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The New Style—Classic looks with modern features comes together in Holley’s Sniper EFI Stealth

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With the new fuel system tested and the Sniper EFI Stealth 4500 tweaked by Rollins on the chassis dyno with favorable results, the next stop was Gainesville Raceway for some test runs.

Written by Derek Putnam
Photography by the author and courtesy of Holley

Although manufacturers haven’t employed carburetors on production vehicles for over a quarter of a century, the simplicity and ease of tuning keeps carburetors popular amongst street and race enthusiasts. Electronic fuel injection presents a number of barriers for enthusiasts interested in switching over, not the least of which have been cost and tuning knowledge. Looking to change the game, Holley EFI has brought the costs down, has equipped its EFI systems with self-learning software programs, and even provides a vintage appearance to its EFI systems in the Holley Sniper product line. We followed the conversion from a Holley Dominator to a Holley Sniper EFI system on a high-horsepower, NMCA Torqstorm Superchargers True Street machine to bring you the details of the installation, as well as the interesting opinion of the subject vehicle’s owner, who also installed the Sniper EFI.

With over three decades of experience, as his father Chip passed the knowledge to him as part of their automotive repair business, Jason Rollins, of Rollins Automotive Speed and Custom, knows carburetors. Eventually, his business evolved from basic auto repair to a performance and racing-based business.

“A carburetor might be viewed as an ancient device, but you can tweak at it with basic parts and hand tools and make it acceptable,” Rollins explained. “I sell and service a lot of carburetors, but EFI has come a long way. With many of my customers demanding fuel injection, it got my interest level up.”

Nearly 600 cubic inches of big-block Chevrolet can require a lot of fuel to keep it happy. Jason Rollins chose a Holley Dominator carburetor, specifically a two-circuit 1,150-cfm Gen 3 Ultra version, to power a ’71 Nova to high-8-second passes without a power adder.

Holley not only supports the carburetor game, but also brings a ton of products to the EFI arena. Part of the EFI team at Holley is Rick Anderson, an EFI technical salesperson at Holley. He doesn’t just work in the EFI game, he lives it with an 8-second Mustang proudly sporting Holley EFI.

“When I was hired at Holley, it was because of my knowledge in fuel injection and my ability to help support dealers and racers,” said Anderson. “The new Holley EFI was launched in 2010 and designed to work on any setup, and can truly grow with the user. From a mild EFI setup to an HP or Dominator system, we offer a lot of options.”

Swapping the carburetor for the Sniper EFI Stealth 4500, it’s easy to see why the “stealth” is in the name. Looking into the engine bay from the driver side or front of the car, at a glance it appears to still have a carburetor on top.

Making the switch from a carburetor to EFI on a serious horsepower application used to mean that a throttle-body injection setup, a custom mass airflow arrangement, or a fabricated intake would be part of the deal. But Holley’s Sniper EFI line up simplifies the installation and its self-tuning, speed-density option can quell the concern of EFI complexity.

“When most people change to Holley EFI and are wiring up everything, it’s easy to say ‘Why am I doing this?’ compared to the simplicity of a carburetor,” Anderson said. “But by the second pass down the strip or your second drive on the street, you’ll instead be saying ‘why didn’t I do this sooner?’”

Cutting Carbs
Although some EFI systems have reasonable price tags, a high-output ride like Rollins’ demands more than a standard EFI system. “Some may not choose a Dominator for a car that sees street use, but that’s where a tuner can shine,” Rollins said.

He did just that, getting the idle, launch and full throttle dialed in first. Then Rollins spent an estimated 10 hours in just tuning his carburetor on the chassis dyno to get the part throttle better. With a ton of time in his Dominator and an 8.99 time slip in hand on motor alone, why did Rollins consider the switch to Holley EFI?

“I’ve installed a lot of the base Sniper EFI systems,” Rollins admitted. “All the additional features made me realize I could make my Nova drive better, gather more data and enjoy using it more.”

Seeing the Sniper EFI Stealth 4500 from the passenger side reveals the EFI side of things, and all the connections that exit at the base. These include the wiring for the main harness, an eight-pin and 10-pin harness connector, the connection for the handheld display, plus individual wiring for a temperature sensor and the oxygen sensor.

The Sniper EFI is built with the controller already mounted to it, leaving the responsibility of only power, grounds, some connections and an oxygen sensor to the vehicle’s owner.

“People look at a carburetor around simplicity and price,” Anderson admits. “The Sniper EFI targets both of those points, making the choice easier.”

When routing the wiring and considering locations for relays, a dry location away from heat is a good idea. Holley also suggests keeping high-voltage wiring separated, as bundling them together can produce problems. Rollins used the entire right side of the engine bay, as well as the firewall, to keep the wiring clean and easy to access.

The Sniper EFI also brings lots of extra features beyond more controlled fueling.

“The more you look at what the Sniper EFI can do, it’s hard to not swap it in place of a carburetor,” Anderson elaborated. “In the case of Rollins’ combination, when he runs on the nitrous system, he can swap to a dry shot and let our Sniper EFI Stealth 4500 control the fuel side. If the bottle pressure gets low during a run, a carburetor jetting would be too rich. The Sniper EFI Stealth 4500 would adjust it where power loss wouldn’t be near as great.”

“Without a doubt, the Sniper EFI is an easy choice when looking at what it does better than a carburetor,” Rollins agreed. “If you do the math between the two choices, on the surface, the costs would be pretty close. But the Sniper EFI also provides extra features like fan controls, nitrous controls, a datalogger, timing control, and a lot more. That saves money that would be spent on extra components, making it the easier decision for me.”

Switching to Holley EFI includes adding an oxygen sensor to your exhaust system. Rollins already installed one on the Nova for monitoring purposes on the shop Dynojet chassis dyno, so he utilized that bung for the EFI system’s sensor.

Rollins’ 1971 Chevrolet Nova was featured in the pages of this magazine before, as the car is a multi-time winner in the TorqStorm True Street class. In its current form, a 598 cubic-inch Chevrolet big-block built by Rollins himself sits between the frame rails. A Dart block provides the foundation, and Rollins filled it with a Callies crankshaft, Eagle connecting rods, JE pistons, and a Bullet solid-roller camshaft sporting duration numbers of 283 on the intake and 301 on the exhaust, and .840-inch lift on a 112 lobe separation. Brodix SR-20 20-degree cylinder heads and a matching intake guide the air, and a Holley 1,150-cfm Gen 3 Ultra Dominator carburetor tops it off.

The Nova has a 15-gallon fuel cell in the trunk, so Rollins had multiple places to install the fuel pump to allow for a gravity-feed routing. He chose the frame rail and added Holley’s VR Series Billet Fuel Filter 100-micron pre-filter (PN 162-577) to protect the pump from any debris.

Despite a few years of mostly trouble-free operation, Rollins opted to swap the carburetor for a Sniper EFI Stealth 4500. Along with an upgrade to the fuel system, Rollins completed the swap in one weekend, and immediately noticed a big difference.

“I installed The Sniper EFI Stealth 4500 in the winter season, and even in north Florida, it can get cold enough to make a first start on a carburetor a babysitting session. But the Sniper EFI Stealth 4500 enabled me to start the car at the touch of a key without pumping the gas at all,” Rollins beamed. “Once you get the tune-up set, it will adjust for weather and temperature versus a carburetor. No jet changes, no adjusting air bleeds, no changes would be required to make everything run at peak performance.”

Chassis dyno testing revealed the EFI graphs were really close to the carburetor versions, with only a two horsepower difference in favor of the carburetor.

“It’s everything I could have asked for,” said Rollins. “It’s easy to see why I install a lot of Holley Sniper EFI systems!”

A post-pump filter is a wise addition for optimal fuel system performance, and we opted for a VR Series Billet Fuel Filter 10-micron version (PN 162-575) on Rollins’ ride. It was installed on the rear of the factory subframe to allow easy access for cleaning.
The VR1 fuel pump has a separate controller, and Rollins mounted it in the trunk to keep it away from heat, debris, and moisture. Holley includes a template for marking and drilling the mounting holes, and Rollins used a 1-inch-diameter, rubber grommet to pass the connection plug through the trunk to the pump.
The final part of the fuel system is a regulator, and Holley specifies a bypass-style regulator must be used with the VR1 fuel pump. With Rollins needing three outlets (two for the EFI and one for a nitrous system), the four-port VR Series EFI regulator was chosen (PN 12-864).
Testing passes revealed a lean spike occurring just after launch, and with the laptop forgotten at the shop, testing was cut short to return to the shop and review the main cell map. Rollins spoke with Rick Anderson, and got a few ideas on a solution. “He told me to not guess at it,” Rollins said. “Use the datalogger and look at the feedback. I’m thinking with a little tune time and a few more runs, it should be an easy fix.”

Fueling the Fire
When switching from a carburetor to EFI, the increased pressure and demands on a fuel system can go up like a wheelstand. To ensure his 1,000-rear-wheel-horsepower Nova would be sufficiently fueled, as well as have room for future power upgrades, Rollins opted for Holley’s VR1 Series brushless fuel pump. Based on a twin-screw rotor design, the VR1 pump can support an EFI system up to 2,150 horsepower, is compatible with pump or race gas, as well as methanol or E-85, and can be submerged in a fuel cell or used externally. A large 10 AN O-ring inlet and outlet, billet construction, and a controller that adjusts the speed of the pump are just a few of the features the VR1 includes. But we were blown away by how quiet the pump is, even with it solidly mounted to the frame.


Screen Time
The Sniper EFI systems include a 3.5-inch touchscreen to view the information an engine provides in multiple layouts, as well as control the set-up and tuning of the system. But Holley also includes free software for use with a laptop, which ultimately provides more options for tuning.

“For a basic combination, the included touchscreen will handle almost anything,” Rick Anderson said. “If you were doing something a little more involved, like a blow-through combination or multiple stages of nitrous, the laptop would allow you to tweak it a little better than the touch screen.”

Rollins agrees that a laptop offers a little more adjustability.

“You can tune it on the handheld, but the laptop allows access to a lot more points, as well as changing the X and Y axis to narrow or broaden the cells you want to look at or change,” he said.


Little Brother
With the success of the Sniper EFI 4150 and the big-brother Sniper EFI Stealth 4500, Holley has answered the demands of the enthusiasts by adding six more Sniper models to its lineup. One that hits the street/strip performance target with a bullseye is the Sniper EFI Stealth 4150 and Super Sniper EFI Stealth 4150. Just like the Sniper EFI Stealth 4500, the new Stealth 4150 combines carburetor looks with modern features and a load of extras that are hard to overlook.

The base Sniper EFI Stealth 4150 is based around a quartet of 100 lb/hr injectors, and will handle up to 650 naturally aspirated horsepower, or 600 ponies with forced induction. The Super Sniper EFI Stealth 4150 adds another round of 100 lb/hr injectors, bringing the number of injectors to eight. This allows the Super Sniper EFI Stealth 4150 to support up to 1,250 horsepower, and you can choose from shiny, black or gold finishes.

Sources:
Gainesville Raceway
(352) 377-0046
Gainesvilleraceway.com

Holley Performance Products
(866) 464-6553
Holley.com

Rollins Automotive Speed and Custom
(352) 335-7223
Rollinsspeedandcustom.com


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