Edelbrock is a reputable company who just developed a dry nitrous kit specifically for the 350Z. They go into detail of their R&D and install in Turbo magazine August issue. Unfortunately, I already have a newly installed wet kit but what I gain from their article was knowledge and very helpful tips, especially the timing retard. Here is what they have to say thru their R&D and best practices. Keep in mind, NX, Zex, and NOS also recommend timing retard, not just colder plugs.

Timing

When we set the timing on a car we are actually finding the point in which the engine will initiate the burn so that at about 10° After Top Dead Center (ATDC) peak cylinder pressure can occur. Depending on combustion chamber design and cylinder filling, this point can be anywhere between 30° and 45° Before Top Dead Center (BTDC). The reason we retard timing with nitrous injection is that the air charge becomes more oxygen dense, causing the air/fuel mixture to burn at a much higher rate. In other words, accelerated combustion occurs. This acceleration in combustion causes peak cylinder pressure to happen much earlier. The problem with this is that instead of using the energy generated by combustion to give the piston momentum we are transferring that heat energy onto the rotating and reciprocating assemblies, and possibly hurting them. In the process we are losing torque and HP. To prevent this, we recommend that you retard the ignition timing 1-1/2° to 2° for every 50 hp added through the nitrous system. This will ensure that peak cylinder pressure occurs at the same point it did before the nitrous was injected into an engine. Also keep in mind that retarding too much timing will also hurt you. If you retard more than the recommended amount, peak cylinder pressure can occur much later in the combustion cycle and that energy will be wasted. In most cases, avoid aftermarket chips or computers that are not designed for use with nitrous. They typically add more ignition timing, which could lead to power loss and engine damage.

Spark Plugs

The last frequently misunderstood factor in adapting a nitrous system to your engine is the spark plug. Three important aspects of spark plugs must be looked at, their heat range, reach and gap. We advise lowering the heat range of your spark plugs 1 step for every 100 hp added with nitrous. The other aspects of a plug that must be looked at are the reach and gap. It is best to use a non-projected type plug. Projected plugs allow a greater portion of the electrode to be exposed to combustion gases and possibly cause pre-ignition. The spark plug gap also plays a large roll in nitrous engine performance, because increased cylinder pressure from the additional nitrous and fuel makes it harder for the spark to jump the gap. The same gap that worked for a non-nitrous set-up may be too much for nitrous, leading to excessive misfires and loss of power. Ideally a gap between .025" and .035" should be used on high horsepower applications where an inductive style ignition system is utilized. Engines equipped with capacitive discharge ignition systems may use gaps larger than .035". It’s very important to learn how to read the plugs after a pass. A plug can tell you a lot of what is happening in the combustion chamber.

 

I have the zex 75 shot wet system. Do you think i should retard the timming?? if so how do i do that on the Z?? Also what kind of plug do you recomend? can you give me an example of a one step colder plug and maybe a model number please?

 

I hope this will help you fine tune and make your nitrous reliable/safe. Use this as a guideline on how much you should retard. This was scanned from my NOS user/installation guide but from my research it is very consistant with the recommendation from the other nitrous companies. Here is another thread I posted addressing the same subject matter.

 

BTW, the stock ECU retards your timing during denotation by a maximum of 4 degrees.

 

LaPuLaPu: Thanks for taking the time to type that out...good stuff.

Anyone know of a non-projected electrode plug for the ZQ35? I assume they mean the ground electrode (the one that is adjusted for gapping) and not the center electrode. The Iridium looks like it's projected (see pic).