Turbo Boost Creep Creeping T25 14B 16G [Merged]

[oldman]

Bruce, you're going to have to convince me as to why a larger flapper valve would not impede on the exiting gases when the volume and speed at which the gases are moving is (pressumably) always increasing at WOT. I think I agree with what you have said, but I also think this impediment is yet another cause of boost creep.

Sure it will have some effect but at 22psi+, boost creep should no longer be an issue. The biggest contributor to boost creep was never the flow capacity to begin with, rather it's the poorly designed entrance to the flapper in the turbine inlet. The biggest issue with an upgraded flapper has always been it's ability to run higher boost levels. My old SBR GT12 with internal 38mm flapper for example will hold 12psi to redline but will not hold anything greater than 21psi.

Your second sentance is a little confusing (grammar-wise) so if you could possibly clarify what you meant that would be great.

I've checked my grammar again and I didn't see anything wrong with it, can you be more specific?

 

[gsxtacy]

well speaking from specific experience of where this guy is...( I was right there 2 years ago )

My Evo III GT/650's/SAFC/SMIC combo ran pretty good. I never could afford $10.00/gallon C16 so I never turned the boost up over 20 psi.

It went the time in my profile full weight (with spare jack tools) with a half a tank of 90 octane and my kids car seat in the back!

Its funny I even still remember my SAFC settings!!

LO:35
HI:65

1K 2K 3K 4K 5K 6K 7K
-28 -28 -30 -31 -32 -32 -32

1K 2K 3K 4K 5K 6K 7K 7.5K
-33 -33 -34 -34 -35 -36 -36 -36

I like the Eprom/Chip setup even better though....still can't afford the DSMlink....

 

[oldman]

The GT housing is cast differently and comes with a 34mm flapper, I don't think I have ever heard boost creep issues on the GT. OP on the other hand is asking about getting away without porting or external on a virgin EVO3 which will mostly likely put him in the 23+psi range. I don't think your SMIC would have held up for a 20-23psi tune.

 

[Coreboy]

Can someone elaborate a little more on boost creep? What causes it and how is it fixed?

 

[DSM4me44]

Boost creep is basically where exhaust gases can't escape fast enough. Porting your turbo exhaust housing, manifold, and/or 02 housing is required. To fix boost creep some can port just one thing, some have to port all 3. I had to buy a monster exhaust housing to fix it. Theres a difference between boost spike and boost creep. Creep you will notice when your WOT and your boost goes up as rpms go up. Spike is where you hit a higher then desired boost level but it drops back and rests somewhere.

 

[Coreboy]

I'm looking at buying a DSM but the guy mentioned some boost creep and told me id have to dremel out the exhaust manifold. That does make a lot more sense now thank you. Is boost spike bad necessarily?

 

[95blackGsTurbo]

Boost spike can be bad depending on the turbo and the amount of spike. A 2-3 psi spike on a 14b or T25 is nothing since there isn't that much of a difference in flow. But if a 60-1 were to spike 2-3 psi that would really lean things out and cause damage. Most cases of spike can be fixed with an o2 dump, external wastegate, or downsizing exahust. Usually only happens on smaller turbo's that spool to fast and the wastegate doesn't react fast enough.

 

[Coreboy]

So there opposite problems basically? Creep is not enough exhaust/flow and spike is too much exhaust/flow?

 

[DSM4me44]

Creep is when they can't escape fast enough out the exhuast. Spike is like he said, a temporary spike in boost due to things like your wastegate not opening quick enough. Porting your manifold isn't going to solve creep really. The best way to try and fix creep is port the turbo and port by the flapper making it open 90 degrees. Then you can try and port the 02.

 

[Coreboy]

Ok. Thanks for the info! Defiantly helped!

 

[RJD2]

I have a 97 GSX, the mods are intake, walbro 255, hard upper intercooler piping, bov, evo exhaust mani, ported evo III 16g, mbc, and 3" downpipe/exhaust. My question/problem is that I installed the 16g and it crept bad so I ported it out and I'm still having the same problem. The mbc I currently have is a DNA motorsport boost controller and I'm wondering if this is just a pos boost controller and I need to get another one or is there something else I can do so it won't creep. I've been reading alot about the hallman pro and a bunch of people say they love it but will it hold boost good with the 16g and my current mods? I'd love to be able to run 15 or 16 lbs. I'm sick of not being able to go wot without it creeping to 20 and over

 

[Tsi_User]

What exactly did you port, any pics? Did you ported the wastegate area so the arm can pivot back farther?

 

[RJD2]

Yeah I did and the inlet, and the o2 housing. Sorry I cant load my pics up yet.

 

[Eastwood95]

You probably need to upgrade to the larger 34mm wastegate flapper, and re-port the o2/turbine areas to compensate. The set-up you have now flows too well on the exhaust side instead of the wastegate side, and the exhaust air will always take the path of least resistance.

Team Rip Engineering sells them.

www.teamrip.com

 

[RJD2]

I see but how would a larger flapper help when the hole under it would still be the same size?

 

[DSMULATOR]

you gotta port out the whole too. Don't go too big or it will leak past it.

 

[c4uldr0n]

If you want to see if your boost controller is causing the problem, take it off and put the vacuum line directly from your source to your waste gate.

 

[Eastwood95]

I see but how would a larger flapper help when the hole under it would still be the same size?

That's why I said you have to RE-PORT the TURBINE/o2/WASTEGATE area after you install the bigger flapper.

 

[nad1]

If you want to see if your boost controller is causing the problem, take it off and put the vacuum line directly from your source to your waste gate.

Does this really work? On a stock T25 setup? I'm having creep problems too with mine, since I didn't port when I put my exhaust on, but I still think the MBC might have something to do with it. I can just plug the hose from the compressor housing straight into the wastegate? Sorry for hi-jacking.

 

[SnowBird]

Dont get too serious about porting behind the flapper, the wastegate arm wont even open it as far as you can open it with your finger with the arm off, people dont understand that sometimes. If you want to definitely get rid of the creep just buy an atmospheric O2 dump. Whats another $120 bucks when you have all those mods and so much time just in porting to try to solve it?

Also, with your exhaust, did you get rid of your car also? If you did that wont help at all. But, get a O2 dump and be done with it.

 

[Dsm78]

I have a 16G evo III and had the same problem. I ordered the 34mm flapper from Slowboy,ported the wastegate hole, ported the inlet, and it works great. I also ported behind the flapper arm and made sure that my 02 housing wouldn't stop the arm from opening all the way. You just have to take your time and make sure everything is smooth and seals up. I had an external dump 02 on my car and it really didn't help that much. This was also before I ported the trubo though. If you do it right this mod will work. I hold steady at 16psi.

 

[oldman]

Yeah I did and the inlet, and the o2 housing. Sorry I cant load my pics up yet.

I would like to see the picture of the inlet, the key is in the inlet.

If you want to see if your boost controller is causing the problem, take it off and put the vacuum line directly from your source to your waste gate.

Boost creep has nothing to do boost contollers, it's strictly an exhaust issue.

Does this really work? On a stock T25 setup? I'm having creep problems too with mine, since I didn't port when I put my exhaust on, but I still think the MBC might have something to do with it. I can just plug the hose from the compressor housing straight into the wastegate? Sorry for hi-jacking.

Although T25 can also creep, it is extrememly rare, are you sure you're not talking about boost spike? Describe your boost creep in detail.

If you want to definitely get rid of the creep just buy an atmospheric O2 dump. Whats another $120 bucks when you have all those mods and so much time just in porting to try to solve it?

Contrast to popular believe, boost creep has little to do with O2 dump, the problem is the flow characteristics of the wastegat path in the turbine housing, not your O2 flow capacity. If the turbine housing has not been ported PERFECTLY, an O2 dump won't do much, the only other option would be going external.

 

[nad1]

Sorry, I meant spike. I apologize. Can I still use that technique to find out if my MBC is responsible?

 

[oldman]

Sorry, I meant spike. I apologize. Can I still use that technique to find out if my MBC is responsible?

Which MBC and how is it hooked up? How much boost are you running and where is it spiking to? There is very little you can do about a T25 boost spike, you can lessen the spike by using ball/spring MBC, short MBC hose route and port the turbine housing almost the same way as if you were porting for boost creep with a EVO3 16G, but you will most likely not be able cure it completely, it pretty much is a part of a T25 along with dropping off at higher RPMs.

BTW, please complete your car profile, it's required and it will make helping much easier.

 

[nad1]

Sorry, it's a 95 Talon TSi AWD Auto Tranny. I will complete the profile after I post this. I have the Dejon MBC and I have the shortest possible hose route, it's hooked to the compressor housing on the turbo, and the wastegate. I'm running and holding about 11-12 PSI, and it's spiking to 15'ish after shifts. I have not done any porting on the turbo, because I plan on doing a 16G setup sometime in the near future.