Just wanted to share my experience with the Forge K24 Wastegate Actuator as some of this info isn't easily available without a lot of digging and some isn't on here at all. Also open to hearing info from the OG's because some of my assumptions might be wrong.
A quick overview, the Forge Wastegate Actuator comes with a green spring preinstalled which I could not get to boost past 10psi. I ended up ordering the spring kit and swapping in the next stiffest yellow spring. After hard resetting the car by disconnecting the battery, I was boosting to the stock 14psi.
When I initially installed the Forge unit I was only boosting to 10psi. I did some research and experimented with adjusting the rod length as well as trying to set it the way IPD does in their video where they watch to see at what pressure the rod starts to move when supplying air to the inlet port on the actuator. This did not work at all, the rod would move around 9psi of pressure at the port and when I would test drive with the TCV power unplugged with that same rod length, it would boost to about 6psi. Adjusting the length of the rod only seemed to change the behavior of how it boosted, it did not change what pressure it boosted to.
I connected the TCV with this setup and it would not boost past 10psi. When the TCV activates, it supplies pressure from the turbo to the wastegate actuator to overcome the spring force that is keeping the wastegate closed, thereby opening the wastegate. I believe the green spring did not have enough force to keep the wastegate closed past about 10psi. It was being blown open by the exhaust gas pressure as far as I can tell. Someone else in another thread speculated this too.
Forge says the green spring is good for 5-10psi and is what should work with a stock setup which I believe to be incorrect. (Maybe it is necessary to shorten the length of the rod by a lot, adding a lot of preload to the spring? This would have the consequence of limiting how far the wastegate could open though as you're shortening the range of motion of the spring...) I installed the next stiffest spring available, yellow, which according to them is good for 10-14psi. I set the wastegate length to the sweet spot I describe below and went for a drive. The car would've boosted to unsafe levels but I let off at 20psi. I then test drove with the TCV unplugged and it boosted to 10psi on wastegate pressure alone. I unplugged the battery and touched the cables together to reset the car. Went for a drive and it immediately boosted right to about 14psi which I'm assuming is stock levels and my gauge is off by 1psi (or the spring is blowing open at 14psi and really I could get that 0.7 psi extra if the spring was a little siffer?) After a few pulls, the behavior got very consistent compared to what I was used to with the oem wastegate (128k miles on it.) It used to hunt around or overshoot boost and now it seems to shoot right up to the same amount every time and just hold more consistently.
The going terminology is that adjusting the length of the rod changes when the wastegate will open. That is BS when using the Forge unit and maybe even the oem unit. The actuator will begin to move whenever the air pressure at the port exceeds the opposing force of the spring. That is a CONSTANT depending on what spring you have installed. Adjusting the the rod length only allows you to set the wastegate to be partially open at rest (rod length too long - pointless in this situation) or if you want to preload the actuator spring (rod length shortened - I don't see a benefit to this.) After experimenting with it for a while, it seemed to make the most sense to me to just set the rod length a hair shorter than the point at which the wastegate is sealed at rest. Maybe someone with more knowledge than me can explain the benefit of shortening the rod to add preload to the spring.
The way I would set the rod length is I would begin to thread the wastegate thimble onto the actuator rod. This will begin to close the wastegate. At a point, the wastegate will be fully shut and if you continue to tighten the thimble, you are adding preload to the spring in the actuator. I find the sweet spot by tightening the thimble until the wastegate stops moving and then going maybe another 1/8th of a turn. This makes the most sense to me but I would love to hear from someone who has more experience than me.
Hopefully if someone out there is struggling with this it will help them think through things. I believe all this to be correct but again would like to hear from someone who's more experienced than me.
A quick overview, the Forge Wastegate Actuator comes with a green spring preinstalled which I could not get to boost past 10psi. I ended up ordering the spring kit and swapping in the next stiffest yellow spring. After hard resetting the car by disconnecting the battery, I was boosting to the stock 14psi.
When I initially installed the Forge unit I was only boosting to 10psi. I did some research and experimented with adjusting the rod length as well as trying to set it the way IPD does in their video where they watch to see at what pressure the rod starts to move when supplying air to the inlet port on the actuator. This did not work at all, the rod would move around 9psi of pressure at the port and when I would test drive with the TCV power unplugged with that same rod length, it would boost to about 6psi. Adjusting the length of the rod only seemed to change the behavior of how it boosted, it did not change what pressure it boosted to.
I connected the TCV with this setup and it would not boost past 10psi. When the TCV activates, it supplies pressure from the turbo to the wastegate actuator to overcome the spring force that is keeping the wastegate closed, thereby opening the wastegate. I believe the green spring did not have enough force to keep the wastegate closed past about 10psi. It was being blown open by the exhaust gas pressure as far as I can tell. Someone else in another thread speculated this too.
Forge says the green spring is good for 5-10psi and is what should work with a stock setup which I believe to be incorrect. (Maybe it is necessary to shorten the length of the rod by a lot, adding a lot of preload to the spring? This would have the consequence of limiting how far the wastegate could open though as you're shortening the range of motion of the spring...) I installed the next stiffest spring available, yellow, which according to them is good for 10-14psi. I set the wastegate length to the sweet spot I describe below and went for a drive. The car would've boosted to unsafe levels but I let off at 20psi. I then test drove with the TCV unplugged and it boosted to 10psi on wastegate pressure alone. I unplugged the battery and touched the cables together to reset the car. Went for a drive and it immediately boosted right to about 14psi which I'm assuming is stock levels and my gauge is off by 1psi (or the spring is blowing open at 14psi and really I could get that 0.7 psi extra if the spring was a little siffer?) After a few pulls, the behavior got very consistent compared to what I was used to with the oem wastegate (128k miles on it.) It used to hunt around or overshoot boost and now it seems to shoot right up to the same amount every time and just hold more consistently.
The going terminology is that adjusting the length of the rod changes when the wastegate will open. That is BS when using the Forge unit and maybe even the oem unit. The actuator will begin to move whenever the air pressure at the port exceeds the opposing force of the spring. That is a CONSTANT depending on what spring you have installed. Adjusting the the rod length only allows you to set the wastegate to be partially open at rest (rod length too long - pointless in this situation) or if you want to preload the actuator spring (rod length shortened - I don't see a benefit to this.) After experimenting with it for a while, it seemed to make the most sense to me to just set the rod length a hair shorter than the point at which the wastegate is sealed at rest. Maybe someone with more knowledge than me can explain the benefit of shortening the rod to add preload to the spring.
The way I would set the rod length is I would begin to thread the wastegate thimble onto the actuator rod. This will begin to close the wastegate. At a point, the wastegate will be fully shut and if you continue to tighten the thimble, you are adding preload to the spring in the actuator. I find the sweet spot by tightening the thimble until the wastegate stops moving and then going maybe another 1/8th of a turn. This makes the most sense to me but I would love to hear from someone who has more experience than me.
Hopefully if someone out there is struggling with this it will help them think through things. I believe all this to be correct but again would like to hear from someone who's more experienced than me.
