external wastegate?
12-15-04, 05:57 PM
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external wastegate?
hi!
my question is : how an external wastegate work
i see many picture of that but i dont understand how it work?
any people can explain me? or tell me a good link?
my question is : how an external wastegate work
i see many picture of that but i dont understand how it work?
any people can explain me? or tell me a good link?
12-15-04, 06:08 PM
#2
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Ok...
External wastegates have a sping inside them set to a certain resistance, generally 10 PSI.... when the boost in the vac line going to the wastegate exceeds the spring pressure, the spring is actuated and the wastegate opens. Internally, the gate isteslf looks like a big assed valve from a piston car... When it lifts off the seat, it allows exhaust gas to pass from the manifold directly into the downpipe without going through the turbo...
Think of it as a blow off valve for the exhaust that acuates at a certain pressure rather than when you lift off the gas...
There are a couple of reason that external wastegates are better 1) the valve lifts completely off the seat in a linear manner, thus allowing better gas flow.. In our stock internal wastegates, the valve swings on a hinge, thus the flow is not quite as good. 2) you cand generally have a much bigger valve in an external wastegate than you can on an internal wastegate... (the 35MM flapper Bryan at BNR put in my Stage III is about the biggest i've seen in an internal wastegate) 3) There is a certain leverage factor with an external wastegate with the length of the actuator rod from the diaphragm to the control link on the outside of the manifold and the leverage force required to move the lever arm and the friction in the bushing of the lever arm with our internal wastegates that is not present in an external wastegate. its gets complicated, but basically, the longer the lever arm, the harder it is to control boost)
External wastegates have a sping inside them set to a certain resistance, generally 10 PSI.... when the boost in the vac line going to the wastegate exceeds the spring pressure, the spring is actuated and the wastegate opens. Internally, the gate isteslf looks like a big assed valve from a piston car... When it lifts off the seat, it allows exhaust gas to pass from the manifold directly into the downpipe without going through the turbo...
Think of it as a blow off valve for the exhaust that acuates at a certain pressure rather than when you lift off the gas...
There are a couple of reason that external wastegates are better 1) the valve lifts completely off the seat in a linear manner, thus allowing better gas flow.. In our stock internal wastegates, the valve swings on a hinge, thus the flow is not quite as good. 2) you cand generally have a much bigger valve in an external wastegate than you can on an internal wastegate... (the 35MM flapper Bryan at BNR put in my Stage III is about the biggest i've seen in an internal wastegate) 3) There is a certain leverage factor with an external wastegate with the length of the actuator rod from the diaphragm to the control link on the outside of the manifold and the leverage force required to move the lever arm and the friction in the bushing of the lever arm with our internal wastegates that is not present in an external wastegate. its gets complicated, but basically, the longer the lever arm, the harder it is to control boost)
Last edited by YearsOfDecay; 12-15-04 at 06:15 PM.
