We managed to build twins in engine bay for a 2013 5.0L F150, Runs great and everything is perfect except that I am targeting 10 psi on WG springs and its going upto 14~15 psi and that is not safe on the stock block.

Mods are

Precision 6266 Turbos with billet CEA compressor on .68AR
Tial WGs 44mm
Tial Blowoff valve
ID1000
PMAS mAF
jms boost controller
Boost leash boost controller.

It was a tight build but I made sure that all pipe sizes were perfect and no issues,

any help is appreciated, I'll post pics of the setup later.

 

I had a similar issue... if its not creeping (which I doubt it is with twin 44's), or a controller issue, you may just need to go to a lighter spring in the wg. Waste gate springs are rated with a certain amount of exh back pressure, and your setup probably has less bp with that much turbine. I had the same issue with a large single turbine on small cid... 14 psi on a 10 psi spring.

 

this is the issue, i changed the springs to single red colored which is rated 5 psi on both WGs and it is still going 14 psi on it..
I tried disconnecting the controller and just add an external boost gauge for reading and it still reads 14
i also tried attaching the controller on the lower ports and adding boost with no changes at all .. still 14 psi

 

pics of the WG connection & location ?

 

WGs are connected up in the engine bay just beside the turbos,

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Hope they are clear enough.

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Pardon me for asking Sir;

did you install the correct fittings or plugs to the right ports?


do you have a way to adjust PRE LOAD?

 

Followed the instructions.

Tried attaching boost controller to upper ports and tried it same issue

Tried attaching ports to lower ports and same issue.

Im gonna try it on the upper ports while letting lower ports plugs removed for vents..

My first ever turbo build and fab excuse my begginer info.. did as much reading as i can.

Thnks for the help.

 

Is there some way you could safely take the wastegate all the way out or hold it all the way open so that the max amount of exhaust possible is not going into the turbine? That would test a lot of the design of the setup. If it still makes boost with the wastegate all the way open or off then a design change is in order, if not then we could look at wastegate operation.

The issue you have is that almost all the exhaust pressure has to be relieved because of the low boost pressure you require and at that boost pressure, the turbos you have require very little drive pressure for the desired boost. If you were running a system that required more boost, less would have to go through the gates (as a rule of thumb), and valve sizing could be much smaller.

Meanwhile if you have a boost gauge, put it inline right where it enters each wg fitting to double check the pressure at the bottom of the gate.

Until the overboost issue is fixed, I would connect the boost reference to the bottom port of the gate with the top of the gate open to atmosphere (not blocked or plugged by anything). Once the problem is fixed, there are some ways to use both ports that add a little more control.

 

Also if you haven't done so already, make sure to plug the extra ports on the lower half as the new gen of Tials have multiple locations.

 

Did as you said.. boost is down to 8 psi on 2nd gear but on 3rd gear after 4k rpm it climbs to 12 psi which i believe is still danger on the motor.

Id like to know why is this happening ?

 

That sounds like boost creep... creep happens when you don't have enough wastegate flow to maintain your desired boost level, and typically gets worse with load, and rpm. Causes are small wastgates, poor flow to, and/or from the wastegates. Your wg's should be large enough, so that leaves poor location, and flow (which is why some asked for pics). Some better pics of how your gates are plumbed would help.

 

just , try this:

USE THE 3RD IMAGE posted as a refrerrence:

1-install either the brown or the green 4.35psi spring on the WG< the one call for the year made of the TIAL WG you are ussing>

2- ONLY install a AIR line from the bottom port of the TURBO compressor housing to the bottom AIR port of WG<plug THE other 2 AIR PORTS at the bottom of the gates>

3- leave ALL the TOP AIR ports of the WG venting out

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Would like to see a pic of the wastegate to manifold connection. The connection should not be perpendicular to the exhaust flow.

 

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Yes, I have kept the top ports open and used the Boost controller to help keep the springs.. Truck runs no on 8 psi with no issues, I will resolve this issue when the new shortblock arrives.. For now its doing great and truck made around 430rwhp on a very conservative tune. I am not sure how much these blocks handle.

Thanks For all the help guys.

 

Did you use any flex joints in the tube from the WG outlet to the downpipe? I'd used some with inner mesh braid in them on my build and they were collapsing when hot and causing major boost issues.

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yes I am using flexible tubes on the manifold.. Cant really do without them..

 

The fix for me was to replace the ones pictured with some that did not have inner braiding and I've had no other problems since.