Fuelsys_edited-1

Musclecars are great and everybody loves classics, but we all understand that technology has advanced since the late ’60s. Upgrading your musclecar with modern technology often requires the builder to take a step back and look at the system as a whole and not just replace components one-by-one as the problems appear. There is always time to do it correctly the first time, and sometimes it’s much safer to plan a system upgrade. Never was a statement more true than when it comes time to upgrade your fuel system.

We started planning our fuel system design starting from a new fuel tank from Rick’s Stainless Tanks. This tank is hand built for street performance systems. Perfect for our needs.

We’ve decided to beef up the ponies in our Blank Slate project car by planting a sturdy 502 ci LSX under the hood. To feed that beast, we need to make some major changes in the fuel system or we face a fuel supply problem that would be on the scale of trying to suck a basketball through a straw. To cure the issue, we’ve decided to use an electric fuel pump and plumbing from Holley and Earl’s Performance Plumbing, along with a tank and pickup from Rick’s Stainless Tanks.

We do our best to not only sell you our product, but to provide you what’s going to be best for you.                        – Hector Guerrero, Rick’s Tanks.

There is a lot of confusion and misunderstanding about fuel systems in musclecars, especially systems with electric fuel pumps. Let’s get right down to the facts:

  • Most fuel system failures are a result of poor system design or installation by installer and not the result of poor manufacturing
  • Pressure and volume are not the same thing
  • The components must work together or one of them might make the other components fail prematurely

Beginning at the Beginning

Designing a fuel system should start at one end, the fuel tank, and go all the way to the other end of the system. In this case, we are designing an EFI fuel system with a return line, so we will start at one end of the system and end up where we started. We’ve previously discussed using custom made fuel tanks in fuel system upgrades with our friends at Rick’s Tanks in El Paso, Texas.

Designed with pickups and a filler tube in stock locations, this tank is a direct replacement for an OEM fuel tank.

Designing a performance fuel system must take into account the fuel tank and fuel pickup, especially with the current trend of higher horsepower engine swaps and custom built chassis builds. The need for larger capacity, better exhaust clearance or simply fitting into a chassis where the frame rails have been modified – while still supporting high performance engines – can be a challenge.

A look inside a custom tank from Rick’s Tanks. The baffling that prevents fuel slosh is very noticeable.

“We do our best to not only sell you our product, but to provide you what’s going to be best for you,” said Hector Guerrero of Rick’s Stainless Tanks. We’ve used Rick’s Stainless Tanks for several of our project builds with great success. From drag racing projects to Pro-Touring projects, we’ve found that Rick’s Tanks has the enthusiast covered for every application.

All of Rick’s tanks are:

  • 100% Stainless steel, built in the USA with USA sourced materials.
  • Unique baffling system to minimize fuel slosh.
  • Baffling runs front to rear and side to side.
  • Tank centers are carved out using CNC machine and are application specific.
  • CNC Machine Formed and TIG Welded
  • Unique fuel chamber keeps fuel at the pump and minimizing starvation, lean conditions and stalling.
  • Brushed finish to allow for easy upkeep and lasting appearance.
  • Stainless steel mounting straps included.
  • Customizing available to meet customer needs for horsepower, fitment, capacity and more.
  • Five year warranty on workmanship.

For our project Camaro, we selected Rick’s stainless steel tank designed for 1969 GM F-Body Camaros (part #SSF69SU), with 0-90 Ohms sending unit. This steel tank is fitted with a -10 AN supply fitting and a -6 AN return fitting. For EFI systems, the fuel tank should contain baffles to control the fuel slosh, especially when the fuel pump is installed in the tank. A well built tank will fit and work like an OE tank while preventing any interruption in the flow of fuel. We like our fuel tanks to look great and provide a higher level of safety like top quality mounting straps.

The tank comes complete with high quality mounting straps and once installed, really adds to the appearance of the rearend as well.

Our billet HP in-line pumps line can support anywhere from 700-800 horsepower in fuel injection applications and 900 to 1050 when carbureted.             – Blane Burnett, Holley Performance Products

Fuel Delivery

Once you have selected a fuel tank and fuel pick up, the rest of the system components can be determined. We picked a fuel tank that did not have an electric pump provision inside the tank, which meant that we would have to have to use an external pump. Using an electric pump for an EFI fuel system is a perfect choice because most of them are designed for continuous use.  The electric fuel pumps designed for higher PSI EFI use can still be used with carbureted systems, but the fuel system must be fitted with a return line to prevent the fuel from being heated under low demand situations.

More pressure is not always a good thing, however. As fuel pressure increases, the flow rate actually drops off (fuel pressure is inversely proportional to fuel volume). As fuel pressure rises, flow decreases because the volume of fuel required to maintain the pressure is higher. “You’re still consuming the same amount of fuel just at different pressures. With EFI, because of the higher pressure your flow rate actually goes down”, says Jay McFarland of Holley. This means that EFI engines require higher capacity pumps than their carbureted counterparts.

We opted to use Holley’s Dominator high flow electric fuel pump (part #12-1800), an inline electric pump that is rated at 200 gallons per hour. This pump does not have an internal bypass so a bypass style regulator and return line is required (part #12-847 for carbureted applications and #12-848 for EFI applications). Also required for the installation of this high pressure, high volume fuel pump, is a screen type pre-filter (100 micron, part #162-572), a post fuel filter (part #162-571), fuel hose and clamps, fuel fittings and a relay kit (part #12-753).

Holley’s Dominator electric dual fuel pump (part #12-1800) was our weapon of choice.

The modern high-pressure and high-volume fuel pumps all require a high-volume fuel filter between the pickup and the pump to prevent debris from damaging the pump. The big installation tip here is to use a high-volume filter to match the rest of the system. It does little good to purchase a high-volume pump and then choke it with a restrictive filter.

The Dominator fuel pump has a unique design that allows the use of one fuel pump for cruising and both pumps when you activate the nitrous switch or start building boost. So, you’re not going to be under-supplied but you can also eliminate the unnecessary recirculating and heating of extra fuel which can lead to poor performance and hot fuel issues. This is perfect for our build – we can throw as much power through power adders as we want or tame it down for good street manners on a cruise.

“The billet Holley fuel system components being used on Project Blank Slate are very versatile and can support vehicles that are carbureted or fuel injected,” said Blane Burnett, Marketing & P.R. Coordinator at Holley Performance Products. “Since the pumps do not have internal bypasses, fuel pressure regulators are required and control the amount of pressure in the system. Our billet HP in-line pumps line can support anywhere from 700-800 horsepower in fuel injection applications and 900 to 1,050 when carbureted. Due to their twin pump design, the Dominator in-line pumps can support anywhere from 1,400-1,800 horsepower when fuel injected, or 1,830-2,100 horsepower on a carbureted application.”

The Dominator fuel pump combined with Holley's 100 micron pre-filter and a 10 micron post filter are a lethal combination for high pressure EFI applications.

Fuel Pump Installation

Electric fuel pumps are more efficient at pushing fuel through the system than pulling fuel, therefore mounting the pump closer to the fuel tank is far more efficient. As we eluded to earlier, most fuel pump failures are caused by improper installation and there are some things to consider when selecting the location for the fuel pump.

Holley recommends a pre and post filter in the system. This should be considered when installing the fuel pump. Getting the components in the best locations is crucial when designing a high pressure fuel system.

In addition to mounting the fuel pump close to the fuel tank, selecting a mounting location below the fuel tank pickup will help prevent the pump from running dry. An electric pump that runs with no fuel in the system will overheat and have a very short life. Mount the fuel pump away from heat sources like the exhaust system. “If you’re afraid of installing the pump for fear of heat soak, fabricating a heat shield would be a good precautionary exercise to undertake,” advises Burnett.

Dirt and crud kills pumps so it’s always a smart practice to install a pre-filter before the pump. Electrical power is everything to an electric pump (no kidding), so you have to have the correct size wire to power the pump. Getting the right voltage and amps to the pump is critical. The longer your power line is, the bigger the affect of the power drop over that distance. Using a relay in the wiring of your electrical system is highly recommended (Holley part #12-753).

Finally, make sure the pump is grounded correctly. You must have a good ground from the pump body to the frame or the engine or your pump’s life will be dramatically shortened. A poor ground will kill electric pumps quickly.

Mounting the fuel pump near the fuel tank and lower than the pickup helps the fuel pump do it’s job.

Features of the Holley Dominator inline billet fuel pump:

  • Billet aluminum construction
  • 10 AN O-ring inlet/outlet for high flow
  • Can be used with carbureted or EFI applications
  • Fully submersible in-tank for custom applications, space savings and less plumbing
  • Compatible with 12v to 18.5v systems for street or race use
  • Compact (7.5-inches x 5-inches x 2.5-inches) for easy installation on frame rails or other tight areas
  • Twin pump design allows the use of both pumps simultaneously or independently – second pump can be activated on demand for power adders such as nitrous or boost
  • Proven durability beyond 3,000 hours in gasoline or diesel fuels
  • Weighs only 5.1 pounds
  • Current draw at 43 pounds and 13.5 VDC is 17.2 Amps

Fuel line size and hose ends play a significant role in designing a performance fuel system.

Other Components

Fuel line, connections, and fuel line routing are also important components in the fuel delivery equation.  A larger diameter line has the potential to flow more than a smaller diameter line, but following the manufacturer’s recommendations helps prevent fuel flow problems. The greatest fuel pump in the world won’t help if the lines that carry the pressurized fuel are inadequate. Like the other components, the fuel lines must be matched to the system to take advantage of the improved flow and pressure. The fuel line’s inside diameter and the length of the line have an impact on well the fuel pump can deliver fuel.

Think about it this way, OEM fuel lines were built to support OEM power levels. Now that you’ve upgraded your engine to make more power, doesn’t it make sense that you need larger fuel lines to feed that power?

An easy way to associate the AN line size to the actual size of a fuel hose is to remember that every dash (-) is 1/16 of an inch. So a -6 AN line is 6/16 of an inch, or 3/8. A -10 AN fitting would support a 10/16-inch fuel line, which is a 5/8-inch fuel line.

Fuel Line Guide

  • -6 AN up to 550 hp
  • -8 AN over 550 hp
  • -10 AN 1000+ hp
Pressure losses can occur at the fuel line connections, especially in fittings that have 90-degree or greater angles. Most smart builders try to design their fuel systems to limit the number of 90-degree and greater fittings. Earl’s Fittings does have full-flow AN hose ends which help prevent pressure loss at the connections.

Rubber line has a far greater resistance to flow than aluminum or steel and can easily be measured as a pressure loss over a known distance. Ideally, there should be no 90-degree fittings, but if you must use them, use full-flow AN connections.

Earl’s hose ends

Tech Tips

We used Earl’s hose ends and Earl’s hose in our project car fuel system. While this combination of Earl’s products make a pretty fool-proof combination, there are a few general rules to follow to make sure that you end up with a clean looking, sanitary fuel system and trouble-free installation.

1. Make sure that there is adequate clearance between the hose ends and anything that they might be able to contact. While the hose is flexible, the hose ends are not!

2. Do not allow the hose to contact a sharp corner, nut, bolt, rivet stem or anything else that might cause damage. At any point where a hose passes through a panel, install a grommet for chafe protection.

3. Do not allow the hose to rub against anything—even if the surface on which it rubs is flat. The stainless steel braid is a very efficient low speed file and will abrade through anything that it moves against. In order to prevent chafing and to keep your hoses where you meant for them too be support the hoses every 18″ or so with either a cushion clamp or a tie-wrap.

Don’t over tighten the hose end connections. Using the correct tool helps prevent over tightening.

4. Do not force the hose into too tight a bend. Follow the minimum bend radius chart. Do not kink the hose, either by too tight a bend, by misalignment between the hose end and the part or adapter on short assemblies or by getting the whole assembly into a helix on long assemblies. Align the hose end with the adapters so that the hose is not placing strain on the hose end or on the adapter.

5. Keep the hoses as far away from extreme heat sources as possible. If you must run close to such things, use an air gap insulating panel and/or fire resistant flame guard sheathing. Do not run fuel lines in proximity to hot fluid lines (or hot anything else) or you will end up with either hot fuel and low power or vapor lock. Do not run hot fluid lines near cool fluid lines or near the driver.

6. Do not over-tighten the hose ends onto the adapter fittings or parts. The seal is achieved by the design of the mating surfaces—not by muscle. It helps a lot to use the wrenches made for the job.

“Whether you’re building a high powered street car or a dedicated race car, Earl’s Performance Plumbing prides itself in providing the correct products for achieving appropriate fluid transfer for engines, transmissions, and braking systems,” claims Burnett. “When selecting materials for products, Earl’s uses the highest quality components for manufacturing hoses/fittings and other plumbing accessories. The majority of which are manufactured at Holley headquarters in Bowling Green, KY.”

Wrapping It All Up

With many car builders the fuel system is an after thought in the build process, and they battle fuel issues until the system is eventually changed to what it should have been in the first place. We weren’t willing to risk months of chasing problems so we put some thought into our fuel delivery system before the installation even began. Clearly, a well thought out fuel system should consider components as carefully as a performance engine build. The installation should be performed as professionally as well.

Look for matched, and dependable components that will support the horsepower that you expect to achieve.

You don’t need the biggest pump, or the most expensive components, but spending the time and money on proven quality components will eliminate future problems and give your car more consistent and reliable performance.

Stay tuned as we continue to upgrade our Project Blank Slate Camaro with a performance EFI system and other goodies in the next few weeks.