Neophite Help
12-01-2001, 12:26 AM
#1
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Join Date: Aug 2001
Location: West Chester, PA
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Neophite Help
I need to take the class 951 101. I would love to know what a wastegate is, what a cat back does, what a MAF is for and even what a man. boost controller is. I apologize for my lack of knowledge but I have tried for 3 months to learn from osmosis. I do not expect someone to waste time holding my hand through every aspect of these fine cars, so I guess I am looking for a good book that covers all of the basics of upgrades and maintance. TIA
12-01-2001, 01:51 AM
#3
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You could head out and get pretty much any turbo book and start there. Knowing how the turbo works can help you understand how all the parts function. But... I will go ahead and school you on the items that you asked about.
Wastegate - It is a bypass valve that is actuated by boost, and is attached to the exhaust before the turbo. The pressure of the exhaust drives the turbine. On the intake side of the turbo is a compressor that creates a boost charge (denser air + more fuel = power!). When the boost reaches a limit (13psi on a stock 951) the turbo needs to slow down so it does not build more boost pressure. The wastegate will open, and divert exhaust pressure past the exhaust turbine. The turbo slows down and stops creating boost.
Cat Back - Our 951's have a catalist in the exhaust to reduce emissions. Unburned fuel will be chemically converted to intert gasses and water in the converter. A cat back exhaust leaves the converter in the car, and removes the restrictive stock muffler and pipe leading to it. A restrictive exhaust is quiet, but you lose much power because of back pressure. (meaning the exhaust turbine has pressure on the outlet side, preventing it from spinning quicker). Most cat back exhaust is free flow and unrestricitive. This allows better exhaust flow and more power, and a better sound!
MAF - Our cars have an antiquated vane type air flow meter. It has a large aluminum flapper valve that is mounted to a spring and a resitor. When you hit the gas, this flapper is sucked open, creating a resistance signal that it fed to the computer. Problem is that this flapper is slow to react, and causes an intake restriction. By converting to a MAF (Mass Air Flow) sensor, you remove that flapper and the resistance with it. The MAF uses a wire that is heated, and a resitor and curcuits that calcualte how much air is moving over the wire by how much it is cooled. This is much faster, more responsive, and adds some power by allowing more air flow.
Man. Boost Controller - Easy one here. It is a manual device that goes between the boost line to the wastegate. This is the line that tells the wastegate to open at a set pressure. With a Manual Boost Controller, you can set how much boost you want to run by stopping the flow of boost to the wasteate. Many of them have a bleed off valve in them where the boost pressure is bled off until where you have it set, so the wastegate thinks there is no boost, and remains closed. Once you reach the set pressure, the boost controller allows boost to reach the wastegate and allows it to open, bypassing the turbo, and reducing boost.
Hope that helps!
Wastegate - It is a bypass valve that is actuated by boost, and is attached to the exhaust before the turbo. The pressure of the exhaust drives the turbine. On the intake side of the turbo is a compressor that creates a boost charge (denser air + more fuel = power!). When the boost reaches a limit (13psi on a stock 951) the turbo needs to slow down so it does not build more boost pressure. The wastegate will open, and divert exhaust pressure past the exhaust turbine. The turbo slows down and stops creating boost.
Cat Back - Our 951's have a catalist in the exhaust to reduce emissions. Unburned fuel will be chemically converted to intert gasses and water in the converter. A cat back exhaust leaves the converter in the car, and removes the restrictive stock muffler and pipe leading to it. A restrictive exhaust is quiet, but you lose much power because of back pressure. (meaning the exhaust turbine has pressure on the outlet side, preventing it from spinning quicker). Most cat back exhaust is free flow and unrestricitive. This allows better exhaust flow and more power, and a better sound!
MAF - Our cars have an antiquated vane type air flow meter. It has a large aluminum flapper valve that is mounted to a spring and a resitor. When you hit the gas, this flapper is sucked open, creating a resistance signal that it fed to the computer. Problem is that this flapper is slow to react, and causes an intake restriction. By converting to a MAF (Mass Air Flow) sensor, you remove that flapper and the resistance with it. The MAF uses a wire that is heated, and a resitor and curcuits that calcualte how much air is moving over the wire by how much it is cooled. This is much faster, more responsive, and adds some power by allowing more air flow.
Man. Boost Controller - Easy one here. It is a manual device that goes between the boost line to the wastegate. This is the line that tells the wastegate to open at a set pressure. With a Manual Boost Controller, you can set how much boost you want to run by stopping the flow of boost to the wasteate. Many of them have a bleed off valve in them where the boost pressure is bled off until where you have it set, so the wastegate thinks there is no boost, and remains closed. Once you reach the set pressure, the boost controller allows boost to reach the wastegate and allows it to open, bypassing the turbo, and reducing boost.
Hope that helps!
