Resolved FP black, boost creep w/ 38mm external??

[boost97gst]

So, my car is basically done. However i can't tune it properly due to some insane creep. I can't hold this thing off. It will peg the 30psi gauge.

What i'm using and what i've done:

EMUSA 38mm 2 bolt gate dump to atmo, PR non recirc'd o2 housing, 3" pipe dumped 2 feet back and FP black/FP mani

I have put in the lightest spring that came with it. Tested with a compressor and opens just fine at 10psi. No problems with the valve.
Idling the car i hooked up the compressor and applied the 10psi to the WG, opens up just perfect and exhaust flows, as it should, right out the dump tube.

This is a bit perplexing. I will buy a tial in a heartbeat but i seriously don't think that's the issue. I can't quite figure it out.
Anyone have any suggestions? Porting the hell out of the wg port on the turbine housing will be the next step but i can't believe it's THAT small that it would runaway boost like it is.

 

[wishihadatalon]

I get creep out of my 38mm on a Punishment t3 manifold with an hx40, but I never really planned on running less than 30psi. I think the porting you are thinking about may help a bit, but the 38 seems to be a small gate for the larger turbos.

 

[donniekak]

Can you hear the dump open when you are going wot? Do you have a picture of the setup?

 

[boost97gst]

Very tough to hear any dump tube since the exhaust is deafening. I'll grab a pic in a minute but I have the boost source to the bottom port, lest anyone think it's hooked to the top. It IS functioning when i apply pressure. I can hear it at idle coming right out the dump tube.

 

[Dsmkauai]

Sounds like you would want a thicker spring to be able to hold boost solid. Same applies for a internal gate. Your just blowing the gate open and therefore have no control of things. I'm not saying it's the emusa gate but could be its not up to par. http://brickspeed.net/forum/showthread.php?tid=1773

 

[boost97gst]

Well, i don't think a heavier spring would allow me to lower my boost.........
About the gate, yes i absolutely question the quality as well but there is one undeniable fact: I can apply pressure to the port and the gate opens, directing exhaust properly.
I actually got this gate years ago and it has been in a box. I ordered it and ended up getting 2 identical gates. I have a spart to test but something isn't adding up, unless the volume of air through the MBC is restricted to such a point that it can't open the gate? That's possible

 

[boost97gst]

I get creep out of my 38mm on a Punishment t3 manifold with an hx40, but I never really planned on running less than 30psi. I think the porting you are thinking about may help a bit, but the 38 seems to be a small gate for the larger turbos.

The Black is a weird turbo..... It's big, but small at the same time. Super laggy. Has a fairly big compressor but the turbine and housing are relatively small in comparison
this SHOULD be all the gate i need, easily, to hold it at 10 psi if i so choose. My target is 35 but i have to have some control over things to tune my best.

 

[boost97gst]

UPDATE: This is for other people who may be running into similar issues. Good and bad.
Good part? My old cheapy EMUSA wastegate(s) both were tested on the car and do their job just fine. I could hear them open at around 7psi. So i don't need a Tial( I WISH it were that easy, i really do)

Bad news: The FP Black just doesn't have a big enough wastegate hole on the turbine housing. I must take the turbo off and bore that puppy out as much as possible.

How i came to this: After testing both on the car using the identical spring and hearing the gate open, still screaming to 30+psi i decided well, the only way to truly rule out the wastegate is to completely remove the springs altogether. And so i did. I even ran the boost source straight to the wg just for the hell of it. The gate was open at idle as to be expected, no spring at ALL. Took it out and sure enough it just rips right up to 30psi. I could hear the gate louder at 1psi and up this time but that was the ONLY difference

So hope this may help someone else in the future. My mods should be up to date.

 

[boost97gst]

Last update, again, for someone who may search for this in the future

Just got off the phone with Forced Performance. Told them my exact setup and asked if it could be held back. NO. It can't. They said opening the wg hole on the turbine would not help much and my only chance at choking it back to 25psi is a more restrictive exhaust. So, there ya have it. Going to grab some logs and see exactly how high the boost is going and work from there.
I'm thinking a dyno would be the very safest and most efficient place to tune this beast, she's flat out scary!
I may end up porting the wg hole to see the effect and i will update this thread.

So, to sum up: FP mani+FP Black+PR non-recirc o2+3" exhaust that's like 3 feet long(at most)= That 38mm gate is next to useless if you want to run this under 30+psi. It's just not going to happen, or so Amber says.
I was a bit confused when she said "if you open the wg hole on the turbine you'll just make it worse". That makes zero sense. Think about it, you're opening the path around the turbine wheel basically. Idk if she's entirely accurate.

 

[henrysan]

Strange how you were told porting the wastegate hole would make it worse, I can only see porting the hole making it easier for exhaust to flow out, allowing more gas to bypass the turbine. I say port it!

 

[JusMX141]

Just got off the phone with Forced Performance. Told them my exact setup and asked if it could be held back. NO. It can't. They said opening the wg hole on the turbine would not help much and my only chance at choking it back to 25psi is a more restrictive exhaust.

While there is truth in the statement of adding some restriction to the exhaust to gain boost control, if the hole in the housing is smaller than the wastegate you're running, then the system will only control boost as well as the hole in the housing will allow. So you could go to a MVS44 like FP uses on their FP30/FP35 housings and it would do absolutely nothing.

Perhaps they don't have a lot of guys using these turbos with super-short exhausts, but I know of a car running a 76/67mm turbine in a .82 T3 housing with a MVS38 gate and it controls boost just fine clear down to 15psi (spring pressure). There's no way a larger a/r turbine housing and larger turbine wheel wouldn't want to creep easier than your setup at 15psi if the wastegate was indeed too small.

 

[bastarddsm]

NO. It can't. They said opening the wg hole on the turbine would not help much and my only chance at choking it back to 25psi is a more restrictive exhaust.

Yeah, that's the dumbest thing I've ever heard. If that is truly true, I'd ship that thing back and get something you can control.

Can you take your gate off and connect your dump pipe right to the o2 housing?.

That will make sure your gate isn't restricting the flow too much.

I used to run one of those EMUSA gates and it was awesome. No issues at all.

 

[donniekak]

Take the waste gate off and see what happens. Post a picture of your setup. It almost sounds like you have the gate on backwards.

My red would run 7-35 depending on my wastegate spring with a 38mm gate. Mine was off the manifold though.

 

[boost97gst]

Yeah, that's the dumbest thing I've ever heard. If that is truly true, I'd ship that thing back and get something you can control.

Can you take your gate off and connect your dump pipe right to the o2 housing?.

That will make sure your gate isn't restricting the flow too much.

I used to run one of those EMUSA gates and it was awesome. No issues at all.

Could but i'd have to make a dump pipe or else it wouldn't fit. The dump tube now is the perfect length and angle as to clear the IC piping.
I too was a bit surprised when she told me that opening the wg hole would "make it worse". That's just not true, it could only help it.


Donnie, ok man. I'll go out right now and get the pic so that can be ruled out. It's not on backwards but i understand your thinking

 

[boost97gst]

Take the waste gate off and see what happens. Post a picture of your setup. It almost sounds like you have the gate on backwards.

My red would run 7-35 depending on my wastegate spring with a 38mm gate. Mine was off the manifold though.

Yea, i think you nailed it in the *last sentence: Off the mani. That's going to make a difference

 

[boost97gst]

Ok, now that we can rule out that it's on the right way hahaha

 

[boost97gst]

While there is truth in the statement of adding some restriction to the exhaust to gain boost control, if the hole in the housing is smaller than the wastegate you're running, then the system will only control boost as well as the hole in the housing will allow. So you could go to a MVS44 like FP uses on their FP30/FP35 housings and it would do absolutely nothing.

Perhaps they don't have a lot of guys using these turbos with super-short exhausts, but I know of a car running a 76/67mm turbine in a .82 T3 housing with a MVS38 gate and it controls boost just fine clear down to 15psi (spring pressure). There's no way a larger a/r turbine housing and larger turbine wheel wouldn't want to creep easier than your setup at 15psi if the wastegate was indeed too small.

Yup.... that's why i'm here. It's got me a bit confused. I honestly think that it's has got to be the size of the hole.

 

[donniekak]

How much does the wastegate open? I've seen the eBay gates get the shaft scored from the clearance being to tight, and seize, or have limited movement.

Before doing anything major I would run the turbo with no wastegate on it and see. Numerous people have run the internal gate version with no boost issue like yours.

 

[boost97gst]

How much does the wastegate open? I've seen the eBay gates get the shaft scored from the clearance being to tight, and seize, or have limited movement.

Before doing anything major I would run the turbo with no wastegate on it and see. Numerous people have run the internal gate version with no boost issue like yours.

Yea, here's pics of open/close. That's with 10psi on it and the 5lb spring in. I can not push it further. i have 2 identical brand new gates and they both travel the same distance and behave exactly the same

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

I think i can take the valve completely out of one of the wastegates. That will be the only way i can run with straight o2 dump. Otherwise i'd need to weld up a new pipe or order flexible pipe off ebay.

 

[bastarddsm]

Try that. Pull one apart, and put it back on. Maybe put a bolt and nut in the guide to block it off.

I feel like that should be opening up enough though.

Whats your dump pipe look like?

 

[boost97gst]

Standard dump pipe that comes w the PR o2 housing.
Thing is, if I remove the valve and it works then what? Unless a tial flows way more I'm still in the same boat. But I am curious.... Going to do it when I get back from a service call. I'll test it and report back

 

[Smilinjay]

I had very similar issues on my 20g with a tial 38mm gate dumped to atmosphere. Mine would creep to 25 psi on a 14 psi spring. I think it was due to multiple variables. Like you, my exhaust was very short (open downpipe). And the wastegate hole in the turbine housing was unported. I have since ported the wg hole and built a 3" exhaust for it. Havent had a chance to test it yet but i'll let you know if this solves it.

 

[Steve93Talon]

In my experience with BW turbos in Bullseye bolt-on housings with the gate on the o2, the hole as cast/machined is insufficient, and porting it makes a huge difference in how low you can control boost without creep. If you didn't pay FP for porting, they cast their hole small enough for their internal flapper option to have some seat area so I'm sure it's got plenty of room for improvement.

Given the pic you posted with the valve fully opened, I'd definitely try a Tial too.

 

[boost97gst]

UPdate: Took the valve COMPLETELY out of the wastegate. So, in effect, straight wg to atmosphere with zero restriction whatsoever.
And? It shot up to 30psi. I have literally ruled out every single component, this couldn't be that complicated: it's the turbine housing. When i take it apart i will measure everything and take pics pre/post machining
Then i will post the results. If there are any doubts i will post a pic of the valve outside of the wg, . It's very true, this thing doesn't have enough wg flow and it's not post turbine, it's inside it.

Thanks all for suggestions and help. Hope to have an update by saturday!

 

[Steve93Talon]

You want to open it up until the flapper seat area is completely gone

You must be logged in to view this image or video.

You can also divert the exhaust gas toward the wastegate passage by porting into the throat area like this

You must be logged in to view this image or video.