Boost creep, and a quick question about over boring the stock wastegate.
 

Ok, I've installed basically all the bolt-ons. Intake, efini Y-pipe, m2 medium style ic, non-seq twins, down pipe, mid pipe, and a cat back. I'm using a profec B for the boost controler, and have a power FC. When going non-seq, I had the wastegate bored over to 1.24", just like the steve scudineria (sp?) sight says.

I installed a cat back and thats when my troubles began.

As it stands right now, anything after 5.5k and the boost goes totally uncontrolable. With the profec B off, I get creep to 16psi on my boost gauge, or 1 bar on the power FC.

My question is, have any of you guys bored the wastegate larger than the little flapper before? And if so, how much? I'm aware that boring the wastegate larger than the flapper will increase spool time, but I'm not worried about it. Any help would be very nice. CJ

i dont get any creep...people say porting the wastegate does solve the problem

thats a nice mph in your sig...what boost was that at...you should get 11s with some traction/

Matty, I have had the wastegate bored out. I was just wondering if anyone has gone any bigger. I ran that time on 13psi with the stock catback. If i where to be stupid enough to take it to the track, I'm shure I'd be in the 118mph area. Need to get the boost issue solved and I'll be back. CJ

Search around, there was a thread recently that mentioned using the pre-control's larger flapper in place of the wastegate flapper so that the hole can be enlarged more.

Jack

Garfinkle has put in the prespool door in the waste gate place . The prespool door is 1/10 inch bigger . He then desided to go bigger to improve the seal so he made a bigger door and opened the hole more while leaving enough material for a good seal .

Smoothing all the radii helps a bunch. If you just bore straight, the flow has to turn around sharp edges and that can choke it pretty good.

I did'nt realy want to get into putting in a custom wastegate with all the trouble. As hopefully by this fall it will be single time. I don't mind though pulling off the turbo's again, and making a new flapper do-hicky, and opening up the wastegate more...but I don't want to get into to much fabrication and stuff.

Marshall, to be honest though, I did just have the WG bored out, without any smoothing out of the edges....perhaps I'll remove some material.:)

Thanks for some idea's guys. Looks like its time to yank em back off the car. ;) CJ

If you bore the hole bigger than the door you will screw it up big time ,use your head , big hole , little door == no boost

I would say you have a problem other than the wastegate size. I have the same setup as you, only I have a Pineapple large raceported motor and I have absolutly no problem controling boost with stock wastegate. I usually run 10lbs on the street, and it holds steady to redline.

how come some cars have a large problem with creep and others dont?

We 2nd gen guys port the WG hole(s) out very large and use piston engine exhaust valves as new flapper doors.

When you bore the WG holes pay careful attention to "back cutting" or "relieving" the holes entrance for increased flow. Reduce the radius on the leading edge of the WG hole and leave the rear sticking out to guide exhaust throught the WG. Just think of total flow through the WG even if it hurts total manifold flow a little.

In extreme cases we divide the WG exhaust exit from the turbine exit inside the turbo and run a seperate pipe out the back for the WG. This allows for less backpressure and less turbulence. I don't know if that is possible on the 3rd gen "log".

Next, pay attention to increasing the WG flapper door's movement. For instance, the 2nd gen WG actuator has 150mm of movement, but in stock configuration moves only~60mm before the flapper door hits the turbo backing plate. If you grind the rear of the flapper you get a little more movement. If you put the divided WG exhaust pipe right behind the flapper arm you get full actuation and MUCH more WG door lift. Again, I don't know how much is possible w/ the 3rd gen.

Good luck!

I'll keep your guys ideas around when I get the energy to rip em off again. Thanks once again.

Radkins, I don't think that theres a problem anywhere. This all began with the catback. Before with the stock cb, it would hold whatever boost I wanted until redline (and to the rev limit :D) Never once had an issue controling boost once I when non-seq. BTW, whats your complete mod list? CJ

Well this is pretty much it.

Pineapple Racing Large-Raceport motor
Greddy Power Extreme CB
M2 DP
MP
M2 Intake
M2 Med IC w/ fan
Profec B
Fuel Upgrades (pump, 1600's, rail)
HKS Twin Power

All that matters anyways. I'm on the stock twins. What I am saying is it sounds like maybe your wastegate isn't opening. We have a very similar setup except I have a very large port, wich means that I should have more of a problem, and I have none. Just cause it happened when you put on the catback doesnt mean its realated. Check your connections on the Profec. It sounds like it isn't seeing boost reading, therefore not opening the wastegate. I just have a hard time beliving that just adding the catback would change your boost that much. That is unless you had boost problems before you put it on.

I dunno....checked everything out, and everything looks great. The thing is, I'm getting creep even with the boost controler turned off. Perhaps the efini Y pipe, and doing the full non-seq makes it flow that much more? I did remove the double throttle, pre-spool gate, butterfly from the rear part of the Y-pipe, and did a little work on the LIM, when I had it all apart.

I've allready checked the wastegate, but will take anouther look at it today. CJ

If you cruise at 5k and then hit it, does the boost shoot to 16, or does it slowly build?

Just got it put back together. I'll let you know tomrow when I take it to work. CJ

I'm having exact same problem.
But I don't have any other mods except intake. +(
I never had any sort of boost problem unitl I installed the HKS ti exhaust. Now everytime I go WOT. The boost shoots up like a mofo.