Hey guys, I'm having a little boost control issue....If i just pull the two lines completely off my wastegate the boost should just run at the spring rate correct? Thanks in advance

 

no. if your wastegate sees no signal it will never open; the boost would build as much as the turbo could pump out.

 

You need to supply full manifold pressure to the wastegate side port to run spring pressure.

-Max

 

if you disconnect the line from your manifold to the wastegate actuator the bypass valve will still open at some point as the exhaust manifold pressure will rise and override the spring pressure. it will push the valve open from the backside...

it will be incorrect to infer that if you have a 10 pound spring in your actuator that it will open at 10 pounds of intake manifold boost due to the following:

1. exhaust manifold pressure will open the wastegate... not intake pressure. exhaust manifold pressure often can be 2X intake pressure or some variant due to turbine housings/wheel sizing. so if you are making 5 psi boost you might be making 10 psi exhaust manifold pressure... the actual pressure should take into consideration post-turbine pressure (the exhaust restriction)... so it should be exhaust manifold pressure minus post turbine wheel pressure... the net pressure between both sides of the valve.

2. the area of the valve. for instance the typical Garrett internal bypass valve port is .66 of a square inch. spring pressure is quoted in square inches so you'd need to make an adjustment if you knew the net pressure acting on the valve to solve for the spring pressure.

you are correct that the boost will be controlled my the sum of the forces (above) acting on the actuator spring and at some boost level it will open.

howard coleman

 

yeah I was thinking that it was the manifold pressure that was forcing the spring open and not the combo...that was dumb of me

 

I know this is the opposite of what you want normally but,,,, Is it possible to turn "off" the boost. Just in times you want 87 octane and better mileage... Just wondering.

 

called right foot or sell you car.

 

You would have to force the wastegate open. There is no way to do that without rigging something mechanically.

-Max