QUOTE(reconraiders @ Aug 7 2007, 12:00 AM) I was referring to the first post by musicfreak. Your post was good. Oh and you're not directing that second part toward me are you? I didn't say anything about you copying and pasting. Your post was much more informative then the first post in the thread. M'kay... I was, directing my hostility toward musicfreak since it's him who's accusing me of plagiarism, right?

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I just wanted to clarify a couple things about turbochargers, specifically, the names and functions of their parts. A turbocharger has 5 basic parts: Housing, bearing, shaft, compressor, and turbine. The housing just houses the components. The bearing supports the shaft.

The meat-and-potatoes of the system is the turbine and compressor. The exhaust gases contain energy that is normally wasted. This energy is in the form of pressure and velocity. In the turbocharged system, we extract the energy from the exhaust gases by forcing it to turn a turbine (15,000rpm is actually slow to some turbines). The gases are then expelled out of the turbocharger to be "discarded".

The turbine is connected, via the shaft, to the compressor. The compressor takes in clean air that is at approximately atmospheric pressure (14.7psi at sea level) and compresses it to a certain "boost pressure". When you hear 30psi of boost, it means 30psi above atmospheric, or 44.7psi.

This pressurized air charge contains more oxygen than the nonpressurized air for a given volume, and at this point, can be directed into the combustion chamber; however, it also contains more heat. We can increase the amount of oxygen by cooling the air charge, so we send this pressurized air through an intercooler to cool it. This causes the already-dense air to become more dense. This would be the best time to direct that air into the combustion chamber.

The faster you spin that turbine, the faster the compressor spins. The faster you spin the compressor, the more boost you get. So how do we control the amount of boost? We use a turbo controller, which controls how much exhaust goes through the turbine and how much gets wasted, or bypassed. When RPM is low, you want it all, but as RPM increases, so does boost, and you can get to a point where there is too much for the engine. A typical stock engine can handle about 7psi of boost. As the charge pressure (AKA intake manifold pressure) reaches 7psi, the boost controller would start opening the waste gate, bypassing the turbine, but keeping it closed enough to maintain the 7psi of boost.

There are a couple small problems with turbochargers. One of them is turbo lag. When you hit the gas, you need to burn the extra fuel you just put it, and then it can be used (as exhaust gases) to turn the turbine. This is usually pretty quick, but the turbine takes time to get up to speed. The smaller/lighter the turbine/compressor, the faster it gets up to speed, but it doesn't boost as much as a large turbine/compressor. We can overcome this by using a 2-stage setup, where we have a small turbocharger AND a large one. The small one is used for the initial boost, and then the large one takes over once it spins up. This is called a sequential turbo setup and is used in the 1993-1995 Mazda RX-7, for example.

The other problem is that once that intake manifold is pressurized, it needs somewhere to go. Normally, this path is through the engine, but what if you need to let off the gas and go to idle (like after revving up your engine, or getting ready to stop at a red light)? You want your engine to decelerate normally, so you need to release this air, rather than make it go through the engine. That's where we use a "pop-off" valve. Whenever your throttle position goes down rapidly (from you releasing the gas pedal), the pop-off valve opens, releasing the charged air. If we didn't use one, it would actually take some time for the engine to slow down to idle, and you might be suprised how long it actually takes.

Well, that's about it for me, and this, too, came straight from my understanding of how turbo systems work. To lend creed to my post, I am licensed to work on Aircraft (Airframe and Powerplant) and I am a soon-to-be race car driver (Honda Challenge) and it was for these purposes that I learned about turbochargers and turbo systems.

For the record: In no way did I copy any portion of any text from any source to write this post. It was solely written by myself, Sean G. Foster, for the purpose of educating those who may be interested in learning how turbocharger systems work.

 

 

 

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Sean Foster, GOOD POST!

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Wow! An excellent post from someone who's actually in the industry. I appreciate all the little details I missed like the waste gate and the release valve. Here's a little subject for you: Talk to us all about Variable Geometry Fans or whatever they're called. I can't recall now, but just as a single engine Cesna or whatever small plane has an adjustable pitch for the prop to vary the amount of air the prop grabs, there are similar features built in to some turbines in higher end turbo chargers...

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Turbo Chargers are however just a small touch i've found with enough research you could turn some crap car like a Ford Torus into a sports car really any car can be tweaked Turbo Charge is very well however perhaps the only thing Illegal is the fastest and thats the NItrogen Gas whitch before it was higher priced and stuff my dad got to ride in a car with it and i saw the picture of the speed reader n20 makes huge differences i also recently found with this Turbo Charger that a Celeb's son had a Toyota Supra zup'd up to 1,000 hp and crashed into a cocanut tree his son was actually driving with someone (not with the celeb) they we're both life flighted his son was ok but the friend is actually still in the hospital so basically what im saying is that speed is awesome but if not handeled correctly can be your last thrill
if you no what i mean --->

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Thank you for sharing, I never knew exactly how a Turbo Charger works. Also, what is the difference between a Turbo Charger and a Super Charger? I have never attempted to figure out that myself, so please shine some light on the subject.

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Super-charging is the same idea as a turbocharger but instead of using the energy contained in the exhaust stream to spin up a turbine and blow air into the intake, a super-charger uses a combination of air from the oncoming air stream and a turbine or fan driven by a belt attached to the pulley system that runs other accessories like power brakes, steering, AC, and water pump. On the front are butterfly valves that remain closed until the supercharger is engaged via a switch in the cockpit. The horsepower needed or consumed during this operation is high, though, and, from what I understand, the fuel economy suffers dramatically as a result. On the plus side, super-chargers can be sized to force much higher air pressures down the intake manifold at any one time generating a more significant increase in horsepower which is why you see them on dragsters instead of turbos. The engine can more easily withstand the stresses of turbo-charging and come more often from the factory with turbo, but there are some cars that have factory "low-profile" super-chargers such as the Buick Super Grand Prix of the late 90's and probably some Firebirds had them too. But I suspect those super-chargers didn't generate much pressure.

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I'd like to thank Sean and Watermonkey for their awesome contributions to this thread. I learned quite a bit today that I've been meaning to do my own research on.

Thanks to you guys, I'm not going to play the stereotypical Azn and "rice" out my car with a turbo or supercharger. I appreciate the fuel economy of my Honda Civic and am trying to improve/maintain it as much as I can.

I can safely assume that a cold-air intake would stress the system in the same manner? (Of course, not to the same extent.)

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No offense to Watermonkey, but your post reminds me of Bill O'Reilly. "SHUT UP. SHUT UP. PRODUCERS, CUT OFF HIS MIC. CUT OFF HIS MIC."

Anyway. I've never tried such things, since I'd be a bit afraid of burning out the engine. Too much power isn't alays a good thing.

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A very informative topic about turbochargers. the good thing about this topic is that it has sources and quotes from different aspect and kind of clears everything off in the turbo chargers aspect.
There is one question though i have in this regard. Do they turbo chargers have a limit of specific engines they can be put on or they can be used with any type of cars. For instance I have a 1000cc cars and a 800cc car, they both operate on petrol or gasoline you may put it. is there by any chace i can put Turbo chargers in them.
Also one more thing. Can turbo chargers work in choesion with NOS. There was also something mentioned about a scoop in the hood cutting the aerodynamics but an old fashioned Turbo charger thingy, if im correct. then can you please elaborate on that?

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