[STEye]

Before Info: I have a catted TurboXS Stealthback utilizing the stock STi axleback.

Today, I put on a resonated testpipe in place of the cat, but still utilizing the stock STi axleback. I'm getting these numbers I datalogged using Tari. I don't think it's creep and I think it should be safe... ** Note this log had the highest boost. Normally it will peak at mid 18 PSI. What do you think?

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-Chris

[ChaoticSTi]

I don't think you should be boosting to 18.8...I think you are experiencing mild creep...you need to go wide open throttle in 5th or 6th gear under full boost to see if you have boost creep...this will cause fuel cut if you do...this is the easiest way to test for it

[polyol]

That is boost spike...not creep. Spike isnt a big deal if it settles down quickly and thats what it appears to do. What gear were you in? Try logging 5th gear @ 3400RPM, see what happens.

It looks very similar to my car TBE no cat 2 resonators. Ive been hitting 18.5psi for well over a year with no problmes. Any more than that and I would be concerned. I will creep if I roll into a 5th or 6th gear run @ low RPM. Avoid hitting boost in 5th gear untill you are past 4000RPM. Avoid 6th all together.

You may need a very mild port on the wastegate housing, it doesnt take much. That should take care of you.

[STEye]

The data log I posted was in 6th gear (On the highway) doing about 60 or so MPH.... That's the thing, I haven't gotten any fuel cut/nor any check engine light.. I was looking through the logs of my setup with the high flow cat, and the max boost I saw (from a set of about 12 logs) was like 18.5 PSI. So to re-interate my setup, it was a catted TXS stealthback with stock axleback. Is mid 18's really that out of the ordinary?

[Muffnbluff]

Originally Posted by STEye

The data log I posted was in 6th gear (On the highway) doing about 60 or so MPH.... That's the thing, I haven't gotten any fuel cut/nor any check engine light.. I was looking through the logs of my setup with the high flow cat, and the max boost I saw (from a set of about 12 logs) was like 18.5 PSI. So to re-interate my setup, it was a catted TXS stealthback with stock axleback. Is mid 18's really that out of the ordinary?

I'm no expert, but it seems like it spikes briefly and settles back down so it's not like your hitting 18.5+ for an extended period. From what I understand you'd only have a problem if it spiked, went back down and then slowly went back up to a really high number as you continued to accelerate.

So I guess I'd log a 5th gear run from 3k - 4k+ and see what happens.

[STEye]

Forgive me for my uneducated mind, but If this were trully a "creep" or "spike" issue, wouldn't my primary wastegate duty cycle be at 100%? (See my lovely data log on first post)
Just to note, I installed the testpipe yesterday, and I reset my AP. From what I hear, the AP can sometimes fix spike/creep issues over time... Any truth to this?

[dcoty]

I have the EXACT same boost spike with my helix catted dp and fujitsubo catback. It very briefly peaks at no more than 18.5 psi and then gradually tapers as redline approcahes. I havnt had any problems what so ever with this setup.

Thanks for posting this, I havent seen anyone else with the spike like I had.

Dan

[ChaoticSTi]

the ap...can band aid boost creep...by helping your wastegate efficiency...but it can't prevent it completely...yeah you are spiking but it isn't that serious I think you'll be okay...but aince you are catless now you might experience creep instead of spike

[STEye]

Did more data logging today on an extended trip... Now I managed for it to spike up to 19.2 (Max on one of 20 the pulls)... I think this is getting too high for my taste... I have heard of some people peaking at 20-21 PSI, which I know is not good... Is the 19 PSI area dangerous if it spikes up to, but comes down immediately? I'm guessing yes.....

I guess I'm just not understanding the severity of Boost spiking..

[sizzflair]

I peak at 20-21 psi.. no problem here yet. It's been protuned by EQ tuning and it's running good so far. At first I thought it was not safe, but a lot of people had different sides of their story. I think the only reason i'm boosting so high is that the weather is cold and I get boost creep. Boost creep gets me to my 'target boost' according to my tuner

[ChaoticSTi]

well if you did twenty pulls and only experienced this once I don't think you have to worry too much...do you have any form of engine management?...I think a cobb ap will solve your spiking enough to keep your nerves down...my ap seems to have somewhat regulated my creep a little bit which makes me happy

porting the wastegate will solve your issue completely but in your case I don't see it being 100 percent necessary

[STEye]

Well out of the 20 or so pulls, 19.2 was the highest. 3 of the 20 pulls netted a peak boost of 19.0-19.2

I do have a Cobb AP that is running Stage2 93oct... I suppose I could go with the LWG realtime map if I wanted to be safe.. I'm just not sure if that is neccessary. I wish this forum had a "blown motors" section, where people that blew their motors could describe their setup and all the implications (Like "I was peak boosting at 20 psi" etc...)

Chaotic, what is your peak boost? Have you ever run Tari? The live boost meter on the AP can be deceiving, as it only reads up to 18.4......

[sizzflair]

^well if you want to know, my mods are in my sig... peak boost is a little over 20. Haven't blown up my motor yet lol. I've been running my baby pretty hard too... and raced... Been about a month and no problems so far

[STEye]

sizzflair, you're protuned.. that would make me a little less worried about boosting higher since you had a tuner check out the different factors (i.e. AFR, etc)... I don't think I'll grenade my motor in the short term (knock on wood!) but I'm afraid of the long term effects.. I guess that means I should go back to stock if that's the case.. hellz no!

I'll just cross my fingers!

[ChaoticSTi]

I have Tari on my laptop but I need to pick up an adapter for the serial connector. Give me until the end of the week and I'll get a log for you and see what my car is doing.