I finally got around to installing a boost gauge, and low and behold I'm boosting terribly low. Prior to adding the gauge I installed a 10.5 hotside, which I would assume cost me maybe a psi or 2 and a 3" intercooler, sacrificing another psi or 2. Excpet that I'm only reading 9 psi of boost (in second gear at 4500-5000rpm), which seems like a 10psi drop under stock . I'm pretty sure I have to adjust the arm on the wastegate, but is there any possibility that the boost gauge reading might be off, before I start playing with the wastegate and blow up my engine.

The boost gauge is a prosport electric peak hold, and I teed it into the vacuum line on the passenger side of the intake, the one with the blue lines across it, I think its the fuel pressure regulator(not sure).

On a side note I got into the throttle on a cold engine just to see how the reading would look. Which I would assume on a regularly boosting evo(19psi) would read maybe 3 psi more. On the first pull I hit 21psi on the second I hit almost 23. It doesn't make sense that on a cold car I'm hitting 11-13 psi more than on a warmed up car. Although this might rule out the boost leak theory, but is it a possibility that the boost gauge is acting up?

On a start up there is a vacuum of about 19psi, second gear at 3000 it seems to zero out and 2nd gear around 5k rpm only 9psi of boost and it dwindles as the rpms get closer to redline.

The car will be tuned probably next week as I install the cams.

 

How are you controlling boost level? What are your complete mods? Set your boost in 4th or 5th. 9 PSI in 2nd may give you 11 PSI in top gear. So, yeah, you could try shortening the adjustable actuator rod by 1&1/2 turns.

 

Who is tuning your car?

 

I'm thinking your wastegate is not closing all the way, prob has something to do with the 10.5 hotside install. I would check that first

p.s. actually, make sure you do not have a kink in your boost guage line before you do anything.

 

Ya I'm going to take a look at that boost line tomorrow, I think something is not right with it.

my mods are: forge recirc bov, 3" intercooler, meagan headers, ebay o2 housing,, 3" turbo back, no cat, 10.5 hotside and a few drivetrain goodies, walbro 255.

The wastegate might be the problem too, I remember in the 9.8 one the arm was sitting tightly on the bolt from the wastegate, it was extended up more than on the 10.5. On this one it just slides on and off without a problem.

I spoke to strictly modified about the tune, but I'm still considering devo

 

Try shortening the adjustable wastegate actuator rod. You state that the turnbuckle(eyelet) slides freely onto and off of the pivoting peg on the wastegate's flapper valve. This means that there is absolutely no preload on the wastegate. Try shorteing the rod by rotating the turnbuckle 2&1/2 turns.

I guess that you are not running a boost controller. I'd install one of those as well. Just curious, but is your car not tuned at all?

 

Its clear where all your boost went......

 

Seriously though... Possibly check your Forge BOV. They have been known to stick and not close all the way.

Let us know what you find.

 

I checked for kinks in the boost line, and ended up rerouting it. Changed the vacuum line connected to the bov, simply because it was terrible looking, actually there is no way it was holding a seal. While I was there I inspected the bov and it seems to be working just fine.

The needle on the boost gauge seems to have shifted lower than before I intially installed the gauge. The vacuum at idle has gone up to 20-21psi from 19, and the boost doesn't even climb to 7-8 psi, lol

Tomorrow I'm going to mess around with the wastegate actuator.

 

does the car feel like its only making 7-8 psi?? or does it still feel like its making power? You should know if you are making 7 or 8 psi. If it doesn't feel slow, then its probably the gauge, or where you are hooking up the gauge.

 

After shortening the wastegate actuator rod a whole turn the boost seems to peak out at 11ps, which is about 3 psi better than previously. I guess I could turn it maybe 2-3 more times around and it would probably climb back up to 19 psi, but the only problem is that I was barely able to slide the eyelet back onto the pivot, with it only being shortened by one turn, so there is no way after 3 turns I would be able to slide it back on. Besides why would it require this much adjustment going from a 9.8 to a 10.5 hotside?

While I was messing around with all this stuff, I did a boost leak test, and the system was holding 26psi, with the throttle body area being the only source of a small leak(common problem).

At this point the only thing I can think of is getting a boost controller and cranking it up to 19psi, the preffered option. Or option number 2, getting a new wastegate actuator.

Do you guys have any other suggestions, maybe changing the source of the vacuum reading, or something with the boost solenoid?

 

Sorry for the repeat post!

 

You need at least two more 360* turns to the eyelet, so:

Don't be such a wimp(JK)! Go to Sears and get one of those Craftsman 24" shanked(Yes, bigger is better) flatblade screwdrivers. First tighten the backup nut right up snug to the eyelet. Then using the top, passenger side, corner of your radiator fan shroud as a fulcrum point, place the tip of the screwdriver blade behind the backup nut, prying up and forward on the eyelet to ease it forward onto the pivot peg.

This method works for me.

 

Ya I don't mind doing that, my only concern is that I'm doing the right thing by shortening the rod so much. I'm not really trying to damage the engine. I guess my question comes down to is the rod supposed to be that short where you have to pry it on with a screwdriver? Even with the 9.8 hotside I could slide the eyelet onto the peg with just my fingers, but than again I don't know how much it was boosting back than.

 

If you have the wastegate actuator rod adjusted to freely slide on and off of the pivot peg on the wastegate flapper valve, then you are simply running zero wastegate preload. This setting will give you the absolute slowest rate of turbo spoolup possible.

You really shouldn´t need to use a pry tool such as the long shanked screwdriver balanced on the corner of the fan shroud to urge the actuator rod forward. I never needed it until preload exceeds 18 PSI on wg actuator´s with heavier internal springs, such as, the FP HD unit.

With the stock WGA on a 10.5 housed-IX type turbo the usual high performance preference is about 3 full 360* turns shorter than the point where it freely slides on and off of the pivot peg. Another rough way to judge it is that from the point where the hole in the turnbuckle(eyelet) and the peg line up axially and slide on and off freely, shorten the rod to where the hole in the turnbuckle only covers half of the peg freely and you have to pull strongly on the actuator rod to get it to mount.

Each actuator is different(Forge, stock Mitsu, Forced Performance, etc.) with variances in springs, diaphragms, angulation of the actuator rod. And even the external configuration of your particular turbo has an impact on the equation.

You yourself have found that since the 10.5 housing´s external dimensions differ from those of the smaller 9.8, then the angular relationship between the WGA´s mounting point on the compressor housing and the pivot peg mounted on the turbine housing have changed. This is part of the problem that you are experiencing. This altered dimensionality requiires adjustments in the actuator rod´s length to maintain the same amount of WG preload.

Another reason, for the change in preload levels is that the exhaust pressure within the larger 10.5 housing and the smaller 9.8 housings differs at any given engine speed and turbo shaft RPM. So, the turbine inlet pressures of the two housings are different.

The turbine inlet is the initial area of the turbine housing from which the turbine bypass ports which lead to the integral wastegate´s flapper valve are located. since the two housings have different inlet pressures due to volumetric differences, then it follows that each housing would exert different seat pressures upon the flapper valve. This requires different actuator rod lengths to achieve the same amount of preload.

The 9.8 housing may require a shorter actuator rod length to achieve the same amount of preload obtained with longer rod length on the 10.5 housing, given the same actuator. Why? Because of higher turbine inlet pressures and the resultant higher seat pressure with the 9.8 housing.