Well, I have the standard problem - boost hits 20.5psi solid in every gear and tapers to 16 psi at redline. I have read every single freaking thread on this, and my car has none of the problems listed

I have a turbo-back, cat-delete, Hallman MBC, Dynoflash, stock airbox. I have taken the intake duct off, to make sure this wasn't the cause - no dice (I'm not missing my plastic retaining pins, either). I just got done pressurizing the entire system to 30psi. I put gas leak fluid on ALL of the fittings, and tightened all of the fittings. The only two leaks were:

1. Hallman MBC (that little hole drilled in the side of the wastegate-side nipple) - Al said this is normal - not sure why it does this, but he's smart, I'm not....

2. The crankcase ventilation hose (that feeds back into the intake tube) - air was very slowing coming out - seems normal enough (maybe it's not)

I have double checked the MBC install - it's not rocket science. WE LOOKED OVER EVERYTHING AND TIGHTENED EVERYTHING. Any thoughts? I frickin' want my 3-4 psi back at redline!!! By the way - I live a mile high......(Denver - guess this could be the problem)

 

Mine tapers to 17~18psi by redline and I am running a Hallman MBC. My brothers Evo tapers as well. I think all cars taper and the ones that don't I think their boost gauge just isn't that accurate.

 

Living a mile high will only promote boost spiking because the air is "superthin". Are you sure that you are not spiking 20.5psi and holding 16psi? Do a test. Increase your boost by 1psi, etc. You can spike 24psi on the stock turbo...

 

hrmmm still strange! mine is at 21 doesnt move what so ever and i can prove it and swear on my life lol i am really confused... did you ever try a new BOV? thats the only thing i can think of and u have the heavy spring in the mbc correct?

evoisdream

 

check your wastegate arm

 

/\ good call that is a possibility to.....

 

Mine doesnt Taper I have the Power agency boost controller/Gauge i hit 21psi still 7Grand.

 

Hmm, maybe putting the heavier spring in the Hallman will do the trick if you have not done so.

 

yeah thats what i was thinking so im thinking the spring bov or wastegate arm PM me and we will figure it out we will get together worst case

 

Well, let's get these in order:

I forgot to mention that I have a Forge DV w/the blue spring - no leaks.

SilverEvo8Owner, when you say check the wastegate arm - I am assuming there is a gasket that could be leaky?

I got the Hallman from Al at Dynoflash, and he ships the MBC's with the heavy spring only - maybe.

Evoisdream, I see you're a moderator now - sweet!!

 

After cam install, I'm spiking pretty bad on temperatures 45 degrees and below. I'm getting fuel cut when it spikes about 3krpm but it holds 19 to redline though. You guys think adding a Forge DV or MR DV would help?

 

I have tested my DV, it is not leaky nor is the spring in-adequate. The spring in my hallman seems to be fine, I hold exactly 20psi all the way to 6300ish-rpm and EVERYTIME right there it will start to taper by 2~3psi by the time redline rolls around. I am interested in the wastegate arm though, I have not thought to tighten that. Anyone have in directions on how I should go about doing this?

 

BTW, guys, here is a quote from shiv that I took from a thread when I did my search on the wastegate actuator. With the wastegate wired shut it only supported 19psi at redline. Now the car did have cams and whatnot, but to wire it completely shut and only get 19lbs, that means a car without cams would probably do 20. This pretty much supports my idea that some of these boost guages that people get aren't accurate and that their car really is tapering, you just don't see it. I SERIOUSLY doubt that your flappers stay completely closed at redline. Here is the quote



"FWIW, I have wired the wastegate shut and have only been able to support approx 19psi just shy of redline. This is on a car with cams, test pipe, exhaust, etc,. It is conceivable that a car with stock cams (lower VE) will be able to support a bit more boost but how much is debateable. Excessive exhaust backpressure can, and often does, force wastegates open. But the solution, imho, is to reduce it (larger hot side, upgraded turbo, etc,.)-- not hit it with a a bigger hammer (stiffer spring).

my 2c,
shiv"

 

Hmm thats hard one. My boost does taper down to 19psi at redline (SUCKS!), but it does hold 22psi to about 6000.

 

I hold 20psi in fourth or fifth gear only dropping 1psi by redline. But in 2nd i taper 2-3psi.
Any ideas?

I have an incabin Hallman boost controller and was wondering if im supposed to tighten the fitting on the side without the little hole.