got the car tuned, can't hold the boost
11-21-2003, 01:54 AM
#1
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Join Date: Apr 2003
Location: fremont ca
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got the car tuned, can't hold the boost
hi all, just got a dynotuned by shiv for my VS stg2 wrx. the car put down 245 whp. shiv told me he could only get the boost up to 16.5 psi which seems lower than other stg wrx's, and the boost can't hold till redline. he said that the header I have ( gruppes v2 header) was the main reason that my car hits lower boost. he also mentioned my car got a better mid range torqe than others. why is that? the header gave me a better mid range and lose some top end? anyone have dyno'd stg2 with headers? what whp did you put out? can you guys post the dyno plot? I really want my car to have 17.5 psi and hold to the redline, so the car may make more power. anyway, big thank to shiv, my car is running much better and strong now
thanks
thanks
11-21-2003, 09:20 AM
#2
Chewwwwy
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the header will majorly improve mid range due to the fact that it flows better. it also will decrease top end for the same reason. in a trubo set up you have to create pressure in order to make pressure.
in order to get up to 17.5psi in the intake side, you have to have a pressuree greater then that in the exaust side. i dunno what turbo you are running, but it may not be able to push that psi with such a large volume of air b4 the exaust side. subarus are notorious for this due to the location of the turbo.
congrats on the stg 2. must be fun to drive.
in order to get up to 17.5psi in the intake side, you have to have a pressuree greater then that in the exaust side. i dunno what turbo you are running, but it may not be able to push that psi with such a large volume of air b4 the exaust side. subarus are notorious for this due to the location of the turbo.
congrats on the stg 2. must be fun to drive.
11-22-2003, 03:09 PM
#4
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Car Info: 02' WRX
Originally posted by international B
the header will majorly improve mid range due to the fact that it flows better. it also will decrease top end for the same reason. in a trubo set up you have to create pressure in order to make pressure.
in order to get up to 17.5psi in the intake side, you have to have a pressuree greater then that in the exaust side. i dunno what turbo you are running, but it may not be able to push that psi with such a large volume of air b4 the exaust side. subarus are notorious for this due to the location of the turbo.
congrats on the stg 2. must be fun to drive.
the header will majorly improve mid range due to the fact that it flows better. it also will decrease top end for the same reason. in a trubo set up you have to create pressure in order to make pressure.
in order to get up to 17.5psi in the intake side, you have to have a pressuree greater then that in the exaust side. i dunno what turbo you are running, but it may not be able to push that psi with such a large volume of air b4 the exaust side. subarus are notorious for this due to the location of the turbo.
congrats on the stg 2. must be fun to drive.
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
11-22-2003, 03:11 PM
#5
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Car Info: 02' WRX
Originally posted by theworx
I used to own a 1G DSM before my sub and I must say the turbo placement in this car is ish. The stock turbo on a 1G can hold 22psi or higher till redline no prob.
I used to own a 1G DSM before my sub and I must say the turbo placement in this car is ish. The stock turbo on a 1G can hold 22psi or higher till redline no prob.
The turbo placement has jack **** to do with the amount of boost a turbo can produce. The amount of boost a turbo will create is a result of turbo efficency, compressor and turbine trim, wheel sizes, bearing quality etc.
11-22-2003, 05:06 PM
#6
Chewwwwy
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Originally posted by Br1t1shguy
Wow, that whole thing about making pressure on the turbine was a collosal load of crap. All the header does is reduce exhaust turbulance and smooth out the delivery of exhasut pulses to the turbine. The only way it wold reduce the pressure differential over the turbine is if there was an exhaust leak. How in gods name could a header reduce exhaust pressure? What? Did you totally pull that out of you're ***?
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
Wow, that whole thing about making pressure on the turbine was a collosal load of crap. All the header does is reduce exhaust turbulance and smooth out the delivery of exhasut pulses to the turbine. The only way it wold reduce the pressure differential over the turbine is if there was an exhaust leak. How in gods name could a header reduce exhaust pressure? What? Did you totally pull that out of you're ***?
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
what he really meant to say was this...
Originally posted by Br1t1shguy
wow, i really dont know jack ish about trubo chargers.
wow, i really dont know jack ish about trubo chargers.
11-22-2003, 05:19 PM
#7
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Originally posted by Br1t1shguy
Wow, that whole thing about making pressure on the turbine was a collosal load of crap. All the header does is reduce exhaust turbulance and smooth out the delivery of exhasut pulses to the turbine. The only way it wold reduce the pressure differential over the turbine is if there was an exhaust leak. How in gods name could a header reduce exhaust pressure? What? Did you totally pull that out of you're ***?
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
Wow, that whole thing about making pressure on the turbine was a collosal load of crap. All the header does is reduce exhaust turbulance and smooth out the delivery of exhasut pulses to the turbine. The only way it wold reduce the pressure differential over the turbine is if there was an exhaust leak. How in gods name could a header reduce exhaust pressure? What? Did you totally pull that out of you're ***?
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
suppose you blow through a small straw (you know, like a coffee straw) to a small fan, vary the pressure you put to the straw, it won't turn the fan that fast...
now, take a regular straw, do the same. spins a little better
now, take a milk shake straw (a little bigger), do the same, spins even a little better more...
now, take a 1" pvc pipe, do the same.... wow the fan doesnt spin at all! too much flow!
with your logic, they would all spin at the same rate w/ the different types of pressure, right? i mean, the only way it would reduce the pressure differential over the fan is if there was a straw leak... right?
11-22-2003, 06:19 PM
#8
Old School
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Originally posted by Br1t1shguy
Wow, that whole thing about making pressure on the turbine was a collosal load of crap. All the header does is reduce exhaust turbulance and smooth out the delivery of exhasut pulses to the turbine. The only way it wold reduce the pressure differential over the turbine is if there was an exhaust leak. How in gods name could a header reduce exhaust pressure? What? Did you totally pull that out of you're ***?
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
Wow, that whole thing about making pressure on the turbine was a collosal load of crap. All the header does is reduce exhaust turbulance and smooth out the delivery of exhasut pulses to the turbine. The only way it wold reduce the pressure differential over the turbine is if there was an exhaust leak. How in gods name could a header reduce exhaust pressure? What? Did you totally pull that out of you're ***?
I'm not usually an ***, but when people just completely BS on car forums, it's damn annoying.
Look at what odyss3y typed you moron. Before you start to sit there and be so ****ing critical of other people, maybe you should really think about what was said. It makes perfect sense to me, and to think that increased diameter piping headers WON'T reduce pressure of the exhaust flow is pretty dumb. sure boost pressure has nothing to do with turbo location, but spool time does...
Put a 10" exhaust on your car, and see if you have any tq to make it move...
-Gagan
11-26-2003, 09:34 AM
#9
that is true...most of the people on I-club are just trying to help, taking time out of there day to voice thier opinions. And if all you do is criticize everyone elses posts then you don't have to post.
Darkspeed just wants some help....
good luck (bet that Stg 2 is fun
)
Rocky
Darkspeed just wants some help....
good luck (bet that Stg 2 is fun
)Rocky
Last edited by qwk_wrx; 11-26-2003 at 09:39 AM.
11-27-2003, 12:18 AM
#10
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Posts: n/a
try checking the diaphram in the wastgate pot. if its bad it will bleed off the boost. check with a hand vaccum pump. if its ok install a threaded rod coupling on the wastegate arm and tighten it up a little to not let so much bypass out when the waste gate opens. if you still need more install a pressure relief bypass valve inline before the wastegate diaphram. set it to trick the waste gate into thinking the boost is lower so it will staying closed longer and and build more boost.
11-27-2003, 02:37 AM
#11
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Join Date: Apr 2003
Location: fremont ca
Posts: 64
thanks suberacer, I just discovered that boost is acting differently these days. instead of getting low boost, the boost actually spikes to 1.3 bar =18.85 psi which I think is too high, I mingt need to turn the boost down. another thing I discovered is that on my dyno sheet, the boost starts to drop from 4200 or 4300 rpm. shiv told me that my car can't hold the boost till redline, but on my boost gauge, when boost hits, it holds all the way to redline. at first I thouht the boost gauge is not accurate, so i hooked up my friends' gauge to see if the boost would drop. guess what, it still holds well and never falls. I am pretty happy that my car actually holds the boost now, but why would my car not hold the boost when it's being dyno tuned? can anyone answer this?
thanks
thanks
11-27-2003, 07:19 PM
#13
Originally posted by darkspeed
thanks suberacer, I just discovered that boost is acting differently these days. instead of getting low boost, the boost actually spikes to 1.3 bar =18.85 psi which I think is too high, I mingt need to turn the boost down. another thing I discovered is that on my dyno sheet, the boost starts to drop from 4200 or 4300 rpm. shiv told me that my car can't hold the boost till redline, but on my boost gauge, when boost hits, it holds all the way to redline. at first I thouht the boost gauge is not accurate, so i hooked up my friends' gauge to see if the boost would drop. guess what, it still holds well and never falls. I am pretty happy that my car actually holds the boost now, but why would my car not hold the boost when it's being dyno tuned? can anyone answer this?
thanks
thanks suberacer, I just discovered that boost is acting differently these days. instead of getting low boost, the boost actually spikes to 1.3 bar =18.85 psi which I think is too high, I mingt need to turn the boost down. another thing I discovered is that on my dyno sheet, the boost starts to drop from 4200 or 4300 rpm. shiv told me that my car can't hold the boost till redline, but on my boost gauge, when boost hits, it holds all the way to redline. at first I thouht the boost gauge is not accurate, so i hooked up my friends' gauge to see if the boost would drop. guess what, it still holds well and never falls. I am pretty happy that my car actually holds the boost now, but why would my car not hold the boost when it's being dyno tuned? can anyone answer this?
thanks
Also a point to note is that given the size of the turbochargers being used and the other pieces on your car is it doubtful that turbo placement or headers are to blame for the lack of holding boost (we have a car with the same headers holding way more boost till redline all day).
What Dave (odyss3y) wrote is correct but something I would like to mention is that in the case of the headers you have the added airflow is not really at the extent to if you like not move the fan as unless something has been changed in the design of the headers from the ones we have seen they are about the same size diameter wise as the stockers but just a better design giving improved flow (not huge no fan moving flow
) which may be why they come with free gaskets that look remarkably similiar to the OEM ones 
Mike
(510) 487-4447
www.mpjperformance.com
www.gb-motorsports.com
11-27-2003, 07:57 PM
#15
doogie - Was that number gained using the bottle? As I have never ever heard of a stock turbo'd car running that kind of number and think the most we have seen is like 230whp on a dynojet.
The above car based on what I understand the stage 2 Vishnu setup is either using a vf30 or vf34 and at 245whp using 16.5psi is well within what you would expect to see on a Dyno Dynamics dyno.
Can you post the dyno sheet of the 255whp run I would like to see the power curve from the stocker at that level.
Mike
(510) 487-4447
www.mpjperformance.com
www.gb-motorsports.com
The above car based on what I understand the stage 2 Vishnu setup is either using a vf30 or vf34 and at 245whp using 16.5psi is well within what you would expect to see on a Dyno Dynamics dyno.
Can you post the dyno sheet of the 255whp run I would like to see the power curve from the stocker at that level.
Mike
(510) 487-4447
www.mpjperformance.com
www.gb-motorsports.com