Boost Creep! Dammit!
 

Grrrr...

As it's getting colder, I'm seeing 14-15 psi toward redline.

Hell, this morning I saw 14 by like 5500 rpms.

I have a ported wastegate, but it appears to not be enough. Perhaps get rid of the Profec B and allow the Power FC to control boost? I'm not sure if this would work b/c my wastegate would still be inadequate.

I *really* want to keep the open exhaust. I like the loud stinkiness and flamage. So a high-flow cat is and silencer are out.

Maybe a more restrictive catback? Pop-off valve? A more restrictive exhaust gasket?

I have heard from some of the non-seq guys that they have ported to the point that their waste flapper will barely seal...and they still have creep with full exhaust.

I could see trying to put in an orifice plate between the dp and mp...try to minimize...just enough restriction to stop creep, but not dramatically affect the benefit of the open exhaust. Should be cheap, but would be trial and error intensive.

I haven't heard of anyone trying it, but maybe you could hard wire your wg flapper all the way open just to test to see if you could rework its actuation to eliminate creep???

How much are you ported? I just did mine, added 1/4" to the diameter....not enough? Are you running non-seq?
~Tom

i pored to the max the flange covers..if u put a light in the turbo u can see a real thin line of light arround the flange..with the profecb off i would creep to 11...b4 i ported i hit 16.5...
i was happy with it...
goodfellas your best bet is to make a restrictive exhaust flange...

My Wg was slightly enlarged and since going FMIC and MP I'm also having mild boost creep with my non-seq clipped turbos. I first tried a 2.5" opening plate between the MP and cat-back.
This did not work. Next I tried a 2 1/8" opening plate. This kept
boost down to 12.5 PSI in 5th gear all the way up to 165MPH when I ran out of open road. With this plate, even though boost did not go above 12.5psi, it would not go lower than 12psi in the low gears.

I'm pulling my turbos this weekend to open the WG somemore.
With my Bonez hi-flow cat, it is easy to keep boost down to 7PSI.
Shows how restrictive a cat is.

Hey Chuck, how do you go about installing such a plate? Do you just go to a machine shop and have them do it....or what? Also, does it have to be welded on? Any info. is appreciated as I am about to install a midpipe and know I will run into some boost creep for sure. BTW, with this plate in place...how much of a hp loss is excpected? Thanks;)

Since I'm a do it yourself (meaning not rich) person, I did it myself. Bought a small stainless steel baking pan at a resteraunt supply store in China town. The metal is a little thicker than 1/16". From that I cut out two pieces. Both a little bigger than the outline of the Mazda exhaust system gasket. Might be easier for most to have a metal shop or machine shop do it for you.

The two mounting bolts holes were easy to drill out. For the center 2 1/8" openeing, I drilled many small holes then used my metal snips to cut it out. Then using my Dremel tool with a carbide tip, I smoothed out the openeing and all edges. Since the SS piece is so thin, I coated both sides with high temp silicone sealant and installed it without any gaskets. Works perfectly without any leakage. My original one which was too large, did not have any signs of corrosion or meltting.

Newbie Q --
What exactly is boost creep & what causes it?

And wouldn't your profec B keep all your boost in check?

so do you mean rich or $$ when you said (meaing not rich) ????

We all know Rich doesn't do anything on his own!!

You can do a search on the forum and find more details, but essentially you have enough modifications that the flow through the wastegate of the turbos is greater than the hole can handle. This is a physical thing, and a boost controller can't make the hole bigger. All a boost controller does is tell the wastegate to open at a different level of boost. When you port the wastegate, you pull everything apart and make the actual hole bigger in hopes that more air will find a way to escape, rather than build more boost.
~Tom

Rich, Here is an easy cheap fix. Take a stock exhaust gasket and set it on the table, make a template (steel) that has 1/4 inch overhang all the way around...Insert between gasket and pipe.This should stop your boost creep and it will cost you a couple of bucks...E-mail me if you need better instructions.........

Carson, you bastard...;)

As a matter of fact, I installed my midpipe all by myself, which is what led to the fucking boost creep. And I also just replaced my PPF all by myself.

You, on the other hand, just blew your motor all by yourself :D

:fruit:

Rich

How come nobody ever brings up a pop off valve when this discussion comes up? Does it bleed too much boost off?--by messing up fuel mixture perhaps? They are cheap and it is how I was planning on handling the situation. BTW does anybody have any great ideas on how to remove broken DP studs with the turbos on the car. I broke 2 and it took everything I had just to break them. Im really looking forward to this one.

Not sure about the pop-off valve thing. I know RP told me not to mess w/it.

Re: the broken studs, check out Spyfish007's post on Brock Stud for some help...

Rich

ah ... ROTFL ... I broke my engine by myself ... true ...

but have you figured out how to put in a SMIC yet?

hell, GoodfellaFD3S, you have all those mods and are seeing 14-15 psi???? I'm pretty much stock with just CB and DP...tonight I was getting 15 psi in 4th up to redline!!!! I dont like it, it scares me...........

Doesn't stock ECU and Wastegate keep things at 10psi?

Sorry - kind of newbie

Goodfellas,

I have some restrictor plates if you want them.
I think 2 are 2 1/4 and 1 is 2 1/2.

After porting my waste gate I am running without them, straight 3 inch dp, mp (with borla xr-1) and N1 duals. I can keep the boost down to 12 psi under WOT. I am a running PFS PMC to control boost.

I used them before porting with some success. With them in the exhaust, I could keep the boost down to 14 psi, but never really got on the gas hard because of the inability to control the boost.


Mike

Hey Mike, I'll take em! PM sent your way...

Rich

POV possibility
 

I think pop-off valves are not very smooth in their action. If you watch racing series where they are used, you can see them pop the valves sometimes and they tend to lose a lot of ground. Instead of just venting the boost that is over the limit, they seem to let you build up to the limit and then dump too much. If you had it set to 15 psi, it might do something like this:

10
11
12
13
14
15
13
14
15
13
14
15

Pretty annoying. I haven't tried running a POV, and different models may behave differently, but this is what it seems to do on race cars when it happens on TV.

-Max

external WG maybe

Pop off valves are normally used as a last ditch safety measure to vent excessive pressure. You do not use them to control boost. If you have boost creep and only dump the turbo compressure output and not restrict the turbine exhaust input, you will end up over revving the turbo and ruin the bearings.

I think Ernie T is using the HKS Pop-Off Valve. I'm curious to know how he feels about using the HKS unit. Check out this link for the HKS Pop-Off Valve. http://www.hksusa.com/html/wastegates.htm