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yep... what's the stock boost level? I'm planning to by the turboXS MBC, but i don't know how high up a boost I should apply~~ Also, should I also install a cat-less uppipe before I instal a MBC?
 

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i was asking the same question a few days ago they told me no over 16#boost (15.5# to 16#at part trhotle on a boost gauge) is about right any over 16 will cause premature damage on the stock turbo and at arround 17.5 the ecu will shut down your fuel supply because of over boosting
 

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ACTUALLY...

From my testing...I'm come up with this.

Stock boost :13.5 psi
Max safe boost : 17 psi
max safe over-boost : 19 psi (short term , under 5000 rpm)
The engine only hits fuel cut if you hold 19 psi until past 5000rpm

The T-25 can handle 20 psi structurally for VERY short periods of time.
So far I've spiked to 19 psi and dropped to 16 past 5000 rpm with my current boost mod..... enough to put me in the 13's at this altitude.
 

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how can you do that ? i mean spike it to 19 and the lowering to 16 is it with the use of a computer or a special boost controller ,i ve also have doubt of what really is part throtle? is it like this that you doit boost it to 19 arroud 5000rpms and the the boost go down since is a small turbo please let me know very intresting
 

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I think the boost spiking at the lower rpm's is something to do with the T-25 itself......
I've seen 2G dsm's with this same turbo do that also. A friend of mine can get his 98 Talon to spike at 20 psi and drop to 13 psi past 5000 rpm , and his boost mod is the same as mine.
I'm using 100% throttle the whole time. Not sure exactly what causes it , but I have some theory's:D
The T-25 cannot handle high boost either thermally or structurally , and might be why it spikes and then DROPS fast......
Thats why I chose to limit my spike to 18 psi , and then only over a 1000 rpm range , right around 4000 rpm. Past 5000 it drops back to 15.5-16 psi
If you wanna see how that was done , look in the thread "$3 boost mod"
The only problem I've come up with is at lower than 35*F(outside air temperature) the boost spikes to 20 and turns on the CE light.....:mad: This maybe because the air is thicker and expands MORE when it gets to the hot turbo......
 

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The highest I ever saw on my stock turbo, when I was stock, was 14lbs. That was without a boost controller. I thnk that fuel cut is right around 17lbs on the stock tune for the ECU.
 

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Yes , it may spike to 14 occasionally.

Most of the time it stabilizes at 13.5 , unless maybe its a cold day.

Ive confirmed max stock boost is 13.5 , from the dealers mouth :)
 

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Well basically to break it down for you the reason it spikes and drops is because your turbo can only flow so much if it spikes that is what your mod set your boost at. It drops because once you reach the high rpm's the turbo can't breath as well which is why a bigger tubo is a good upgrade because it can hold more boost at higher RPM's because it can breath better. If you would liike more info on what your turbo can do look up a flow cart of your turbo and see how much it can flow this will show you how much horsepower your turbo can make what psi it can hold . The only downside is the charts are a pain to learn to read. So basically what I am saying is buy a boost controler turn it to 16 psi and it will hold to redline which is better then spikeing.
 

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Something I noticed recently....

My car, bone stock, would read about .14 on the stock boost gauge. After changing up-pipe, down-pipe, and adding an HKS blow-off valve (set at the setting HKS reccommended) my car now goes to .15. I guess the stock bypass valve was letting more pressure escape than my BOV. I adjusted the BOV to release sooner, so boost is now just a tad below stock. I'm in the process of getting an aftermarket engine management system, and once I do I'll readjust the BOV and add my EBC.

But, I didn't realize that a BOV would have that kind of effect.

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Yes , it can make all the difference. The stock BOV is designed to start blowing off boost around 12 psi(don't know the BAR equivalent) to assist the wastegate with controlling overboost. I have a Greddy type-S on my car , which can be set to hold 30+psi. You're HKS one is probably set around 16 psi , maximum reliable boost for the T--too-small turbo.
Most turbo cars BOV's are designed that way , to blow off boost early from the BOV , and some can control over-boost even if the wastegate were to fail completely.
 

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You know when you add exhaust mods your boost should increase because it is allowing your turbo to breath better the blow off valve makes a difference but not very noticable. If your boost went up at all I would put money on the fact that it was because of your uppipe and downpipe. Downpipe especially.
 

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i definetly agree with awdwrx bov will not give you more boost they are only means to control that the turbo dont spools the opposite way when the throttle is released and the boosted air gets trapped on the intake and moves back to the turbo and spoolit backwards, also its a mean of cooling the boost chamber (intake)when used to vent to the atsmosphere because it do not re route the already compressed air back to the turbo again t o recompresseit (to make compressed air or boost in order to do that it creates heat) the only thing boosting your car its the better exaust flow letting the turbo spool faster with more exaust flow
 

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I agree with all the above also , but one thing you must realize is , a lot of the factory parts were designed with keeping the WARRANTY safe.
The BOV may leak or release too early , the ECU may run the injector cycles richer than it should , the exhaust is also severely restricted in an attemp to prevent overboost. Once you start replacing exhaust and intake parts , the BOV will be overun in very short order. That was a common problem on DSM's , the BOV would start leaking at like 9-10 psi , one solution was to put it in a vice and "crush" it so that spring pressure was greater.
I've done static (off-car) tests of the factory WRX BOV , and it starts bypassing at about 12 psi. Any aftermarket BOV is a good investment before you get too far with mods....................
 

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Your both right except the purpose of the BOV is to increase turbo life yes a after market BOV will help you build boost quicker but not more then your turbo can flow. If the BOV is leaking all it is doing is slowing down boost buildup which means you spend less time in your peak power. basically saying the car goes slower.
 

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the t-25 is crap, i put up with it every day, my boost is set to 15, and after 5000rpm it drops to 10:mad: , any way, the only way to go is bigger!Thumbs Up
 

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well since wrx's already run low 14's with 13.5psi, how fast in the 1/4mile would a 17psi wrx run?? since 17 seems to be the highest it'll go on the stock turbo.
 

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I know how you feel with the T-25 I used to have a 92 GSX and the stock turbo had to go along with some other mods that were added :D

And at 17 psi you will still be in the 14's but it will be faster if I had to guess I would say best would be 14.o if all you had was a boost controller and you made a good pass with a good driver.
 

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The 92 GSX had the 14B turbo , which can flow almost DOUBLE the cfm the T-25 can......
I had a 92 GSX , so I know ....I still have the turbo off it , and was planning on installing it on the WRX , since it will support about 330 Hp easily.
Buschur Racing is working up a retro-fit kit for it.
 

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well lets say i had a boost controller, plus other mods such as intake, exhaust, headers, blow off valve, and other little mods. how fast would i be running then?? i expect somewhere in the mid-high 13's
 

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I'll let ya know as soon as Bandimere opens again !Thumbs Up !Thumbs Up

I'm expecting mid-high 13's just with 17psi....even at this altitude.

The turbo is the biggest hold-back , and the injectors are only good to about 300 Hp.

So with just those 2 , I'd say low 13's
Throw on an catless exhaust , and CAI , probably 12's :eek:

WRX's respond VERY well to mods , $1000 probly get ya 40+ Hp
 
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