We used a simple fuel pressure gauge with a peak hold needle to record our highest fuel pressure value from a run. The gauge is an all stainless, bottom 1/4NPT pipe, glycerin filled gauge with a maximum indicating needle. Glycerin filling is needed to dampen the needles from racer vibrations. Stainless is needed for resistance to the corrosive alcohol & nitro that we were running. The face was standard with lexan or composite. A glass face should be avoided due to cracking susceptibility. Either a rear fitting or a bottom fitting are available.
Installation on Blown Alcohol/Nitro Racing Engine
It was installed on the fuel injection distribution block after the metering valve. The gauge worked very well recording our fuel pressure values of 130 to 150 psi. This pressure location is after the barrel valve. As a result, part throttle fuel pressure spikes that occur before the barrel valve are ignored.
Our most recent fuel pressure gauge purchase was a Noshok 25-510-300-MIP. It was purchased from a local Noshok distributor. The Noshok corporate phone number is (440) 243-0888 to find a local distributor. Other gauge manufacturers are:
1. McMaster-Carr model 3842K717. We am not sure that P/N has all the features. Phone number; (330) 342-6100
2. Wika, Lawrenceville, GA (770) 513-8200 http://www.wika.com
3. Chicago Stainless 2N-6-1/4NPT-GF-BT. Again we am not sure that P/N has all the features. Phone number: (800) 927-8575
4. Reptech, Cato Western, Inc. (800) 822-0804
Fuel Pressure Peak Recording Needle
The extra needle to store the peak value after a run is called different names from the different manufacturers: maximum indicating needle, maximum pressure register, tattle-tale indicator or needle, drag follower or pointer.
The gauge scale can be specified from any of these suppliers. A 0-300 scale was chosen for our FI application. That scale puts our 150 psi target reading in the middle of the scale, that is the most accurate and repeatable reading range of the gauge.
Cost & Delivery
Around $100 to $150 USD. They all have to be built from a pre-order, taking 1 to 3 weeks. No one had them in stock when we ordered our gauge.
Pressure Gauge + Check Valve Alternative
For blower boost monitoring, we installed an Autometer boost measuring kit. It uses a lower cost gauge with a check valve to hold the highest reading. Circle Seal Controls (951) 270-6200 http://www.circle-seal.com makes the check valve used in this kit. It is the 2200 series, available in various sizes. The check valve can leak in time. We always carried a spare for our boost gauge. We considered switching over to one of the gauges with peak indicator needle for boost reading, but this setup with the check valve worked fine for many years.