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4 port boost controller

Boost Control

Discussion and questions related to the course Boost Control

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What is the purpose, benefit/downside to four port boost controllers. How are they piped on externally waste gated setups


but i have been told they are a lot more sensitive to duty cycle changes than a 3 port.

can anyone confirm this and are there any circumstances that contribute to the sensitivity? High boost low boost etc.

With a 4 port solenoid you can completely remove pressure from the bottom port of the wastegate (with a typical 3 port installation this side of the wastegate always has boost pressure applied to it). This provides the potential for a much wider range of boost control than a 3 port solenoid can achieve since with the 3 port we always have exhaust pressure acting against the wastegate valve and trying to open it, as well as the boost in the bottom of the wastegate head also trying to open it.

To give some example, with a 10 psi spring in a wastegate, you may be able to achieve a maximum boost pressure of perhaps 25 psi with a 3 port (hence a range of 15 psi) but a 4 port may allow you to reach 35 psi or thereabouts.

can this be applied in principle to a blow off valve on the intake tube before entering the throttle body and supercharger to control over boost and what air valve bodies are most utilized for this application

You could make it work but if you're really concerned about overboost on a supercharger, size the system correctly so it doesn't tend to overboost in the first place, and put a fuel cut in for emergencies.


do you recommend this setup/where have you used it before? Jay's tech tips on realstreet youtube channel makes it sound like the way to go. Plumbing wise the what are the 4 ports, 1 normally closed (to the top of the WG as in exhausting normally) 2 normally closed (to the bottom of the waste gate holding it closed against engine exhaust pressure) 3 input 4 vent? is duty cycle set up the same on a 4 port as a 3 port? IE will the parameters be the same, starting with open loop and then adding in your PID for closed loop? For background I'm new to tuning and using a AEM infinity on a dual externally waste gated twin turbo system.


It really depends what range of boost control you need. Certainly the 4 port will give you a wider range of control than a 3 port solenoid can. Realistically the only downside I see with a 4 port over a 3 port is that the boost will be a little more sensitive to changes in duty cycle.

I was just about the create a new topic on 4 port boost control solenoids when I saw this post.

Andre, why wasn't the 4 port boost control solenoid described and dealt with in the boost control course?

@Chris, we may add a module on these solenoids. In my own experience they still aren't that common outside of drag racing, however I'll admit they do seem to be gaining popularity. The reality though is that other than the plumbing side of things, the operation and tuning is identical.

Thanks a lot for the response and understood.