Are you ready for the new 2011 Spec Miata rules regarding open timing and fuel pressure on all cars? You're going to need a fuel pressure regulator to start with, and the AEM unit we have is a good start, although you will have to do some custom plumbing. We have not developed a car with this yet as the rules are still not yet inked in the rule books, but we would suggest getting things dialed in before January!

The AEM universal adjustable regulator bolts directly to any high volume fuel rail. It is CNC machined from 6061 T-6 aluminum. The fuel outlet and inlet ports are tapped to 9/16-18 thread, which allows the use of several different hoses. The vacuum reference is 1:1 ratio so for every pound of boost on a turbocharged or supercharged application yields a 1-pound rise in fuel pressure. The range of adjustability is from 20 PSI to the maximum the fuel pump can deliver. A unique feature of the AEM adjustable pressure regulator is that the discharge port in the regulator is changeable. This allows the user to tailor the regulator return volume to match their fuel pump. A common problem that occurs when using a fixed orifice in a “universal” regulator is that the fuel pressure cannot be effectively controlled when the fuel pump volume is significantly higher than stock. In the case of too small of a discharge orifice, there is a large pressure spike associated with rapid deceleration because the orifice cannot flow enough fuel when the diaphragm is fully deflected to the open position. This causes a momentary rich condition, which may lead to a rough idle quality until the pressure stabilizes. Conversely if the discharge orifice is too large the adjustment is difficult because the response of the fuel flow out of the orifice is too rapid which makes the adjustment screw too sensitive. The AEM regulator is packaged with three orifice sizes, .100”, .150” and .200”. They are easily changed by removing the diaphragm and simply unscrewing the orifice and replacing it with the desired size orifice. The size range provided with the kit is enough to cover any pump from a stock Honda pump to the largest after-market pump available. The replaceable orifices are color coded for easy identification.