am i going to run into any problems running 6psi on a S-trim without the FMU for it? i've got 42# injectors and still deciding on fuel pump (racetronix kit, or just a wally hp)

 

The LT1 F-body cars have a pump that is inside a plastic bucket. This bucket in combination with the fuel pump in it is designed to draw fuel from the bottom of the tank via suction. This keeps the bucket full at all times so that when the tank is low on gas and you are doing some hard cornering or acceleration the pump does not run dry and start aerating the fuel. This happens as the fuel sloshes from side to side in the tank leaving the center low on fuel. This can cause detonation and possible engine damage. The bucket also allows the car to operate with lower fuel levels in the tank due to its scavenging effect. The bucket can also effect motor cranking time as the priming time is reduced under certain conditions. The return line from the fuel pressure regulator is diverted back into the bucket via a filter sock inside so that the unused fuel also helps keep the bucket full at all times. Keeping the pump constantly immersed in gas within the bucket can extend the pump’s life by not allowing it to be exposed to open air. Open air within the tank contains moisture and in time will cause the pump to rust / seize up especially if left to sit for long periods of time without the tank topped-up (i.e. winter storage). The Racetronix pump assembly is modified so that it will seal in the bucket’s rubber check-valve so that its function is retained. The Racetronix pump assembly is fitted with a factory style fuel tube not a rubber hose. This hose is important as when the fuel module is placed back in the tank it must pivot which can cause the rubber hose to kink. This fuel tube is much more resistant to the solvents in today’s gas and it will not crack, split, swell and collapse like a rubber hose. The standard Walbro kit comes with a short length of 50PSIA rated rubber hose. The Racetronix fuel module is equipped with a one-piece soldered wiring harness made from mil spec. Teflon/silver wire. This is the same type of wire used at the factory as Teflon is the most resistant to deterioration when exposed to gas. This harness has a Walbro connector at one end and GM pins at the other which fit directly inside the factory connector. Due to the age of the F-LT1 cars much of the in-tank connectors are black / corroded due to age. The Racetronix harness replaces all these questionable components. The standard Walbro kit comes with a plastic coated in-line wiring adapter. This adapter must plug into the existing questionable factory in-tank wiring thereby adding additional connections and length.

If the bucket’s function or any of the other kit’s features are not important to you then a standard GSS307 or GSS340 255L/Hr pump can be retrofit onto the F-LT1 module. The Racetronix kit is not required to get an F-LT1 system running but rather as a better option in order to retain factory functionality and maximize pump performance.

Jack
Racetronix

 

I have been running that same combo except with 38# lucas injectors and the inline t-rex that comes with the vortech. It ran just fine with the 6# blower and even had enough for the cam. I have since went to a Racetronix Walbro 340 (see above haha) and dumped the t-rex and stock fuel pump.

 

I've been running my Trex and 40 lb injectors for quite a while now, no problems other than a bad tune. I'm going to upgrade to a walbro intank and ditch the Trex when I get my stroker built.