I bought a Autolite fuel pressure regulator a while back. I am wanting to put a NX kit on my car. I wanted a fuel pressure, N20 pressure and an A/F ratio gauge in a gauge pod on the drivers side pillar. A friend of mine said that I cannot have the N20 and fuel line inside the car and still be NHRA legal. I thought that is what the fuel pressure isolator does? Can anyone help me? Do I have to have elec gauges? I always heard mech is the best. Thnx for hepling on such a bonehead question. Also, anyone know where the rules are posted on-line so I can check em out. Thnx again.

 

I know for a fact that you have to have a elec., Fuel pressure guage.

I had a mech. N20 guage in my car. I didn't know they made an elec. guage until a couple of months ago. So I think you are safe with the mech. N20 guage.

 

AutoMeter makes the #5282 high pressure isolator for the mechanical fuel pressure gauges, but from my experience, including a complete diaphragm failure on their earlier #5280 high pressure isolator (subsequently recalled by AutoMeter), I would strongly recommend against using a mechanical fuel pressure gauge inside the passenger compartment. By the time you buy a mechanical gauge, the braided hoses and the high pressure isolator, you are going to be close the the same cost as a totally safe electronic gauge.

As far as the nitrous pressure gauge.... I am not aware of any prohibition by NHRA of a mechanical nitrous pressure gauge insde the car. After all, you can put the entire bottle and supply system inside the passenger compartment, at long as it has the pressure relief vented to the outside. The mechanical nitrous pressure gauges come with a "restrictor" fitting that mounts to the connection off the main nitrous line, and prevents excessive nitrous flow into the passenger compartment in the event of a gauge or line failure. The nitrous is not harmful in small quantities and is not flammable. The only thing you don't want to do is have a flow high enough to displace all the oxygen in the compartment, or cause a "cloud" you can't see through due to the autocooling of the nitrous phase change.

 

Are the elec gauges as accurate as the mech gauges?

 

AutoMeter says yes, Stewart Warner says no. Take your pick.