waste gate question
#11
06-25-2007, 09:11 PM
RE: waste gate question
ORIGINAL: theguy1084
Cant I just vent the WG to the atmosphere. There is nothing like a monster carbon footprint..I guess I assumed you guys would know I was going BT when I said that I was building an engine
Cant I just vent the WG to the atmosphere. There is nothing like a monster carbon footprint..I guess I assumed you guys would know I was going BT when I said that I was building an engine
It will be stupid loud, as it's open most of the time when you are cruising. Just think of running the car with out a muffler, & that's what it will sound like.
performance wise it's better to VTA, but in the real wold, it's better to get it back into the exhaust.
#13
06-25-2007, 09:41 PM
RE: waste gate question
i dont think there are any because there are too many variatons in dp depending on turbo and turbo location. the wg is not open all the time only when you hit full boost. so driving in vac and lower boost the wg is closed
#14
06-25-2007, 11:41 PM
RE: waste gate question
ORIGINAL: Jeff
i dont think there are any because there are too many variatons in dp depending on turbo and turbo location. the wg is not open all the time only when you hit full boost. so driving in vac and lower boost the wg is closed
i dont think there are any because there are too many variatons in dp depending on turbo and turbo location. the wg is not open all the time only when you hit full boost. so driving in vac and lower boost the wg is closed
Jeff, the wategate is closed to make boost, & open to divert the exhaust & not spool the turbo. It's open most of the time, unless you always drive at WOT.
So sitting @ a stop light, you are going to attract a lot of attention, cuz it's going to be super loud, do to it being an open exhaust WG.
#15
06-26-2007, 08:07 AM
RE: waste gate question
Found this on Boostcruising.com
Inside the wastegate is a diaphragm which creates a seal, and a spring which holds the wastegate closed. Spring rates vary depending on the amount of boost you want to run, typically they are given in a "bar" value for example 1 bar would be 14.7psi. This would mean that in order to open the wastegate you would need to excerpt a greater pressure than the 14.7psi spring holding the wastegate closed. In order for the wastegate to work you must have the compressor reference port hooked up to the compressor side of the turbo, if you don't have this vacuum line attached than the boost pressure will not be limited to the set spring pressure; it will build unlimited boost pressure until your engine is destroyed.
Normally pressure from a spooling turbo pushes against the diaphragm (though the vacuum line attached to the compressor reference port) which in turn pushes against the wastegate spring. When the pressure from the spooling turbo exceeds the spring pressure the wastegate's plunger opens releasing the excess pressure through the dump tube into the exhaust after the turbo or to open atmosphere.
Boost controllers serve two functions; increase boost levels beyond the set wastegate spring pressure and reduce the "pre-opening" of the wastegate-controlled boost pressure.
Normally pressure from a spooling turbo pushes against the diaphragm (though the vacuum line attached to the compressor reference port) which in turn pushes against the wastegate spring. When the pressure from the spooling turbo exceeds the spring pressure the wastegate's plunger opens releasing the excess pressure through the dump tube into the exhaust after the turbo or to open atmosphere.
Boost controllers serve two functions; increase boost levels beyond the set wastegate spring pressure and reduce the "pre-opening" of the wastegate-controlled boost pressure.
#16
06-26-2007, 08:55 AM
RE: waste gate question
ORIGINAL: 2k S4
True on the variations, my guess it's going to be custom.
Jeff, the wategate is closed to make boost, & open to divert the exhaust & not spool the turbo. It's open most of the time, unless you always drive at WOT.
So sitting @ a stop light, you are going to attract a lot of attention, cuz it's going to be super loud, do to it being an open exhaust WG.
ORIGINAL: Jeff
i dont think there are any because there are too many variatons in dp depending on turbo and turbo location. the wg is not open all the time only when you hit full boost. so driving in vac and lower boost the wg is closed
i dont think there are any because there are too many variatons in dp depending on turbo and turbo location. the wg is not open all the time only when you hit full boost. so driving in vac and lower boost the wg is closed
Jeff, the wategate is closed to make boost, & open to divert the exhaust & not spool the turbo. It's open most of the time, unless you always drive at WOT.
So sitting @ a stop light, you are going to attract a lot of attention, cuz it's going to be super loud, do to it being an open exhaust WG.
#17
06-26-2007, 11:47 AM
RE: waste gate question
ORIGINAL: Jeff
not true. mine was never open at a stop light only when i hit full boost. the turbo isnt producing boost at a stop light. thats why your in vac and not positive boost pressure. the turbo isnt spinning as fast. but once you put load on the motor and more exhaust is flowing the boost levels will go up tell you hit the opening point of the wg. this is set with a mbc or the n75. then it opens and its loud as hell
not true. mine was never open at a stop light only when i hit full boost. the turbo isnt producing boost at a stop light. thats why your in vac and not positive boost pressure. the turbo isnt spinning as fast. but once you put load on the motor and more exhaust is flowing the boost levels will go up tell you hit the opening point of the wg. this is set with a mbc or the n75. then it opens and its loud as hell
The WG is open any time you are not in boost, it's only closed/closing when you are building boost. The job of the WG is to not spool the turbo when there is no load(it's open) & as load is applied, it starts to close forcing the exhaust over the turbo.
If the WG is closed @ idle, it will spool the turbo @ idle. As the WG starts to open, boost will be lost, as the exhaust will go through the WG & not the turbo.
Anytime you are in vacuum, the WG is open, letting the exhaust flow like a NA car. As it closes, you will start to build boost.
When you are cruising in top gear on a flat surface, you are in vacuum, so the turbo is not be spooled, this is cuz the WG is open & allowing the exhaust to flow thew the WG & not the turbo. Then when you hit the gas, the WG closes, you start to build boost.
Boost is controled by the WG, you can only build boost with a closed WG. If you run any logs on the N75, you will see it's open most of the time, unless you are under increasing loads.
#18
06-26-2007, 12:10 PM
RE: waste gate question
The waste gate also opens up when the boost gets to high, to relieve pressure and avoid damage.
So, you're both right.
Most automotive turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down.
So, you're both right.
Most automotive turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down.
#19
06-26-2007, 01:22 PM
RE: waste gate question
the wastegate is closed at idle. i never herd the noise and i would have because mine was externaly gated to the atmosphere. watch this vid and tell me if you hear my wg open.
http://www.youtube.com/watch?v=Co3265WLCiE
the wg only opens when i hit my desired full boost(what ever the mbc is set at) if it was open at idle it would be loud and you could hear it from the underside of the car. but you cant, only noise you hear is from my muffler
http://www.youtube.com/watch?v=Co3265WLCiE
the wg only opens when i hit my desired full boost(what ever the mbc is set at) if it was open at idle it would be loud and you could hear it from the underside of the car. but you cant, only noise you hear is from my muffler
#20
06-26-2007, 02:42 PM
RE: waste gate question
why fight with the guy that has done it?
The only way to open the WG is pressure not the vacuum. At idle the car is at ~800rpms (find me a turbo that spools under 1k) and wont be making any boost so no need to open it, same when crusing, it will be closed because there wont be any load to make boost to open the WG either.
The only way to open the WG is pressure not the vacuum. At idle the car is at ~800rpms (find me a turbo that spools under 1k) and wont be making any boost so no need to open it, same when crusing, it will be closed because there wont be any load to make boost to open the WG either.