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

[Mr Peepers]

Boost creep is having boost gradually rise uncontrollably in the higher revs.

I doubt you will have creep problems with your t25 since the WGA/flapper isn't limited in it's range(like a 14b/16g) and the fact that the turbine and turbine housing are very small(compared to a TD05H) and will cause enough backpressure in the upper rpm range that the exhaust gas will WANT to go out the wastegate hole.

Also, you won't really lose any torque by going from a 2.5 to 3" since most of the gains through scavenging are null after the turbine anyway. You will likely spool up a tad quicker; which is pretty much the point of a turbo car as far as having torque goes.

 

[BigSorn]

if your that worried, just get a o2 dump.

 

[misterskeetz]

Don't worry, you're fine. I have done it to my car myself with the stock T-25 and everything stays perfect. I think ditching the burnt out exhaust sensor led to some idling problems that could STILL let me drive best kind (even months before this mod when I first bought it in May 2004), but besides that, nothing. de-cated my exhaust system. Ran a 3" Custom built exhaust + APEXi N1 Muffler = Sweet, sweet sound, especially at top speed, and I've seen flames shoot out too! (Just 1 or twice).

So keep your sensor (or replace the burnt one?) run 3" the whole way, and throw in a much needed Boost Gauge to kill some curiousity. You will lose some Torque compared to a 2.5" but I'm sure you'll get it back with some more throw on's. No worries.

I am glad you like the sound. I think it would be nice as well but then I think the HKS hi-power might be more to my personal liking. As far as flames shooting out...some might think that's great and all. It looks cool. I would be more concerned with my cars wellbeing at that point. That's my .02

I have full 3" turbo back, but I do have a cat. I don't have creep at all with the T-25. I'm full 15psi boost around 2400RPM. It's almost too soon for my likes.

NICE! Acceleration is a must!

Boost creep is having boost gradually rise uncontrollably in the higher revs.

I doubt you will have creep problems with your t25 since the WGA/flapper isn't limited in it's range(like a 14b/16g) and the fact that the turbine and turbine housing are very small(compared to a TD05H) and will cause enough backpressure in the upper rpm range that the exhaust gas will WANT to go out the wastegate hole.

Also, you won't really lose any torque by going from a 2.5 to 3" since most of the gains through scavenging are null after the turbine anyway. You will likely spool up a tad quicker; which is pretty much the point of a turbo car as far as having torque goes.

THAT is the kind of answer I was looking for. Thanks peeps!

if your that worried, just get a o2 dump.

If I don't have to spend the money on something that I may not even need...I can put that money to good use elsewhere.

 

[scoby41]

(compared to a TD05H) and will cause enough backpressure in the upper rpm range that the exhaust gas will WANT to go out the wastegate hole.

I've read something about porting the area around the flapper....? At this point I'm running a 1g manifold so I dunno.

 

[Mr Peepers]

http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html

http://www.dsmtuners.com/forums/turbo-system-tech/290438-rate-my-porting.html etc

I wasn't referring to porting, but this seems to be what you're asking about.

 

[scoby41]

I might just do that since everything is still apart at this point.....

 

[talonman2000]

Definitely worth a shot (porting). When I had my 3" turboback setup I didn't experience any boost creep, and it sounded glorious .

 

[cavillac]

not 100% positive but i think thats what boost creep is, it should drop a little bit but the creeping is keeping it steady

No, its pretty well known that the T25 sucks at maintaining boost levels in the upper RPMS...
I would start off with 10 or 11 and it would drop to 7 or 8 after like 5k rpms..Now that the car can breathe it starts with 11psi and stays at 11 psi without going up or "creeping"

 

[squarebush]

I have the exhaust system that you are looking for, for sale! Check your PM's. It's an Apexi N1 3" downpipe, and the Apexi N1 3" catback system.

 

[spydermanX98X]

t-25's aren't really known for creeping, but like a 16g unported definately is. Boost creep would be like you set your mbc to 21 psi and it hold at 21 all the way till lets say 5.5k or 6k and then rises fast to 26 and then goes down when you lay off the gas.

 

[doober75]

if your that worried, just get a o2 dump.

wont have to worry one bit then

 

[scoby41]

if your that worried, just get a o2 dump.

Would this be a better option that porting the wastegate?

 

[webconnect]

Getting an open dump is a cheat to get rid of boost creep. To get rid of it any other way, your going to have to port the wastegate and turbine inlet.

 

[BigSorn]

and it sound MEAN. imho.

 

[scoby41]

Getting an open dump is a cheat to get rid of boost creep. To get rid of it any other way, your going to have to port the wastegate and turbine inlet.

Rog

 

[webconnect]

Rog

????

 

[scoby41]

oops, sorry! rog = roger which is short for cool guy army lingo... "i understand"

 

[Mr Peepers]

An o2 dump is hit or miss as far as creep goes IMO. It really depends on what's the biggest restriction in the WG path, and that's often either the 90* entrance angle and/or the limited flapper travel(in the case of a TD05H WGA).

 

[akirmanidis08]

So ive been plagued with boost creep since ive had my car, which is about 2 months now.

The only major mod done to my car is a straight thermal 3 inch exhaust.

After doing so much research etc etc

the problem was a broken actuator

before i replaced it, my car would boost all the way up to 22 psi and then hit fuel cut

this was due to the actuator not functioning properly.

all i did was replace it and now my car runs perfect at 8 psi constant when im on it.

so check your actuatuors for any dents, any signs of bending could be your problem

its not always necessarily that you need a ported turbo

 

[870josh]

I bought a 92 talon with an evo3 16g and 3" full back catless exhaust. It's running on the stock bsc and is getting boost creep. At about 5k rpm, it reaches 20-21 psi, at which point I'm pretty sure it's hitting fuel cut, the car just lurches down and I'm pretty sure it backfires, it makes some god awful explosion noise.

So, I drove it home and popped open the hood and it's got oil on the valve cover, I'm assuming from the valve cover breather hose. Does boost creep explain all of the symptoms? Just wanted to see what you guys thought, going to port out the internal wastegate next weekend and add the 34mm flapper to see if that helps, and also going to do a boost leak test.

I'm just making sure my logic agrees with yours and ensuring that there's not some worse underlying problem with my car.

Thanks for your time

 

[870josh]

Okay upon further inspection and some common sense, I've figured that the oil isn't from the breather valave on account of the breather valave being vented under the car . There is a bolt missing from the top right corner of the valve cover, the hole is stripped and needs to be retapped, could that be the source of the oil on the valve cover?

+ I realize evo3 16g is notorious for boost creep, before anyone decides to point it out to me

+ I pulled the line from the valve cover breather up and it's got a steady stream of white smoke coming from it at idle, is this normal?

+ when you first push on the accelerator it bogs down a little bit and then revs, is this a sign of a leak? This was at idle and when out of gear.

+ the AFM (or whatever it's called) is bugging out or I've seriously got something wrong, this was taken at idle after idling for 5 mins or so:
VID00067.flv - Video - Photobucket - Video and Image Hosting

+ this seems off, is it? VID00068.flv - Video - Photobucket - Video and Image Hosting

I know I'm asking a lot of questions but I'd really like to get this thing running well. I'd ask my Dad the mechanic but he doesn't have much of a clue about these cars, or turbo cars in general.

+ it's been overfilled with oil, about a half of an inch above the "high" mark on the dipstick, would that be enough to cause smoke out of the valve cover breather?

 

[TheAButton]

Ya my boost is doin that same damn thing so what exackly is this actuator your talkin about, im sure if you told me what it looks like and where it is then I could replace it and see if that helps

 

[Mr Peepers]

Good catch, if the actuator body is bent or dented it can seriously limit the travel of the arm. Before anyone goes replacing theirs though, check to make sure it's not actually opening as far as it should. Stock movement is about 3/8". Test it with the WGA off the car or at least off the flapper since some of the travel is used up to hold the flapper shut.

 

[fanaticdsm-er]

Or you can use Mr peepers MWGA mod to completely eliminate creep even when you up the boost. WHich btw, ive been trying to get a hold of you Mr. Peepers, clear your pm box.

 

[96ETT]

Ya my boost is doin that same damn thing so what exackly is this actuator your talkin about, im sure if you told me what it looks like and where it is then I could replace it and see if that helps

This is the actuator:

eBay Motors: Mitsubishi DSM Eclipse turbo wastegate actuator 16G (item 330301405703 end time Jan-24-09 06:43:47 PST)

This one looks painted and if yours is factory still it should be bronze color.