Boost Problem

[GN87Mike]

I can use some help. I have a problem not being able to hold a constant boost (26 lb.) during a run. See my signature for my combo. I foot brake and have no problem getting 26 lb as I launch but the boost drops immediately to 19-23 lb through 1st, 2nd and third. When the converter locks at the top of 3rd I hold a steady 26 lbs. Attached is the power logger file of my last run (10.64 - 126.3) and time slip.
I did a test to verify my wg operation. No adjustments have been made since the run. I set a dial indicator on the wg arm and supplied regulated air to the RJC controller (see picture). The RJC is adjusted close to max and the wg actuator rod is 7.5 turns tight. The one thing I can't simulate is the exhaust pressure trying to open the puck. With the dial zeroed at zero pressure - at 20 lb it shows .000", at 25 lb it shows .001", at 30 lb it shows .004", and the wg opens with .076" movement at 32.5 lb. When I reduce pressure back to 30 lb the dial returns to .005". I assume from this that with the exhaust pressure helping to open the puck that it is controlling at approx 26 lb of boost.
Attached is a picture of the wg puck and the exhaust housing. It's not the best but I do have steady boost at lock up. The wg hole measures .965"- .980".
So is my converter too loose? Do I need a new turbine housing.....maybe a .85? Should I just go to an external gate? I think I can pick up a little if I correct this...it's one of my winter projects .

Thanks,
Mike

 

[bison]

You would need a dual port wastegate actuator with a smart electronic boost controller that could increase and decrease the pressures going to the actuator. Running a converter like a 9.5" PTC will load the engine a lot harder. It is also beneficial to run taller gearing in lower gears to increase the load. The converter needs to be worked hard through the 330' to get the best times. The way you're currently configured you arent seeing enough load until you are locking the converter. At that point the ex energy is increasing a lot


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[GN87Mike]

Thanks Bison....I've been wanting to get a PTC. I'll talk to Dusty. Is my converter bad or just not right for me now?

 

[bison]

Thanks Bison....I've been wanting to get a PTC. I'll talk to Dusty. Is my converter bad or just not right for me now?

I wouldnt say its bad. Id say its less than ideal though

 

[fastblackracing]

What do you have for an air intake set-up? I have seen many cars with less than ideal setups restricting the air coming in to the turbo which is like throwing away free HP. Also any exhaust leaks even seemingly small ones pre-turbo will cause you to have boost control issues.

 

[GN87Mike]

For the air inlet I have a Tin Man cold air set-up to the stock MAF with one screen (old school) then straight to the inlet (see pic). As for the leaks I have looked several times with a mirror and can't see any signs. The TA race headers are less than two years old. I do run Felpro 1400 gaskets and they were re-torqued. Thanks for the suggestions.

Mike

 

[fastblackracing]

You probly have something to gain if you can get your set up to work with taking that last screen out of the maf those screens are more restrictive than you realize and I agree the converter would help as well.

 

[GN87Mike]

Wow.....I didn't know you could run the stock MAF without a screen. I had been told years ago that one screen was needed to stabilize the air so the readings were good. I guess at WOT it doesn't matter anyway. I think where I'm headed after I get the converter and boost straightened out is to go to maybe an LS1 or Z06 style MAF and a chip that allows wide band control of the fuel.

Thanks,
Mike