What is Turbo Lag & Turbo Spool? (& How to Prevent it)

If you are interested in performance cars, you have probably heard of both turbo spool and turbo lag. But what is the difference and what is it? Let's find out!

Turbocharger

If you’re new to owning a turbocharged vehicle, two terms you’re going to have to get used to are turbo lag and turbo spool. But while these two terms often get used in the same conversation, they’re completely different things.

In this guide, we’ll walk you through everything you need to know about both terms and give you some helpful tips on how you can reduce both, but chances are you’ll only want to reduce one! Don’t believe us? Just keep reading. 

What Is Turbo Lag?

Turbo lag refers to the difference in time between when you press the accelerator when the turbo kicks and delivers extra air to your engine.

Understanding why turbo lag exists requires a quick lesson on how turbos work. Turbos work by taking energy from the exhaust with an exhaust impeller and then transferring it to build pressure into the intake pipes with an impeller on the intake side. This extra air increases the amount of power that your vehicle can produce.

But since it is quite a big area to build pressure into the intake pipes, it takes a little time to give you the power output you’re looking for. This lag time is called turbo lag.

How Can You Reduce Turbo Lag?

Turbo Spool

While you might be thinking you can’t reduce turbo lag since you’re dependent on the vehicle increasing the amount of exhaust before it can effectively use it, you’d be wrong. While it’s impossible to eliminate turbo lag completely, it’s not impossible to reduce it.

That’s because your turbo system isn’t 100 percent efficient, and the more efficient you make it, the less turbo lag you’ll have. Below we’ve highlighted three different ways you can reduce turbo lag.

1. Downsize Your Exhaust Downpipe

If you’re decreasing your exhausts downpipe, you’re going to decrease your turbo lag, but the tradeoff is that you’re going to reduce your top-end horsepower too. That’s because a smaller downpipe increases the speed of the exhaust, which increases your turbo spooling.

While this increases how quickly the turbo can spool, it also decreases overall airflow, which reduces overall turbo effectiveness. You’ll have to find a balance somewhere, but if you have an excessive amount of turbo lag, this can be an effective way to reduce it.

2. Upgrade Your Blow-Off Valve

Upgrading your blow-off valve is all about improving the effectiveness of your turbo. An upgraded blow-off valve gives you a more responsive unit, decreasing turbo lag and giving you a more effective turbo.

However, you might end up increasing the overall amount of noise that your blow-off valve creates. This might not be a big deal to you, but just know that it’s a possibility. Furthermore, know that this is not going to be as effective as downsizing your exhaust downpipe.

3. Upgrade Your Intercooler

The shorter the distance between your exhaust and your turbo, the less turbo lag you’ll have. Some units prioritize the shortest possible pipes over everything else, and if you opt for one of these units, you’ll reduce the amount of turbo lag that you’ll have.

Just know that while there are no downsides to upgrading your intercooler and piping, you’re not likely to see significant results when it comes to turbo lag. Instead, you’ll shave hundredths to tenths of a second off your turbo lag time.

What Is Turbo Spool?

Turbocharger

Turbo spool is the time it takes from when the turbo starts building pressure until it reaches full pressure. As you might figure out, it is therefore very different compared to the turbo lag – the turbo lag is when you press the accelerator pedal until it starts creating power.

Also, the turbo spool is determined by the size of the engine and the turbocharger. It can also be increased with things as an improved turbo impeller, for example.

Summary

Turbo lag and turbo spool are two extremely different terms that you need to be aware of if you drive a turbocharged vehicle.

The good news is that if you’re looking to reduce turbo lag, you have a few options, just know that you’re never going to eliminate it.

Still have questions?

Ask any car question in our new community!

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.