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Thread: Turbocharger Terminology

  1. #1
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    Default Turbocharger Terminology

    I can't expect anyone to learn anything about turbochargers, if they don't understand the language being spoken.

    That said, here's a nice glossary *in progress*

    A/R: Area/Radius. I'll come back to this later, as I could write a novel on it by itself

    Absolute Pressure: Absolute pressure is the total pressure exerted by all elements in the system. This includes atmospheric pressure, vacuum created by the throttle blade, and pressurization due to forced induction.

    Atmospheric Pressure: Really before understanding absolute pressure, you need to know about atmospheric pressure. The planet is immersed in an ocean of gas. The atmosphere has weight - approximately 14.7 psi (pounds per square inch) @ sea level. As you move to higher elevations, the pressure lessens. Anyone that lives up in the mountains can attest to it, as the air is thinner. This is also why someone in Denver running 15psi is not running the same pressure that I am here in Florida, running 15psi. I will explain this more in pressure ratio.

    Blow Off Valve: A blow off valve's primary purpose is to keep your turbo alive through sudden changes in pressure in the intake tract. A blow off valve generally is used in a MAP based system, as the valve dumps the excess pressure to the atmosphere, which would throw off the readings of a closed metered air flow system.

    Boost: The term boost generally refers to any pressurization of the intake tract over that of the atmospheric pressure. The problem people don't see, is that an engine is a glorified air pump. Any pressurization that takes place, is due to restriction in the air pump system. Boost is technically the engine's inability to flow the amount of air being forced into it

    Bypass Valve: A bypass valve and a blow off valve have the same functions. The difference is the bypass valve is used in a metered air system, as the excess pressure is bled off from the intact tract, through the bypass valve, and dumped after the air flow meter, and before the turbo. The air has already been metered, and then flows through a circuit back into the turbo again. This keeps the turbo spinning more efficiently than just dumping the excess pressure to the atmosphere. If you want maximum spool between shifts, you want to use a bypass valve. Stock, the 87-92 Toyota Supra does not have a blow off valve. It has a bypass valve, which is also known as a Compressor Bypass Valve (CBV).

    CHRA: Center Housing Rotating Assembly. The 'meat' of the turbo, minus the exhaust and compressor housings.

    Compressor Inlet: This is the point where the atmospheric air enters the turbocharger.

    Compressor Outlet: The is the point where the pressurized air leaves the turbocharger.

    Compressor (or Flow) Map: Another I will come back to...

    Exducer/Inducer: The inducer is the area of the turbine (or compressor wheel) that the air initially comes in contact with. The exducer is the area of the turbine (or compressor wheel) that the air leaves through. These are what let a turbocharger do its job.

    Pressure Measurements: There are many measurements used for pressure. PSI is the most common here in the US of A. 1 Bar = 100kPa (kilopascals - kPa) Atmospheric pressure @ sea level is defined as 101.325 kPa, so atmospheric pressure = 1.01325 bar. 1 bar = 14.5 psi - not 14.7 as commonly thought. Bar is also not the standard of SI pressure, that belongs to N/meter^2 (Newtons per meter squared) as I recall.

    Pressure Ratio: The pressure ratio that the turbo sees is defined as the absolute outlet pressure, divided by the absolute inlet pressure. This is taken only at the turbo itself - pressure losses due to the intercooler and piping are seperate from what the turbo itself sees!

    Pressurization: Simply increasing the force of air over that of atmospheric force.

    Trim: Trim is the inducer squared divided by the exducer squared. It is a ratio, and therefore, a 50 trim T3 and 50 trim T4 wheel are two different beasts!

    Turbocharger: A device used to pressurize the intake manifold system of an automotive engine. Energy from the exhaust is used to rotating a turbine sitting in the exhaust, that is connected via a shaft to the compressor sitting in the intake's air flow. As the exhaust wheel spins, the compressor wheel also spins, force feeding air into the system. The center unit that contains the shaft and wheels is known as the CHRA.

    Vacuum: A condition where absolute pressure is lower than the atmospheric pressure.

    Wastegate: A device used to control how much energy from the exhaust is fed into the turbocharger. The wastegate's job is to divert some exhaust energy from the turbine wheel. This can be done with an internal wastegate (integrated into the exhaust housing), or external wastegate (non-integrated into the exhaust housing).

    If you have any terms you'd like added, just PM me

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    Default Re: Turbocharger Terminology

    >>I will no longer respond to tech questions via PM. If you have a question, put it on the forum so everyone benefits from the answer.<<


    Mike "Nightmare" Donohue

    "Stupidity is permanent and often fatal, Ignorance is curable with education..." -- Me

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    Quote Originally Posted by jetjock View Post
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    Default Re: Turbocharger Terminology

    i will be interest by some explanation on bearing
    example for the boss jr series:
    http://www.suprasport.com/LIPP-BOSS-Jr_p_5350.html
    what the difference between Thrust Bearing and Triple Ball Bearing ?

    i already try some car with ball bearing turbo and the difference is impressive , they are really faster too spool

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    Default Re: Turbocharger Terminology

    Quote Originally Posted by guido View Post
    what the difference between Thrust Bearing and Triple Ball Bearing ?
    Standard sleeve bearings are just what they sound like. It's a metal sleeve that operates in a similar manner to a rod or main bearing in an engine:



    A ball bearing setup uses a sealed bearing assembly that consists of an outer sleeve, and inner sleeve with ball bearings in between them:



    Ball bearings outperform sleeve bearings in all areas, but they are more expensive.
    >>I will no longer respond to tech questions via PM. If you have a question, put it on the forum so everyone benefits from the answer.<<


    Mike "Nightmare" Donohue

    "Stupidity is permanent and often fatal, Ignorance is curable with education..." -- Me

    Frequently Asked Supra Questions: Rod Knock - HKS WG Springs - Injector Sizing - What is A/R? - Buy a TSRM - HKS HG FAQ - AFPR - Machinist - Overboring - Vac Diags - Motor Oil - Seafoam - Spark Plugs - Air Filters - V6 vs. I6 - Solder vs. Crimp Connectors - How to make power - Stroker Motors - Unreliable 7M's? - Piston Slap - Home made race fuel - Budgeting a build - Tuning and Vf

    Frequently Asked Forum Questions: What will get you banned? - Posting and you - Ideals - Membership - Usage - BBCode - Smiles - Scammers - How to make thumbnails - History

    Other Bullshit: Global Warming - Global Warming Facts - Religion & Politics - Collectivism -War On Drugs - Founding fathers were Diests - Religion and The Constitution - Size of the Federal Gov't - Canadian Healthcare - Socialists -European opinons of the U.S. - U.S. standard of living - U.S. - the worlds best customer - Modern Education - A Government created problem - Environmentalism is a big problem - Taxes - Socialism death toll - Can't afford healthcare? - I am my own god - Atlas will shrug - Not paying a "fair share"? - Income taxes are not a necessity - How to succeed, a 60 second lesson - How a liberal approaches facts. - Who is responsible for the financial crisis? - You asked for it. - Understanding Women - Understanding Men - Personal question? Answer is probably here. - Why I carry a gun. - Fuck the rich? - US Politics in a nutshell - The one principle that matters - Why anarchy is a fools errand - This is what it feels like to be me. - Living an awesome life - The crash is coming

    Since the beginning of recorded history, which is defined by the invention of writing by the Sumerians around 6,000 years ago, historians have cataloged over 3700 supernatural beings, of which 2870 can be considered deities. I donít believe in 2,870 gods, and you donít believe in 2,869. You're nearly as much of an Atheist as I am.

    Government is a good thing: Through correct principles, I govern myself.

    Public Notice: Contrary to popular belief, I do not consider everybody who disagrees with me to have brain damage. Those who don't have brain damage will be able to explain and justify their points of view in a logically defensible way. That's the way the Rational Discourse game is played. If you don't want to play the Rational Discourse Game, don't expect anybody (least of all me) to take you seriously.

    Quote Originally Posted by jetjock View Post
    If you drive like that on public streets I won't be disappointed if, as long as you were alone, they one day hose you out of a twisted mass of smoking metal into a bucket and melt what's left of your car down into tuna cans.

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