Upgrade Your External Fuel System With An In Tank Solution

Aeromotive fuel system

The days of sumped fuel tanks and external fuel pumps on your high performance street car are all but gone. Fuel pump and tank technology has evolved with the times, and companies like Aeromotive have introduced in-tank fuel pump systems that can support up to 1,000 horsepower while being barely louder than your wife’s Camry.

Darin Burgess is a prime example of someone that was tired of listening to his old school, bilge-pump-sounding external fuel pump. It was loud, and Darin was trying to convert his track-only 1966 Chevelle back to street duty. “It was like a blender running at full bore in the back seat,” mentions Burgess. His high compression, naturally aspirated Chevelle was growing mothballs, because it was no longer fun to drive, so when it came to install a new fuel system to help bridge that gap, this upgrade was a no-brainer.

All our major hardware laid out.

When you put fuel under a vacuum, it reduces the boiling point, which can lead to suction side cavitation – Kyle Fickler

“There is a real need in the market for a well-engineered tank for EFI conversions and carbureted enthusiasts wanting to take advantage of the latest in-tank fueling technology,” explains Kyle Fickler of Aeromotive. “Our focus on complete systems goes back to our introduction of Fox Body Mustang tanks that allowed us to offer complete systems. We currently offer more than 40 tanks, and if you look at the application guide, you realize that many of the cars need a replacement tank. Being able to offer one with the latest fueling technology was a logical step.”

Eventually, Darin wants to up the ante by adding a 150 to 200 horsepower shot of nitrous. How would the fuel system stack up when a power adder is placed in the mix?  “Aeromotive provides horsepower ratings based upon real world applications,” said Fickler. “EFI ratings are always less than carbureted, and forced induction ratings are always less than naturally aspirated.

Cars have a limited electrical power source – either the battery or the alternator. Physics dictate that as pressure goes up, the pump slows down, so the horsepower the pump can support is less. engines using E85 require 30 percent more fuel than those using gasolines to make the same horsepower, so E85 ratings are 30 percent less than gas ratings. Nitrous applications typically have a Brake Specific Fuel Consumption (BSFC) about midway between a normally aspirated and forced induction application.”

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Darin’s 1966 Chevelle is super clean. It was previously a track-only car and he’s been wanting to drive it more frequently on the road. It’s fitted with a 12:1 compression 427ci big-block Chevy.

The heart of the install is Aeromotive’s 18317 Stealth fuel system designed for the 1964 through 1967 Chevelle. Just like all Stealth fuel tanks that Aeromotive offers, this system starts with a brand new, OE style fuel tank.

The tank features a recess in the front, designed to clear the pump housing-hat and fuel level sending unit. This means the tank will fit just like a stock unit, and not require any sort of sheetmetal messaging to clear the fuel pump. Aeromotive goes the extra mile, and even powdercoats the tank in silver.

The Parts

PN 18317 – Aeromotive Stealth Fuel Tank

  • Silver powdercoat finish
  • EFI-style internal baffling
  • 0 to 90 ohm universal fuel level sending unit
  • Black anodized pump hanger assembly
  • 340 Stealth Fuel Pump (PN 11140)
  • Pre-pump filter sock assembly
  • (3) ORB-06 ports – outlet, return and vent
  • Fuel Injected Engines: Up to 850 hp – naturally aspiratedUp to 700hp – boosted
  • Carbureted Engines: Up to 1,000 hp – naturally aspirated up to 800 hp – boosted

PN 14201 – Aeromotive Holley 4150/4500 Fuel LogPN 13304 – Aeromotive X1 Series Fuel Regulator

PN 12321 – Aeromotive In-Line -10AN fuel filter

Various Aeromotive Fittings

Inside the tank, a trap door baffling system ensures that the fuel pump won’t run out of fuel during high G-loads when drag racing or road racing.

“The universal Aeromotive Phantom systems utilize a fuel-resistant foam baffle and rubber basket assembly that can be cut-to-length for varying tank depths, and is sized appropriately for the various Phantom Systems,” explains Fickler. “For example, the Dual Phantom has a larger-capacity bucket and baffle assembly than the Phantom 340.  Our Stealth musclecar tanks utilize metal, and an internal baffling and tray assembly designed for both EFI conversions and carbureted cars that need to enjoy the benefits of in-tank fueling.”

The top of the pump hat is equipped with ports for fuel feed, return, and vent. Lugs for power and ground energize the pump, while the fuel level sending unit has a standard one wire connection.

Cleaning the fuel before it’s supplied to the engine is Aeromotive’s 10-micron 5 1/2-inch filter. This filter features ORB -10AN ports and can support up to 3,000 horsepower without impeding fuel flow.

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Aeromotive builds a trap door fuel baffle system that allows fuel to flow in but not out. This insures that there won’t be any fuel starvation at the drag strip or autocross.

Once the fuel is clean, it’s sent to Aeromotive’s Dual Action Adjustable Fuel Log, which works for both 4150 and 4500 series Holley carburetors. The sockets at the corners of the log can swivel up to 20 degrees while in/out ports are -10AN in size. Dual 1/8 NPT ports are perfect for accessories like fuel pressure gauges and sensors.

Before the fuel heads home, it passes through an X1 series regulator designed for carbureted fuel pressures. Even though this regulator is tiny, it can support 2,000 horsepower through its triple -8AN ports. The regulator is adjustable from 3 to 15 psi.

That little Aeromotive X1 regulator can support up to 2,000 horsepower, while the 10 micron fuel filter ensures nothing gets stuck in it.

A Side Note On Cavitation With In-Tank Versus Externally-Mounted Fuel Pumps

“When you put fuel under a vacuum, it reduces the boiling point, which can lead to suction side cavitation,” explains Fickler “To function properly, an external fuel pump needs to create enough vacuum to draw the fuel out of the tank through the suction side plumbing and through a filter before it reaches in the inlet of the pump.  Even if you work hard to reduce the restriction of the pick-up tube, the plumbing, and the filter, you cannot avoid putting the fuel under a vacuum, which reduces its boiling point. Aeromotive in-tank solutions, such as our Phantom and Stealth systems, overcome this by always having positive pressure at the inlet of the fuel pump.”

When you put fuel under a vacuum, it reduces the boiling point, which can lead to suction side cavitation – Kyle Fickler

Continuing, Fickler explains, “Next, let’s consider trends in modern hot rods that serve as additional heat sources to increase fuel temperature. Our cars sit low to the ground, making more horsepower with larger and hotter exhaust. Along with the radiant heat from the road, all of this under car and under hood heat serve to heat the fuel.  A properly designed system with an external pump takes into consideration all of these potential issues, i.e., heat sources, inlet restriction, etc. and will work as intended. However, mismatched components or poor plumbing practices can easily lead to suction side cavitation in this harsh environment.”

To slow down the ability for the fuel to heat up, Fickler explains some of the alternatives. “As horsepower levels have increased, particularly in forced induction applications, so has the need for larger, more efficient fuel pumps. Assuming a 15 gallon fuel tank, a large fuel pump will circulate the entire volume of that tank every five minutes when it is full. It does that whether the car is idling at a red light or cruising down the highway.

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Installation of the new tank really was an uneventful, bolt-in task.

That simple math equation helps explain the benefit of the Aeromotive Fuel Pump Speed Controller PN 16306 to reduce the cycle rate.  All of this points to the simple fact that whether you use an external or in-tank fuel pump, work hard to ensure that you have cool, liquid fuel at the inlet of the fuel pump. Overheated or aerated fuel at the inlet will lead to poor performance, suction side cavitation, and potentially reduce pump life.”

The Rather Uneventful Installation … In A Good Way

Darin’s old fuel system served him well and has been in his Chevelle for about 15 years. Since he normally runs leaded race gas, it was wise of him to install all new hoses and fittings with his new system.

(Top Left) Darin's original setup needed some updating. (Top Right) Aeromotive's fuel log only takes a few minutes to install. (Bottom Left) The Aeromotive X1 regulator is mounted on the firewall and ready to be connected.

Wiring is straight forward and uses a standard four socket relay.

Can You Hear Me Now? Good.

Aeromotive’s Stealth Fuel Systems have been a godsend for the musclecar community that’s looking to make horsepower upgrades that supersede block-mounted mechanical fuel pumps or even loud, external pumps. When we say that you can’t hear the fuel pump when Darin’s Chevelle is running, we mean it. In a matter of a half day’s work, we were able to bring the fuel system of this Chevelle to the 21st century.

Article Sources

About the author

Mark Gearhart

In 1995 Mark started photographing drag races at his once local track, Bradenton Motorsports Park. He became hooked and shot virtually every series at the track until 2007 until he moved to California and began working as a writer for Power Automedia. He was the founding editor for its first online magazines, and transitioned into the role of editorial director role in 2014. Retiring from the company in 2016, Mark continues to expand his career as a car builder, automotive enthusiast, and freelance journalist to provide featured content and technical expertise.
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