Old School Actuator Question......

[Steevo]

I have searched the boards for a definitive answer!


1- To determine the boost in which the actuator is set at - can I fit a car tyre valve or similar into the vacuum line off of the actuator port and use a pump/gauge to determine the pressure it opens?

2- When shortening the bar to increase the boost, can you have too short a movement (if that makes any sense) thus preventing the actuator from working correctly?

Thanks

[casper]

Yes to both.Ideally you want the correct spring in the actuator for the boost you intend to run.This will give you the correct amount of preload.Too much preload can stop your actuator from moving to open the wastgate.Then you have overboost.

[Steevo]

Thanks mate
Are the springs specific to actuator type or universal?

[JP Racing]

Most actuators are sealed unless you go after market. If you have an after market one you would have to get the correct spring for the right actuator

[casper]

Most turbo suppliers such as tt or cr turbo will be able to supply you with what you need.As a for instance cr turbo supplied mine with an initial lift pressure of 18lb so with minimal preload and no bleed i can run the desired 20lb.

[Steevo]

So if the actuator opens at 10psi for example, is that not the pressure you will see at the carb top?

[Brigsy]

It all depends on how much pressure drop there is in the boost circuit.

To be honest i would keep adjusting the actuator until you see the required boost. The o.e is usually good for 15lbs boost. I dont think you can get the rod short enough on the original actuator to effectively cause an overboost situation.

The science of actuator spring ratings goes out the windows with gt turbos. Anything over 15lbs boost (manifold) use a -31. Anything over 22lbs boost (manifold) use a -34. If you need to use a bleed valve to hit your required boost level.

[Steevo]

It all depends on how much pressure drop there is in the boost circuit.

To be honest i would keep adjusting the actuator until you see the required boost. The o.e is usually good for 15lbs boost. I dont think you can get the rod short enough on the original actuator to effectively cause an overboost situation.

The science of actuator spring ratings goes out the windows with gt turbos. Anything over 15lbs boost (manifold) use a -31. Anything over 22lbs boost (manifold) use a -34. If you need to use a bleed valve to hit your required boost level.

Thanks Brigsy, I'm going to see what pressure it opens and go from there. Does this look standard

[casper]

I had an actuator that had an initial lift pressure of 14lb.I kept on shortening the rod as i wanted to run 20lb.In the end i went too far and saw massive over boost.:cryHaving loads of preload is not the right way.

[Brigsy]

Thanks Brigsy, I'm going to see what pressure it opens and go from there. Does this look standard

That could be a 14lb actuator? What pressure does it crack open at?

My -34 on the van has 15mm preload and a bleed off to make the desired boost casper

[Steevo]

I tried rigging up to the actuator using a foot pump and gauge but it didn't quite work! I may need to invest in something else to do it