Went out at lunch to log some boost runs w/o the wg actuator hooked up to verify my boost control settings weren't hurting spool. Fortunately that checked out good. But I did notice something unusual. In fourth boost peaked at 17psi/4500rpm and made a slight fall to 16.7 by 5500rpm. As if there was boost control. Seeing that- I decided to try fifth and that showed a rapid rise with no signs of stopping to 18.5 psi @ 4500rpm at which point I let off.

I'm confused as to why boost would peak and hold in 4th, yet shows no stopping in 5th. Wished I'd stayed in it a little longer with 5th - but they way the boost was coming on, I figured I better stay ahead of the curve.

Somebody learn me.

 

enough exhaust to force the wastegate open slightly?

 

hmmm. I'm not going to argue that. It's certainly logical. I know for a fact that the wg was coming open at lower boost because I ran it w/o the helper spring when I installed the new turbo. I lost like 1k in spool up. I am using a bone stock merc wg housing from a stage1.5 turbine with a stage3...

I guess the next step would be to tighten the helper spring and see what happens.

 

by chance did you see what 3rd gear did?

 

No- started in 4th at 1300rpm. But I can see the point in knowing what the lower gear does I think - establish a pattern?

 

 

So tonight's (much cooler) homedepot run to pick up another shop light and 4ft fluorescent 10pk showed the following:
3rd = 17.5psi
4th = 18.7psi
5th = 19psi and rising
I'd say that's a pattern.

 

This is surprising to you two? Although I'm not positive exactly why this happens, (engine load, turbo speed,) but ya when I Installed my gt2871 I noticed this happening when I left my mbc on set at 9psi for my t25.

1st gear soild 7psi
2nd solid 7psi
3-4 creep to 10-12
5 15+psi

 

Not now. But keep in mind, I've got a 10psi actuator without any signal hose attached to it. So in theory the actuator should never open the internal gate, whereas your actuator is opening the gate and you're getting overboost/creep because the gate can't relieve enough of the boost pressure. OTOH I'm not getting overboost because there's no boost limit control- I'm getting boost limit because it looks as though the exhaust flow is forcing the gate open and bleeding off boost pressure. Such are the limits of using OE parts designed for far less duty I suppose.

EWG is in the future, just not the immediate future. And coincidentally the max boost I'm seeing w/o the signal hose is just 1psi over my boost target, so it's not a deal breaker. Though I know it's gotta be leaking before I'm seeing it in the log.

 

I suspect I was on the right path....and i suspect if you wire the wastegate closed tight, you'll reach +19psi in 3rd.

 

Doh! This was posted over at Mx6.com by a guy who ran pinksallout in his FE3 power mx6 with a t3/t4.
He couldn't get more than 15psi. He said he fixed it (not how) and was then getting 30psi.

 

Space the wastegate out or shorten the WG arm... ie: raise your base boost pressure.

Internal WGs don't like going much past double their original #. By increasing their base psi up, you can get a higher end result with the mbc.

Personally... I dislike IWG... I'd still go EWG if you were already planning on it. With an ebc... you can literally force the WG closed for earlier spool... instead of just cut off its vac source like an IWG.

 

Helper springs!

 

Dave I was doing this to compare a baseline to my EBC performance. That's reason for no boost line to the actuator. And it does look the same- so that was accomplished. But I was sidetracked by the fact that my boost was just leveling off. And to your point- the can is ~10psi and the boost leveling off around 17psi + depending on gear.

I play a bit with the helper spring and see if I can improve spool at all. With the prior turbo and the mbc logs revealed wg leaking as each time I torqued the spring down spool would improve, but I was also getting creep - so with all things cheap I had to compromise. Since then the helper spring was removed and reinstalled with the new turbo, so it needs some tuning.

My object now is to get the thing back on the dyno since it has been over year with many changes. Then the ewg.

 

am I reading this right? is the actuator to weak to keep the wastegate closed?

 

I had that same problem on my FE3 powered 626. I was using a turbonetics dual-port actuator and it kept blowing open if I had it adjusted for 6psi. I had to make it tight enough for 11psi before it would stop doing that crap.