Checked Out According to...
Checked Out
According to Zex's Matt Patrick, getting the fuel pressure set correctly is crucial to optimal performance and longevity when it comes to running any carbureted nitrous-plate system. As to the proper way to set fuel pressure, Patrick recommends checking out Zex's fuel-flow check tool. The tool temporarily attaches to the fuel solenoid's feed line, so you can simulate the normal fuel flow the nitrous kit will see when it's activated. Once the fuel system is in the "flowing" mode, you can then check and set fuel pressure to the correct level.
Cracked Wide Open
Once we had the kit on and everything was double-checked for proper connections, power, and leaks, we strapped the Mustang to the DynoJet chassis dyno and let her sing. Our first dyno run was aborted due to the fact that the air/fuel ratio was in the toilet. With the meter reading 10:1, we knew the engine was running way rich. Wanting to stay on the conservative side, we made a small jet change, swapping out the 76 primary and 82 secondary jets for 72s in the front and 76s in the rear. The result was a 330-rwhp hit, with the torque figure coming in at 323 lb-ft-not bad for a small little 306ci naturally aspirated motor.
We then jetted the nitrous kit for a 100hp shot of the sauce, and pulled the timing back from the N/A setting of 40 degrees to 36. Once everything was in order, the Mustang was fired up, and we ran the engine up to 7,800 rpm, this time on the bottle. The result was 410 rwhp and 435 rwtq, but realizing the bottle pressure was low (900 psi), we knew there was more power to be had if we could get the bottle pressure up. After letting the bottle sit in a tub of hot water for a few minutes, the pressure was at an ideal 1,050 psi. Once the bottle was installed and the feed line was hooked back up, we cracked the bottle open, planted the right pedal to the firewall, and realized a 429-rwhp and 501-rwtq dyno pull.
Thanks to the Zex nitrous kit, the Mustang safely made almost 100 hp more than it did naturally aspirated, while cranking out a stump-pulling 500 lb-ft at the same time. Mission accomplished.
We had to set the fuel pressure...
We had to set the fuel pressure for the nitrous system, and did so by turning the key, activating the electric fuel pump, and flowing fuel into a plastic bottle while we set the fuel pressure to 6 psi.
With the nitrous spraying...
With the nitrous spraying and the engine singing at full throttle, the little 306 pumped out 429 rwhp and 501 lb-ft of torque at the wheels. That's an increase of 100 hp and 178 lb-ft of torque. After changing the carb jets on the baseline pull to remedy a rich condition, the engine was living happily in the 12:1 air/fuel ratio range.
You can see how the nitrous...
You can see how the nitrous required us to start the dyno run a bit higher in the rpm range to avoid the possibility of blowing the carb off the top of the engine. Even so, the graph speaks for itself.