Turbochargers have revolutionized how engines produce power by forcing more air into the engine, increasing combustion and boosting performance. However, if you’re new to turbocharged vehicles, you may not be familiar with the terms “turbo spool” and “turbo lag”. While these terms are often used in the same conversation, they’re completely different concepts. So, what is turbo spool, and how is it related to turbo lag?
In this article, we’ll walk you through everything you need to know regarding turbo spool and its profound impact on your engine’s performance. Discover how it works, what affects its speed, and how to optimize it for maximum, powerful boosts!
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What Is Turbo Spool?
The term “turbo spool” refers to the process of the turbocharger “spooling up”—the time frame in which the turbo starts building pressure until it reaches the point where it can deliver full boost pressure for optimal performance. The spool is often determined by the size of the engine and the turbocharger itself but can be increased with modifications such as an improved turbo impeller.
But is turbo spool bad? The turbo spool is a necessary procedure in turbocharged engines and is not bad. For those looking to upgrade or replace either turbo, we have a range of options available; explore various turbo chargers for sale that cater to different needs and engine specifications.
Relation to turbo lag
A time delay occurs between pressing the accelerator and the time when the turbo delivers the target pressure and performance. When you press the throttle, the blades inside these pressure-generating devices can take a second or two to spin up fast enough to create enough pressure.
That is called “turbo lag.” Essentially, the turbo spool is a phase within the overall turbo lag time but not the lag itself.
How Turbo Spool Works
Turbo spools involve several steps. Exhaust gasses are taken with an exhaust impeller and then transferred into the intake pipes to build pressure. This spins the turbine faster and increases air intake pressure, maximizing your vehicle's power.
Ultimately, the turbo relies on this exhaust pressure to reach critical RPM (revolutions per minute) to generate a significant boost. This means that the turbine must spin at extremely high speeds—often between 80,000 and 200,000 RPM.
As the turbine accelerates, the car produces a distinctive sound, commonly referred to as the “spool sound” or “turbo whine.” The faster it spins, the more pronounced the sound becomes.
Factors Affecting Turbo Spool Speed
Several factors can affect turbo spool speed, from turbo size and compressor design to the weight of the rotating parts and exhaust flow. Here is a detailed overview:
Turbo size
The size of the turbocharger itself is the most decisive factor that affects spool speed. For instance, smaller turbos produce spool-up time faster, offering a quick response.
However, the expense for this is high-end performance, as their boost capacity is usually less powerful. As opposed, a bigger turbo will have the ability to generate a lot more power, but the turbo lag is often more pronounced as it takes extra time to spool up.
Compressor design
The next factor that can have a significant toll on turbo spool speed is the shape and aerodynamics of the turbo compressor. This directly impacts how efficiently the turbo can draw in and compress air.
Modern, high-end compressor designs often feature extended-tip or billet wheels, increasing the airflow while reducing resistance. This allows for much faster turbo spool times and more efficient boost pressure generation.
Weight of rotating parts
Oftentimes, high-performance turbos feature premium blades crafted from lightweight materials to reduce inertia. This allows the blades to accelerate quicker and respond faster to changes in exhaust pressure, significantly reducing turbo lag and optimizing boost pressure.
Conversely, heavier rotating blades require more energy to start spinning. This can result in slower turbo spool times.
Exhaust flow
Another factor contributing to spool time is exhaust flow. The smoother the flow, the faster the turbine spins. Any restrictions in the exhaust system can slow down the turbo spool, delaying the time until the turbo can reach full boost pressure.
Boost pressure developed
The level of boost pressure that a turbo is designed to produce is another influencer to spool times. Similarly to the turbo size, turbos set for higher boost levels may require more time to build up the necessary airflow, exhaust energy, and reach target pressure. In contrast, turbos designed for moderate boost typically achieve spool faster.
Troubleshooting Common Issues With Slow Turbo Spool
If you experience spool times slowing down unexpectedly, several underlying issues could cause this problem. First, you need to troubleshoot common mechanical issues. These include damaged rotating blades, intake leaks, worn-off bearings, and bad tuning, which can impact the turbo’s efficiency and increase spool times.
Furthermore, a bad wastegate is a common problem you must look out for. If the gate valve isn’t fully seated, it could cause turbo lag.
Apart from this, double-check your exhaust manifold gasket for leaks. A leak before the turbo will reduce the pressure, slowing down the turbo spool. While leaks further down the exhaust usually have less impact on boost pressure, they may still affect performance.
Improving Turbo Spool Time
There are several ways to deal with slow spool times. Here’s how to make a diesel turbo spool faster:
- Retune the engine - Faulty ignition timings require proper tuning to make the turbo spool work normally.
- Repair faulty parts - Get a professional to work on necessary repairs to optimize your vehicle.
- Upgrade blow-off valve and intercooler - These modifications create a shorter distance between your exhaust and your turbo, giving you a faster response and less turbo lag.
- Set up an anti-lag function - If you want to reduce spool times to the absolute minimum, consider setting up an anti-lag function.
Source: shutterstock.com / Photo Contributor: Scharfsinn
Conclusion
While often conflated, turbo spool and turbo lag are completely different concepts. Turbo lag refers to the physical process of the turbo spinning up to produce a boost, whereas turbo lag is the delay between pressing the accelerator and the turbo providing power.
A good understanding of what is turbo spool, how it works, and the factors affecting it can help you fine-tune your vehicle, contributing to better power delivery and better driving experience. With this knowledge, you can confidently make smarter modification choices and maintain your engine’s health over time.
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