Installation Tips:

Tip #1: Before installing the fan spray nozzle, put a dab of White-out on nut-like part of it, directly opposite of the fan opening. This helps you to aim the nozzle after the intake is installed back on the vehicle. This is very handy when changing NOS jets. It is easy to see if you have inadvertently turned the nozzle while tightening the line to it.

Tip #2: This is to be done at your own risk! After assembling the solenoids, it may be a good idea to connect them to the NOS bottle to check for leaks before installing them in the car. It is a terrific pain to have to remove them from the car and then disassemble them only to turn one fitting one more time and then reassemble them and then re-install them. You get the idea....

I would suggest that one person holds the solenoids with a rag, using both hands, while another opens the bottle. If all is OK, carefully open the rag and listen for any leaks. If you find any, turn off the bottle valve and slowly loosen the line from the bottle until you hear the N2O coming out of it. Wait until it stops and then loosen a little more....if all the NOS is out, disconnect the solenoids from the line completely and then proceed to fix the leak. Repeat this step after making the adjustments to ensure that you fixed the problem!

Tip #3: As mentioned in the primer, there is a large factory grommet in the firewall through which I ran my wiring between the solenoids/switches/relay. You may want to make Quick-splice connections just inside of the grommet to facilitate easy removal/re-installation of the system....in the event that you need to remove the system for any reason!

Operating Tips:

Tip #1: Fuel Pressure Safety Switch
I installed the Fuel Pressure Safety Switch that was included in the 5115 NOS kit. This gets threaded onto the fuel rail test port (see photo). Upon testing my car, I noticed that the NOS would cut out at or about 5200 RPM. After disconnecting the FPSS the NOS operated normally. The safety switch is preset for 50 psi.

I finally got my hands on a fuel pressure gauge and did some testing! Note that the for jetting sizes aa / bb, aa=N2O jet and bb=by-pass jet. Also, note that the pressure drops at a steady rate starting from 2000 rpm and ending at 6800 rpm (when I shifted). From the looks of things, it wouldn't hurt to have an additional fuel pump in order to maintain the volume, even on a relatively small jetting.

IMPORTANT: These runs were made using 2nd gear only. If I continued shifting, as in a full run, they would most definitely become successively lower through each gear (this is why the Fuel Pressure Safety Switch would engage in 3rd @ 5200 rpm using the 42/59 and FPRCV). Unfortunately, I don't want to get out on the highway and do a 4-gear NOS run (100+mph) with 6 different jettings so, we'll have to assume that by 3rd gear, these numbers would be about 10 psi lower at 6800 rpm, and 4th gear would be lower yet.

Readings were taken from an AutoMeter Ultra-Lite mechanical fuel pressure gauge.

I have just installed a nice set of Cyberdyne digital gauges, an Air/Fuel ratio gauge and a fuel pressure gauge. I will attempt to make full passes with various jettings in the near future with the new gauges. These will now tell not only the exact fuel pressure (digital readout compared to the AutoMeter's analog), but when and how badly the car is leaning out. As such, these figures below may change for a more exact representation.

* This measurement taken with the Fuel Pressure Regulator Control Valve connected in the pressure TEE setup. As you can see, it does restrict pressure to some extent.

The Fuel Pressure Regulator Control Valve serves a function at start up only. When cranking the engine, it immediately max's the fuel pressure (43psi) which then drops to ~37psi when started and idling. With it by-passed, the pressure climbs up to 43 psi while cranking and then drops to ~37psi after starting and idling.

Tip #2: Fuel Pump
It is not a bad idea to install a "helper" fuel pump...especially looking at how the pressure drops. An automatic PGT would never survive. The only thing making this feasible on the 5-speed, is that when you let off the gas to shift, the fuel pressure pops back up (although not as high). A second fuel pump can be added in-line to the stock fuel lines. This connection can be made outside of the gas tank. Just be sure that you choose a suitable mounting location for it.

An add-on pump simply works in conjunction with the stock pump and helps it to maintain VOLUME, it does not increase the pressure. In other words, the by-pass jet would stay the same (unless changing the N2O jet too), but unlike starting at say, 70psi and dropping to 30-40psi by 4th gear (on a 5-speed), the pressure would start at 70psi and stay there through the entire run.

Tip #3: Jettings
To clear up any confusion, I spent a long time on the phone with NOS Tech Support regarding the matter. The jettings that NOS "recommends" for the PGT is 36 N2O and 42 by-pass. Anything above and beyond that is at the user's discretion and risk.

Since there was a good deal of debate about it, I verified that with a dry manifold system, the smaller the by-pass jet, the greater the fuel pressure and the larger the by-pass jet, the less the pressure. Also, after talking to the NOS Tech, I have traded out my .059" by-pass for the more reasonable .042" jet. This effectively increased the fuel pressure and I noticed a difference right away. The reasoning here is that even though I spray as much N2O as the Mustangs, they have 8 injectors and the PGT has 6. To maintain a feasible air:fuel ratio, we must increase our fuel pressure to make up for the 2 injector debt.

Keep in mind that the .042 by-pass is NOS' ideal jet for the .036" N2O jet. So, increasing from that N2O jetting to .040" or .042", we should technically be less than a .042" by-pass to maintain the same ratio (as N2O goes up, fuel pressure must go up which means a smaller by-pass).

So my current jetting is .040" N2O and .042" by-pass. When I go back to the .042" N2O (after I get a clutch), I will probably drop the by-pass to a .036" or .039" jet and may even add a pump.

NOTE: You can not simply continue to increase the pressure in the fuel rail. Too much pressure will cause the injectors to go static, effectively shutting them off. If this happens, you will continue to spray N2O into the cylinders and not have the fuel to match.....a bomb waiting to go off. I would have serious reservations about using a by-pass of about .032" or less and definitely not without an additional fuel pump!

It is difficult to find two people that think the same jetting is the same shot. So, according to NOS Tech, these are the N2O jets and their rated HP.

*  A direct port setup would be much safer for 100HP+ levels.
**NOS Recommended for PGTs.

My fuel pump recommendations are subject to change! I have just installed both a digital Air/Fuel Ratio meter and a digital Fuel Pressure gauge. I have as yet however had time to run the car with NOS at the track to determine A/F ratios and fuel pressure with various jettings. I will report my findings as soon as I get around to it!

Tip #3: Running Rough
If the car runs rough while using NOS there could be some relatively easy fixes for this:
First, make certain that you only use Premium grade gasoline when using N2O (92 octane--NO RACING FUELS OR OCTANE BOOSTERS)
Second, make certain that you have the correct gap in the spark plugs (.035" on mine with no problems). Gapping a little smaller may help if detonation occurs...range from .030-.035.
Third, too high of a spark plug heat range (I use a 6 heat rating and have no problems). A 7 maybe more conducive to the N2O, however.
Fourth, clogged fuel filter. Replace it!
Fifth, too much N2O flowing (no problems with the .042 jet). Smaller jetting is the answer!
Sixth, weak ignition component. Do those Ford/Mazda plug wires or distributor every go bad? :-)

Tip #4: Slipping Clutch
Well, as you may or may not know, the Probe's stock clutch stinks. It barely handles the stock HP/torque and the NOS will simply man-handle it! I got a few days worth of NOS use out of the stock clutch with the .042 N2O jet installed. After that, it was a waste of time. Since I didn't have the $$$ to install a better clutch, I figured a smaller N2O jet would lighten the load on it ($2.50!). I tried a .036 jet first. The clutch hooked up perfectly, but the car seemed much slower than on the .042 jet. After that, I tried a .040 N2O jet. There was very little clutch slip and a lot more pull than the .036 so I stuck it out with this one!

Since trying all of the above jet combinations (fuel pressure tests) I noticed that the 36/42 jetting was much stronger than the 36/59 as I originally tried. The 36/42 is a good option for any PGTers that want to be a little more conservative with the juice.

I have run my best times to-date with the .040 N2O jet and .059 by-pass jet. (13.9x's as opposed to 14.4x's on the .042--how's that for clutch slip?) I haven't run with the new 40/42 setup yet...

Note that recently, even the .040 jet has been giving my stock clutch grief. As of the last time at the track, the flywheel would break loose from the clutch when I sprayed, even if it was fully engaged first! The smaller jet bought me a few months, but it's time for a clutch now....no doubt about it.

More coming....?

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