Starting with the basics...
03-19-2003, 05:55 PM
#1
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Starting with the basics...
I've had my new WRX for 2 weeks now, and am strolling along in the break-in period. I have never been overly proficient with car technology, except how to do basic repairs on a 1977 Firebird (power steering, water pump, etc.)
So now I'm educating myself all over again. Over the past 2 weeks I have read everything I can get my hands on. Magazines, websites, etc...
I've learned what a cat back is (I think... and not a feline's posterior), a blow off valve (but not really what it does), up pipe, down pipe, anti-roll bars, etc. etc., and the list goes on. I'm interested in tuning the WRX in the future, and I always believe that knowledge is power.
But dang if I can figure out what the heck OEM stand for! In context, it seems like Factory Parts, but I don't know. Everyone mentions it, but I haven't a clue what it means.
Anyone tell me?
Also, is there a layman's guide to all the parts that everyone mentions in their lists of modifications? Like, what, in layman's terms, a cat back actually is? What actually, simply, does a BOV do? Etc. Anyone know of a good site for folks trying to learn all this?
What are good WRX websites?
What magazines are good about information, specifically WRX's? I've browsed through Turbo Magazine, Super Street, Sport Compact Car, HCI. Some seem better than others, some are very "Fast and the Furious" oriented, some show more female models than car models...
Anywho, thanks for any info you can provide!
So now I'm educating myself all over again. Over the past 2 weeks I have read everything I can get my hands on. Magazines, websites, etc...
I've learned what a cat back is (I think... and not a feline's posterior), a blow off valve (but not really what it does), up pipe, down pipe, anti-roll bars, etc. etc., and the list goes on. I'm interested in tuning the WRX in the future, and I always believe that knowledge is power.
But dang if I can figure out what the heck OEM stand for! In context, it seems like Factory Parts, but I don't know. Everyone mentions it, but I haven't a clue what it means.
Anyone tell me?
Also, is there a layman's guide to all the parts that everyone mentions in their lists of modifications? Like, what, in layman's terms, a cat back actually is? What actually, simply, does a BOV do? Etc. Anyone know of a good site for folks trying to learn all this?
What are good WRX websites?
What magazines are good about information, specifically WRX's? I've browsed through Turbo Magazine, Super Street, Sport Compact Car, HCI. Some seem better than others, some are very "Fast and the Furious" oriented, some show more female models than car models...
Anywho, thanks for any info you can provide!
03-19-2003, 07:18 PM
#2
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Join Date: Dec 2002
Location: Sacramento CA
Posts: 10,029
Car Info: 02 Impreza WRX sedan
Originally posted by jsabotin
But dang if I can figure out what the heck OEM stand for! In context, it seems like Factory Parts, but I don't know. Everyone mentions it, but I haven't a clue what it means.
Original Equipment Manufacturer (or Manufactured).
--
0==WW==0
"…axles of evil…" - george w. bush
But dang if I can figure out what the heck OEM stand for! In context, it seems like Factory Parts, but I don't know. Everyone mentions it, but I haven't a clue what it means.
Original Equipment Manufacturer (or Manufactured).
--
0==WW==0
"…axles of evil…" - george w. bush
03-19-2003, 10:20 PM
#4
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Join Date: Mar 2003
Location: Michigan
Posts: 1,370
Car Info: Viper ACR & H1
A blow off valve prevents air from rushing back into the turbo "backwards" when you let off of the accelerator, and it can hold more boost than a stock one will.
A Cat Back is the part of the exhaust that comes after the caytalitic converter and goes all the way to the end.
vividracing.com
fastwrx.com
gruppe-s.com
scoobymods.com
A Cat Back is the part of the exhaust that comes after the caytalitic converter and goes all the way to the end.
vividracing.com
fastwrx.com
gruppe-s.com
scoobymods.com
03-19-2003, 11:56 PM
#5
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https://www.i-club.com/forums/showth...=&threadid=727
The thread I just put has a lot of terms and abbreviations as well as their meanings that you may find useful... they are all at the bottom of the thread (and there are LOTS).
Your stock WRX comes with a wastegate, which is fine as it is. Basically, the wastegate allows exhaust gases that propel the turbo to actually bypass the turbine blades. This happens at various times, like when the wastegate senses that the turbo is spinning at a higher or lower speed than normal (like when you back off the throttle completely during high revving or shifting). If you listen closely even on your stock WRX, you can hear it sometimes, but it's very quiet, especially with the intake silencing materials still installed. An aftermarket BOV pretty much does the same thing, except with greater efficiency and a more noticeable, head-turning sound ranging from a "whooosh" or a "pssst". Since it's capable of bypassing more exhaust gases, you don't really need those until you have mods that increase airflow (uppipe, downpipe, boost control, etc.). A lot of people get them because they sound cool (which is totally fine).
To get technical, your turbo is forcing air into your engine through the intake manifold. When you shift and release the gas, the butterfly on the throttle body closes, but the turbo is still blowing air, so it's got to go somewhere. Rather than bouncing off the throttle body and remaining in the piping and going backwards, the BOV opens, and air is vented. That way, the air has somewhere to go, and there is less stress on the engine's various parts. In addition, the turbine blades can still spin at the same speed rather than slowing down due to air coming back at it. BOVs don't increase hp or torque, but it will help power delivery in between gears as well as acceleration.
The thread I just put has a lot of terms and abbreviations as well as their meanings that you may find useful... they are all at the bottom of the thread (and there are LOTS).
Your stock WRX comes with a wastegate, which is fine as it is. Basically, the wastegate allows exhaust gases that propel the turbo to actually bypass the turbine blades. This happens at various times, like when the wastegate senses that the turbo is spinning at a higher or lower speed than normal (like when you back off the throttle completely during high revving or shifting). If you listen closely even on your stock WRX, you can hear it sometimes, but it's very quiet, especially with the intake silencing materials still installed. An aftermarket BOV pretty much does the same thing, except with greater efficiency and a more noticeable, head-turning sound ranging from a "whooosh" or a "pssst". Since it's capable of bypassing more exhaust gases, you don't really need those until you have mods that increase airflow (uppipe, downpipe, boost control, etc.). A lot of people get them because they sound cool (which is totally fine).
To get technical, your turbo is forcing air into your engine through the intake manifold. When you shift and release the gas, the butterfly on the throttle body closes, but the turbo is still blowing air, so it's got to go somewhere. Rather than bouncing off the throttle body and remaining in the piping and going backwards, the BOV opens, and air is vented. That way, the air has somewhere to go, and there is less stress on the engine's various parts. In addition, the turbine blades can still spin at the same speed rather than slowing down due to air coming back at it. BOVs don't increase hp or torque, but it will help power delivery in between gears as well as acceleration.
03-20-2003, 01:00 AM
#6
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jsabotin, about the worst thing you can do is to believe something you read on a message board on the internet if you're after accurate information. Keep your sources varied and come to your own conclusions after analyzing information from different sources...
Wastegates are used to control turbine speeds, bypassing the exaust flow from the turbo when additional boost is not required. On almost all automotive applications this means the wastegate will open once maximum amount of allowable boost is reached. Most will also open to some degree while cruizing. This is why a manual boost controller in most new cars will cause higher exaust gas tempreatures as the hot exaust gasses go through the turbine until the set amount of boost is reached.
A blow off valve has a completely different function... A "blow off valve" is used to "vent" excess pressure into the atmosphere in some applications, more often it's used to vent the excess pressure to the intake directly infront of the intake side of the compressor (effectively used as a recirculation valve, more on that later). "Excess pressure" occurs when throttle is closed after a period of using turbocharger boost. The use of a recurcilation valve helps in keeping the turbocharger spooled up during a shift. A blowoff valve only functions for that loud venting sound so many people seem to enjoy, and to keep the compressor blades from shattering. The pressure build up between the throttle butterfly and the compressor blades can be brutal, as you go from near full boost w/a given amount of flow to nearly no flow very quickly and the entire intake tract becomes very highly pressurized sending a violent shock wave back to the turbocharger. Anyway, most stock "blow off" valves are also open at idle, while cruizing, or another situation when "bypassing" the compressor housing of the turbocharger is beneficial (to efficiency-->fuel economy). This is similar to why a wastegate may be open when boost isn't desired.
Ahmet
Wastegates are used to control turbine speeds, bypassing the exaust flow from the turbo when additional boost is not required. On almost all automotive applications this means the wastegate will open once maximum amount of allowable boost is reached. Most will also open to some degree while cruizing. This is why a manual boost controller in most new cars will cause higher exaust gas tempreatures as the hot exaust gasses go through the turbine until the set amount of boost is reached.
A blow off valve has a completely different function... A "blow off valve" is used to "vent" excess pressure into the atmosphere in some applications, more often it's used to vent the excess pressure to the intake directly infront of the intake side of the compressor (effectively used as a recirculation valve, more on that later). "Excess pressure" occurs when throttle is closed after a period of using turbocharger boost. The use of a recurcilation valve helps in keeping the turbocharger spooled up during a shift. A blowoff valve only functions for that loud venting sound so many people seem to enjoy, and to keep the compressor blades from shattering. The pressure build up between the throttle butterfly and the compressor blades can be brutal, as you go from near full boost w/a given amount of flow to nearly no flow very quickly and the entire intake tract becomes very highly pressurized sending a violent shock wave back to the turbocharger. Anyway, most stock "blow off" valves are also open at idle, while cruizing, or another situation when "bypassing" the compressor housing of the turbocharger is beneficial (to efficiency-->fuel economy). This is similar to why a wastegate may be open when boost isn't desired.
Ahmet
03-20-2003, 01:08 AM
#7
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Posts: n/a
To correct "DeeezNuuuts83":
A blow off valve does not vent exhaust gasses, only intake. The reason it's so audible is because often times the velocity/energy of the pressurized intake air is used to make the sound. This usually forces the use of stronger springs in blow off valves also, which isn't very desirable. Stock bypass valves use boost pressure when under boost on the opposite side of the valve (this kind of goes against SuboobaruWRSEX's post also), thus enabling the use of a softer spring that opens @ less extreme pressures in the intake when desirable (shifting, idle, cruize). Some blow off valves are better than others (dual chamber, etc.), but the use of an aftermarket part is often not necessary before a significant amount of additional air is being moved over stock.
Ahmet
A blow off valve does not vent exhaust gasses, only intake. The reason it's so audible is because often times the velocity/energy of the pressurized intake air is used to make the sound. This usually forces the use of stronger springs in blow off valves also, which isn't very desirable. Stock bypass valves use boost pressure when under boost on the opposite side of the valve (this kind of goes against SuboobaruWRSEX's post also), thus enabling the use of a softer spring that opens @ less extreme pressures in the intake when desirable (shifting, idle, cruize). Some blow off valves are better than others (dual chamber, etc.), but the use of an aftermarket part is often not necessary before a significant amount of additional air is being moved over stock.
Ahmet
03-20-2003, 11:05 PM
#8
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Originally posted by Ahmet
To correct "DeeezNuuuts83":
A blow off valve does not vent exhaust gasses, only intake. The reason it's so audible is because often times the velocity/energy of the pressurized intake air is used to make the sound. This usually forces the use of stronger springs in blow off valves also, which isn't very desirable. Stock bypass valves use boost pressure when under boost on the opposite side of the valve (this kind of goes against SuboobaruWRSEX's post also), thus enabling the use of a softer spring that opens @ less extreme pressures in the intake when desirable (shifting, idle, cruize). Some blow off valves are better than others (dual chamber, etc.), but the use of an aftermarket part is often not necessary before a significant amount of additional air is being moved over stock.
Ahmet
To correct "DeeezNuuuts83":
A blow off valve does not vent exhaust gasses, only intake. The reason it's so audible is because often times the velocity/energy of the pressurized intake air is used to make the sound. This usually forces the use of stronger springs in blow off valves also, which isn't very desirable. Stock bypass valves use boost pressure when under boost on the opposite side of the valve (this kind of goes against SuboobaruWRSEX's post also), thus enabling the use of a softer spring that opens @ less extreme pressures in the intake when desirable (shifting, idle, cruize). Some blow off valves are better than others (dual chamber, etc.), but the use of an aftermarket part is often not necessary before a significant amount of additional air is being moved over stock.
Ahmet
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