AVCR and external wastegates.

[chin suru]

ok, so I picked up my 240. Its got an Apexi AVCR, but its currently using a .8 bar spring in the TiAL 38mm HP wastegate to control boost. I downloaded and looked over the manual for the AVCR and noticed it said for external wastegates it says "please set the spring rate so that MAX boost pressure can be controlled with a 70% duty cycle." How do I do this? Why can't I just lower or raise the duty cycle instead like I can supposedly do with an internal wastegate? Thanks to anyone who can explain this.

-Andrew

[myprojectb13]

What they mean is to pick a maximum desired boost level. Say you want to boost a max of 1.2bar. You would want to use a wastegate spring that is 1.2bar X .70 = .84bar. That way you are using a duty cycle that is only 70% over the spring rating.

[chin suru]

but I don't wanna get a new spring. I wanna just change the duty cycle but the manual basically says I shouldn't..."why not?" or "can I?" is what I'm really asking.

[myprojectb13]

So don't go over 1.2bar. I'm sure you can, it does go up to 100% duty cycle, but thats going against Apexi's recommendation. At 100% you would be boosting 1.6bar with your .8bar spring.

[chin suru]

yeah, I'm just wondering if it will ruin anything (solenoid or WG) to go against the recommended 70%