Boost creep, grr!

[Mike M]

Hey everyone. I've recently got my Lancer Shelby back up and running with a very different top end and am suffering from serious boost creep issues, ie 24psi when I'd rather have it set to 10-14.

My setup...
2.5 Wisecos/ARPs throughout (old motor, nearly everything after this is brand new)
Todd Nelson ported G-head (new this year, had lightly ported head before)
+1mm valves, Comp conicals, PT cruiser lifters
TU R2 camshaft
T3/T4 50 trim hybrid, 63AR turbine (with ported wastegate) with a stage 2 exhaust, new large can WG
TU 3" SV, TU cast mani, 3" exhaust with open dump - (open during all testing)
Modifed 1 piece intake mani (cut open, runners shortened/ported, 3.8V6 elbow), 58mm TB
Large NPR intercooler
FWDP S5 3bar/+40s

I think that covers most of it. Now to the problem and what I've done.

It's been overboosting since I first got this thing running a couple weeks ago. It's much better than it has originally been. After setting my ignition timing the problem improved dramatically, and ign. timing has been double checked since, its right on. I originally had too much tension on the wastegate arm (adjustable). I have removed tension multiple times, each time the boost comes on slower at most RPMs but at high RPMs (45-5k+) the boost will still spike to 20-24 depending on what gear.

For nearly all testing I'm plugged manifold vacuum direct to wastegate.

This morning I removed A LOT of tension from the arm, to the point where I barely need to put any effort into putting it onto the swingvalve. I'm confident that its not a tension problem. I actually even had to shim my Z bracket closer to the swingvalve because my adjustable arm was on its last thread.

So with such little tension I have been out playing with the car more this evening and it is still creeping at high RPMs, through most the range it actually sits around 12, lower than it has been before.

Now I'm back to thinking it could be camshaft timing. I have degree'd my cam (not exactly by the book, no solid lifter and was having issues with my too short dial indicator, so I wasn't able to do the forward/backward then divide by two... but I think I got it in the ball park. Anyway - I have an adjustable gear of course. I am continuing to advance the camshaft - each time I advance it (2 deg on the cam gear) the boost will still creep but only at an even higher RPM. I'm at the point where it will only start to creep after approx 5200 RPM but this thing wants to pull higher.

So, any thoughts. Do I keep advancing the cam timing? Not that the marks are entirely accurate but I'm ~14^ ahead of centerline on my cam gear, which is ~5^ ahead of my measured centerline. I can't guarantee my measurements were exact but I'm confident it isn't that far out if any. With my camshaft adjustments, is it possibly the cam being too retarded causing overboost, so I should keep advancing?

Is there anything else stupid I'm missing? I've never dealt with such stupid boost creep before... but I've never had such a far from stock setup before either.

Thanks for any input, now to go drink away my sorrows, set off fireworks and enjoy the rest of Canada Day

[bakes]

I think you wastegate hole is still to small to dump what is needed to control boost at low levels . I had this same problem with my S60 (fm475cam)on my lancer had the wastegate puck removed and i was still making 22 psi boost I had to open the wastegate hole to the max before it would control 16-18 psi .

[Mike M]

I know what you mean, and its a possibility... maybe I'm moving so much more air this time that its becoming an issue. The only stock part was the cam last year, everything was modified... its just everything is even better this year.

BUT... I did port my wastegate hole when I first got my TU 3" SV, I don't think I ported it to the absolute extreme but I really don't think there would be that much more to go...

Would still like to hear from more people, I know its a possibility but I'm seriously not in the mood to pull everything off to try that as the next step.

[Mike M]

No more ideas?

The more I think about it the more its probably the wastegate. If I get ambition I'll go pull the WG arm off and see if it still creeps. (as laggy as it would be with it open at low revs). Although my cam timing has an effect on when it creeps, I don't think it is so far out from my measured centerline that it is the cause of the creeping.

I'm just bitter because I've already ported my WG hole and its something I never even thought of improving this year when I put this setup together. I don't even know how much improvement there can be had, and I don't want to believe that a good flowing external gate is required for this setup.

[tryingbe]

How big did you "port" the hole? I'd agree, drive with the wastegate arm off and see what happens.

It's a US quarter in the picture.

[Mike M]

I can't say exactly, I did it like two years ago when I got my TU 3" SV which has the larger puck, but I definitely opened up to take advantage of the larger puck anyway. I'll take it for a spin this afternoon I guess

[Mike M]

Disconnected wastegate arm and set my cam timing back to measured centerline and went for a drive, definitely laggy but will still hit 20-21psi in 3rd, more in 4th.

Will perhaps pull turbo tonight when it cools down.

Grr.

External wastegate with open dump time? Considering the TU mani has a boss that only needs to be machined and drilled

[bakes]

When i went from my Gen1 TU 3" swing valve to the second gen the puck got bigger do to the duel pattern . I put Persian blue on the puck face and closed it , removed the swing valve and then i left about 1-1.5mm over lap and went happy with die grinder.

[Mike M]

Well, I popped the turbo off (thank crikey for TU manifold... it really wasn't too bad) and there is definitely mucho room to improve, so I whipped out the die grinder with some junk bits and opened it up a lot. Would have started reassembly tonight but I've mangled one of my turbo to mani studs.... now to find out what size TU used and try to find some tomorrow.

[Mike M]

It's back on. Once again, thank the turbo gods for the TU manifold allowing the turbo to be removed and reinstalled that easy.

Boost no longer spikes to 24! It's fairly steady at 10-12 through most of the rpm range, but after 5k it creeps to 15psi. This is at least acceptable. I will still put a boost controller on it soon and see how it acts at a bit higher boost.

Thanks for the ideas and help

[bakes]

Any time Mike!

[boost geek]

Some people get too much boost, I can't squeeze enough out of mine.

[Mike M]

Hah! I will run 25 at the track but I just wanted to tame it for the street

On another note, with the new setup I never heard a squeak of detonation at 24psi on 94 octane when creeping

[OmniLuvr]

so what stage turbine wheel are you running?

i would also try running a full exhaust if you arent at the track, the open dump will flow a lot better causing more exhaust to flow through your better flowing turbine wheel and less through the wastegate. throw a little more backpressure in the mix and the creep should go away... or you could add an external, but thats no fun when you have already purchased a tu 3" sv and dp...

[4 l-bodies]

Some people get too much boost, I can't squeeze enough out of mine.

Yeah I was thinking the same thing. I remember Nic Kuehn's GT3076 turbo. Ported the wastegate hole in the exhaust scroll (v-band outlet) so it wouldn't boost creep. It was ported too much and anything short of tying the actuator arm it would just blow the wastegate flapper open. Even tried a Holset (18 PSI spring) actuator on it and it would still blow it open around 14-15 PSI. Too big of surface area hitting the swingvalve puck. The fix in Nic's case was to pull off the turbo and replace the housing.
That is just crazy, some people can't attain enough boost, while others have too much. In this case probably similar modded motors. I don't get it?
Hey Mike you mentioned in an earlier post the turbo would develop overboost with the actuator door hanging open? Did I read that right? Glad your parts are cooperating. Hope it was worth the effort and the expense.
Todd

[Mike M]

Ahoy!

To OmniLuvr, it is a stage 2 exhaust wheel in a 63AR. Also, I could very easily hook up my exhaust (just a y-pipe with a cap after the DP) but my reasoning was... if I can't make it work with my exhaust open, what the hell is the point? I know very well that it could help with the creeping. The thought of running an external crossed my mind, but I have all the components to make my internal gate work, and so few TDers use external gates that it just tells me there ain't nothin wrong with a properly functioning internal gate! Thanks for the input though

Yes Todd, you read that correct. With the wastegate arm disconnected and the door flapping in the hot exhausty breeze the car would be laggy (of course, hole in the turbine housing!) but at high RPM it would very much indeed still push 20+ PSI and likely more.

I didn't get a chance to install my boost controller yet, if I set it to approximately 18PSI for street driving I hope to see the boost climb quick and stay steady at 18 even though it creeps from 12-15 at the moment. As the more boost I run, the less exhaust needs to run through the wastegate hole. Something like that.

And yea Todd, minus working out the querks I haven't had any serious issues... now once I get the boost controller in I hope to be able to really feel what it can do. It definitely wants to rev higher, whether its still even a good idea with a 2.5. Also where my calibration used to be pig rich, it now runs in the mid 11s under boost... which for the time being is far more acceptable than when it used to bury itself at 10.0 (lowest the AEM reads). Still ran 12.7@110 at SDAC like that though... weee!!

[4 l-bodies]

So we have two quick Lancer Shelby's up in Canada huh?. Now we need a black one up there to complete the color selection.
That is pretty weird with the overboost with the puck flappin in the breeze. Would never have thought that was possible... I just bought a new S-50 w/stage2 wheel, w/ATP swingvalve. Now you guys got me thinkin whether to port or not port housing? Porting is sort of a one way street, easier to remove metal than to add it back in.
Todd

[Mike M]

Actually Todd, its one quick one and one fast one, LOL It's ON bakes!!

I can't really recommend anything, only let you know what I've done. I don't want to have your wastegate blowing open due to excessive surface area.

I put my boost controller in, and we're hitting around 18-19 and the car feels GOOOOOD Almost had a run in with a Dart Demon (maybe) - but he turned off

[bakes]

Ya hooo now i have someone to play with !!!!! but you going to have to wait till i get back from my Vacation i not going to insure it till i get back.