I have the fuel pressure isolator mounted on a bracket which in turn is mounted to the firewall of the car. The NHRA book, last year's, says it's O.K. to mount fuel isolators to the firewall, however, I was told, just last week by a fellow racer, it must be removed - nothing on the firewall fuel related. Has the rule changed for this year? Thanks in advance. Len
Len, From 2002 NHRA Rulebook page 194 General Regulations 1:5 Fuel Systems "Location: ... Fuel pressure gauge isolators, with steel braided line, may be mounted on firewall." "...Regulators, cool cans, fuel dist. blocks must all be minimum 6" in front of firewall."
From 2002 NHRA Rulebook page 194 General Regulations 1:5 Fuel Systems "Location: ... Fuel pressure gauge isolators, with steel braided line, may be mounted on firewall." Gary, your the man.... I'm good..now have another question. Using the rule book with a rear mounted battery, i.e., in the trunk, I have the battery sitting in a manufactured tray. The tray is bolted through the trunk to a piece of 1/4 inch aluminum roughly the size of the battery. I also have the J bolts that hold the battery to the battery manufactured tray. I welded closed the J bolts per instructions in the book but the book mentions that they battery rack should be bolted to the frame or ........am I good here? Thanks again. Len
Can't say on that one Len. The book says "frame or frame structure". Sounds like they mean it. Next point: If it's in a 'tray' and not a box: "Rear firewall of .024" steel or .032" aluminum (INCLUDING PACKAGE TRAY) required when battery is located in trunk. In lieu of rear firewall, battery may be located in a sealed steel .024, aluminum .032, or NHRA accepted poly box. If sealed box is used in lieu of rear firewall, box may not be used to secure battery and must be VENTED outside of body." If you're in a tray you need to have the package tray act as firewall with steel or aluminum. ??? Someone else jump in here. All I know is what I get from the book.
good luck on the isolator, mine works horribly; it reads anywhere from 2-5 psi low depending on the day. I think maybe it is sfighting the tension of the diaphragm when under pressure. As a suggestion which I haven't tried yet, put a vacuum on the fuel side to pull the diaphragm a little bit before filling the gauge side with antifreeze.
I never got my isolator to work properly either. Sent it back..... They were trying to say it was working accurately after bleeding but I had another gauge in the engine compartment and it was not. Tried the high pressure isolator....it sucked too. (note: this was over 5 yrs ago) They do have an electric one now...but it's pretty pricey. Bruce BQUICK
