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The Vortech V-3 Si-Trim supercharger makes 6.4 Hemi magic


Written by Jason Reiss

Photography by the Author and courtesy of Vortech Superchargers

There is no secret in the automotive community regarding the performance capabilities of the centrifugal superchargers manufactured by Vortech Superchargers. The company has been whipping up gear-driven centrifugal supercharger units for the better part of three decades.

Although the company made its name with Ford’s Fox-body Mustang, founder Jim Middlebrook and his team took their collective talents and applied them across the landscape of modern performance cars to provide reliable and powerful performance increases to many late-model vehicles. The subject of today’s discussion is the 6.4-liter Hemi engine under the hood of the 2018 Dodge Challenger, boosted with authority by one of Vortech’s V-3 Si-Trim superchargers.

There are two ways you can buy a Vortech supercharger kit for the Challenger —complete, or as one of Vortech’s well-known Tuner-style kits. The latter systems omit the ECM calibration and fuel components so that the builder/tuner can select the best setup to suit the needs of a particular build.

No matter which version of the Challenger you have (manual trans or automatic), you’ll want to follow along with Vortech’s incredible detailed installation guide. It’s available on the company’s website if you’d like to look it over before purchase. Don’t be afraid of the many steps; it’s this attention to detail that will help you install the kit seamlessly and have you up to speed in no time. Ellis says a solid weekend wrenching with a couple of buddies, but you’ll want to get the processor shipped out to Livernois ASAP to have it unlocked, to ensure you’re ready to go when the install is complete. The front fascia needs to be removed for access to the bumper area for intercooler and charge pipe installation.

Here we’re primarily discussing the complete kit, although we have some dyno results from a build that utilized one of the tuner kits calibrated by a well-known tuner on the East Coast.

The V-3 Si-Trim supercharger is Vortech’s most popular unit, and for a good reason: it’s capable of achieving 775 horsepower and 26 psi boost pressure while remaining well-mannered under the hood of a street car. With its self-contained internal lubrication system and helical-cut gears, the Si-Trim reaches 78-percent peak efficiency in Vortech’s test laboratory, which utilizes the SAE’s J1723 testing standards.

Vortech supplies a drill guide to use to mark the correct position for the harmonic damper dowel pin you’ll install. A right-angle drill is important here, as installing this pin ensures the damper can’t spin on the crankshaft. The factory does not use a traditional key, so this step is important.
Hellcat fuel injectors are supplied in the complete kit to ensure adequate fueling capabilities. These are plug-and-play for all Hemi cars and flow 600 cc per minute.The testing specifies a standard basis for supercharger efficiency rating, reference inlet air supply test conditions, a method for correcting observed efficiency to standard conditions, a method for presenting test results in an accurate and usable way, and a method to compare superchargers without the effects of engine dynamics and intercooling.

There are strict requirements for the laboratory equipment, testing accuracy, conditions, and presentation of the results. We could go on and describe some of the engineer-speak that’s involved in executing the proper testing, but let’s rest assured that Vortech is testing its superchargers using these standards to ensure they meet performance goals.

Follow along with the captions for some of the installation highlights and read on for the details of why this system is groundbreaking.

Vortech’s MaxFlow plug-and-play fuel pump voltage booster plugs right into the factory fuel pump connector for simple installation. Think of it as an amplifier for your fuel pump — it ensures the juice is there to support extra fuel volume when the loud pedal is pressed.

Overcoming Challenges

The 6.4-liter SRT Hemi engine found in the engine bay of several of Dodge’s performance cars is an excellent platform for performance; its 392 cubic-inch displacement is on the larger side for a production V8, with 485 horsepower and 475 lb-ft of torque available for motivation in factory trim. With a 4.090-inch bore, 3.720-inch stroke, and 10.9:1 compression, the 6.4-liter Hemi takes full advantage of the most important feature of these engines: the deep-breathing, twin-plug cylinder heads that feature Dodge’s signature hemispherical combustion chambers.

“The piston design does not allow for even the slightest error, which is why we took two-and-a-half years to perfect our production tune. It literally cannot be stressed strongly enough — the tune is everything on these cars,” Vortech’s Brian Ellis explained.

Further discussion with Ellis reveals that the Hemi’s cast pistons — which feature a ring land that’s located right at the top of the piston — won’t tolerate boost if the calibration is not spot-on.

“If there’s any detonation at all, the whole top of the piston comes off,” says Ellis.

In anticipation of customers stepping up their engine combinations over time, Vortech provides an air-to-water charge cooler that mounts to the bumper and is capable of cooling enough boost to make 1,000 horsepower.

Calibration Is Key

Back in 2009, Dodge started locking the PCM with encryption on some of their models, which meant that a new tune file couldn’t be loaded consistently. The difficulty of working with this configuration pushed Vortech to step away from building kits for the Hemi platforms for several years because the PCM just couldn’t be flashed properly for a production-level supercharger kit format.

Not coincidentally, there is one crucial caveat to the Hemi’s operation: when it’s equipped with a supercharger and power is boosted significantly, you must pay careful attention to the engine tune. That last part hasn’t always been a workable process, though. Reliability and durability were the chief concerns when it came to the development of the system; Vortech has built its reputation for street-style superchargers upon those tenets and the 6.4 Hemi kit is no different. It is no secret that the Gen III Hemi in boosted form is no picnic to calibrate properly.

Vortech supplies a thick heat exchanger core and water pump to keep the intake air-charge temperatures consistent no matter what type of ambient conditions exist. The use of a Hellcat surge tank completes the installation and ensures that OE-type appearance.

So, to maximize the performance of the Hemi platform when equipped with the V-3 Si-Trim supercharger, Vortech’s engineers worked countless hours to develop its out of the box, 50-state-legal tune, which produces a whopping 730 horsepower and 645 lb-ft of torque at the crankshaft, using 7 pounds of boost pressure.

Although at first glance the Si-Trim blower might seem small for this particular engine combination, he says it’s perfectly matched to produce the most reliable and safe maximum horsepower suited for the factory stock engine. For those guys who eventually decide it’s time for a built engine with forged pistons and the like,  the charge cooler will support 1,000 horsepower, while the bracketry will hold most of Vortech’s head units, up to and including the YSi-B, which is capable of far more performance than the Si-Trim blower included with the kit.

Vortech’s design team worked diligently to keep the charge cooler and its attendant inlet and discharge tubes routed cleanly behind the bumper. Not shown is the Vortech Maxflow Race BOV blowoff valve, which offers billet construction and a compact design.

According to Ellis, there’s more to consider.

“In addition to having the PCM unlocked, what’s significant about our kit is that it has the capability of tuning properly for the boost. The current software out there, any of the main names that you know, they have the capability of tuning just fine for naturally aspirated vehicles, but none of them even have the parameters available to them to create a safe, ‘out-of-the-box’ tune file for boost. Virtually every other ‘complete’ forced-induction kit out there is band-aiding the tune. They turn the knock sensors completely off or dumb them down to the point that they don’t see any knock, and with the ring land right at the top of the piston, there is no limp mode. Your first notification of a problem is a blown engine, which is unacceptable,” he emphasized.

To keep the packaging nice and tight to the engine, Vortech’s engineers decided to use a crankshaft-driven jackshaft assembly on the mounting bracket. It’s basically a pass-through pulley supported by a bearing at the bracket. Driven by a serpentine belt on the front side, it allows the supercharger to be mounted with its pulley at the rear of the blower and be spun by a cog-belt-drive configuration.

The system is calibrated to make 7 psi of boost pressure. With forged pistons, one can run more, but in factory configuration with 91-octane fuel (the best you can get in California), that’s about all you can get safely. When the Vortech team performed its research, 7 psi was determined as the safe limit on a stock engine with the supplied tune. With good, 93-octane fuel, maybe 8 psi is the absolute limit, according to Ellis.

Since Vortech’s calibration team was able to dig into the PCM software and unlock several more calibration tables, they can tune nearly on the same level as the OEM, with all of the factory safeguards in place to ensure the engine remains tuned safely. With help from Dan Millen and his team from Livernois Motorsports, Vortech was able to provide a complete tuning solution that is simple for the end user.

“We didn’t just accept what was available and go with that. We made it so that it was safe to our specifications, and until it was capable of being done, we just didn’t do it. It took a long time and a lot of painstaking research and development, and we’re super proud of the product. They work, they’re safe, and it’s up to the standard that people would expect from Vortech,” says Ellis.

The tried-and-true cog drive means there won’t be any belt slippage at the blower side. Additionally, Vortech supplies the unit with a preinstalled drain hose to make supercharger oil changes easy.
Here, we can see the supercharger in place with the secondary drive system. It’s an ingenious way to minimize the footprint of the installed system.
Vortech supplies the necessary cable to install the tune once you receive the processor back from Livernois Motorsports.
Vortech also dropped a photo on us showing the system installed on a Challenger with the Shaker hood. Although there are subtle differences during the installation process, you Shaker owners should not fear the Vortech boost.
These dyno results are from High Horse Performance, one of the few shops that can provide an accurate dyno tune for the Hemi cars. HHP is so well-known that people ship cars from all over the country to have the HHP team work its magic. On a 93-octane tune-up, HHP squeezed out 641.19 horsepower and 553.58 lb-ft at the tires, or about 20 horsepower more than the factory 91-octane tune, factoring in a typical 15-percent drivetrain loss. Keep in mind that the factory-supplied tune makes 730 horsepower and 645 lb-ft at the crankshaft, which comes out to about 620 horsepower at the tires. More importantly, the Vortech added 174.2 horsepower at the tires. Stout numbers for sure!


High Horse Performance

(888) 894-1115


Vortech Superchargers

(805) 247-0669