Hx35 Boost Spiking/Falling....More of a BOV or MBC Problem?

[spadepro22]

It holds 18psi WG pressure fine without the mbc connected and with the mbc connected it holds around 23-24psi to my desired rpm. Anything above that it falls back down to 24-25ish psi. Right now it hits 30psi before falling to 29-28ish in the 5000rmp range and around the 6000rpm range its falling down around 28-26ish and around 6600rmp up to about 7700rpm its falling down around 25-24ish. I say its spiking because when I up the boost it hits 2-3psi more on the top before it falls down to the boost I was looking for.

I have a TurboXS dual mbc and a NGR bov with the setting way more on the soft side and I was wondering if this could be a combination of both or one or the other? Boost leak test has been done and there was no leaks but probably won't hurt to do another one(don't think this is the problem).

 

[My1GLaser]

It's the .55 A/R BEP housing causing high exhaust pressures which blow the WG open. I've been dealing with it for a couple years myself. It is better now that I have a T3 .70 A/R BEP turbine housing with a 3" O2 housing, but the boost still tapers. You need more WG spring! I have the big and small blue one in a 38mm Tial and it holds 30 psi rock solid. I run 35-40, but it still always tapers back to right around 30psi. If I spent less time fixing my broken drivetrain, I would be able to solve the tapering issue...

 

[spadepro22]

It's the .55 A/R BEP housing causing high exhaust pressures which blow the WG open. I've been dealing with it for a couple years myself. It is better now that I have a T3 .70 A/R BEP turbine housing with a 3" O2 housing, but the boost still tapers. You need more WG spring! I have the big and small blue one in a 38mm Tial and it holds 30 psi rock solid. I run 35-40, but it still always tapers back to right around 30psi. If I spent less time fixing my broken drivetrain, I would be able to solve the tapering issue...

Only thing about putting in stronger springs is running WG pressure when tunning. I also have the 38mm with spring combo for min 18psi. How hard is it to change springs with the WG on the car? I remeber the shop had a little time with it off the car.

 

[My1GLaser]

It's actually easier on the car cause its already bolted securely to the manifold. Get 2 bolts that are about 20-30mm longer than the ones that hold the top down now. Replace 2 of the bolts with those, but just thread them in far enough that the top won't pop off when you remove the other 4. Remove the 4 short bolts. Then remove the 2 longer ones equally until the top comes off. Make sure they are directly across from each other.

I have a small green spring that I will sell you pretty cheap. Pm me if you're interested.

 

[spadepro22]

I still have all the springs that came with my tial wg(thanks though). Its the punishment racing one thats on the 02 and not the manifold, so would this method still work? Should I be concerned about dialing in a tune if my wg pressure is pretty high though?

 

[My1GLaser]

Yeah you shouldn't have a problem taking the spring out, except it might not be as accessible as it is on the exh mani.

It's probably safer to dial in the tune on the lower pressure then install the stiffer WG spring.

I vaguely remember someone using the stock BCS hooked up through ECMLink as a boost control to help stop the boost tapering off in the upper rpms, but I haven't gotten around to doing it yet...

 

[spadepro22]

Is this a common problem with the bep .55 housing?

 

[LandSpeed-DSM]

Is this a common problem with the bep .55 housing?

When ordered mine from Bill @ BEP and told him what was going to be done with it he offered an OE Borg actuator of some sorry that was strong enough to dangle a 5th grade from.

 

[spadepro22]

When ordered mine from Bill @ BEP and told him what was going to be done with it he offered an OE Borg actuator of some sorry that was strong enough to dangle a 5th grade from.

But my housing is setup for external gate.

 

[LandSpeed-DSM]

This is what I get for posting from a phone. It may be time to use an EBC to put boost to the top of the gate.

 

[spadepro22]

Ok, so I got the wg springs changed out to 1.6 bar(23ish psi) and its running minimum wg 26ish psi. When I turn the boost up around 30 psi it still drops to 26ish. Surely it should hold 30 psi with this spring setup right?

 

[My1GLaser]

Yeah I think it should. I am currently running WG pressure right now with the big and small blue springs in a Tial 35mm and I am hitting 26psi. I don't think I started having boost taper issues til 35psi. It does lead me to believe that you have a lot of back pressure, since it won't run more than the spring pressure. I could be wrong though, but when I start cranking my boost back up I will definitely have to resolve this for myself as well!

Have you tried hooking up a line to the top of the WG? I didn't like the way mine acted when I hooked up a line to the top port though! Damn thing spiked up to like 45 psi once and scared the shit out of me!!!!

 

[LandSpeed-DSM]

You need to use Link and the IR solenoid or something like AEM EBoost to be able to control the signal line to both ports.. unless your looking for everything shes got to give, that's the only reason you'd want to send boost to the top of the valve alone forcing the gate shut under all conditions.

 

[My1GLaser]

I probably should have asked if he had ever hooked up a second line to the top port!

What's an IR solenoid? I'd like to try that! I had a line hooked to both ports, but nothing to control the signals other than direct boost pressure on top and the MBC on the bottom one.

 

[spadepro22]

I have a dual boost controller with one line on the bottom of the boost controller running to the turbo compressor housing and the other line running from the side of the boost controller to the top of the wastegate.

My1GLaser, it will run more than spring pressure, it just always seems to drop back down close to spring pressure.

 

[iBoostDSM]

I'm not too sure what a dual boost controller is, but to me it doesn't sound like it's set up right. You have both ports of the mbc going to the wastegate? The bottom should be going to a boost source.

I have my hx35 in a .55 housing running 30psi and it doesn't budge all the way to redline. I'm using a hallman mbc with a line to the side of my tial 38 on the o2 housing.

 

[spadepro22]

I'm not too sure what a dual boost controller is, but to me it doesn't sound like it's set up right. You have both ports of the mbc going to the wastegate? The bottom should be going to a boost source.

I have my hx35 in a .55 housing running 30psi and it doesn't budge all the way to redline. I'm using a hallman mbc with a line to the side of my tial 38 on the o2 housing.

Its setup right, and only one line going to wg. Correction tho, the line is ran to a bottom port of the wg, but I do have the top port above it blocked off.

 

[iBoostDSM]

I have an old school 2 bolt tial, the mvs looks a lot more complicated haha. My guess is that it's something to do with the wastegate. Definitely not something to do with the turbine housing.

 

[spadepro22]

The IR solved the problem using top and bottom port. I have boost control now.