It’s All in the Delivery

VaporWorx is the New Standard in Transferring Fuel to the Engine

By Jeff Smith   –   Photography by the Author

The horsepower race continues to escalate. We have production OE engines now achieving over 800 hp and Chrysler is now delivering a four-digit flywheel horsepower number straight off the factory floor. With these outlandish power numbers also comes increased demand for a high-performance fuel delivery system.

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001 VaporWorx schematic reveals the system’s simplicity vaporworx fuel pump
This VaporWorx schematic reveals the system’s simplicity. With a fuel pressure sensor in the single high-pressure feed line, the controller reads the pressure and modulates pump operation to maintain the desired fuel pressure. The elegance of this design embraces the fact that most street driving involves part throttle operation where a lower volume of fuel is required. PWM control maintains the desired pressure while reducing pump load, keeping the pump cool while improving durability.

On the surface, the solution would seem fairly simple: just add a monster pump capable of delivering fire-hose-capacity fuel at the high pressure needed to feed an 800hp, supercharged engine. But add the requirement of a light-throttle cruise down the highway while knocking down 20 mpg and things become a bit more complicated. In the past, this demanded a return system that could bypass a large amount of fuel returned to the tank.

002 VaporWorx schematic reveals the system’s simplicity vaporworx fuel pump
We will be using this VaporWorx electronic pressure regulation kit that includes the actual black box controller, an OEM fuel pressure sensor, and the pre-terminated wiring harness from the controller to the pump. The small blue tool is for the fuel pressure adjustment on the controller box. With the box connected and engine running, merely set the line pressure where you want it and the system will maintain the fuel pressure at that level. Its strength is in its simplicity. Depending upon the system, the controller can handle between 50 and 120 amps of continuous current draw, which is more than enough to cover even a pair of large pumps. For example, the ZL1 pump only demands 16 amps at full output and far less under PWM control.

What is rarely discussed is the fact that bypassing fuel increases the heat generated in the fuel, which generally creates multiple problems as fuel temperatures hit 130-plus degrees F on really hot days from multiple sources, including the heat reflected off the pavement. These high fuel temperatures often cause percolation and vapor lock problems. A typical distillation curve amply illustrates why gasoline functions much differently (in a bad way) at 130 degrees compared to 70 degrees F.

003 setting fuel pressure using the supplied small screwdriver vaporworx fuel pump
Once the VaporWorx PWM controller is installed, with the engine running, all you have to do to set fuel pressure is use the supplied small screwdriver to turn the potentiometer in the controller to the desired fuel pressure. Set it once and then forget about it because it will not need to be adjusted unless some part of the system has been changed.

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One of the less-than-desirable aspects of a typical return fuel delivery system is that the in-tank pump must run at max capacity 100 percent of the time. This works great for short-duration, drag race applications, but for a high-horsepower street car, this also means a high-volume pump running at max capacity all the time. A full recirculation system adds significant heat to the fuel as it pulls heat from the engine through the fuelrail. This eventually overheats the fuel, which causes cavitation problems at the pump inlet where the pressure is the lowest. All of these details work together to escalate fuel temperatures.

004 This is the ZL1 pump we chose vaporworx fuel pump
This is the ZL1 pump we chose for our 600hp, NA LS 427-powered Chevelle. The pump sits inside the white plastic reservoir and fuel level is maintained at the top as long as there is fuel in the tank. This keeps the pump inlet covered while also cooling the pump since it is always submerged in fuel. These factory modules also come with a large, integral fuel filter so no external filter is required.

As the high-horsepower aftermarket becomes more sophisticated, it’s interesting how trends point back toward well-researched OE solutions to meet these challenges. Long before there were 800hp OE engines, the new car companies developed a far more sophisticated returnless fuel delivery system. A returnless system controls the fuel pump by way of pulse-width modulation (PWM).

This is a process where voltage is applied in segments (rather than continuously) to produce a desired pump speed. As an example, if 13.5 V of constant voltage is sufficient to produce full-pump capacity, then pulsing that voltage half of the time at 13.5 V will produce a 50 percent capacity pump output. The process is more sophisticated than this simple explanation, but it’s the essence of how PWM works. A main positive aspect of PWM is that the pump no longer runs at 100 percent capacity all of the time. With PWM control, the pump will last much longer, which is why it is not unusual for an OE performance pump to be operating perfectly well beyond 100,000 miles.

005 The arrows indicate the multiple inlets to the pump on the bottom vaporworx fuel pump
The arrows indicate the multiple inlets to the pump on the bottom of this white plastic reservoir at the bottom of the tank. At these points are high-pressure fuel jets that shoot fuel across siphons to pull fuel from the tank into the reservoir. These are strong enough to literally suck the tank dry. The male pipe opening on the left is used as a separate inlet into the bucket when used in vehicles with separate saddle tanks. It can also be used to connect to separate external pickups for an autocross/road racer inlet package.

In the past, attempts have been made to simply cut the continuous supply voltage from 13.5 to half voltage (6.75 V) but this does not work because the pump is designed to operate at 13.5 V. The result is this lower voltage destroys pump efficiency and leads to early pump failure. Pulse width modulation of full voltage achieves the same average voltage (6.75 V) while still applying the full voltage to maintain efficiency.

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An analogy to PWM is like riding a bicycle on level ground. By pedaling half the time, you can maintain a given but slightly slower speed compared to the speed generated by pedaling at a constant rate.

006 This round metal can is an integrated pressure regulator vaporworx fuel pump
This round metal can is an integrated pressure regulator, but it is not used in the traditional sense. Instead, this regulator is connected to the fuel pump outlet and is used only to relieve excess pressure in the line to the engine when the pump and engine are not running. This prevents excessive over-pressure in the line during a heat soak situation because when pressure exceeds 100 psi, the injectors won’t open. This regulator relieves pressure above 85 psi and dumps the fuel back into the pump bucket reservoir.

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This PWM signal is monitored by a highly accurate fuel pressure sensor and computer control based on several other functions such as throttle position (TPS), rate of change of throttle position, manifold absolute pressure (MAP), and others. All of these inputs help determine the PWM signal control of the fuel pump to maintain a constant 58 psi.

007 This is the stamped steel tank that we will use vaporworx fuel pump
This is the Rick’s stamped steel tank that we will use to upgrade the fuel system for our ’65 Chevelle. We are bolting in an LS7 crate engine from Scoggin Dickey Performance Center. The tank has the large locking ring already in place and is ready for our ZL1 Camaro pump.

In order to achieve constant pressure, the OEs had to design a pump and reservoir that maintained a steady source of fresh fuel at the fuel pump inlet. This was accomplished with the now-familiar tall, white fuel pump reservoir or “bucket” assembly. This design uses a small volume (roughly 20 percent) of fuel bypassed from the fuel to operate several jet pumps that maintain a full fuel level in the bucket at all times, even when tank level is near empty. These jet pumps literally will suck the tank dry unlike traditional “pump-on-a-stick” arrangements where fuel slosh can uncover the pump inlet.

008 adapter fittings thread together to form a leak free seal vaporworx fuel pump
Most OE manufacturers use what is called a quick-disconnect (QD) fitting that slips over a collar on the fuel line and seals to the line. The VaporWorx QD adapter fittings thread together to form a leak-free seal that is far superior to previous aftermarket versions.

This reservoir design always has fuel at the inlet to maintain a constant fuel pressure. This eliminates the need for external pickups unless the vehicle will be subjected to serious autocross or track day use. Then a pair of in-tank lateral pickups can be added to ensure fresh fuel is fed to the pump even under extreme cornering situations.

VaporWorx owner and system designer Carl Casanova wanted to incorporate this OE system into his ’68 supercharged LS Camaro that has now survived multiple One Lap of America races, which are much like a road racing version of Drag Week with greater distances between racetracks. Just to survive this event and finish is a testament to the car builder’s art.

009 VaporWorx offers either straight or 45 degree QD fittings vaporworx fuel pump
VaporWorx offers either straight or 45-degree QD fittings off the main outlet from the tank that will also locate the pressure sensor that VaporWorx recommends be located near the pump outlet for optimal performance.

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Casanova realized that the OE performance pumps are more than capable of supplying sufficient fuel even up to 900 normally aspirated (NA) horsepower and even more with dual-pump systems. The big challenge was to find a way to integrate the OE PWM technology into a simple, stand-alone electronic module. The result is the PressureWorx controller package. For a 600hp, NA application, for example, the universal ZL1 controller is the best application. Casanova says that fully 80 percent of his market is similar systems.

The key to the VaporWorx system is the PressureWorx PWM controller that is very simple to install and adjust. To wire it, you merely connect battery positive and pump positive wires and ground wires. The only other wiring is connected to the pressure sensor and switched power. With the pump powered up and the engine running, you use the included tool to adjust the fuel pressure to the desired psi. Once it’s adjusted, that might be the last time you ever have to think about it. If there is a desire for manifold referenced fuel pressure, just connect two wires to the engine MAP sensor or use a VaporWorx-supplied MAP sensor to achieve a 1:1 manifold referenced fuel pressure.

010 VaporWorx recommends using Goodridge PTFE lined convoluted hose and reusable fittings vaporworx fuel pump
VaporWorx recommends using Goodridge PTFE-lined convoluted hose and reusable fittings for high-pressure fuel lines and connections. The Goodridge hose can be nearly tied in knots and not kink, unlike other expensive PTFE-lined hoses. Another benefit is that the lines and hose fittings can be constructed without expensive crimp tools.

This is the heart of the system but there may be questions as to its durability. As a testament to this, Casanova’s own Camaro now has over 75,000 miles on the controller in his car.

Casanova initially designed this system to replicate the factory returnless design, which offers significant advantages. However, higher horsepower applications can still benefit from a return-style system, so VaporWorx has expanded its design to offer control over dual-pump systems working within a return-style configuration.

011 VaporWorx offers a Super ZL1 pump vaporworx fuel pump
For more aggressive combinations, VaporWorx offers a Super ZL1 pump that is capable of delivering sufficient fuel at pressure to feed 830 supercharged horsepower on gasoline or nearly 1,000 hp normally aspirated on gasoline.

There are many more options to the VaporWorx PWM concept such as systems specifically for the LT direct-injection Gen V engines. However, this overview should offer enough information to reinforce that this is a highly refined system that uses OE technology that can now be employed by nearly any performance enthusiast in search of the best fuel delivery system available.

Parts List

Description PN Source
PWM control for ZL1 pump PWZL13B VaporWorx
Camaro ZL1 pump for NA 600 hp, GM M100291 RockAuto
VaporWorx straight QD -6 with press. adapter AN6FMOK-180 VaporWorx
Vaporworx 45-deg. QD-6 with press. adapter AN06FMOK-45 VaporWorx
Vaporworx corner pickup kit CPTKIT VaporWorx
Dorman fuel pump module seal 911245 RockAuto
’64-67 Chevelle Rick’s steel tank for OE pump 15161 Rick’s Tanks
’68-72 Chevelle Rick’s steel tank for OE pump 15071 Rick’s Tanks
’64-67 El Camino Rick’s tank for OE pump 15161 Rick’s Tanks
’67-68 Camaro Rick’s tank for OE pump 15081 Rick’s Tanks
’69 Camaro Rick’s tank for OE pump 15091 Rick’s Tanks
’70-73 Camaro Rick’s tank for OE pump 15021 Rick’s Tanks
’68-72 X-body Rick’s tank for OE pump 15041 Rick’s Tanks

 

OE Fuel Pump Recommendations

HP Rating Fuel Pressure GM Pump
Normally Aspirated
Under 600 hp 60 psi LS3 Camaro
Under 775 hp 60 psi ZL1 Camaro
Under 950 hp 60 psi CTS-V
Supercharged
Under 650 hp 60 psi ZL1 Camaro
Under 810 hp 60 psi CTS-V
800 hp 60 psi VaporWorx Super ZL1 pump

 

Gen5 and Gen6 ZL1 Fuel Module Performance Data

Performed by RC Engineering in Torrance, CA

PSIG Amps Lb/Hr Gal/Hr. Ltr/Hr CC/Min BHP at 0.5 BSFC BHP at 0.6 BSFC
45 14.9 463 77.2 292 4869 926 772
50 15.3 436 72.7 275 4585 872 727
60 16 391 65.2 247 4111 782 652
65 16.4 368 61.3 232 3870 736 613
70 16.8 344 57.3 217 3617 688 573

 

PSIG: Gauge pressure

Amps: Amperage required to run the pump at the rated pressure

Lb/Hr: Pounds per hour of fuel delivered by the pump

Gal/Hr: Gallons of gasoline per hour

Ltr/Hr: Liters of gasoline per hour

CC/Min: Cubic centimeters of gasoline delivered per minute

BSFC: Brake Specific Fuel Consumption. This is the amount of fuel in pounds required to produce 1 horsepower for 1 hour. NA engines are rated at 0.50 BSFC lb/hp/hr while supercharged engines up to 800 hp are typically rated at 0.60 lb/hp/hr.

BHP at 0.5 BSFC: Horsepower potential at a brake specific fuel consumption of 0.5

Parts List

Description GM PN AC Delco PN Source
LS3 Camaro pump module 19208719 M100080 RockAuto
ZL1 Camaro pump module 19260557 MU2101 RockAuto
CTS-V pump module 19207950 M10235 RockAuto
VaporWorx control kit, Camaro     N.A. PWZL13B-23IT VaporWorx
RetroWorx tank adapter panel     N.A. RWTAK VaporWorx
VaporWorx QD adpt. to -6AN     N.A. FPOFGMQCAN6 VaporWorx
VaporWorx fuel mod. plug kit     N.A. FMPLUGKIT VaporWorx

 

Sources
Rick’s Tanks
(915) 760-4388
rickstanks.com

RockAuto
(866) 762-5288
rockauto.com

VaporWorx
(805) 390-6423
vaporworx.com

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