IMO, that kit is not safe at all. Its a dry kit, but as Dave stated, there is no way to enrich fuel.
On the ZEX dry kit, they add additional fuel pressure using a small amount of nitrous to push harder on your fuel pressure regulator. This added pressure pushes on the internal diaphram inside. 1psi boost=1 psi increased fuel pressure. Zex does it nicely and everything is contained in a box.
An NOS dry kit works almost the same way. The kit uses two solenoids. One for nitrous, the other for fuel enrichment using the same technique as ZEX.
In this kit, they give you only a nitrous solenoid. There is no way to increase fuel. You'd have to do this yourself. The only real way to do it on a EFI car is to get into the computer and command it to dump in lots of fuel during WOT. You'd have to have two programs, one for street and one for nitrous use.
Yes your car does go into open loop during WOT, but that doesn't mean much. All it means is that the o2 sensors are ignored and that the car uses load vs RPM to guess as to how much fuel to add by looking at a table. Load is a function of airflow and displacement, and the airflow values are taken from the MAF table. The MAF does not control fuel enrichment. All it does is tell them computer the amount of air entering the engine. The computer uses these values to determine load, and then it looks under a table at WOT to determine fuel. You'd be spraying after the MAF anyways, so the car never knows that you have started spraying, or that there is any additional airflow/oxygen into the intake track. Its very accurate until you start making airflow mods on your car and its flowing a lot more air than stock. This is where a tune comes into play and you adjust your transfer fuctions.
Another myth is that you can run an adjustable regulator and crank up fuel pressure and under WOT and nitrous use, it'll even out. WRONG.
The factory computer is designed to run on a fuel pressure of 39psi static. IF you crank this up to 50psi or whatever, the computer will "see" this increase pressure from the 02 sensors during closed loop. The car will automatically compensate for this increased pressure by making the injector pulse width smaller, providing less fuel, and you're back where you started again.
So people ask, "Well the car is in open loop during WOT, and doesn't look at o2 sensors...". Well that are right and wrong. The car doesn't look at your 02's under WOT, but it still uses your KAM, or Keep alive memory. It remembers any changes that were made using the computers adaptive control, and it uses these changes under WOT as well. So if it sees a huge increase in fuel pressure it'll trim it out under part throttle, but under WOT, it will remember the decrease in injector pulse.
Basically, thats a bandaid fix, and it'll work for about 5 min, and then the car will trim it out, and you're back to where you started.
SOOOOOOO.......to sum it all up, your best bet is going with either a ZEX or NOS kit if you're set on using a dry kit. If you like a wet kit, then go with NX. A lot of this stuff is from personal experience. I run a zex dry kit and I'm pretty happy with it. However, since I'm running a SC car, the fuel enrichment jetting charts do not apply. I have my own wideband set-up, so seeing what the exact ratio is and making changes is easy.
Spraying before your MAF with a dry kit will not give enough fuel enrichment. Sure it might see some aditional airflow, but I'm almost certain that it'll peg the MAF. The MAF can only see a max of 4.7 volts. Under WOT as is, I'm sure you see around 4.1-4.2 volts. Once you peg that meter, the car uses a stored fuel table and guess as to how much fuel to add using no sensors to get its information from. So basically, the computer is driving blind.
On a side note, I agree, Dynotune is a great place. They are actually my local dyno as well. I got their purge kit and the rest of their stuff is top notch. However, just knowing how the ECU's on theses cars work, I'd never spray before the MAF. Its not the correct way and its not a safe way at all.
I hope I answered some of your questions.
Black 92' SC 5-Speed
Last edited by fastsc92; 06-08-2005 at 11:52 AM.