Understanding wastegate minimum and maximum settings....

[Blazer406]

Let me see if I have this right......

For stock style internal wastegates.......

The minimum boost setting would be with the rod adjusted out all the way until you barely have to pull the rod to hook up to the puck pin..... on a standard stock actuator... this would be 13-14 psi.... and 18-19 psi on a HD actuator.

If I understand it... you cannot adjust the stock (non HD) actuator any higher than about 2x the minimum setting... and have good boost control.... anotherwords 26-28 psi is tops for the stock actuator... to control boost.

That would make the HD actuator good to 36 psi or so....

Now.... if you wanted an actuator that had a minimum setting of 8 psi... so you could have a "launch boost" setting..... then... that actuator would be theoretically topped out at 16 psi..... which is no good.

What options are there for a launch boost capable actuator... that will also be good to 26+ psi? Is a CO2 controlled system the only alternative?

 

[Blazer406]

Upon further reading.... it appears the maximum can be raised higher than the 2x "rule of thumb" with an electronic boost controller.....

I would like to have a actuator that had a 7-8 psi minimum.... but be able to use it up to mid 20's on the boost.

 

[V6RACER]

There are ways to do this with an internal gate but it takes some creativity.

The easiest way is with external gate, boost controller, and C02

 

[Blazer406]

What I really want... is an adjustable "launch" boost.... settable from like 8 psi... to 15 or so psi..... that is actuated by some switch (could be brake switch... or transbrake switch)... then a high boost setting for the first part of the run when the engine isn't under as much load.....say 28 psi..... then at some point (could be time based).... scale back to say 24-25 psi for the remainder of the run...

Looking for options....

 

[bison]

That would make the HD actuator good to 36 psi or so....

I doubt you would ever get it that high without bleed off at high rpm. You need CO2 and a boost controller to do what you want. Jason has a nice setup on his car. Ive never seen one like it before.

 

[V6RACER]

I doubt you would ever get it that high without bleed off at high rpm. You need CO2 and a boost controller to do what you want. Jason has a nice setup on his car. Ive never seen one like it before.

I've done a few things and still have a few ideas that could possibly work without a boost controller. It would take a lot of trial and error but should work. Just need a few solenoids and some common sense.

 

[bison]

I've done a few things and still have a few ideas that could possibly work without a boost controller. It would take a lot of trial and error but should work. Just need a few solenoids and some common sense.

From what ive seen you will need more than the HD actuator spring to keep the gate from being pushed open from the backpressure. Starts to be a slight problem around 650hp with a GTQ in a Precision .85ex housing. Im sure it would be a lot worse at 800+hp.

 

[Blazer406]

I have toyed with the idea of several stages of boost control using seperate wastegate solenoids.... it wouldn't be that hard to do...... it would look funny under the hood.....trigger the different stages with things like the transbrake switch.... a microswitch on the shifter..... or something else....

I guess I was just wondering if I retrofit an 8 psi actuator under the hood.... would I be able to get to 25+ lbs with something like the RJC Boost Controller?

 

[pacecarta]

msbc-1 (now its the Exile/Deeds et-01) and a dual port external gate

this isnt new stuff , has been out there a while and youll find one in most of your competition buicks


i run an external gate (HKS on the 86 and on the 87 i run a Tail) with 5# spring , i run with no c02
the gate could be installed on an external DP , on the crossover or off the passenger header venting to atmosphere if desired, but mine are on an external setup down pipe

i can hold launch boost any where above 5psi (digital map based controlled so its accurate every time)

launch boost engaged and releases off t-brake on the 86 , on the 87 i footbrake so I've it tied the launch to the brake lights with a seperate arm switch to make the pedal activate launch mode which i trip on before i get to the tree

once released from launch mode it allows me to run any boost i want up to max of controller which is well beyond any boost you'd run on a buick provided your gate is sized for your HP .
It has 5 programmable timered stages(up to 4.99 seconds per stage or can have stages tripped on shift)
and if desired you can ramp the boost in with the programmable ramp stages to prevent tire spin
.
i usually run through three stages in a pass , I hit the bottom harder out of the hole , pull boost 1 psi in 2nd and run the last 1/8 about 2psi less
if you have WB controlled fueling it makes the changable boost work that much better as your not running overly rich when you drop the boost at the big end

 

[RUQWKNF]

The problem is, the actuators that Garrett sells that can actually go down that low, are way too small for this application. The tiny can and tiny spring would be blown away by the extreme volume that a decently sized Buick 3-bolt turbo can produce. The small actuators were designed for the T25/GT25/GT28/GT30 family of turbos. I would hate to see someone go through all the trouble to fabricate the necessary brackets to make the tiny actuators work, only to have zero boost control. Talk about a lesson in futility.

Jason is right, it is highly recommended to convert to an external actuator with CO2 when wanting to do staged boost levels. I used to deal with staged boost control setups all the time on race car applications, when I was at PTE. This was back when the only decent electronic controller was the Innovate boost controller. Now we have the AMS1000 and AMS500 systems.
A Tial 44mm wastegate would work well in this instance, as there are tons of spring combinations to choose from.
Hope this helps a little.

Patrick

 

[DailyDrifter]

Sorry to hijack, but what is the point to CO2? Do you pressurize one side of the wastegate to allow it to open more to get the lower boost? Just curious.

 

[ct67_72]

very simple. 2 stage boost control, on a switch, or something like an aem treuboost. they can be used a few different ways, either from wastegate setting to controller setting for an inexpensive 2 stage, or controlled boost switching to controlled boost. or multistage electronic boost control. turbosmart makes nice 2 stage units.

 

[Blazer406]

Sorry to hijack, but what is the point to CO2? Do you pressurize one side of the wastegate to allow it to open more to get the lower boost? Just curious.

As I understand it.... which may or may not be right... is this is typically used on a dual port wastegate....typically an external dual port wastegate.... and yes... the CO2 pressure on the back side of the diaphram allows for a more precise boost control when the CO2 is applied thru good solenoids... or stepper motors....and controlled electronically.....again if I understand it correctly.... the pressure on the back side of the diaphram acts just the opposite if it were on the front side... like typical setups..... i.e. the pressure holds the wastegate fully closed.... remove the pressure... and the gate begins to open..... kind of turning the wastegate actuator into a double acting cylinder... of sorts....with an internal spring....

 

[Blazer406]

The problem is, the actuators that Garrett sells that can actually go down that low, are way too small for this application. The tiny can and tiny spring would be blown away by the extreme volume that a decently sized Buick 3-bolt turbo can produce. The small actuators were designed for the T25/GT25/GT28/GT30 family of turbos. I would hate to see someone go through all the trouble to fabricate the necessary brackets to make the tiny actuators work, only to have zero boost control. Talk about a lesson in futility.

Jason is right, it is highly recommended to convert to an external actuator with CO2 when wanting to do staged boost levels. I used to deal with staged boost control setups all the time on race car applications, when I was at PTE. This was back when the only decent electronic controller was the Innovate boost controller. Now we have the AMS1000 and AMS500 systems.
A Tial 44mm wastegate would work well in this instance, as there are tons of spring combinations to choose from.
Hope this helps a little.

Patrick

What if it were a dual port... and you used both ports..... would this maybe help out that weak spring?

I guess I was hoping for a poorboy way to end up with a good steady launch boost... and the ability to go one or more stages way above the launch boost......but on a budget...

You know... I'm always trying to think "out-of-the-box".

 

[Tony Shoaff]

Look into the Turbo forum under Bracket racing and boost control. Mr. Wilson has a nice wastegate set-up I am going to try with the AMS 500. Good luck.