I have a 6port turbo, internal wastegate BNR, Haltech… the standard stuff. Turbosmart Wastegate 7psi. I’m only seeing 6.1 psi peak. Does the wastegate open after the advertised number or does it open before and “guarantees” that I would “never” see over seven psi? Currently, I’m running no boost control, just the mechanics of the wastegate. Could it be pressure drop from the intercooler?

freeway travel has been awesome. 180* coolant, 80*-90* AIT about 15* over ambient. Driving in city freaks me out. I’m waiting for a traffic light and seeing AIT raise to 110*-120*. I’ve read conflicting opinions on a fan on an intercooler. Im leaning against it, but I do have a free output on my ECU if needed.

thank you.

 

The relative size of the valve face to diaphragm will make them more or less sensitive to the efficiency of the turbo system. Relatively small inefficient turbos require more exhaust manifold pressure to generate boost so will generally make less than rated boost, especially with a valve which is similar to diaphragm area.

 

The turbo is a S5 turbine from the mentioned BNR offering. So likely not bleeding edge efficiency. The IC claims less than two psi pressure drop. Combine the two and the 6.1psi pencils out in my mind. Thank you Slides!

 

To answer your question, no. The wastegate rating is not 1:1 what you will see. That number is essentially the nominal pressure that it will be fully open. Wastegates have what is called cracking pressure. This is the point where the valve/piston/diaphragm just start to move/open. With the variables mentioned above, this will be something of a +/- thing. So a 7psi spring will be fully open at 7psi +/-1 or 2.

There are some cases where it actually is dead on but it's all an equipment thing. For your air temp, don't freak out too much. Stock air temp range on the fd is 55c-70c. To me, that's insane but it's a stock parameter. What's important is that when you're driving the air temp is under control.

 

same principle as a thermostat, the temperature in that case is the opening point, not the full open point though. the rest is up to the flow characteristics and backpressure in the system slowing down the flow.

an oversized wastegate would result in less boost than the threshold, an undersized wastegate would get creep and more boost than the open point. thing about wastegates though is they hold well when fully sealed, once that pressure breach occurs they lose their ability to work against the exhaust now trying to force them to remain open, which is why it's generally better to go slightly bigger than smaller. less boost can mean several things though, a boost leak or restriction in the exhaust, improper timing causing efficiency issues, to name a few.

a 1psi difference though wouldn't alarm me, especially if less than the expected result. creep is worse than the alternative.