What's the stock boost level for our cars? - Subaru WRX Forum
Reply
 
LinkBack Thread Tools Display Modes
#1 Old 01-09-2003, 03:06 PM
WRXtuners Member
 
Join Date: Nov 2002
Location: Burnaby, British Columbia
Posts: 11
minsin is an unknown
What's the stock boost level for our cars?

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?

Question your very own EXISTENCE
minsin is offline  
Sponsored Links
Advertisement
 
#2 Old 01-09-2003, 05:49 PM
WRXtuners Member
 
Join Date: Dec 2002
Location: Caguas, Puerto Rico
Posts: 182
koki is an unknown
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
koki is offline  
#3 Old 01-11-2003, 03:36 AM
WRXtuners Member
 
Join Date: Dec 2002
Location: Denver Colorado
Posts: 33
WagonRex is an unknown
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.
WagonRex is offline  
#4 Old 01-12-2003, 09:39 AM
WRXtuners Member
 
Join Date: Dec 2002
Location: Caguas, Puerto Rico
Posts: 182
koki is an unknown
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
koki is offline  
#5 Old 01-12-2003, 02:14 PM
WRXtuners Member
 
Join Date: Dec 2002
Location: Denver Colorado
Posts: 33
WagonRex is an unknown
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
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..... This maybe because the air is thicker and expands MORE when it gets to the hot turbo......
WagonRex is offline  
#6 Old 01-17-2003, 10:12 AM
WRXtuners Member
 
Join Date: Dec 2001
Posts: 54
STiWRX is an unknown
Send a message via AIM to STiWRX
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.

Bill Janczewski
STiWRX is offline  
#7 Old 01-17-2003, 07:03 PM
WRXtuners Member
 
Join Date: Dec 2002
Location: Denver Colorado
Posts: 33
WagonRex is an unknown
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
WagonRex is offline  
#8 Old 01-18-2003, 12:06 PM
WRXtuners Member
 
Join Date: Jan 2003
Location: Las Vegas
Posts: 9
AWD WRX is an unknown
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.
AWD WRX is offline  
#9 Old 01-21-2003, 11:20 AM
WRXtuners Member
 
Cosmo's Avatar
 
Join Date: Dec 2002
Location: Virginia
Posts: 4,591
Images: 15
Cosmo is known to be trustworthy and helpful Cosmo is known to be trustworthy and helpful
Send a message via AIM to Cosmo
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.
Cosmo is offline  
#10 Old 01-21-2003, 12:03 PM
WRXtuners Member
 
Join Date: Dec 2002
Location: Denver Colorado
Posts: 33
WagonRex is an unknown
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.
WagonRex is offline  
#11 Old 01-22-2003, 05:40 PM
WRXtuners Member
 
Join Date: Jan 2003
Location: Las Vegas
Posts: 9
AWD WRX is an unknown
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.
AWD WRX is offline  
#12 Old 01-22-2003, 07:02 PM
WRXtuners Member
 
Join Date: Dec 2002
Location: Caguas, Puerto Rico
Posts: 182
koki is an unknown
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
koki is offline  
#13 Old 01-24-2003, 01:30 AM
WRXtuners Member
 
Join Date: Dec 2002
Location: Denver Colorado
Posts: 33
WagonRex is an unknown
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....................
WagonRex is offline  
#14 Old 01-24-2003, 10:13 AM
WRXtuners Member
 
Join Date: Jan 2003
Location: Las Vegas
Posts: 9
AWD WRX is an unknown
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.
AWD WRX is offline  
#15 Old 01-24-2003, 10:50 PM
WRXtuners Member
 
Join Date: Jan 2003
Location: Oregon
Posts: 9
1badtsi is an unknown
Send a message via AIM to 1badtsi Send a message via MSN to 1badtsi Send a message via Yahoo to 1badtsi
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 , any way, the only way to go is bigger
1badtsi is offline  
Reply


Currently Active Users Viewing This Thread: 2 (0 members and 2 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On