How Turbochargers Work

By Staff Writer
Jan 22, 2023 | Turbocharging | Posted in Drivetrain , Exhaust | From the Nov. 2012 issue | Never miss an article

The standard internal combustion engine’s operation is good, but it could be better. While the pistons’ intake strokes do draw air into the combustion chamber, that process is limited by the ambient air pressure. 

Now if that intake charge could be fortified—say compressed so there’s more oxygen included—then the engine’s volumetric efficiency could be greatly improved. Increased volumetric efficiency equals increased engine output. That’s where the turbocharger comes in.

The turbocharger features a pair of turbine fans contained inside a housing. The fans are connected by an axial shaft. As the energy from the exhaust stream spins one fan, the other fan compresses the intake charge. This increases its air pressure and ultimately delivers more oxygen into the engine. 

The result is often referred to as boost, the increase in pressure above normal atmospheric pressure—usually 14.7 psi. However, getting this system to work properly has taken some time and development, as several hurdles had to be overcome.

Intake Charge Heat:

While delivering a compressed intake charge helps performance, the actual compression process heats that same intake charge. Hot air doesn’t help performance.

A common solution has been the intercooler, a device that helps the compressed intake charge shed heat. However, fitting an intercooler to the intake stream can provide its own issues, like delayed throttle response, packaging issues and pressure drops.

Throttle Response:

The naturally aspirated engine’s intake system can be relatively simple. Look at a row of side-draft Webers, and it’s fairly easy to see how the intake charge has a straight shot right into the combustion chambers. The result is near-telepathic throttle response.

With a turbocharged engine, things aren’t always so instant. Between the compression process itself and the intake air’s trip through the intercooler, throttle response can be a bit laggy. On the street, this can be an inconvenience. On the track, a delay in the application of power can send a car off the track and into the weeds. Cures have included better turbocharger designs, improved engine management and more efficient intake systems.


Adding a turbocharger to an engine creates several packing issues, as there is a lot of new equipment to fit under the engine—not only the turbo(s) themselves, but the intake and exhaust plumbing, and oil and coolant for lubricating and cooling the turbos’ bearing sections. The turbocharger also creates lots of heat, requiring appropriate thermal management, such as ventilation and insulation. 

While today’s engineers do a great job regarding equipment placement, many past turbocharged cars were dogged by cooked underhood components and horrible service procedures.


Too much of a good thing can be bad. While increasing the intake charge helps performance, too much air pressure can damage the engine. The wastegate was developed to limit the amount of boost seen inside the cylinders.

This boost also can lead to detonation, as it causes the fuel to prematurely combust. Recent improvements in fuel quality, ignition control and engine management have greatly reduced this problem.

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View comments on the GRM forums
pinchvalve GRM+ Memberand MegaDork
1/26/18 12:44 p.m.

Cliff's Notes: Magic whirly-thing uses air to make fast-fast.  

MazdaFace HalfDork
1/26/18 12:47 p.m.
pinchvalve said:

Cliff's Notes: Magic whirly-thing uses air to make fast-fast.  

Probably my favorite post in literally ever.

Bobcougarzillameister MegaDork
1/26/18 12:54 p.m.

In reply to pinchvalve :

I thought there was unicorn dust sprinkled on the blades.

NickD UltraDork
1/26/18 1:47 p.m.

This hasn't been posted yet? Ya'll are slacking

Trans_Maro PowerDork
1/26/18 1:59 p.m.

Can cause danger to manifold which makes your floorboards fall out.

sleepyhead GRM+ Memberand HalfDork
1/26/18 2:45 p.m.

In reply to Trans_Maro :

I thought that's what happens when you spray the NAWS too soon?

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
1/26/18 3:16 p.m.

Here's how they work on rotaries.

te72 New Reader
1/27/18 1:18 p.m.

In reply to Keith Tanner :

Wish you weren't so right... they're so much fun while they last.

Fueled by Caffeine
Fueled by Caffeine MegaDork
1/27/18 1:55 p.m.

ohh... snail shaped pre muffler

scottdownsouth Reader
1/27/18 2:43 p.m.

More boost Scotty ! we still have head gaskets and no knocking sounds !

JoeyM Mod Squad
3/19/20 12:03 p.m.
NickD said:

This hasn't been posted yet? Ya'll are slacking

You beat me to it.  I came here to add this:


JoeyM Mod Squad
3/19/20 12:06 p.m.
Trans_Maro said:

Can cause danger to manifold which makes your floorboards fall out.

I thought you had to push the little red button to do that.  Isn't that the 'floor ejector' button?

1SlowVW Reader
3/19/20 12:08 p.m.
Fueled by Caffeine said:

ohh... snail shaped pre muffler

Told someone the other day that mine was a smog pump.

ShawnG UltimaDork
3/19/20 1:51 p.m.

So sad that the forum post this came from has been deleted, some people will remember:

3/19/20 2:12 p.m.

In reply to Trans_Maro :So.... You're telling me my Mom's 74 Ford Pinto had a TURBO??  Way to go Mom!  And I just thought she had the optional Flintstone brakes (hidden under the plywood)!!!


slowbird Dork
3/19/20 4:44 p.m.

In reply to ShawnG :

Every so often I remember that drawing and laugh. One of my oldest internet memories.

03Panther Reader
3/21/20 1:47 a.m.
pinchvalve said:

Cliff's Notes: Magic whirly-thing uses air to make fast-fast.  

You're not in traffic, you are traffic.

I like that!

ShawnG UltimaDork
3/21/20 9:24 a.m.
GabiJohnson said:

Told someone the other day that mine was a smog pump.

Came up with that all by yourself? cheeky

dean1484 GRM+ Memberand MegaDork
3/21/20 9:24 a.m.

Guess that means I have twin smog pumps

dean1484 GRM+ Memberand MegaDork
3/21/20 9:40 a.m.

It is interesting how things have evolved. Turbo use to I mply Performance but now it is a key part of making cars much more economical.  My Biturbo 4matic CLS 550 has been averaging a shade over 30 mpg. The ford eco boost was instrumental in changing turbos association from performance to economy. 

A 401 CJ
A 401 CJ GRM+ Memberand SuperDork
3/7/21 5:32 p.m.

In a nutshell, it makes more power because it enables you to burn more fuel.  The rest is marketing.

WebFootSTi None
6/12/22 4:20 p.m.

LOL to all the boys and girls from a guy who drives an STi...

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