Turbos and boost - Subaru WRX Forum
 
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#1 Old 01-05-2004, 12:29 PM
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Turbos and boost

I have read a bunch of articles on how turbos work, and I can understand the theories behind it, but not really HOW its working. When you increase boost are you building up more speed in the turbine, which compresses the incoming air more? The higher the boost, the more the compression? Also what is a turbo doing at below its spooled level? Does air just go through it w/o any compression? And then when it hits its spool level it starts compressing the air to whatever level and then you get the additional hp? I got "Training WRX 2nd ed" in the mail the other day and have started reading through it. Great read so far but for every question it answers three more take its place
Thanks for any info!
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#2 Old 01-06-2004, 07:45 PM
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"A turbocharger consists of two main components - the compressor section and the turbine section. These are also sometimes called the cold and hot side or intake and exhaust sides. The sections look similar; both have housings with an inlet/outlet for gas and have a fan-type structure inside.

The fan blades of the compressor side and the turbine side and connected by a common shaft, therefore, when one side turns, so does the other.

The turbine section is mounted to the exhaust manifold, where exhaust exits the engine on its way out to kill birds and cause acid rain and the greenhouse effect. As the exhaust exits, if a turbocharger is in place, the hot gas spins the turbine wheel.

Because the turbine wheel and compressor wheels are connected, the compressor wheel also begins to turn. As the compressor wheel turns, it pumps air into the cylinders of the engine. More air, more fuel, more power.

Although it sounds simple, the turbocharger is truly a precision device. At times, they spin upwards of 150,000 rpm, making them some of the fastest cycling things that man has created.

The turbine shaft requires careful handling and heat control, solved in most turbochargers by a fluid-type bearing that circulates oil around the shaft for friction and cooling purposes."

Off the IGN site.

Che
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#3 Old 01-07-2004, 06:36 AM
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Thanks for the response, but most of that stuff I am already aware of. Why is it that a turbo 'kicks in' at a certain rpm if its always spinning if there is exhaust passing through it? And is increasing the boost just keeping the wastegate closed longer, resulting in spinning the wheel faster, resulting in more compression, resulting in more O2 in the piston chamber, resulting in more power?? And if I increase the boost does it effect the spool up time?
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#4 Old 01-07-2004, 04:05 PM
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The wheel may always be spinning, but not getting enough air, or not spinning fast enough to compress the air, which when that occurs you feel the kick in power.

By setting your boost, you are not changing the speed of the compressor wheel, you are simply delaying the opening of the wastegate, thus allowing the Turbo to build up more pressure and boost before it hits the point where the wastegate opens.

There's a lot to learn about........ I'm sure www.howstuffworks.com would be helpful.

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#5 Old 01-08-2004, 07:10 AM
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Thanks Blue, always good to hear from ya. A friend of mine said something similar, that there may be a small compression but the significance kicks in at whatever rpm and THATS when you feel the power.
I checked out the info on howstuffworks.com and it said how a turbo works, just not the boost info i was looking for. A friends father who has rebuilt more engines than days i've been driving advised me to find out what each component does to the car before going and swapping everything out in the sake of more HP, so thats what I've been looking into. Would like to be able to give a why these new parts are great for the car rather than just 'they make me go faster'.
What i still dont understand though is that the waste gate is in the turbine section of the turbo right? Not the compressor section. Or am I backwards on that?
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#6 Old 01-08-2004, 09:39 AM
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Quote:
What i still dont understand though is that the waste gate is in the turbine section of the turbo right? Not the compressor section. Or am I backwards on that?
You mean the inlet or intake side which is actually the compressor side. The Waste Gate is on the Exhaust side, so that when it opens it allows all the "waste" air to be expelled into the downpipe, or atmosphere (However you have your wastegate set up) An external wastegate will normally be set up to vent to the atmosphere, an internal is normally into the downpipe. And the "Turbine" you stated, is the entire spinning wheel, Exhaust side AND Intake Side.

My advice is to go to www.nasioc.com and read EVERYTHING there is to read about what people have posted on larger turbos, especially the newer ones that are out there on the market now. Most of the threads there, there are very knowledgeable people speaking about exchanging pieces here or there to do a certain thing to the turbo's capacity or spooling efficiency. Very helpful. Believe me, all this info I know is 85% reading knowledge and the rest is what I've learned working on my own car.

Blue
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#7 Old 01-08-2004, 10:33 AM
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Well, take what you read on NASIOC with a grain of salt. This is, after all, the same board that recently had a 4 page thread arguing which uppipe bolts to use and why. They tend to overanalize and overcomplicate things. And, a lot of the "experts" aren't....
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#8 Old 01-08-2004, 02:12 PM
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I dont need an expert, just someone who knows how this thing works, inside and out, and what boost is all about
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#9 Old 01-08-2004, 06:49 PM
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Originally posted by Maverick
I dont need an expert, just someone who knows how this thing works, inside and out, and what boost is all about
What you need is a larger percentage of Subaru owners weighing in with their knowledge. Something you are not going to get on this forum, not for a while at least, which is why NASIOC is a wonderful place to learn.

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#10 Old 01-09-2004, 06:39 AM
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Problem is that the firewalls filter out the forums on NASIOC so I cant be on 'em at work. Havent checked out this new tech-forum thing that was just started on this site though...
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#11 Old 01-16-2004, 05:51 AM
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HEY BLU... WHat is NASIOC?>????
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#12 Old 01-16-2004, 05:51 AM
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ROKKKC on
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#13 Old 01-16-2004, 09:27 AM
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Quote:
Originally posted by rokstar
HEY BLU... WHat is NASIOC?>????
Check it out: www.nasioc.com
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