Can't hold boost on a 56mm 6 Blade HX40.

[doesitonall4rs]

Ok guys I switched set ups finally from my tried and true bolt on HX35 to the 70A/R HX40, with a T3 DNP manifold and a Tial 44mm wastegate.

The car is at 30psi and I cannot get it to hold 30psi at all! Getting really frustrating, had the car out Friday night boost was at 31-32 (Map sensor verified) and it tappers down to 26-27psi by 7K, if I rev it out to 8K the boost probably will drop even more.

I am running a Hallman Pro Boost controller and a 10Psi spring in the wastegate, The hallman has the heavy spring in it.

Without writing a novel there are 0 boost leaks, I spent about a week boost leak checking the car and fixing absolutely every single leak.

Is there any other things I can check? This set up should easily be able to keep up with my engines demands.

I also attached a log from the shootout where the car went 11.5@120 holding 24psi.

Any help is appreciated!

 

[GSTurbo1]

HMMM.... Did you open throttle body while boost leak testing, may have intake seal barely cracked or busted bleeding out at those high psi's. I guess it's externally gated with that tiall 44mm WG, try to lightly lube it with some white lithium grease

 

[doesitonall4rs]

IM pressurizes even if you do not open the throttle body, I know this because my boost gauge is connected to the IM and when I add pressure to the air line right before the turbo I read my actual boost leak test pressure off the boost gauge.

All my Boost leak checks have been done at 30-35Psi.

Some of the things that are on my mind are....

- Definite Boost Control Issue either within the wastegate or the Boost controller itself, however I disassembled it and everything seems great, its a rather simple device.
- The intercooler on the car is an old Buschur core measuring 8 X 24 x 4, not sure how much this will actually cause a drop in boost.
- I am running a 2G MAF with the MAF Clamp feature running off the MAP sensor, Not sure if the turbo is having a difficult time moving air threw the MAF sensor. I am currently logging ~60lbs/min in airflow.

 

[JusMX141]

I am running a Hallman Pro Boost controller and a 10Psi spring in the wastegate

Right there's your problem.

That light of a spring will struggle to hold anything more than 20psi no matter what boost controller you're using.

 

[Jon91TSi]

You might need a heavier spring in the wastegate. I ran into the same problem with 15 pound springs in my Tial MV-R, I had to run 25 pound springs and then use my MBC to get to the 35-37 pounds I was looking for.

 

[jrohner]

I am running a Hallman Pro Boost controller and a 10Psi spring in the wastegate, The hallman has the heavy spring in it.

Exhaust backpressure is pushing the wastegate open. Get a heavier spring and you'll probably be fine.

 

[doesitonall4rs]

Right there's your problem.
That light of a spring will struggle to hold anything more than 20psi no matter what boost controller you're using.

You might need a heavier spring in the wastegate. I ran into the same problem with 15 pound springs in my Tial MV-R, I had to run 25 pound springs and then use my MBC to get to the 35-37 pounds I was looking for.

Quick question guys, with the 25lb spring which boost controller are you running?

I ask because you know how there is a small "Bleed" hole on the fitting going towards the wastegate do you guys with heavy springs in your wastegates still use that fitting or switch over to a straight barb with no side bleed hole on them?

 

[JusMX141]

You need the bleeder hole otherwise pressure will remain in the line once boost goes away and the MBC ball drops or the wastegate will stay open.

 

[Jon91TSi]

Quick question guys, with the 25lb spring which boost controller are you running?

I ask because you know how there is a small "Bleed" hole on the fitting going towards the wastegate do you guys with heavy springs in your wastegates still use that fitting or switch over to a straight barb with no side bleed hole on them?

That was on a hallman pro, I'm now on a profec b spec 2 ebc. Same difference though you need a heavier springs to hold that kind of boost pressure.

 

[92GSXtacy]

Definitely double up on your wastegate springs! I didn't know anyone even put 10psi springs in DSMs !

 

[bastarddsm]

your also probably getting close to the limit of the compressor......

 

[doesitonall4rs]

I have a big red spring in there now, looks like if i get a small blue to be used along with the red spring it will yield 17psi, you guys think thats sufficient? Really i am not plannin to run more than 33psi on the car.

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[SpoolinTalonAWD]

get both blue springs and run 20psi low boost. Then dial in the rest with your MBC

 

[doesitonall4rs]

I had a friend that gave me the small tial Blue spring, so this netted WG pressure of 17psi, Was out testing the car Friday Night boost seems to hold a little better but still drops, Boost hit 32psi at around 5K rpm and then settles down to 27-28psi.

I attached both logs from the 10psi spring and the 17psi dual springs

The 30psi Ohio pull was on the 10 psi spring.

 

[jrohner]

I think my wastegate has a 12psi or something spring, and I don't even have ANY boost source going to it and it runs 32psi tapering to 28.

You should just get it sprung so that it's at about the lowest boost you want to run, and then use a boost controller if you want to up it some more.