Project Fox Big Block Budget Fuel System From Russell - Feed Me, Feed Me!
Project Fox's Thirsty 532 Big-Block Gets Fed With A Budget 1,000hp Fuel System From Russell.
From the April, 2010 issue of Popular Hot Rodding
By Stephen Kim
Photography by Stephen Kim
The snowball is rolling, and poised to bury you in an avalanche of debt. But fear not, for exercising a few wise decisions and plotting out your battle plan in advance is all it takes to prevent your budget-built project car from mutating into an oxymoron. As our foray into the promised land of single-digit e.t.'s continues to progress, it came time to plumb up a fuel system for Project Fox's 532. Peering out in misery from between the shock towers like Robert Downey Jr. gazing out the window of a Malibu rehab facility, the 775hp big-block was begging for a hit of some tasty 93-octane brewski. Although feeding a motor with such a voracious appetite can get quite costly, we managed to pull off the feat for $804, thanks to a dollar-stretching turnkey fuel system from Russell Performance.
Fuel filters must be carefully...
Fuel filters must be carefully matched to the pump, as any restriction they impose will reduce pump performance. Russell's 8.25- inch inline filter is more than up to the task. It features an anodized aluminum housing, and a replaceable 60-micron nylon filter element.
While budget-priced high-performance hardware is certainly part of the equation, we could have easily spent four times as much money on a fuel system had we stuck with EFI on our '93 Mustang. The 52 lb/hr injectors necessary to fuel nearly 800 hp would have gobbled up two-thirds of our entire $804 budget. Furthermore, the stand-alone engine management system, wiring harness, mondo throttle body, and custom intake manifold mods necessary to run EFI could easily ring up another $3,000. Since plans call for running at either idle or wide-open throttle-and not much in between-who gives a hoot about the driveability advantages of EFI? The comprehensive Russell fuel system (PN 641523) includes a monster 160-gph electric pump, 20 feet of -8AN hose, an inline filter, hose clamps, all necessary fittings and wiring, a pressure regulator, and a fuel pressure gauge.
The Edelbrock pressure regulator...
The Edelbrock pressure regulator included with the Russell kit is adjustable from 5-10 psi by turning the adjustment screw located at the top of the unit. In addition to a gauge port, the regulator has two outlet ports, making it compatible with both single- and dual-feed-style carburetor logs.
Keeping things simple and cheap has been the underlying theme of Project Fox since the beginning, and we decided to skip on the mini-tubs while the chassis was under construction. Larger wheel tubs usually require installing either a narrower gas tank or mounting a fuel cell in the trunk, neither of which are appealing in a dual-role street/strip car. Fortunately, with the luxury of being able to retain the stock fuel tank, there's still plenty of room in the trunk to stash fat bags of cash hustled off unassuming victims on cruise night. Or so we've heard.
At the risk of sounding obsessive-compulsive, we have to give a huge thanks to the folks at Bill Buck Race Cars once again for pulling an all-nighter this time around. With Project Fox now plumbed up, all it needs is a cooling system, exhaust, and an interior rehab before it's ready for action.
Russell offers a choice of...
Russell offers a choice of either blue and red hose ends, or black and silver pieces. For a low-key appearance, we opted for the latter. Included in our bundled system were three straight ends, three 90-degree ends, and one 45-degree end.
To ensure proper fitment in...
To ensure proper fitment in a wide range of applications, Russell offers fuel logs for both Holley and Edebrock/Carter carburetors in braided steel or nylon. Carb inlets with an integrated fuel filter are also available.
To convert our Mustang's stock...
To convert our Mustang's stock EFI tank for carbureted duty, we ordered a fuel sump from Competition Engineering. It features dual 1/2-inch NPT female fittings. To channel fuel from the sump to the pump, we attached a -8AN 90-degree hose end to the sump with a 1/2 to -8AN pipe adapter fitting. Since our system doesn't use a return line, the other end of the sump was capped off.
The first step in installing...
The first step in installing a fuel sump is draining the fuel tank. Unless all traces of oxygen are removed from the tank, there may be residual fuel in a vaporized state that could potentially create a nasty explosion when the welder fires up. To prevent this, Buck purges the tank thoroughly with Argon gas. With the prep work out of the way, after centering the sump on the backside of the fuel tank, Buck traced around the sump with a marker, cut out a hole, then TIG-welded the sump in place. It's much easier to check for leaks before the tank is re-installed on the car. Since they won't affect flow in any way, we left the stock sending unit in place, and capped off the hard lines. The factory vent is always retained.
Fuel pumps should be positioned...
Fuel pumps should be positioned at or below the height of the sump. The drawback of running a stock tank instead of a trunk-mounted cell is that it requires dropping the pump down closer to the ground. To accomplish this, Buck mounted the pump on a custom bracket made of 1/8-inch steel plate, which was first welded to the Mustang's framerail. To prevent gunk from ruining the fuel pump's internals, Russell recommends installing the filter between the tank and the pump. The pump's compact size allowed us to position it parallel to the side of the car, and connect the filter directly to it at a 90-degree angle.
Although it may cut down on...
Although it may cut down on mobility underneath the car, it makes sense to route the fuel lines with the wheels, tires, and all suspension components installed. This makes it much easier to spot potential interference issues with moving parts. After angling the feed line upward using a 45-degree hose end on the pump outlet, we routed it along the passenger-side framerail, and inboard the spring/shock assembly, to clear the rearend and control arms using the supplied cushioned clamps.
With the rearend cleared,...
With the rearend cleared, the feed line was positioned just outboard of the passenger-side subframe connector. There is no set rule on where the clamps should be placed, but positioning them 10-12 inches apart is close enough to get rid of slop and free-play.
Some people prefer routing...
Some people prefer routing fuel lines into the engine compartment through the trans tunnel, but even with a scattershield, we felt it was safer to go up through the fenderwell instead. With the stock plastic liner removed, we found an existing hole sized just right for our -8AN hose. Before clamping the hose down inside the fender, it's a good idea to turn the front wheels from lock to lock to check for interference.
As a general rule of thumb,...
As a general rule of thumb, it's best to mount the regulator as close to the carb inlet as possible. We found a suitable location on the passenger side of the firewall, right behind the shock tower. Before mounting it up, we attached a pressure gauge to its 1/8-inch NPT port.
Since we're using a single-feed...
Since we're using a single-feed fuel log, we blocked off one of the outlets on the pressure regulator, then attached two 3/8-inch to -8AN adapter fittings onto the remaining ports. We don't anticipate the motor moving around much under load since it's attached to the K-frame with solid mounts, so the feed line has just enough slack in it to allow easy removal of the valve cover.
The main supply line was fed...
The main supply line was fed through the fenderwell, then attached to the regulator with a 90-degree hose end. While it's true that hard-90s should only be used when no other hose end will get the job done, they don't hurt flow much at all. According to Russell, if 90-degree turns were so detrimental, no one would make 90-degree fittings. The truth of the matter is that 90-degree hose ends are produced in massive quantities because they're an essential component of almost every fuel system.
Cold temperature makes the...
Cold temperature makes the fuel log stiff, which makes it difficult to attach the inlet fittings to the fuel bowls. An easy solution is to remove both carb inlet fittings from the fuel log, and then attach them to the fuel bowls. Since the fuel log has -AN fittings, it's much easier to thread them onto the carb inlet fittings after they have already been attached to the fuel bows.
In theory, keeping the fuel...
In theory, keeping the fuel lines as short as possible reduces the load placed upon the pump. The most obvious benefit is that it makes for a clean, clutter-free install. The final step in installing a fuel system would usually be wiring it up, but the electrical system in Project Fox hasn't been buttoned up just yet. Nonetheless, hooking the Edelbrock pump up is as easy as wiring the supplied relay to a switched ignition source.
How Much Pump?
Russell's comprehensive fuel...
Russell's comprehensive fuel system includes every nut, bolt, clamp, fitting, and wire necessary to route fuel from the tank to the carburetor. No impromptu trips to the hardware store! The system is offered with either a 120-gph pump that supports up to 480 hp for $615 (PN 641593), or with a 160-gph pump that's good for over 1,000 hp for $740 (PN 641523).
Determining how large of a fuel pump a motor requires is contingent upon power output, brake specific fuel consumption, and target fuel pressure. The BSFC of most naturally aspirated motors ranges from .400-.500 lb/hr (per horsepower), while forced induction applications vary from .600-.650 lb/hr. We know from prior dyno testing that Project Fox's 532 big-block burns between .400- and .450 lb/hr of fuel while cranking out 775 hp. Furthermore, like most carbureted motors, it operates at 6-7 psi of line pressure. Using this info, all it takes is some simple math to calculate the fuel volume necessary to feed this thirsty mill. Since motors are far less forgiving of lean air/fuel mixtures than rich mixtures, it's good practice to add a safety margin of 10 percent to the BSFC figure. Thus, multiplying our big-block's 775 hp by a conservative BSFC of .500 yields a fuel volume requirement of 387.5 lb/hr of fuel.
Like most fuel pumps on the market, the advertised 160-gph rating of the Edelbrock pump included in our Russell kit represents its performance under free-flow conditions. That rating drops to 80 gph at 6.5 psi. Nonetheless, it still flows more than enough fuel for our application. Since gasoline weighs roughly 6 pounds per gallon, the Edelbrock pump's 80 gph rating equates to 480 lb/hr of flow. Even with our safety factor of 10 percent, this beast of a pump flows 20 percent more fuel than our big-block demands. In fact, the pump's output can feed 960 naturally aspirated horsepower, even while assuming a super-conservative BSFC of .500 lb/hr. Using a more realistic BSFC figure of .450 lb/hr, the Edelbrock pump is good for 1,066 hp.
The Edelbrock pump included...
The Edelbrock pump included in the Russell kit isn't just impressive for its flow rate, but also for its lack of size. Compared to other pumps on the market that move a similar volume of fuel, it's roughly 33 percent smaller. The slick black anodized housing conceals composite rotors and carbon-fiber vanes that provide greater durability, and reduced friction and wear. Edelbrock says its pumps are 4 to 14 decibels quieter than comparable units.
As with most carbureted fuel systems, we opted to run a deadhead-style pressure regulator and forego the return line option. Although return lines are most often associated with EFI, there is a time and place to run them, even in a low-psi carbureted application. In extreme situations, the constant recycling of fuel from the tank, to the motor, and back to the tank decreases the potential for overheating the fuel. Return-style systems also respond more quickly to changing fuel demands, which means that the carb's fuel bowls will stay full a greater percentage of the time. Nevertheless, many of the biggest and baddest carbureted motors around run just fine without a return line. For the sake of keeping things simple and cheap, Project Fox will make do with a more common deadhead-style system. Should the need arise, however, converting to a return-style fuel system is as easy as swapping in a bypass regulator, and plumbing a return line from it to the tank.
The 20 feet of -8AN hose supplied...
The 20 feet of -8AN hose supplied with the Russell system is more than enough to reach from the tank to the carb. It's offered in both stainless and nylon-braided hose that's rated at 350 psi of pressure. This extremely durable and abrasion-resistant hose is also compatible with oil and coolant.
Different brands of fuel hoses have different flow rates, as two hoses with identical outside diameters don't necessarily have the same inside diameter. Consequently, it's difficult to generalize how large of a fuel line a given application requires based on horsepower alone. After selecting a fuel pump that provides adequate flow for an engine's needs, it's simply a matter of matching up the size of the fuel supply line with the same size fittings a manufacturer supplies with the pump. That's because pump manufacturers conduct exhaustive testing to determine the proper inlet and outlet sizes that work best with the flow characteristics of their pumps. According to Russell, using a feed line larger than the size of the pump outlet won't necessarily improve flow. High-pressure EFI motors can get away with running a feed line that's one size (1/8-inch) smaller than the pump outlet, but when factoring in the negligible cost savings in doing so, it make no sense at all.
This same rule of thumb applies to the fuel supply line (from the tank to pump inlet) as well, but with one exception. The only time when it might be beneficial to run a slightly larger supply line is when the pump inlet has an NPT port. In such a scenario, Russell suggests using a supply line that's one size larger than the port inlet. For instance, if a fuel pump has a 3/8-inch NPT inlet port, it's advisable to run a 1/2-inch (-8AN) supply line.
|WHERE THE MONEY WENT
|Russell fuel system
|Comp Engineering fuel sump
|THE COST SO FAR
|'93 notchback Mustang
|Sold old wheels, tires, engine, trans
|532 big-block Ford
|Phoenix Turbo 400 trans
|Strange 8.8 rearend
|Comp Engineering rear suspension
|AJE front suspension
|Bill Buck custom 10-point cage
|Engine and trans install
|Russell fuel system