Fuel Delivery for 700hp and beyond, ditching the FMU.
Fuel Delivery Introduction Fuel Delivery for 600 hp Fuel Delivery for 1000hp
When the LT1-Edit software became available, I decided to tinker with the fuel delivery system again. Since the plan was to ditch the FMU, the first change was to replace the high pressure SX 18201 pump with the Granatelli shown in the 2 pix below. The next change, which was made once the LT1-Edit software was in hand, was to replace the 30 lb/hr Bosch injectors with 50 lb/hr MSD squirters.
The more challenging part of this revision was replacing the FMU with a Paxton regulator. I have had ongoing problems with the fuel getting hot and then passing that heat to the pump, which generally complained by howling loudly. The Paxton regulator gave me the option of sending unneeded fuel back to the tank without first passing through the fuel rail, where it picks up engine heat. The pix below detail the routing scheme I used.
Those of you who read this page before June '01 will realize that I've changed the fuel system again, this time because the previous routing made the TH400 bellhousing bolts almost impossible to get to. This provided the excuse and motivation to "fix" other parts of the system that were less than pleasing. Like moving the downstream 10 micron filter (there is a 60 micron filter in front of the pump, and a 10 micron after) from under the rear seat to behind the rear seat as shown below left. The new lines that run under the car are located closer to the bottom of the tranny tunnel than before. The black line seen in the center and right-hand pic is the new TH400 shifter cable. The larger supply tube is 1/2" aluminum, while the smaller return line is 3/8" aluminum. The supply tube connects with the stuff described in the next paragraph with AN tube nuts and sleeves from Earls. The return line also uses Earls tube nuts and sleeves to connect to a -6 AN hose coming from the bottom of the regulator as seen in the underhood shots.
The 3 pix lined up below are 3 different views of the -8 AN hose plus 1/2" aluminum tube supply side combo that runs from the fitting chain shown above (its the lower line in the pix) to the inlet of the regulator. The tubing is bent to wrap around the steering column where it pokes through the firewall. The -6 return line shown above right is nearly a straight shot from the fitting chain (near right edge of the right hand pic) to the return outlet on the bottom of the regulator. The bottom left pic shows the new fuel rail inlet made from 1/2" aluminum tubing and some AN fittings. Obviously, it feeds both rails in parallel - there is no outlet from either rail. What used to serve as a crossover tube now just maintains balance between the rails.
BTW, yes, I bent all this junk myself. <pats self on back>
Some have asked about using the Paxton regulator in a "flow through" configuration like this, which "deadheads" the fuel rails. The bottom right pic shows 3 ways that the regulator can be plumbed into the system. I chose "Figure 1" for the reasons stated in the second paragraph above.
The 3 shots below attempt to show the new stuff as installed. For now the regulator is only supported by the fuel lines. Because of engine movement, and the lack of slack, I can't attach it to the firewall. "Someday" I'll build a bracket to attach it to the cylinder head.
The last 3 pix show the two heat shields I made from sheet aluminum with heat reflective material from Racer Wholesale glued on. The Vortech Aftercooler sits on the heat shield shown below right. Another thing seen in these pix is the brake line rerouting work I did to clear the Aftercooler. The line for the front brakes goes to the out-of-focus line lock solenoid seen in the lower right corner of the left pic.
