A Better Sniper

Holley’s Upgraded Sniper 2 Throttle Body EFI

By Jeff Smith   –   Photography by the Author and Courtesy of Holley Performance

One of the benefits of electronic engine control is that designers keep coming up with ways to make it better. As good as Holley’s original Sniper throttle body EFI has proved to be, the engineers from Bowling Green, Kentucky, couldn’t resist improving it with the Sniper 2. This is much more than just a superficial face-lift, and it will require most of this story just to outline all the changes, so let’s get cracking.

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According to our Holley sources, the software is largely the same as the original Sniper except for the addition of the wireless Bluetooth connection and new transmission control–both of which we will detail in a moment. More importantly, the new ECU has been updated to be more robust in filtering out radio frequency interference (RFI), which can be a great benefit to resist electrical noise that is common with CD high-voltage ignition systems.

001 The Sniper 2 complete part kit holley sniper 2
The Sniper 2 comes in a multitude of different optional configurations. The throttle body houses four 100-lb/hr injectors that will support 650 hp naturally aspirated or 550 hp supercharged. The throttle body is all new, positioning the ECU internally, which minimizes the number of external wiring connections to simplify the installation.

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The throttle body has been completely redesigned to make it easier to install while also upgrading its functionality. For the basic system that will not control ignition, the main power harness only requires five connections to the vehicle for power, ground, switched ignition, fuel pump, and rpm. One additional upgrade is the throttle position sensor (TPS) is now integrated into the throttle body itself instead of bolted to the exterior. In addition, the throttle body has been redesigned to eliminate the outside fuel distribution hoses in favor of a cast-in fuel distribution channel.

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We have experience with the original Sniper system, and one upgrade we noticed immediately is a change to the throttle linkage. The original Sniper employed a very short throttle arm that made the linkage extremely sensitive to input from the throttle pedal. This made cars with tight converters difficult to drive in low-speed situations. One solution was to fabricate an extension to the original linkage to lengthen the throttle connection to slow down the movement of the throttle blades. The Sniper 2 features a more common Holley throttle linkage and includes factory positions on the linkage for the throttle valve (TV) for either the 200-4R or the 700-R4 overdrive automatic transmissions plus a separate provision for a TH350 kickdown linkage.

004 holley sniper 2
Holley’s power distribution module (PDM) provides a convenient place to locate wiring and reduces the number of connections to the battery. This includes connections for the throttle body, fuel pump, two electric fans, and ignition. The connections are clearly labeled on the cover and easily made with positive, slip-in fittings. The PDM integrates three relays: one for the throttle body, one for the fuel pump, and one for a 25-amp electric fan while including diagnostic lights to help with troubleshooting. The PDM requires its own specific Sniper 2 wiring harness.

The four 100-lb/hr fuel injectors positioned in the throttle body can support up to 650 naturally aspirated horsepower or 575 hp supercharged as a pull-through system but is not configurable for a blow-through supercharger. There are several options for this application with the original Super Sniper if you are looking for that arrangement.

006 The complete Hyperspark system includes a billet aluminum distributor matching coil control box and wiring harness holley sniper 2
The complete Hyperspark system includes a billet aluminum distributor, matching coil, control box, and wiring harness. All this plugs directly into the existing harness connector included with the Sniper 2 throttle body along with a power and ground connection.

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Holley has created a term called the Holley Ecosystem to describe a complete systems approach to the Sniper 2 system that includes a Hyperspark ignition, digital dash possibilities, as well as the multiple options for EFI fuel delivery. The Hyperspark ignition system is designed to be as simple as possible to wire into the Sniper, including a wiring harness with a direct plug-in connector that makes it supremely easy.

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007 Holley engineers have come up with this simple way to properly set rotor phasing when using the Sniper 2 Hyperspark ignition holley sniper 2
Holley engineers have come up with this simple way to properly set rotor phasing when using the Sniper 2 Hyperspark ignition. Once the distributor is correctly installed in the engine at TDC for Number One cylinder, merely rotate the distributor body until the plastic cover lines up with the rotor and fits over the notch in the distributor body. Lock it down, mark the location of Number One spark plug wire, and you’re ready to go.

Older EFI systems that also controlled the ignition required the installer to run through a complex series of steps to set distributor rotor phasing. The Holley Hyperspark system massively simplifies this process by using an innovative plastic cover. Once the distributor is dropped into place with the engine at top dead center on Number One cylinder, you merely line up the distributor body for Number One cylinder on the cap with the plastic cover over the rotor and lock the distributor down. It’s that simple.

Plus, the Sniper 2 throttle body is configured to use a simple connector to tie the distributor into the EFI system. The basic inputs of idle, cruise, and wide-open throttle timing can be initially input using the handheld programmer, but the Sniper 2 also offers the ability to configure the entire ignition curve using a laptop. This offers the employment of a far more sophisticated advance curve that is essentially the same as that generated by the much more expensive Holley HP and Dominator ECUs.

008 This fall Holley will offer an optional Bluetooth wireless module that will make it possible to view a dashboard holley sniper 2
This fall, Holley will offer an optional Bluetooth wireless module that will make it possible to view a dashboard and perform changes using either an iPhone or Android smartphone. Here, a smartphone has been configured as a dash display.

EFI Troubleshooting/Tuning Tips: A Handful of Helpful EFI Techniques

Of course, if you prefer, the Sniper 2 EFI can also operate with a separate ignition like a stand-alone HEI ignition. This is often suggested as a good starting point when adding EFI to a carbureted engine. Once the EFI fuel curve is working to your satisfaction, then the ignition control can be added. This minimizes confusion when attempting to convert two control mechanisms simultaneously. The Sniper 2 is configured so even something as simple as an ancient points-triggered ignition can be used on the ignition side.

Also new for the Sniper 2 is the ability to expand wiring control with the use of the optional power distribution module (PDM). The PDM is a compact box that integrates the wiring for all the different inputs and control outputs into a simple enclosure that also offers relay control for external devices such as separate cooling fans or other switched devices. This is especially handy when using the Hyperspark ignition system but is certainly not required. Mainly, the PDM is designed to centralize wiring and their required connections. If chosen, the PDM does require its own separate wiring harness for a more simplified connection to the Sniper 2.

Among the more interesting options for the Sniper 2 is what we referenced earlier as the wireless connection where instead of using the included Sniper 2 handheld device for initial inputs and tuning changes or to monitor engine operation, you can opt for a wireless dongle (available Fall 2023) to use with either an iOS or Android smartphone.

009 The hardest part of bolting on the Sniper 2 was wiring the system into the power distribution module holley sniper 2
The hardest part of bolting on the Sniper 2 was wiring the system into the power distribution module, which was pretty easy with the instructions that walk you through the installation.

Read More: How to Transform Your Holley 3310 into a More Aggressive-Looking 4150

If you want to add a high-tech look to your Sniper 2 installation, Holley offers an optional 5-inch display screen that is large enough to be used as a supplemental dash. Plus, the screen comes with a GPS antenna that can be placed at the base of the windshield as input for the speedometer. Connecting the display is incredibly easy with a small, multi-pin CAN connector from the Sniper 2 throttle body.

We decided to test this system on a 357ci small-block Chevy we had built for dyno testing. We bolted the small-block to our Summit test stand and then began our installation. The small-block had a Holley single-plane intake manifold that allowed us to bolt the Sniper 2 directly in place of the carburetor. Electrical connections were simple using the power distribution module. It’s easy to wire the PDM backward if you are not paying attention (like we did) so make sure to orient the PDM with the 12V-plus connector at the top next to the indicator lights.

Another option available in Fall 2023 is a Sniper 2 with electronic transmission control. For GM enthusiasts, this means the Sniper 2 will be able to manage either the 4L60E or 4L80E or any of their performance variants. This offers the ability to set shift firmness, accurate shift points at both part and full throttle, as well as other details like rear tire size and gear ratios to optimize transmission operation. All of these parameters can be set using the handheld controller with no laptop required. This brings the Sniper 2 even closer to full electronic control of the entire drivetrain at an affordable price.

012 Here we’ve installed a Sniper fuel tank and 400 lph pump in our ’66 Chevelle holley sniper 2
Here we’ve installed a Sniper fuel tank and 400-lph pump in our ’66 Chevelle. There are multiple options for fuel delivery, but the important point is to have a complete system design for EFI where the fuel pressure does not fluctuate.

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We wanted to test the Hyperspark along with the Sniper 2 so that required removing the existing distributor and dropping in the Hyperspark distributor with the engine positioned at TDC on Number One cylinder. With that accomplished, we merely lined up the clear plastic cap to sit over the rotor along with lining up the distributor body notch. It took almost as much time to describe this process as it did to complete the rotor phasing.

With all the grounds and wiring connections completed through the PDM, and with power supplied to the handheld, we quickly ran through the installation using Holley Wizard software in the handheld that needs only a few simple inputs to establish base fuel and spark maps that will allow the system to start and run.

With the inputs in place, the engine started and once the coolant temperature stabilized at around 170 degrees F, we didn’t have to adjust the throttle body idle speed screw in order to achieve our commanded idle speed at 850 rpm.

We double-checked that the computer was commanding 15 degrees of initial timing at idle with our timing light. This only required a minor adjustment by loosening the distributor body and adjusting the static timing until it matched what we input in the handheld under locked timing.

014 the engine fired right up holley sniper 2
With all the wiring in place, including the Hyperspark ignition, and with the inputs completed with the Wizard installation process on the handheld, after a couple of cranks, the engine fired right up. We also checked ignition and squared that up, and the engine now runs just fine.

Refining the Ride: Suspension Upgrades for Them Ol’ Tri-Fives

The entire Holley Ecosystem with the Sniper 2 throttle body, Hyperspark ignition system, and power distribution module all worked together to create a seamless installation on our small-block. The only thing we didn’t detail in this story is the necessity of a quality in-tank fuel pump system. Holley has you covered there as well with several options for a complete new Sniper tank and pump system for many popular Chevy muscle car body styles. We’ve installed two of these Sniper tanks in cars and the results have both been successful.

The Sniper 2 should more accurately be described as a major upgrade rather than a completely new system, so for those who have been waiting to see what comes next, your time has arrived. If you’ve been thinking of converting your carbureted street cruiser to EFI, this Sniper 2 just might edge you closer to the tipping point. You don’t have to bother with changing the intake manifold and it’s very close to a bolt-on-and-go system.

Technology can be a wonderful thing.

Parts List

We’ve selected just one system for a part number example, but there are several Sniper 2 options that can be examined more closely on Holley’s website.

Description Source PN
Sniper 2 EFI system, black throttle body 550-511-3XX Summit
Power Distribution Module 554-200 Summit
Hyperspark 2 distributor, harness, coil for Sniper 2 VK020300 Summit
MSD CD box connector to Sniper 2 558-329 Summit
Sniper 2 Bluetooth dongle smart phone adapter 558-498 Summit
Sniper 2 4L60E/4L80E transmission controller 551-103 Summit
Fuel Pressure regulator, return style 12-882 Summit


Holley Performance Products
(866) 464-6553

Summit Racing
(800) 230-3030

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