Generally interpreted as an aesthetic mod, Velocity stacks are one of the most misunderstood pieces of tuning equipment. Fundamentally, Velocity stacks are long cylindrical-shaped trumpet-like air intakes. You may come across these on old muscle cars that ran on carburetors. Earlier carburetors used to spit out the air-fuel mixture which resulted in cars catching fire. The implementation of Velocity stacks helped resolve this.
Velocity stacks are not only limited to carburetors but the modern application of these can be seen on throttle bodies of fuel-injected engines. Since air and fuel are supplied individually to the engine, Velocity stacks are used to replace the ducting from the airbox and provide a cleaner (Laminar) airflow. And so we tell you why this clever tuning component is good for supercars, sports cars, and even bread-and-butter ones packing high-revving engines.
Updated July 2022: We have updated this article to give you a clearer understanding of velocity stacks and how this clever tuning component can help the high-revving engine breathe easy-and-smooth.
A Velocity Stack is a relatively inexpensive and less complex solution to get more power out of your engine.
Benefits Of High Revving Engines
Have you seen a Pagani Zonda running up Goodwood hill? Or heard of a Lexus LFA in action? These are the sort of examples that resonate with high-revving engines? A high revving motor can go closer to 9000 rpm or even more, as opposed to 6000 rpm for a regular ICE. So, why make engines rev higher? It’s simple, more power!
As torque remains fairly consistent across a given powerband, horsepower will rise as the revs do. So, when an engine is free to rev higher, it can make more power. An engine revs higher if it’s an oversquare design (bore is greater than stroke). This means the piston has a shorter distance to travel from the TDC to BDC. That said, the piston will be moving slowly as opposed to an undersquare design.
However, the piston speeds are significantly different with an oversquare engine having pistons reciprocating twice as fast as the pistons in an undersquare unit (of the same displacement). Consequently, for the piston's speeds to match the oversquare unit, the engine speeds have to be twice that of an undersquare unit. This translates to the engine revving more thereby making more power.
Apart from better power, the aural pleasures on offer are heavenly. Also, a wider bore means that engineers can make the valves larger. This can help with better airflow at higher RPMs. The Honda S2000, considered to be a future classic, revs to 9000 rpm and makes 234 horsepower. What if there is a way to increase power by simply adjusting the way air is sucked in? And the answer is Velocity stacks.
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Purpose Of Velocity Stacks On Engines
Velocity stacks are designed to increase the volumetric efficiency of an engine by allowing for more air to be sucked in whilst being able to act as a resonating pipe that adjusts the pressure pulses inside the intake plenum. In simpler terms, Velocity stacks help for smoother airflow. This, in turn, supplies more air to the engine and if there is more air, you can burn more fuel which ultimately ends in the engine making more power.
The length of a Velocity stack plays a significant role in producing efficient airflow. Velocity stacks of varying lengths are used to optimize the air intake. The intake pulses generated are utilized to create a positive pressure over the intake valve. This pressure buildup gets disrupted when the valve opens and thus leads to a larger charge of air entering the cylinder.
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Velocity Stacks On High Revving Engines
The volume of air passing through the engine is directly proportional to the engine speed. Therefore, a high-revving engine sucks in more air than a long-stroke unit. Now if you managed to own a high-revving screamer chances are that you must at some point look to make more power out of it. There are multiple ways to increase horsepower: you can have an ECU flash, have a supercharger bolted, or slap on a turbo.
While they do make significant power upgrades, they are still expensive and vastly alter engine characteristics. Velocity stacks on the other hand are relatively inexpensive and offer 3% more power while keeping most of the engine characteristics the same. In addition to this, you get induction noises that tingle your aural receptors.
The icing here is that a Velocity stack is not a highly complex engineering solution but a simple one that if done right can lead to a decent power bump at a lower cost. Through the well-revered DMS community, a member mentioned swapping a 4-inch turbo intake with a Velocity stack on one of their customer cars that made 490-wheel horsepower. After a dyno run the car made 517 WHP, that’s an improvement of close to 31 bhp with no real changes!
Sources: Wikipedia.org, Making for Motorsport Via YouTube
