My interpretation of how a turbo works

[mr_wizard]

I've read SEVERAL resources on how a turbo works exactly. This is my interpretation of how it works, please tell me if it's right.

When a car accelerates, obviously it produces exhaust. With a turbo setup, when that exhaust leaves the motor and goes into the exhaust manifold, the turbo (or turbine) attached to it spins up, thus the compressor attached by the spinning shaft also spins up and causes a compression of the air (the remaining exhaust goes down the downpipe and out the exhaust). Now, since the air is hot from all of this, that compressed air needs to go from the compressor straight through an Intercooler (which I use to think was the same thing as a radiator, guess I was wrong), which is basically an add-on to the radiator (the intercooler cools the compressed air and sits behind the radiator). And from there, I don't know.

Where does that compressed cooled air go? Does it somehow connect to the side of your intake, that then goes to your motor somewhere, or what?

Also, the wastegate is also called a "BOV" right? I know a waste gate opens up and lets some of the exhaust back-pressure bypass the turbo and into the catback exhaust after there's too much boost going into the turbo to prevent it from over boosting.

But I have a feeling a BOV is different and NOT the same thing as the wastegate just because that release some other pressure every time you "shift"?

Few other facts I know. Since more air molecules are being force inducted into your motor, the motor needs more fuel. Sometimes, if the boost is high enough, you will need better fuel injectors.

So off the top of my head, pieces needed for say a 10 psi turbo set up are:

Turbo compressorTurbo turbineexhaust manifold that will fit your turbointercoolerpiping from compressor to intercoolerpiping from intercooler to....?wastegate or BOV to release pressurefuel injectors if you have high boostboost gauges if you want, but not necessary

Thanks for all your help guys. I'm doing a turbo setup in the near future, I'm just hoping I can learn exactly how it works so maybe I can do it myself rather than pay someone 500+ to install and tune it.

[1995240sxSE]

wow dude right ball park but u need to research a complete turbo setup and research each part! I am by no means a turbo expert and I would love to read this post in a day or two! There should be a LOT of good info rolling through in here!!!

[wild_maxx]

the FMIC (front mount intercooler) is kidna like a radiator for air... it sits in front of the rad. usually in the lower bumper area of a car to get cold air running thro the fins to cool the intake charge.

After the FMIC cools the air it travels thro the "cold pipe" into the intake phlenum then into each intake running while mixing with fuel and then combusting in the cylinders.

A wastegate and a blow off valve are 2 different things

BOV = to relase pressurized intercooler pipes once the TB (throttle body) closes. It does this to prevent compressor surge and damaging the turbo.

A wastegate is used to control boost levels.

[TheOne]

http://auto.howstuffworks.com/turbo.htm <<good starting point on learnin what and how a turbocharger works.

http://www.turbomustangs.com/turbotech/main.htm <<a bit of the same + some tips.

[C-Kwik]

I've read SEVERAL resources on how a turbo works exactly. This is my interpretation of how it works, please tell me if it's right.

When a car accelerates, obviously it produces exhaust. With a turbo setup, when that exhaust leaves the motor and goes into the exhaust manifold, the turbo (or turbine) attached to it spins up, thus the compressor attached by the spinning shaft also spins up and causes a compression of the air (the remaining exhaust goes down the downpipe and out the exhaust). Now, since the air is hot from all of this, that compressed air needs to go from the compressor straight through an Intercooler (which I use to think was the same thing as a radiator, guess I was wrong), which is basically an add-on to the radiator (the intercooler cools the compressed air and sits behind the radiator). And from there, I don't know.

I'm a bit confused as to how your describing it. Almost sounds like you are thinking the exhaust gasses are compressed and put back through the intake. If you are, then it's wrong. If not, then this is just clarification. The intercooler is designed to cool the compressed intake air as compressing air increases it's temperature. Cooling it gives you denser air(more oxygen) and helps reduce the propensity for a mixture to detonate.

Where does that compressed cooled air go? Does it somehow connect to the side of your intake, that then goes to your motor somewhere, or what?

The compressor is actually going to be in the intake stream. The intake piping between the compressor and the intake manifold must be essentially sealed so that the pressure does not escape.

Also, the wastegate is also called a "BOV" right? I know a waste gate opens up and lets some of the exhaust back-pressure bypass the turbo and into the catback exhaust after there's too much boost going into the turbo to prevent it from over boosting.

Wastegate and BOV are very different. A wastegate is designed to control boost by diverting air around the turbine as you reach a set boost level. Without it, a turbo will continue to increase boost level until something gives or the engine can no longer put out anymore airflow through the turbine. On any typical turbo, this will likely be well beyond any safe boost level for a typical motor. A BOV or blow-off valve is a device that lets air out of the pressurized intake piping when you close the throttle under boost. This is to prevent compressor surge. Surge occurs when there is too much pressure and not enough airflow. This can seriously damage the turbo if it is too severe or occurs too much. The BOV also opens(perhaps partially) during part throttle when vacuum is present in the manifold and pressure in the intake. It is also preventing surge during this time. While you can control boost with a BOV-like device, it's not recommended. A wastegate works by allowing the turbo to extract only as much power as needed to produce the boost and airflow the motor needs. Releasing intake air as a method of reducing boost means the turbine is actually using all the energy it can out of the exhaust. This means higher backpressure than is needed for the boost and airlfow you want. It would also cause less efficient air compression as the compressor would heat the air as such as it needs to produce the actual boost produces at the compressor. Some of the heat would be lost as the pressure is released, being that the compressing process is not 100% as it is, you'ld end up ultimately with more heat than is needed(more work for the intercooler). It would also make turbo sizing much more complicated as well as you'lds need to maximize efficiency for a turbo that is not wastegated. The short of it is, don't bother with boost control methods that work on the intake.

Few other facts I know. Since more air molecules are being force inducted into your motor, the motor needs more fuel. Sometimes, if the boost is high enough, you will need better fuel injectors.

Not necessarily better, but perhaps bigger. Just need to make sure you can provide enough fuel. You'll also need a way to control or compensate for the larger injectors(remapped ECU, stand-alone ECU, piggy-back ECU, hacked MAF. On a KA, you'll be getting real lean beyond 4-5 psi with stock injectors.

So off the top of my head, pieces needed for say a 10 psi turbo set up are:

Turbo compressorTurbo turbineexhaust manifold that will fit your turbointercoolerpiping from compressor to intercoolerpiping from intercooler to....?wastegate or BOV to release pressurefuel injectors if you have high boostboost gauges if you want, but not necessary

Thanks for all your help guys. I'm doing a turbo setup in the near future, I'm just hoping I can learn exactly how it works so maybe I can do it myself rather than pay someone 500+ to install and tune it.

Turbo(turbine and compressor are part of the same unit)Manifold that will fit yor motor and turboFMU or larger injectors with approprtiate compensations for the larger injectors.Piping from turbo to intercoolr then from intercooler to throttle body.Wastegate 'and' BOVoil lines to and from turbo.

this is a bit rushed as I have to get going. If you have questions, ask away and either I or any of the other knoledgable people here will answer...

[nismofly]

depends on the size of the turbo you want to run 10 psi on, anything more than like a t3 and youll probably be close to needing z32 mafs, definately need injectors (fmu ftl)

[fabio420]

To clarify, the air going into the engine is being blown in by the compressor side of the turbo, and it fresh air coming from the intake of the compressor, minimal ehxaust gases go back into the engine, if any, the ehxaust gases just spin the turbine and go out the downpipe.

[mr_wizard]

Awesome! Thanks for the info guys. It all makes sense now. I talked with a couple people on AIM for awhile about it as well which really helped. I'm just not sure where the BOV would hook up? I know it would have to be between the compressor and throttle body since that's where the reverse pressure would be?

[nismofly]

i think most people do it on the pipe between the intercooler and throttle body, commonly known as the "cold pipe"

[KATwo40]

If you mount the BOV on the cold pipe, throttle response is better, but greater potential for surge exists because the compressed air must exit the intercooler piping from the compressor all the way to the throttle body. Factor in the pressure drop created by the intercooler and you'll find that a considerable amount of air still chooses to go out the compressor, rather than the BOV, thus creating a small amount of surge. My setup is this way and I don't like it. Unless I slowly lift off the throttle, I still get surge.

Mounting on the hot pipe reduces some throttle response, but the surge is cut down. Also, most of the air escaping on the hotside is...well, hot. One might conclude that purging that hot air puts you one step ahead in reducing intake air temps.

As for the turbocharger and it's theory, I'd like to recommend that you hit http://www.amazon.com and purchase a copy of Corky Bell's "Maximum Boost." It explains turbocharger theory and application for the beginner quite in depth. You'll not only understand the process, but you'll have some applicable knowledge and be able to make the appropriate selections of turbocharger, intercooler, manifold, etc. Some of Mr. Bell's theories I don't completely agree with, but for the most part, it's definitely worth the $20 for the book.

[Chezedik]

It would. It is called evaporative cooling. Caused by a pressurized 'whatever' becoming depressurized (and usually evaporating, but not in this case), this spreads the quantity of heat in the air, and lowers the intensity (temperature). This is how your AC system works, for those of you who still have it. Of course, this is kind of a moot point since the adiabatic process will reheat the air charge as it is compressed. Oh yeah, BTW most of the increased air charge temps are not from transferring heat from turbine to compressor, but simply by compressing the air.

[crzycav86]

Props for being brave enough to start a totally newb post. We were all there before though.

Looks like you've been set straight though.

[sunnys14]

everyone was a noob once...

[iwantawd]

http://www.turbobygarrett.com/....html

[MarkEmark]

Anyone else detect a hint of irony that the posters name is "Mr. Wizard" ?!?!?

hahah...just kidding, glad you've been set straight

[Nismo_Freak]

[white90esex]

Let me throw in my two cents!

OK. Lets start at the intake filter.....

Air comes through there, goes through the MAF (mass air flow sensor) then into the intake of the turbo. It then travels its way through the intercooler tubing (aka hard pipes, hot pipes, cold pipes, and other things... dont use PVC) It then travels into your intercooler then out. Goes past the BOV wich then goes through the throttle body then in to the intake mani.

Alittle after getting mixed with fuel and combusted into a gas it exits the motor spining the exhaust turbine on its way out. It goes past the Wastegate and out the exhaust.

To let you know, the BOV must be connected to the intake manifold after the throttle body. This is to lift the piston to release the air in the pipes. It does that because there is a vacuum caused by your throttle body closing and your engine trying to suck wich causes the vacuum.

The wastegate in my case is controlled by a spring with certain amounts of pressure on them. Once the exhaust exits the motor it has alot of pressure and if the spring is set a 5lbs then it will release at that.

FMIC will cool like a radiator for air.

You must run an oil line to your turbo wich is easy.

Cant think of anything else..... Its all really simple

[partymonster 975]

http://auto.howstuffworks.com/turbo.htm <<good starting point on learnin what and how a turbocharger works.

http://www.turbomustangs.com/turbotech/main.htm <<a bit of the same + some tips.

Trust this, how stuff works is an awsome site!

[scarboroughdub]

[Chezedik]

The wastegate in my case is controlled by a spring with certain amounts of pressure on them. Once the exhaust exits the motor it has alot of pressure and if the spring is set a 5lbs then it will release at that.

No, your wastegate opens when there is enough boost pressure to overcome the spring, not from exhaust pressure.