BLT troubles

[98DiamondStar]

Did boost leak test this afternoon and found a couple of small boost leaks, however, both before and after repaoring them I can not seem to build more than 4 p.s.i. while running the test. I'm using a 12 volt compressor like you'd find on the shelf at any Walmart. I'm testing from the filter end of my dejon intake pipe.
One thing I have read about is valve overlap and setting yous crank at 30 degree ATDC. Does this work and can I effectively set it there by using the timing marks on the cam gears?
Tomorrow I'm going to try to use my buddy's garage and big boy compressor, and test icp separate from TB forward.
Any tips/trick would be much appreciated

 

[razrman8]

I have never seen a boost leak test done from the turbo intake. But, you are in luck. Many of us have gone through countless boost leak tests.

I would like to direct your attention to my post , #3, in this thread: http://www.dsmtuners.com/forums/newbie-forum/392491-cant-build-over-12-14psi-mbc.html#post152464937 . It is a definite good way to start going about a boost leak test. I would start at the throttle body elbow. Once you have sealed up leaks there. Continue on to the turbo inlet.

Is your car showing anyother symptoms? What exactly is it doing?

 

[Gysgt Guy]

I did mine from the TB elbow to determine if my turbo seals were bad. You should be able to build pressure up just as easy as from the turbo.

 

[Calan]

Hook the tester directly to the turbo inlet; not to the filter end of the intake. If you have a stock PCV system, you are excessively pressurizing the crankcase which is not good for seals, gaskets, etc.

You want to put the motor to 20*-30* ATDC to ensure that all the valves are closed. If you don't, you'll just blow air out the exhaust pipe if you have intake/exhaust valves both partially open on a cylinder.

 

[98DiamondStar]

I have never seen a boost leak test done from the turbo intake. But, you are in luck. Many of us have gone through countless boost leak tests.

I would like to direct your attention to my post , #3, in this thread: http://www.dsmtuners.com/forums/newbie-forum/392491-cant-build-over-12-14psi-mbc.html#post152464937 . It is a definite good way to start going about a boost leak test. I would start at the throttle body elbow. Once you have sealed up leaks there. Continue on to the turbo inlet.

Is your car showing anyother symptoms? What exactly is it doing?

I've never taken the time to do a good blt on this car. I picked it up about six months ago, it was running fine for the most part... After I installed ECMLink, GM MAF, FIC 750 cc injectors, and the blitz VTA bov I couldn't dial in the airflow per rev. It was wanting to hover around 0.19... quick blt showed lower seal on injector #2 was pinched and torn on install. ( My bad) fixed that and tried to test again but can't really build much power. I initially started at the filter side of the because I happened to have a coupler and air fitting that would attach directly. Today tho, I hope to learn a little heading to the handy hardware store shortly for one more fitting to test at tb elbow.

Hook the tester directly to the turbo inlet; not to the filter end of the intake. If you have a stock PCV system, you are excessively pressurizing the crankcase which is not good for seals, gaskets, etc.

You want to put the motor to 20*-30* ATDC to ensure that all the valves are closed. If you don't, you'll just blow air out the exhaust pipe if you have intake/exhaust valves both partially open on a cylinder.

I've got a dejon intake pipe and I'm running gm maf blow through so the vent hose from the valve cover wasn't hooked to the turbo intake pipe.
This may seem like a silly question, but how do I know when the crank position is 20* - 30* after TDC?

 

[MY1GDSM]

Just set the motor at Top Dead center an turn the crank 20-30 degrees... .

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[98DiamondStar]

OK, so I positioned the crank at what I believe to be between 20 and 30* and still with only 3-4 psi max (testing from tb elbow) I find a good leak at the tb shaft. uppon removing the seals I notice the spring side is pretty much gone. I haven't yet installed the tb to get another blt done. I'm just wondering how much can a bad shaft seal effect overall air intake in terms of what's going in that my GM MAF didn't get to see?
This much I can tell you... Why I did this I have no idea but I placed my had over the filter side of the dejon intake pipe while the car was running. Expecting the car to spudder and die, to my amazment, no change! Yet at WOT on my autometer boost gauge and mt Greddy Profec display it will hold 10 to 15 psi depending on HI/LO boost control.
My initial symptoms/reasons for doing the blt were low airflow/rev on dsmlink and after the FIC 750"s went in it smoked black through the midrange rpm's.

 

[Gysgt Guy]

What's the output pressure on your air compressor?

You need to do it from the turbo as well. Try that and see if your getting the same results.

 

[98DiamondStar]

From the turbo yields same preasure results. I'm using a low volume high preasure tiny 12V compressor. ya know... one of those emergency tire inflator ones?

 

[MY1GDSM]

If you do use something with higher volume an pressure make sure you have control of the pressure and that it's not set to high.

 

[98DiamondStar]

Yeah, I have read that you shouldn't BLT anything over 5psi what you are going to run for boost.