18lbs. then slower spool?

[dwdsm]

I noticed that after 18lbs. on my bb50 trim the spool slows about half speed untill it reaches the desired 23 lbs. There is absoutly no creep or drop in boost after this. Leaking BOV? MBC? Or is this normal with a Mitsu turbo (efficency problem). What do you think? Boost leak test showed nothing.. I thought it could be the neck down in the vacume line to the MBC but now I'm not so sure.
Thanks

 

[TurboAnything]

thats funny cause my S256 spools twice as fast after 18psi. It seems like you have a leak did you pressure test everything to over 18psi? That type RS is junk and they are hard to keep from leaking i had to bottom out the adjustment screw to stop it from hissing.

 

[dwdsm]

I'll recheck after I install my JMF manifold. I don't think it was leaking at all. It doesn't want to blow off unless you get into it 10LBS.+ I do have a dyno sheet in my profile.

I think I'm just looking for anything to add a little more power to hit 11.5's. I hit 11.8's at the track this year on pump (obviously). I am adding a aluminum driveshaft and a JMF manifold (street). Shaving a few pounds and we will see.

 

[CanadianTSi]

The wastegate is probably starting to crack open. I would try shortening the arm slightly and see if that helps.

 

[Lonnie gandee]

I would also check for vac/boost leaaks.....Are you still internally regulated???

 

[dwdsm]

external turbosmart 38mm gate

 

[dwdsm]

I want to keep this one alive. I am thinking of running the dual blue springs for the Tial. It should be 23.5 psi. perfect for a pump tune. I am still thinking the MBC is causing this... I think it's getting over run and leaks...has to be.. If not I'll do a boost leak test again..

 

[slowgsr]

external turbosmart 38mm gate

Once you start to spool you should build boost exponentially, and the jump from 18 to 23psi should almost be instant within a few hundred RPM at WOT.

What Wastegate Spring are you using Please say atleast a 1bar.

 

[dwdsm]

I am using the 1 bar only I believe...I am switching to a Tial as soon as I get a chance to bolt it on and was thinking of running just off the 23.5 psi blue springs.. or 1.5 bar and then getting the proper boost with the MBC.

 

[turboglenn]

It sounds to me like your wastegate is starting to open early. Which would not be uncommon depending on what type of MBC you're running.. I know if i turn my "gain" knob too far down( for lack of better term). it will do the same thing because it starts partially opening the gate once there's some amount of boost and slows the spool