Data: Stock Style Fuel System Limitations

Rick 91GT

Mustang Master
Nov 29, 1999
I see this topic brought up a lot and thought I would share some recent real world data straight off the dyno.

331, AFR 185, spyder intake, v2sq 2.85" pulley, 6.87" lower.

Stock fuel lines
-8 feed from stock hardline to Edelbrock fuel rails
-6 return to stock hard line
Gs340 high pressure 255lph with vortech t Rex inline
60lb inj

5000rpm car went violently lean...550rwhp

Replaced trex with gsl392 255lph inline
6300rpm car goes to 13.5:1 and steadily goes leaner ....604rwhp

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I have to wonder if that T-Rex is slowing fuel volume down a bit.

Aren't those things designed to help the in-tank pump keep flow up at elevated pressures (say, an FMU)?

At regular pressures, I have to wonder if the in-line pump might hinder the ability to flow all the volume demanded by that combo and 60 lb injectors.