Finding Real-World Gains With A Vararam Industries TCR-7 Intake

Since the dawn of hot rodding, the intake system has been one of the first areas where gearheads have looked to add more performance to their rides. The logic is obviously sound – air and fuel are the core ingredients you need in order to make power in an internal combustion engine, and the intake system dictates how much air can potentially be brought into the engine at any given moment.

In the era of carburetion, this was essentially as simple as putting on a better-breathing air cleaner and swapping out the jets, but times have changed. On a modern vehicle like the C7 Corvette, software manages the air/fuel mixture, and it’s designed to adjust parameters as needed to keep the engine happy.

But beyond tuning concerns, the reality is that the OEMs are cranking out some very well-designed powertrains these days, and swapping out factory components for aftermarket performance parts doesn’t automatically equate to more usable power. But that doesn’t mean there isn’t room for improvement in the stock C7 intake system.

Tucked into the svelte bodywork of the C7 Corvette, the 650 horsepower LT4 V8 offers some seriously potent factory performance. But Vararam discovered that Chevrolet left some performance on the table when they dropped that supercharged mill into those tight confines, and its new intake is designed to bring those lost ponies back into the mix.

“In the case of the Corvette, there’s just not enough plenum volume,” explains Patrick Ledford of Vararam Industries. “The fender area that they have in the vehicle does not support the flow capacity of the engine. They also did not allow us anything but a small hole for cool air to be introduced into the system, so we had to figure out a solution.”

For years, Vararam has specialized in designing some of the most efficient air-induction systems you’ll find anywhere. Rather than focusing on headline-grabbing peak power numbers, the company’s performance philosophy revolves around making horsepower and torque under the curve, where drivers will more often experience the benefits of the upgrade.

Its latest offering is the TCR-7, an intake designed to address the weak points of the factory design in C7 Corvettes. We sat down with Ledford to get the details on this new system and get a better understanding of how Vararam’s research and development process yields a more effective induction system.

 Out-Flowing The Competition

Ledford says that while Vararam has a well-established R&D process, the C7 induction system brought a few surprises to the table. “We found the restrictions by data logging the car like we always do,” he says. “But then we also run our own series of flow tests. We’ve got the ability to hook together three flow benches to make them into one. Doing that creates the total flow capacity of a running engine, and we can do that on a vehicle. We can close the hood and pull from it and actually see if, for instance, a fender is going to be fully capable of delivering the air needed to make 500 horsepower, 700 horsepower, or whatever an engine is supposed to be producing.”

Ledford says that the aerodynamics of the filter and the assembly itself also play a role. “A lot of people think that a big, conical filter will inherently allow for a lot of flow – it doesn’t,” he tells us. “You’ve got a situation where the height to width ratio has to be exponential in order for it to be efficient. The problem is that you just don’t have that kind of room in the engine bay.”

The TCR-7 intake is a true drop-in component – no cutting or drilling is required to install the Vararam kit on a C7. While it might not look radically different from your typical C7 cold air intake at a glance, every inch of this intake has been meticulously developed to be as efficient as possible. The intake tube features Vararam’s patented reverse venturi intake tube from the COPO race program, and the expanding tail section is designed to pull air off the walls of the tube, thereby reducing drag. A heat shield wrap is installed where the tube and air box meet in order to delay heat penetration, and on the other side of the air box, a secondary inlet draws from a high-pressure zone to add cooler air to the mix. Vararam’s design goes far beyond simply providing a bigger gulp of air, and it equates to more power throughout the powerband while staving off heat soak longer than the factory hardware.

Creating the best solution, given the real estate available, requires the consideration of multiple factors. “The biggest concerns are the plenum volume of the boxes, how the air actually travels into the filter, and how much plenum volume is behind the filter before it goes into the actual intake tubing,” he says. “These things are just general factors of breathing – the air filter acts like a control valve, and it becomes your venturi pinch point. You’re trying to accelerate air into it, and you’ve got to pull air out of it efficiently as well.”

The C7’s tight packaging presents a challenge for engineers like Ledford who’re looking to extract every ounce of potential from the platform. “They just didn’t leave us any room,” he says. “It seems pretty clear that GM is aware of that too because they’re making the fender openings larger and larger with each successive model, so the ZR1 has a much more open fender area than the Z06 does, and the Z06 has a slightly larger opening than the Stingray does. But the bottom line is that it’s still not enough to provide the physical flow that the engine wants.”

It’s no secret that making it easier for an engine to breath will yield better performance, but improving upon the extensive research and development that General Motors has invested in the Gen V engines isn’t simply a case of installing a physically larger air intake. “People don’t realize that you have to manipulate the airflow,” Ledford says. “And they also think a bigger hole is better, but that’s not the case. If you make it too big and too open, it just doesn’t pull properly – you’ve got to physically draw a vacuum from a cool air location.”

By opening up this area of the induction system and the plenum volume behind the filter, Vararam was able to introduce the flow that the LT engines were asking for. The induction system’s improved efficiency actually allows the LT4’s engine controller to ratchet up the boost on its own with no tuning or intervention required by the user. “On the Z06 we added two pounds of boost,” he explains. “And we did it by simply removing the air flow restrictions.”

Gains By Design

More boost often translates to more horsepower. “When we’re designing intakes, we typically go in and choose the highest volumetric efficiency point in the cylinder head’s flow and manipulate the airflow in that area – basically accelerate it beyond what the engine can pull,” Ledford says. “That gives us more torque and frees up the engine to accelerate quicker, so there’s more top-end power to be had as well. And we’re able to get that power without affecting drivability or requiring a custom tune. On a Z06, we’re looking at about 60 rear-wheel horsepower just by swapping in this intake and doing nothing else. With LT1s we’re guaranteeing 18-20 rwhp.”

Considering the scope of engineering behind the Vararam intake, it comes as little surprise that the company’s manufacturing processes are just as sophisticated. “With us using injection molded tooling now, the precision that we can maintain is beyond what the OEM offers,” Ledford says.

During the prototyping stage, Vararam uses a 3D printer to make a physical rendering of its design to test fitment and performance in the real world. The final product is manufactured using an injection mold that provides a level of production accuracy and overall quality that's beyond factory spec.

“The materials we use make a difference too. All of our rotational-molded materials are twice as thick as what our competitors use. By doing that we’re delaying the heat soak – it gives the air time to come through and help intercool the plastic materials themselves.”

“Vararam’s engineering efforts with the TCR-7 result in usable performance that drivers will feel behind the wheel, and that’s something that can’t be said for some of the competition,” Ledford says. “The factory intake kit actually pulls in cooler air than a lot of the aftermarket cold-air kits do,” he explains. “The data doesn’t lie. It’s often down to a couple of issues – the materials often aren’t right for what they’re doing, and at the same time, they’ve got a restriction in the system. That can cause the ECM to pull timing to compensate, whereas, with our kit, it’s actually adding timing because it has the airflow it needs and the air we’re feeding it isn’t hot.”

Although it’s an easily understood performance metric, peak power often doesn’t tell the whole story about the potential performance gain of a component. Power under the curve, where the car spends the majority of its time in the real world, is often a much more useful measurement. As the chart indicates, the Vararam intake really starts to make its presence felt in the mid-range, though it’s important to note that the gains stay fairly consistent all the way up to the fuel cutoff point, around 6,500 rpm. “Dynamic testing is what we do 99 percent of the time,” Ledford says. “The very last thing we do is put it on the dyno. We can see the boost and the manifold pressure – we have a good idea of what kind of power it will make by just doing the math.”

The factory intake kit actually pulls in cooler air than a lot of the aftermarket cold-air kits do. The data doesn’t lie. It’s often down to a couple of issues – the materials often aren’t right for what they’re doing, and at the same time, they’ve got a restriction in the system. That can cause the ECM to pull timing to compensate, whereas with our kit, it’s actually adding timing because it has the air flow it needs and the air we’re feeding it isn’t hot.

Ledford says that he’s sometimes asked why GM doesn’t design their induction systems the way Vararam does – after all, there’s horsepower being left on the table right out of the factory. “It’s called ‘Good Enough,'” he says. “A cost/benefit ratio is what it often amounts to – why would factory engineers need to worry about improving a part if they’re hitting the power numbers they want with no drivability issues? That’s often where development stops. It’s not a matter of, ‘Can we do better?’ They’ve reached their goal. That’s why the Z06 uses the exact same air filter, plenum housing, and tail box section as an LT1 car.”

Ledford says that the “pulse” of the engine is an important consideration when developing an intake. “It’s not a constant flow, so you have to manipulate volumes and velocities in different areas so you can reduce drag,” he explains. “You want to keep the velocity as high as possible. You can feed the engine all the air you want, it’s the computer you have to keep happy.”

Fortunately for enthusiasts, “good enough” won’t cut it for companies like Vararam, and C7 owners stand to benefit from that. The TCR-7 is available now for both LT1 and LT4-powered Corvettes, and Ledford says they’ll likely be able to support the new ZR1 and its LT5 right out of the gate as well.

“As far as we can tell, they didn’t change anything in the air box design versus the Z06,” Ledford tells us. “We have an LT5 air box en route to us right now just so we can double-check to make sure the CAD file we have is identical to the final product that Chevrolet is using. But as far as we can tell, there’s no difference.”

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About the author

Bradley Iger

Lover of noisy cars, noisy music, and noisy bulldogs, Brad can often be found flogging something expensive along the twisting tarmac of the Angeles Forest.
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