Won't boost past 20psi?
Just go ahead and cut 1/4" off the tip of the actuator rod. Reassemble sans the backup nut. Rotate the turnbuckle all the way down. This should increase spring pressure roughly 3-4#.
Your hunch is probably correct. Ultimately, the stock actuator is just not up to the task of controling boost in your particular application.
Last edited by sparky; Mar 11, 2013 at 04:54 AM.
A factory wga will be fine to 30 psi if it's working propery. If you have a wga that is fully open at 10psi then there is no way it is going to make more than 20psi with any boost controller simply due to insuficient preload and spring tension. The exhaust back pressure will push the flapper open. Preload the wga as much as you can whilst being capable of opening fully, then run it on wastegate pressure only (to test functionality). You should be able to double the wga psi with a boost controller.
Sure you can try to run 30# peak on a stock MHI VIII, or IX actuator. But, it is not ideal. Above 24# peak pressure you really want at least a HD 18# actuator. Over 28# peak you want a 25# WGA. Even the FP 18 pounder has ro be radically modded to perform well over 28#.
Part of the problem of running a wimpy actuator at relatively high peak boost levels is something that you mention. You may have to preload it so much that the spring binds or the diaphragm can't overcome spring pressure. In that scenario the flapper may not be able to fully open.
On the other hand, if you run the stock WGA too loose then you kill turbo spoolup, because the flapper will ride up off its seat and neither a boost controller(EBC, or, MBC), or a BCS will fully keep the flapper shut above 22# with an unmodded stock actuator. So you kill spool.
Even an FP 18# actuator has to be chopped to provide decent spooup and at the same time control peak boost at over 24-25 PSI. I wouldnt want to run the stocker at 30#.
Sure, probably someone out there runs the stocker at 30 PSI+
Part of the problem of running a wimpy actuator at relatively high peak boost levels is something that you mention. You may have to preload it so much that the spring binds or the diaphragm can't overcome spring pressure. In that scenario the flapper may not be able to fully open.
On the other hand, if you run the stock WGA too loose then you kill turbo spoolup, because the flapper will ride up off its seat and neither a boost controller(EBC, or, MBC), or a BCS will fully keep the flapper shut above 22# with an unmodded stock actuator. So you kill spool.
Even an FP 18# actuator has to be chopped to provide decent spooup and at the same time control peak boost at over 24-25 PSI. I wouldnt want to run the stocker at 30#.
Sure, probably someone out there runs the stocker at 30 PSI+
Last edited by sparky; Mar 11, 2013 at 07:12 AM.
Thread Starter
Joined: Feb 2010
Posts: 854
Likes: 1
From: Clarksville, TN
Sparky help me out bud, I cut about 1/4 threads off the rod turned the turnbuckle all the way down then a full turn back. Boost is at 10 with the turbo straight to WGA, which is where it was. Could this WGA be bad and not be able to get to all the boost I'm wanting? I use to run over 25psi on a stock 9 turbo a while back.
Something sure seems fishy, doesn't it? Something isn't quite right, huh? I mean you cut a 1/4" off the actuator rod, removed the backup nut, and ran the turnbuckle all the way down to where the tip of the actuator rod bottoms out, and etc. You'd think that you would be seeing more than 10#. LOL
Last edited by sparky; Mar 14, 2013 at 09:46 PM.
I mean 8-10# is about base spring pressure with the stock MHI WGA. Base pressure being as low as she'll go for any particular actuator with the actuator rod adjusted to its loosest setting, also defined as the point where the hole in the turnbuckle freely slides on and off the peg on the flapper valve's pivot arm.
The funny thing is that for boost to flatline at 10# like that, the flapper has got to be full open, understand? This is self evident if all else is working properly and there are no boost leaks, pre turbo exhaust leaks, and assuming that the flapper is not broken.
When the flapper is broken or the actuator rod disconnected, a stock turbo will usually only boost to 8#. Connecting the flapper to the flapper's pivot arm will add two PSI which brings it up to 10-11# roughly.
But, you've gone and put additional tension on the flapper by cutting the actuator rod and adjusting the turnbuckle to its tightest setting. So, something is fishy.
When the flapper is broken or the actuator rod disconnected, a stock turbo will usually only boost to 8#. Connecting the flapper to the flapper's pivot arm will add two PSI which brings it up to 10-11# roughly.
But, you've gone and put additional tension on the flapper by cutting the actuator rod and adjusting the turnbuckle to its tightest setting. So, something is fishy.
I would like you to figure out a way to wire the flapper valve's pivot arm in such a way that the arm cant move and thus the flapper will stay shut. Once you wire it shut...take it for a WOT trial run to see if it will boost higher than 10#. Now, you will have to be ultra careful not to overboost. That is you must keep a close eye on the boost gauge and lift off the go pedal if the needle swings past your target boost level.
We are trying to determine whether it is your turbo's flapper valve, or the WGA itself that is bad. Of course another way would be to swap that actuator out for a known good one.
We are trying to determine whether it is your turbo's flapper valve, or the WGA itself that is bad. Of course another way would be to swap that actuator out for a known good one.
Last edited by sparky; Mar 15, 2013 at 07:42 AM.
What I dont understand, so maybe you could help me is that you say that your car wont boost over 10#, but later on you state that it boosts to 20#. I am just trying to form a complete picture of what is happening.
I reread all your posts and I am still slightly confused. Had the turbo been boosting normally with the Forge actuator before installing the stock actuator? Is the low boost situation only manifest after installation of the stock piece?
Last edited by sparky; Mar 15, 2013 at 07:50 AM.
Thread Starter
Joined: Feb 2010
Posts: 854
Likes: 1
From: Clarksville, TN
the 10psi is turbo to WGA, i can get it to 23ish with my hallman but it wont go any further. I will find a way to force the flapper closed at all times and see where the boost goes. Should technically be limitless, correct? If the boost is still low then its the flapper? Or could be the turbo correct? I will see if I can get it to 25+ and then lift. Car when fully tuned will be at around 30psi on E85.
If the flapper was broken then an MBC alone could never have raised boost to 23#. Believe me. If the flapper were broken boost would flatline at 7-8 PSI. So, let's eliminate flapper valve failure from the list of possible suspects in this case. Don't mention it anymore....please!
Last edited by sparky; Mar 16, 2013 at 07:30 AM.
Again I had the same problem on my ef3, a pin in the compresor housing was bent which caused me to lose preload and wouldn't make boost past 20psi if that at times. Called MAP and the fixed or under warranty I would give them a call and describe the issue they have really good service
On the stock-frame 16G turbos there are two bolt holes located along the outer edge of the compressor housing casting. These bolt holes only serve as attachment points for the WGA mounting bracket. No pins AFAIK. Maybe the MAP turbos are different though.
Last edited by sparky; Mar 16, 2013 at 05:00 PM.