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DIY electric boost controller
https://www.rx7club.com/forum/attach...postid=2244427
Looking at this DIY rpm switch diagram, I was thinking in modifying to be a boost controller. The modification would be as follows: Use the boost sensor output and feed it into the Tach input as signal. The output would be going to a solenoid that bleeds air from the wastegate line and stops bleeding the air once desired boost is obtained. The boost controller would be hooked up EXACTLY like the stock S5 TII EBC but will be ran off this circuit instead of the stock ECU. What do you guys think about it? For the S5 TII owners, you have everything already, just need to build the ciruit and wire it up. I understand that the boost sensor voltage is calculated as follows: Out(V) = 0.169V/psi*P(psi) + 2.318V How is the RPM voltage like so that I an make the necessary adjustments. TIA |
how do you control the cycle of the solenoid?
If you have it open above set boost and then close below set boost u will need to have a feed back control loop. Which i do not see in that diagram. that is merely a switch. I do not belive that circuit is able to regulate boost. Go pick up any text book on control systems. You will need a pretty complex PID control i think to make this thing work. |
plus i don't see why u need an electronic boost controller if you are just wanting to shorten the boost threshold.
Why not just use a manual boost controller or a home depot ball and spring? the point of electronic boost controllers is to allow you to set the boost level based on either RPM or injector duty cycle and esentially have two maps so u can have a high and low and change on the fly. the real advantage of electronic boost controllers is when u have a t51 or T78 on huge port motor. Then you start getting traction problems when you hit the boost threshold. At this point you want to decrease your duty cycle on your electronic boost controller at say 4000 rpm (if that is when you turbo kicks in and makes your rear wheels light up like a christmas tree) You set the solenoid duty cycle lower so that you maintain traction. Remember faster 1/4 mile = traction, not burnout. I have the apexi unit. So you can adjust different RPM soilenoid duty cycles for different gear. So you then set a lower duty soilenoid when u get to boost threshold at say 1st gear. |
Originally posted by Cheers! how do you control the cycle of the solenoid? If you have it open above set boost and then close below set boost u will need to have a feed back control loop. Which i do not see in that diagram. that is merely a switch. I do not belive that circuit is able to regulate boost. Go pick up any text book on control systems. You will need a pretty complex PID control i think to make this thing work. If the voltage coming in is less then 3.75v (~8.5psi), then have the solenoid open and vent the pressure going into the wastegate. If the voltage is above 3.75v (or whatever you want MAX boost to be at), then have the solenoid close and feed the pressure into the wastegate line so it opens wastegate. |
Originally posted by Cheers! plus i don't see why u need an electronic boost controller if you are just wanting to shorten the boost threshold. Why not just use a manual boost controller or a home depot ball and spring? Originally posted by Cheers! the point of electronic boost controllers is to allow you to set the boost level based on either RPM or injector duty cycle and esentially have two maps so u can have a high and low and change on the fly. [/B] I don't think you get that with any BASIC electric boost controller like the earlier EVC, or Profec B. You only get that with the AVC-R or EVC V or Profec E-01 which cost at least $350 usd. Even the basic ebc will cost around $100usd at the cheapest USED. The EBC I want to build will cost me $10 cdn TOPS. Originally posted by Cheers! the real advantage of electronic boost controllers is when u have a t51 or T78 on huge port motor. Then you start getting traction problems when you hit the boost threshold. At this point you want to decrease your duty cycle on your electronic boost controller at say 4000 rpm (if that is when you turbo kicks in and makes your rear wheels light up like a christmas tree) You set the solenoid duty cycle lower so that you maintain traction. Remember faster 1/4 mile = traction, not burnout. I have the apexi unit. So you can adjust different RPM soilenoid duty cycles for different gear. So you then set a lower duty soilenoid when u get to boost threshold at say 1st gear. [/B] HOWEVER, I only have $20 for this project. My wastegate is directly feed from the compressor so the boost threshold SUCKS. Having this EBC would greatly increase my low and mid range tq. Right now, I don't get full boost until 4500rpm ~12psi. With the boost controller, I should have that by 3000rpm, which is a huge improvement for only $20 |
ball and spring is way better then the stock one anyways. just pick up a manual one for $25
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Originally posted by Scott 89t2 ball and spring is way better then the stock one anyways. just pick up a manual one for $25 |
Originally posted by pd_day Why can't I just hook up the boost sensor as input. If the voltage coming in is less then 3.75v (~8.5psi), then have the solenoid open and vent the pressure going into the wastegate. If the voltage is above 3.75v (or whatever you want MAX boost to be at), then have the solenoid close and feed the pressure into the wastegate line so it opens wastegate. woah super fast, then when it hits set limit of say 10 psi it would go like 10, 11, 10, 12, 11, 10, 12, something like that... After my midterms i'll try running that circuit in pslice or simulate it in matlab... and start feeding it input sigs. |
what if I build in some kind of Pulse Width Modulation to simulate duty cycles?
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