not hard to get it dead on. To adjust the timing, the CAM ANGLE SENSOR, or CAS for short, it used to adjust the base timing. 
There are three 10mm bolts that hold the CAS in place. Loosen these with the engine off.
Since the engine rotates clockwise (looking at it from this perspective), turning the CAS clockwise will retard the timing whereas turning it counterclockwise advances the timing. Move the CAS in the appropriate direction to adjust the base timing. Of course, the engine must be running to test it and once you have the CAS loose a little, you can start the engine and then begin moving the CAS a little to get the timing mark aligned to 15 degrees.
This process ensures that the timing values in the ignition timing map of the ECU are in fact, correct. As an example, if the timing in the ECU is running 20 degrees at full load, but the CAS is set to 17 degrees of base timing, the ACTUAL timing the system will be running is 22 degrees. All the CAS is for is simply to make the value in the ECU agree with the actual timing being run. The timing light allows you to verify what the ACTUAL timing is because it flashes the light off when the plug REALLY fires and the markings on the pulley allow you to see what the position of the crankshaft REALLY is. Moving along:
FUEL PRESSURE
In order to check the fuel rail pressure, you need a pressure sensor put inline with the fuel line to the fuel rail. The pressure sensor defined above will allow us to do this, but we have to connect it in. Since the fuel system always holds some degree of pressure, even when the car is not running, we must ensure that we dont unhook a line a pour raw fuel into the atmosphere, or into a hot engine bay. We start first by cutting off the fuel to the filter as such.
 Since the rest of the system is also under pressure, we must clamp off the other side where we are going to disconnect the fuel line from and tie in the pressure guage. We also use a rag here because even in this short piece of hose, there remains enough pressure to spew a catastrophic amount of fuel out and start a fire. Ideally, one would do this while the engine is cold. Relieving as much pressure as possible by removing the gas cap also helps.
Once done, place your rag as follows and loosen the hose clamp and remove the hose from the filter.
 In the VG30, as well as most other fuel injected vehicles, have an operating fuel pressure of ~3bar. 1bar = 14.7psi so 3bar is effectively ~44.1psi. The aspect that complicates this simplicity is the fact that the manifold is not always at 0psi. In fact, it is rarely at 0psi. Since the tip of the injectors is inside of the manifold, this means that the vacuum or pressure that the injector tip 'feels' also affects the fuel delivery. Since the ECU controls the duration of time that the injector is held open, it assumes that the fuel pressure is always the same, there must always be a 44.1psi differential between the fuel rail pressure and the manifold pressure. This is to ensure that no matter what vacuum/pressure the manifold is under, a 'x' millisecond pulse of the injector will always deliver the same amount of fuel. You can see what I mean here:
 Ok, now that you have everything connected, you are ready to test your fuel pressure. You can see in this picture that there is about 10psi of pressure on the guage. The engine is not running here and hasn't been started since the install of the guage, but you can now see why I pinched off the hoses. 10psi of fuel pressure will puke enough fuel to start a Sonny's BBQ in your driveway so BE SAFE! Now, in this picture you can see that the fuel pressure is appx 35psi. Remember the pressure differential I was talking about? Well, at idle, the manifold is at about -10psi of pressure. In order to maintain linear fuel delivery, there must always be approximately a 44.1psi pressure differential; so 35 + 10 = 45psi. We are good here.
 This next picture is a demonstration of how the fuel pressure regulator works. The hose I am holding in my hand is what connects the fuel pressure regulator to the manifold. The fuel pressure regulator is the device that maintains this 'pressure differential' such that the fuel delivery is linear per pulsewidth of the injector. Since I have unplugged the FPR(fuel pressure regulator), the FPR 'thinks' the manifold is at 0psi. You can see here that the fuel pressure has now raised to ~44psi, as it should.
 I want to point out that since the fuel pressure control systems are a 'passive' system and not 'active', there will always be slight variations in fuel pressure from what you see here. However, there should not be anything greater than about a 5psi difference in these tests. This is primarily what makes the difference between one Z and the next - some fuel systems simply work a little better/worse than the next Z, but the actual effect on the system as a whole is marginal as long as there aren't large variances. I have setup the fuel pressure guage as well as a manifold pressure guage to demonstrate how the fuel pressure regulation system works in finer detail. 
You can see here that the fuel pressure is slightly higher at 0psi of manifold pressure than it was in the original test. This is due to the fact that the ECU ALSO varies the fuel pump voltage (which affects its output). You can see here that at 45MPH with the manifold at 0psi, the fuel pressure is at 55psi. This is actually a little on the high side as we should be seeing a fuel rail pressure of ~45psi at 0psi of manifold pressure, but this is due to the fact that I am still using a non-turbo fuel pump controller in my car (my car was converted from non-turbo). However, this is not bad, if anything, it is simply safer. In this condition you should see at least 44psi at the fuel rail. If you see less than 44-45psi, you have a problem and it must be fixed.
In the following picture you can see that the manifold is at 5psi of pressure and we ALSO see that the fuel pressure has raised up from 55psi to 60psi. This is the fuel pressure regulator at work. Since the manifold is at 5psi more pressure, it also raises the fuel rail pressure so that the fuel delivery per injector pulsewidth is consistent. This is important as the ECU is assuming that no matter what pressure the manifold is at, 'x' millisecond of injector pulsewidth will ALWAYS deliver the same amount of fuel. This is very important when tuning a car too.
 The next test is running the engine at 7000RPM, which is at 95% of its operating range. You can see that the manifold pressure is at ~15psi and the fuel rail pressure is at ~65psi. This is 10psi more at the fuel rail than when the manifold was at 5psi of pressure. 55+10 = 65psi of fuel rail pressure. This is consistent with what we should see.
 IMPORTANT!!: I am running the engine at 7000RPM here in the above photo. This is when the fuel system is at 95% of its expected delivery rate. You have to consider that as the engine RPM increases, so does the fuel rate. When I converted my non-turbo to turbo, I used the non-turbo fuel pump. It worked great at ~14psi. However, when I raised the boost to 16psi on the non-turbo pump, as the RPM increased to around 5500RPM, I began noticing the fuel pressure falling off all the way down to 45psi! This is VERY BAD! The reason this occured is because the non-turbo fuel pump was unable to keep up with the demand of fuel at higher RPM. It maintained ~65psi until around 5000RPM and then sharply fell off at 5500RPM down to 45psi at the fuel rail. This is a catastrophic failure waiting to happen because when the fuel pressure falls, so does the fuel delivery. This is not a problem with the fuel pressure regulator, this was simply the non-turbo pump falling on its ass. I corrected this problem by putting a twinturbo fuel pump into my car. THIS IS THE PHENOMENON THAT YOU ARE NOT WANTING TO SEE! You want to ensure that the fuel pressure is maintained ALL THE WAY THROUGH THE RPM RANGE that your engine operates within. If it does not maintain this pressure, the fuel delivery will fall and this will cause a lean condition. Lean conditions lead to detonation, broken pistons, burned valves, and catastrophic engine failure. This test concludes the 'fuel delivery' aspect. If your fuel system does not maintain proper pressure, you simply need a bigger pump. AIRFLOW:
This is one of the three vital components to proper engine performance. Just as much as a dirty air filter will affect performance, a leak in the intake system will also promote piss poor performance. The intake system of the Z, in both the non-turbo as well as the twinturbo version, consists of a multitude of intake plumbing components. In the non-turbo Z there is a total of ~10 feet of piping between the air filter and the throttle bodies. The twinturbo variation has over 20 feet of plumbing. Unfortunately this system is not composed of a single pipe. In fact, there are a dizzying number of clamps, hoses, and pipes that comprise the intake system. In the design of the 300ZX(Z32), the engineers employed a Mass Airflow Sensor with the ECU (Engine Control Unit). This sensor measures the intake air so as to determine proper fuel delivery, as well as a multitude of other control parameters. Since this system relies so heavily on the accuracy of the measured intake air, it is critical to have an 'air tight system' in order for it to properly perform. In order to ensure that the intake system has no leaks, we can use Sir. Bernoulli's principle: PRESSURE The test is simple and requires simple equipment. For those who have a single intake, removal of the MAS and filter and installation of the 'plug' is easy. Those with dual intake systems need to dig up their original intake "T" and use it for this test. The hardware is installed as such:
 
In the picture above you can see that the manifold is at 5psi of pressure. DO NOT EXCEED THIS PRESSURE The reason I only have the intake system at 5psi and no more is because of the facts that 1/4" of the intake system is not subjected to positive pressure. None of the non-turbo intake system is under pressure. In addition, since the intake system is also part of the PCV system (positive crankcase ventilation), you do not want to overpressurize the crankcase for fear of blowing out the oil seals along the camshafts and crankshaft. 5psi is enough to hear any leaks and not too much to blowout seals. Once you have the system pressurized, you will be able to easily locate any boost leaks. Typically it only involves tightening the loose hose clamps that hold the system together. Locate all leaks and fix them. SPARK PLUGS
(This is the long awaited post of the century, and last century if you are counting. =) In the stock configured 300ZX(Z32), the NGK (japanese manufactured) platinum tipped plugs are used. NA stock = PFR6B-11 gapped to 0.044" (1.1mm)
TT stock = PFR5B-11B gapped to 0.044" (1.1mm) While these plugs perform well under stock configuration, they do not perform well under a modified, high output configuration. The nomenclature used in the plug numbering denotes several aspects of the plug's design and performance. What interests us the most is the 4 character in the naming scheme. The NA is a "6" and the TT is a "5" in the above examples. This number denotes the ability of the plug to diffuse heat away from the tip and into the plug body, where the cooling system absorbs the heat. The higher the number, the better the plug's ability to keep the tip 'cooler'. As you increase the output of the engine, the cylinder temperatures also increase. What this means is that you need a spark plug that also increases in its ability to dissipate the heat. By not changing the plug's thermal dissipation when you increase the output of the engine, you raise the likelihood of 'spark knock'. This phenomenon is analogous to detonation and it should be avoided at all costs. To mitigate the posibility of 'spark knock', you should use a spark plug that has a higher ability to dissipate heat. This simply means you need a plug with a higher 'thermal dissipation' number. Here's the breakdown: NA stock: PFR6B-11 ; upgrade to the PFR7B-11
TT stock: PFR5B-11B ; upgrade to the PFR6B-11B For the NA guys, this is all you need to do. However, for the TT guys, there is an additional parameter that you must concern yourself with. Since a stage3+ upgrade to a twinturbo ALSO includes running higher boost pressures, we have to account for the higher air/fuel densities in the combustion chamber. In the stock configuration, the plug gap is set to 0.044" (1.1mm). While this performs well in both low and high load conditions, it will not perform well in high load conditions when you raise the bar. The higher density of air and fuel in the combustion chamber (a result of running higher boost) requires a higher voltage for the spark to 'jump' the gap. Since you do not have the ability to easily increase the spark intensity, you must resort to alternative, and less expensive methods of promoting proper ignition. Instead of increasing the spark intensity, one can simply reduce the gap tha the spark has to jump thereby allowing a spark to jump at all under high boost. The typical plug gap is 0.044", but by reducing the gap to 0.035", one can increase the chances that the spark will actually 'jump' the gap. -0.035" has proven to be an 'ideal' gap to set the plugs to. Conversely, if you make the gap too small, you will notice misfiring at low load/cruising conditions as the spark is simply too small to ignite the low density of air and fuel in the combustion chamber. This is why you dont set the plug gap to 0.010" and expect it to perform well - just about everything is a tradeoff and this one falls at mid-road of the equation. Using the feeler guage pictured in the "Weapons Of War", you can properly gap your plugs. 
COMPRESSION TEST:
Since you already have your plugs out because you are changing them to the proper plug and gapping them to the right spec, you are already set to perform a compression test.
A compression test simply shows you the engine's ability to perform one of its most vital functions: compressing the air and fuel mixture sufficiently. The reason the engine compresses the mixture of air and fuel is because it optimizes the oxidation of fuel to create pressure and heat energy to push the piston, which is connected to the crankshaft and eventually to the wheels. A worn out engine will yield lower compression numbers simply because the cylinder or rings are no longer producing an 'airtight' seal, or the valves and/or valveseats are burned/broken. Since the non-turbo engine has a different 'compression ratio' than the twinturbo, you will be expecting different compression values between the two. Here are the factory specs: non-turbo: 186psi is 'perfect', minimum of 136psi.
twinturbo: 174psi is 'perfect', minimum of 121psi. If you perform a compression test and you see numbers lower than the minimum specified, your engine is worn the "F" out and you need to rebuild it BEFORE you plan on upgrading it. If your test yields higher numbers than 'perfect', there is likely a problem with your compression tester and you should acquire a new unit and perform the test again. Typically you will see ~150psi for a twinturbo in good shape and ~165psi for a non-turbo in good shape. Anything less than this is indicative of a problem and it should be addressed.
At this point, if everything checks out OK and you have performed the plug upgrade to the parameters specified, you are ready to upgrade your vehicle. If any one of these tests come out 'substandard', the problem should be corrected before upgrading is even considered.
In addition to these tests, you should ALSO perform an ECU self-diagnostic. The process as well as diagnostic codes are defined in the link below.
[ http://www.ttzd.com/tech/diagnostictech.html ] If there is any problem detected, this should be rectified BEFORE any upgrades are put in place. There are a number of different codes that will put the vehicle into 'safety mode' of which will inhibit performance. Correct the problem first, upgrade later. I hope this post comes as an informative, preliminary post that reduces any fallacy that anyone may have as well as enlighten them on the 'importants' of safely upgrading your car. -l8rz
ADMIN: Please leave this in the general forum for a day or so simply to get exposure as not all members frequently check the technical forum. I think this post will warrant "FAQ" credentials so move it over on tuesday/wednesday. Thanks!
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The 6 P's:Proper Preparation Prevents Piss Poor Performance. - 
