Upgraded Internal Wastegate Actuator: EVO X - Gain 40whp?
May 14, 2009, 08:53 PM
#34
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well there is still some debate. endgame is right that a wastegate alone does not add hp but its function and ability for the motor to have boost ingested the same at 5500rpms as it does at 7500rpms is what makes power. the graph usually begins to drop on the higher end of the revs because boost is tapering off. therefore, if boost was the same all the way across, with a proper tune, there would be more power there than before. so you see, its not just the wastegate itself that makes the power but its ability to hold boost better with proper afr's and timing that will.
May 14, 2009, 08:59 PM
#35
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also something to consider. say the stock turbo reaches max effeciency at 25psi right, so anything above that would continue to just blow hot air. if the wastegate's ability to hold boost is frail then the boost will fall off and the turbo is no longer as effective. now, if the wastegate can hold that 25psi throughout then the turbo is effective all the way to redline and isnt just trying to blow hot air into the motor. the VE changes because boost is aiding in it making power all over (as long as the tune helps coordinate this) you would only be not making power because of mechanical disabilities (outflowing the heads, cams, exhaust, etc). so 25psi at 4800rpm to redline and properly tuned will make more power than just 25psi or boost spiking at a higher boost level but then tapering off.
May 18, 2009, 02:25 AM
#37
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How boost is produced and controlled:
As rpm rises exhaust gases enter the turbo through the turbine and the turbine wheel starts to spin. Linked by shaft and spinning at the same time the compressor wheel starts to turn and air is drawn through the intake into the compressor and on to the intercooler, throttle body, intake manifold and ultimately engine. The air that does NOT enter the engine produces pressure in the intake manifold. This is manifold absolute pressure (MAP). MAP - atmospheric pressure (roughly 14.7) = your boost. Ultimately the faster the turbine spins, more air is drawn through the system and more boost is produced until the heat produced surpasses the efficiency of the turbo.
The wastegate is responisible for controlling turbine speed. It does this by bypassing ("wasting") exhaust gas around the turbine wheel. It operates on the concept of air pressure verses spring tension. The air pressure that opposes the wastegate spring is referred to as the wastegate actuator signal. Once this operating signal overcomes the spring tension the wastegate begins to open bypassing some exhaust gas away from the turbine wheel slowing it down. The minimum pressure the valve starts to open is called crack pressure. This can be adjusted, usually only a couple psi by adjusting the pre-load on the spring. An upgraded spring or actuator will have a higher crack pressure than stock and thus not bypass exhaust gas until a higher actuator signal is reached MAINTAINING a higher overall boost pressure.
While this may sound like a good idea, the Evo already has means of controlling wastegate function by adjusting the strength and timing of actuator signal via boost control solenoid. Also the air into and out of the solenoid is limited by restrictors in the air lines known as "boost pills". These are a safety feature that limit the maximum amount of air the solenoid receives and sends to the wastegate. Tuners can and have used the stock system effectively though modifications to the air lines/boost pills are sometimes required depending on the program/method used. Also manual/electronic boost controllers can be used to bypass the stock solenoid if so desired. These work pretty much the same way by restricting air to the wastegate keeping it closed until a preset psi is reached, then sending out the actuator signal to the wastegate.
Keeping the wastegate closed until max psi is reached helps improve spool. If the wastegate was allowed to open the instant crack pressure was reached it would start bypassing air slowing turbine wheel acceleration and making it take longer to achieve peak boost.
Ultimately it comes down on the method your tuner prefers to use. WGA, MBC, and electronic boost controllers can be used seperately or is an addition to engine management techniques tuners use to help control boost. I would not recommend any of them without a tune since it pays (and is safer) to optimize timing, fuel flow, and a/f ratio with the added airflow the boost is going to produce. Hope this helps everyone out.
As rpm rises exhaust gases enter the turbo through the turbine and the turbine wheel starts to spin. Linked by shaft and spinning at the same time the compressor wheel starts to turn and air is drawn through the intake into the compressor and on to the intercooler, throttle body, intake manifold and ultimately engine. The air that does NOT enter the engine produces pressure in the intake manifold. This is manifold absolute pressure (MAP). MAP - atmospheric pressure (roughly 14.7) = your boost. Ultimately the faster the turbine spins, more air is drawn through the system and more boost is produced until the heat produced surpasses the efficiency of the turbo.
The wastegate is responisible for controlling turbine speed. It does this by bypassing ("wasting") exhaust gas around the turbine wheel. It operates on the concept of air pressure verses spring tension. The air pressure that opposes the wastegate spring is referred to as the wastegate actuator signal. Once this operating signal overcomes the spring tension the wastegate begins to open bypassing some exhaust gas away from the turbine wheel slowing it down. The minimum pressure the valve starts to open is called crack pressure. This can be adjusted, usually only a couple psi by adjusting the pre-load on the spring. An upgraded spring or actuator will have a higher crack pressure than stock and thus not bypass exhaust gas until a higher actuator signal is reached MAINTAINING a higher overall boost pressure.
While this may sound like a good idea, the Evo already has means of controlling wastegate function by adjusting the strength and timing of actuator signal via boost control solenoid. Also the air into and out of the solenoid is limited by restrictors in the air lines known as "boost pills". These are a safety feature that limit the maximum amount of air the solenoid receives and sends to the wastegate. Tuners can and have used the stock system effectively though modifications to the air lines/boost pills are sometimes required depending on the program/method used. Also manual/electronic boost controllers can be used to bypass the stock solenoid if so desired. These work pretty much the same way by restricting air to the wastegate keeping it closed until a preset psi is reached, then sending out the actuator signal to the wastegate.
Keeping the wastegate closed until max psi is reached helps improve spool. If the wastegate was allowed to open the instant crack pressure was reached it would start bypassing air slowing turbine wheel acceleration and making it take longer to achieve peak boost.
Ultimately it comes down on the method your tuner prefers to use. WGA, MBC, and electronic boost controllers can be used seperately or is an addition to engine management techniques tuners use to help control boost. I would not recommend any of them without a tune since it pays (and is safer) to optimize timing, fuel flow, and a/f ratio with the added airflow the boost is going to produce. Hope this helps everyone out.
May 21, 2009, 02:40 PM
#38
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Don't waste your money on this. The stock waste gate actuator works fine. Just get a pill for ~$20 and you can hold boost. Look at my dyno with stock waste gate and the pill. It holds boost fine.
Jul 15, 2009, 08:02 AM
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what pill? i peak at 27 and taper to 17 and want to try and fix this. i was under the impression that the wga would just keep your boost from tapering so bad which inturn would give you more power at the end of your power band. I am using the ap stage 2. would the pill benifit me?
Jul 16, 2009, 03:07 AM
#42
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what pill? i peak at 27 and taper to 17 and want to try and fix this. i was under the impression that the wga would just keep your boost from tapering so bad which inturn would give you more power at the end of your power band. I am using the ap stage 2. would the pill benifit me?
WoW!!!
