Low Boost, High Boost

[LNah]

Sort of get it now. For eg, if i were to set the high boost at 12psi on the controller, what it does is to trick the actuator into keeping closed until boost pressure reaches 12psi and then the controller will do as what paulr33 describes as "tell the actuator to open" and the actuator will open up the wastegate to regulate the pressure. Or else, without the controller, the actuator will always open up at 7psi and boost pressure can't go up anymore. The controller does the same thing for any boost setting.

Is my understanding right? Please correct me if wrong anywhere. Also, if the actuator will always open up at 7psi without the use of a controller, then why do most of you guys use an aftermarket ecu other than rearranging the fuel map for tuning?

[R3N3]

Sort of get it now. For eg, if i were to set the high boost at 12psi on the controller, what it does is to trick the actuator into keeping closed until boost pressure reaches 12psi and then the controller will do as what paulr33 describes as "tell the actuator to open" and the actuator will open up the wastegate to regulate the pressure. Or else, without the controller, the actuator will always open up at 7psi and boost pressure can't go up anymore. The controller does the same thing for any boost setting.

Is my understanding right? Please correct me if wrong anywhere. Also, if the actuator will always open up at 7psi without the use of a controller, then why do most of you guys use an aftermarket ecu other than rearranging the fuel map for tuning?

yep, you seem to be getting it . the reason for upgraded ecus, is that theres only so much the stock ecu can do, it doesnt really have any capability for tuning. and it will hit R&R on quite minimal mods (intercooler exhaust etc). also one of the major factors is that it dost support uprated injectos (therefor not much fuel = not good lol), E85 tuning and better fuel economy even. the list could go on forever. have a search on ecus ie nistune link etc. you will see the capabilities these things have. just keep reading

[paulr33]

yep lnah you got it spot on

there are some other things to note

you can't run less boost the actuator spring

ie you cant make the car run 4psi if you have a 7psi spring

because when you floor it, boost will increase until the actuator opens

so you cant make your controller (or any) give you less boost than the spring in the actuator, only more

and the best setup is to run the ideal pressure target in the spring actuator and bleed 1 or 2psi you need

ie dont use a 7psi and use a electronic controllre to run 22psi - its too much work for controller

if you wanted to run 22psi you would change the actuator to an 18psi actuator and bleed 4 psi

but this means, the minimum boost you run when you floor it (and the engine builds pressure) is 18psi

[LNah]

I see. Sort of get a rough picture of why you all say that squeezing extra power involves much more than just a simple mod to the air filter and exhaust. The air filter and exhaust are probably just the bare minimum, imo. More like setting up for the steps that follow on.