what would control wastgate ?

[jethro]

Someone today was pointing out that if I took my H1C and put on a smaller exhaust housing (now have 18.5)
to get a quicker spool-up that it might run too fast at idle and lower rpm's----- that a waste gate might be needed
to vent off some boost and close gradually as RPM or engine load increased- or some other combination of variables.

Now If this was a gasoline engine I would think a vacuum signal from the intake manifold might be a nice indicator of how much
pressure is needed from the turbo------- what do we do on the 6bt ???? no engine operated vacuum.....
I will have no computer (1-st gen) ....... how do I operate a waste gate if I go to a turbo that has one ???????
Would it have to be something involving the TPS and RPM pickup- like maybe the difference between them ???????
and is that something that is all ready made (off the shelf) for the 2-nd gen trucks ?

I am a beginner at 6bt so there are things I don't know.....

Thank you for any hints !
Tim

[burnt_servo]

almost all non computer controlled turbos with a wastegate use a variation that in principle works the same way .

a pressure hose runs from the intake side of the motor to a diaphragm operated actuator . the actuator is connected to the waste gate ( or other similar device that reduces exhaust gas pressure on the turbine wheel) .

no computers to mess with , fuss or muss .

[Tacoclaw]

No such thing as spinning too fast at idle, diesels want as much air as they can get at all times.

Gassers have the butterfly closing off the intake, so it's pointless for them to be doing any work since it doesn't go anywhere, diesels do not.

[1992gen1_fan]

The wastegate on a 6bt just needs a boost line connected to a fitting in the pressure side of the compressor housing. Simple as it gets. The down side at idle is that the tighter housing will take a bit longer for the turbo to cool down. The extra air at idle won't hurt the diesel engine.

[PToombs]

The size of the exhaust housing will not change the idle setting at all. Only changing a fuel setting on the pump will change the idle. The wastegate opens at higher boost to dump exhaust gasses around the turbine wheel to prevent it from overspeeding. If you are dumping a lot of fuel to it it will overspeed anyways. For what you are doing it will be fine, it will increase spooling speed and get more air in the engine.
Just hook a hose from the wastegate to a fitting in the compressor housing (most have an elbow or a plug in a hole in the face of the housing) or run a hose across to the intake and get your boost signal from there. My 2nd gen has a hose that goes to the intake and it is Tee'd into the AFC line.

[jethro]

That seems pretty simple-
It just sets the high end open point.
Is there any need for one that is open slightly at idle and closes as rpm starts to come up ? (in addition to the normal one...)
(sounds like no ?)
just wondering......

[PToombs]

Nope! Open at idle defeats the purpose because it won't spool because it's leaking past the wheel.

[dr_funk]

No such thing as spinning too fast at idle, diesels want as much air as they can get at all times.

Gassers have the butterfly closing off the intake, so it's pointless for them to be doing any work since it doesn't go anywhere, diesels do not.

While diesel engines don't have a throttle body to close off like gas engines do, they can still suffer from compressor surge. The amount of air that can flow through the engine is dependent on RPMs and is still limited. If you're running at high boost and then dramatically cut the RPMs by letting off the throttle, the amount of air that can flow through the engine at that moment drops dramatically, and your compressor will potentially surge. It isn't as dramatic as on a gasoline engine with a throttle body, but it can still happen.

[Tacoclaw]

I think you'll have more problems with the turbine housing choking it than you will a 359ci engine at any rpm, especially idle.


Our turbos bark when the throttle is chopped but I think it has less to do with physically fitting the air and more to do with the loss of drive pressure to keep driving the compressor wheel.

[dr_funk]

It's both, actually. The drive pressure from the exhaust side drops and the intake resistance increases. The lack of drive pressure means there's nothing to keep the compressor spinning in the correct direction. The increase in intake resistance means the boost pressure spikes, and since there's no drive pressure to keep the compressor spinning forward, the intake air can bring the compressor to a halt or spin it backwards as it pushes its way back out to the atmosphere. That's the "barking" sound - the intake air escaping backwards past/through the compressor.