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Stealthy Option

Stealthy Option

July 2010

By Kev Elliott

Plumbing the purple pig with an Aeromotive Stealth Fuel System


OK, so you've looked at the pictures and are wondering why I have what looks like a race car fuel system in my custom. And it's a valid point, as the Aeromotive tank, filter, and fuel log sure look like race parts, and indeed can be found on many race cars. Aeromotive is a major supplier of fuel system components for many drag race teams, as well as OE suppliers for the current Cobra Jet Mustang.

For starters, I needed a complete system, as my stock tank had already been repaired once and no longer had fuel gauge provisions. And, considering how rusty the car was when I bought it, I felt safer replacing the stock fuel lines from front to rear. Seeing as I'd gone a little beyond my original plans with the Smeding 383 stroker motor, I wanted a system that was capable of delivering enough fuel to feed the 400-plus horsepower engine. I also wanted to incorporate a return line should I ever decide to swap out the carburetor for fuel injection. After all, if I'm going to the trouble of fitting a complete fuel system, why not do the job just once, and incorporate the capability to handle whatever may happen in the future? With the Aeromotive system, I'm confident that I'll never run it to its maximum potential of 1,000-plus horsepower capability, but I can also be confident that I won't lean out the motor either, no matter what I do to the engine farther down the road.

However, Aeromotive products are not just for race cars, indeed they offer multiple options for street rods and muscle cars and even a couple of "universal hot rod systems" for late-model EFI or crate engine swaps, with inline pumps, filters, and regulators, as well as Stealth fuel systems. The first type of these uses a fuel pump completely submersed in a baffled fuel tank sump box, which can be welded into almost any existing fuel tank. It is this system our sister magazine STREET RODDER used in their '52 Chevy Road Tour car last year. Aeromotive also offers an aluminum fuel cell in the Stealth series, which again features an in-tank pump. In this case, it's the company's A1000 pump, which is probably their most versatile fuel pump (ideal for 200hp carbureted engines all the way to l,000hp EFI engines) and claimed to be the most durable of its kind. The Eliminator pump is also available in this cell, though it's bigger and unnecessary for my application, as a smaller pump for lower horsepower applications will be available soon, which will be a non-billet, pump more akin to what you'd find in an OEM application.

So what's so good about placing the pump inside the fuel tank? Advantages include cooler temps and dramatically reduced pump noise, ideal fuel pump environment, and a reduction in installation time, not to mention the Stealth cells eliminate the risk of fuel pump cavitation, owing to hard cornering, launching, or braking thanks to innovative baffling. There's a reason the OEMs have been using in-tank pumps for a couple of decades! The Stealth cells are compatible with carburetors or EFI, so long as the correct regulator is selected.

For my application, Aeromotive recommended their 13204 Carbureted Bypass Regulator, designed specifically to be used with the A1000 or Eliminator pump in a carbureted application. It is capable of adjusting the base fuel pressure from 3-15 psi, and features an AN-10 inlet port and -8 return port, with two -6 outlet ports and a 1/8-inch NPT gauge port. Pressure isn't provided by the fuel pump, but rather by the regulator restricting the volume flowing through the pump, thereby driving the pressure up to a set point. With a bypass regulator, once the pump has created enough pressure to open the regulator bypass, the regulator leaks just enough flow to maintain the desired pressure. The regulator requires some flow through the unit while pressure is being adjusted, and the correct method to set pressure is with the pump on and the engine running.

It should also be mentioned that Aeromotive offers a fuel pump speed controller. This is mainly required by EFI systems with an inline pump rather than an in-tank version, which can help prevent cavitation and vaporization caused by low pressure in the pre-pump plumbing, caused when the constantly re-circulating fuel becomes hot after running through the engine bay and back to the tank a few times. Given that 8 gallons of fuel will re-circulate every three minutes, you can see how heat can build up. Activated by a signal from the tachometer, the speed controller will reduce pump speed at lower rpm; ramping up to full speed at 2,500 rpm. However, unless the car will sit idling for hours, the controller is not required with a fuel cell system, which eliminates the pre-pump plumbing and associated low-pressure issues.

If you're a regular reader you'll already have seen the dropped trunk floor I fabricated to house the fuel cell and RideTech compressor and pump for the air suspension. The remainder of the installation involved drilling holes to route the braided fuel lines through the floor, fabricating a mount for the fuel filter on the righthand chassis rail, and mounting the regulator to the firewall. Actually, there was a little more to it than that, as I chose to run rigid stainless for both the feed and return lines rather than run braided hose front to rear. The hardest part of the install was figuring out the plumbing and the fittings needed, and I resorted to drawing the system out on a large sheet of cardboard to make sure I got it right. This may sound lame, but considering the number of fittings required to switch from braided to hard line, and in and out of the various components, it worked out the best way for me.

I was also trying to figure out how to run the Aeromotive fuel log in a "full-flow" manner. But given its physical size and the location of my A/C compressor, it didn't work out, no matter how I tried. I even ordered special Fragola banjo fittings from Summit Racing in the hope they'd clear the compressor, but to no avail. I eventually resigned to run a semi-"dead head" system, whereby the fuel passes through the regulator to the fuel log, which is blanked off at the forward end, the return line to the tank running back from the regulator. By comparison, the "full-flow" system involves the fuel entering the front of the log, with the regulator actually attached to the rear of the log rather than the firewall, and with the return line again running from the regulator. Speaking to the guys at Aeromotive, though the full-flow system is what they usually recommend, I was assured the alternative was perfectly adequate for a street application. Let's face it, it's what we've all seen many, many times before on street cars with more power than my Chevy, and that's without a return line.

Once I got my head around the layout of the system-thanks to my cardboard diagram-and worked out the routing of the hoses and hard lines, the complete system was a breeze to fit and I really liked the simplicity of the pumpin- tank method. Not only does the fuel system look good, I know it'll handle whatever I throw at in the future, and am excited that the project is one major step closer to completion.

1. The two big boxes from Kansas where Aeromotive is based-contained the Stealth fuel cell, enough braided hose to run the feed and return lines, a fuel filter, regulator, fuel log, filter mount, and fittings. However, as I opted to run hard line, I had to order extra fittings in addition to those supplied.


2. Placing the fuel log, filter, and regulator on a piece of cardboard, I planned the semi-ìdead headî system and worked out the extra fittings I'd need in order to use the hard line for the long chassis runs. The regulator is shown plumbed incorrectly here, but the number of fittings is the same, though I used a 90-degree hose end on the regulator inlet eventually.


3. For the hard line I went to Classic Tube, who supplied three 6-footlengths of 1/2-inch stainless steel tubing. This has on inside diameter of 7/16-inch and accepts AN-8 fittings. Though harder to bend than regular steel lines, stainless can still be bent by hand so long as you have the correct bending tool.


4. When using AN fittings on fuel systems, the flare required is 37 degrees, and not the 45 degrees for brake lines. It's also a single flare, not a double flare. A special 37 -degree flaring tool is required, this version having a trick clutch setup so the tool can't be over lightened, producing a perfect flare every time.


5. Here's the completed flare with tube nuts and sleeves sourced from Summit Racing. While most Summit fittings are shown in their catalog in the usual blue and red colors, if you check you'll notice most are also available in black, with a ì-Bî after the regular part number. I managed to plumb my entire system using black fittings from three suppliers.


6. An alternative to using tube nuts and sleeves, as well as not requiring the tubing to be flared, would be to use these compression-style Summit fuel line adaptors, except they're designed for aluminum fuel line, not the much-harder stainless, so are unsuitable for this application, especially given its high-pressure operation.


7. I needed a method of attaching my bent and flared stainless lines to the chassis, and what better than stainless line clamps from Kugel Komponents? Available in a number of different sizes from 3/16 to 7/8 inch, as well as in single or double clamp design, I used 1/2 and 5/8 inch in both single and double variants.


8. The double 1/2-inch Kugel clamps worked perfectly to attach the hard lines to the framerails. The upper tube is the feed line while the lower is the return.


9. I mounted the Aeromotive fuel filter inside the lefthand chassis rail, fabricating a small bracket and welding it to the top of the 'rail as the aluminum mount protruded above it. These filters feature a replaceable 10-micron fabric element. Aeromotive recommends running the system for a couple hundred miles then replacing the element, as the fuel system should never be dirtier than when first installed, owing to initial debris in the lines, then routine replacement annually or at 10,000-mile intervals. These filters flow 2,000 pounds per hour with a pressure drop of less than 1 psi and measure 5 1/2 x 2 inches. They also feature ORB-10 ports (more on this later), with fittings available to adapt to AN -10, -8, and -6 line sizes.


10. The fuel lines are again clamped to the chassis at the point where the floorpan joins the toeboard, the lines following this angle upward. The lower, return line was bent to run directly above the feed line. If you're wondering why they cross over at this point, all is about to be explained.


11. I removed the front dip again for easier access, which also made taking this picture possible. The return line goes into the bottom of the regulator, mounted on the firewall, while the feed line goes into the front part via a 90-degree filling. By crossing the hard lines over, they run neatly to their destinations. While there should be no movement between the chassis and body, it's still wise to use flexible braided hose here. I'll fabricate a mount to secure the ends of the hard line.


12. The mention of braided hose brings us to the joyous task of fitting hose ends. Wrapping the braided hose with electrical tape while cutting it to length with a cutoff wheel means the braided covering doesn't fray during the process.


13. If you've ever fitted ends to braided hose you'll know the pain of stabbed and bleeding fingers from the frayed braiding. Well, suffer no more! Thanks to this neat gizmo from Koul Tools you'll never stab yourself again. I sourced this from Speedway Motors by the way, along with the adjustable aluminum AN wrench.


14. With the fitting placed in the appropriately sized Koul Tool (which comprises two halves that press together with the hose end as shown), you can see how it creates a funnel-line orifice into which the hose is pushed


15. With the two halves together and placed in a vise, and the electrical tope removed from the end of the hose, a little grease is dabbed on the tool entrance, and the braided hose twisted into the fitting until it won't go any further.


16. The tool is then removed from the vise, split apart, and the hose and filling removed. The orange spacer is used to ensure the fitting is butted up to the opposite end of the tool, and can be placed in various slots to accommodate fittings of various lengths.


17. Though holding fixtures are available to prevent damaging the anodizing and the fittings themselves, I didn't have any so I used more tape in the vise as protection. The second part of the fitting con now be inserted, again with a little grease. The tapered part goes into the rubber hose inside the braiding, and the threaded part threads into the female part of the fitting.


18. The fitting is now assembled, until the thread won't turn any more. The hose end is now secure and ready for use. I used an air line to blow any debris out of each hose once the ends were fitted. You'd be surprised how many small rubber particles are exhausted!


19. I mentioned ORB parts when discussing the filter. The fuel cell outlet, filter, regulator, and fuel log all use these (ORB is an abbreviation for O-ring Boss). The components have a groove around the part, for which fittings such as these, equipped with O-rings, are required, making a secure seal. On the left is a-6 fitting for the regulator, with the larger fitting on the right required for the fuel log. A similarly O-ring-equipped blanking plug is used at the other end of the log on my system.


20. I had hoped to be able to run a full-flow system (gas entering one end of the fuel log with the return line to the tank exiting the other end) by using these banjo fittings from Fragoloa to clear the A/C compressor, but there simply wasn't enough clearance. Of course the compressor could be re-mounted, but I'd already run the A/C hoses and didn't want to take a step backward. However, these banjo fittings are way shorter than an ORB adaptor and regular 90-degree fitting if you find yourself in a similar tight situation. The Fragolo line is carried by Summit Racing.


21. From this angle you get a good view of the feed and return lines neatly coming through the body support, to and from the regulator, one above the other. Of course if this were a drag car I'd not be permitted to mount the regulator on the firewall owing to flywheel explosion safety rules. It does make a neat installation though, and allows a short length of braided hose to feed the fuel log. Perhaps too short, as there's minimal flex to allow for sideways engine movement. I'll see how much movement there is when I fire the motor, and may possible change this hose for a longer, but unfortunately more unsightly, version.


22. From this angle you can see the valve cover is still removable with the fuel line routed the way it is. The dual-action adjustable fuel log features ball and socket assemblies on each carburetor inlet allowing plus/minus 20-degree movement, useful for clearance in racing applications around throttle stops or nitrous plates, but useful here to clear the vacuum module on the distributor. With the rear of the log adjusted up and the front downward, I gained the clearance needed. Once the desired position was found, the swiveling assemblies were locked in place. The log also telescopes to fit various carburetors. While the fuel pressure gauge can be mounted on the regulator, I opted to mount it on the log. Both feature 1/8- inch NPT ports for gauges, and are supplied with bungs fitted


23. Moving to the rear of the car, I drilled these holes in the floor/C-notch bulkhead and filled thick rubber grommets before installing the braided hoses. The round holes are for the feed and return fuel lines, while the elongated hole is for two fuel cell vent hoses.


24. Double 5/8-inch Kugel line clamps were used to attach the braided feed and return hoses to the crossmember at the front of the C-natch, ensuring they remain well away from the intended exhaust pipe route and any moving ports. Single 5/8-inch clamps locate these hoses en route to the fuel filter ahead of the rearend.


25. The final part of this install was to hook up the fuel cell. The two vents at the rear of the tank contain rollover valves, and as the fillings place the hoses almost 3 inches above the tank, I was confident in routing them downward through the floor. The fuel pump is located toward the rear of the car (nearest the camera), its braided hose running forward parallel with the return line and through the bulkhead. These will both be clamped to one of a pair of steel straps which will secure the fuel cell, but which I have yet to make. Hey, I've been busy!