Pumps do not produce pressure; they produce flow. Restricting the flow of a pump creates pressure. The greater the restriction of flow, the greater the pressure up to the point where flow ceases altogether. The definition of a system means a group of interacting, interrelated, or interdependent elements forming a complex whole.

A nitrous system has more than one restriction besides the actual jet(s). The solenoid is one of the restrictions. The jets in a nitrous system are a metering device and way for the tuner to restrict or un-restrict flow. They’re not the only restriction to flow. A flow path has pressure drop from Point "A" to Point "B". The actual fuel jet your using out of your plate system will flow more fuel and have less pressure drop than the same jet does in the flow path of the nitrous system.

Here is an experiment you can try: Put a Fuel pressure gauge close to the inlet of your fuel solenoid and put your plate in a bucket and activate the fuel side of the system and let it flow fuel into the bucket with a .110 jet. Observe the reading on the pressure gauge and leave the pressure set right there. Then take the .110 fuel jet out of the plate and put it into your Flow tool and flow the fuel again. You will notice the fuel pressure will drop without changing the regulator setting with the actual fuel jet in the flow tool. The reason is the .110-inch fuel jet flowing in the flow tool does not have all the restrictions that the fuel enrichment side of your nitrous system does.

A Holley #70 Jet or its equivalent .073-inch Flare jet will have the same PSI reading on the gauge in the Flow tool as it does when you flow the actual plate into a bucket with whatever jet you choose. The Holley #70 Jet/. 073-inch Flare jet approximates the same amount of restriction/pressure drop and pressure range the nitrous system operates at on all of the jet settings.

You can use the "Area" method/ "Fuel jet" way of flowing your Nitrous systems fuel side. Although since the fuel jet will have less restriction through the flow tool the Nitrous system fuel side will actually have 1/2-3/4 of a PSI more fuel pressure through the plate/ nozzles than what your reading on the Flow tool's gauge by using this method of flowing the fuel pressure. If you flow your fuel pressure this way it causes you to “chase your tail” every time you change settings with your nitrous system. This does not provide consistent results and makes it harder to establish a good Tune-up. I am not trying to tell you there is not anyone going fast that tunes their nitrous system this way. What I am telling you is they are doing it the wrong way and it took them MUCH longer to get their car sorted out than it would have if they would have been setting their fuel pressure the correct way.

There is a lot of Nitrous Experts online everyday out there that give out a lot of bad information. Which that is shameful because all that does is make using nitrous harder for the novice sportsman that is taking what these “experts” say as the gospel. There are some that even have a program on their website’s that calculates the Flow jet orifice diameter and there are also some that sale flow tools that recommend the area method of flowing the fuel pressure. This only serves to document their lack of knowledge in regards to Nitrous Oxide Injection and racing with nitrous oxide

I hope this helps you understand.
Have a Great Season!
Robert Lane