"WRSX" no exhaust - Page 2 - Subaru Impreza GC8 & RS Forum & Community: RS25.com

**poormansporsche** · 03-10-2010, 01:46 AM

Not sure I'm following.

cheers

poorman

**poormansporsche** · 03-10-2010, 01:55 AM

[/QUOTE]

Guy from MRT seems to know what what I'm talking about. Last 1/4 of the video he mentions tuning in regards to restriction. Start at 3:00 min in. And as he points out there used to be a clip on their website about the dangers of running aftermarket exhaust without tuning properly.

cheers

poorman

squidmaster · 03-10-2010, 01:56 AM

wrx has extremely common problem where the pressure hose from the wastegate cracks and doesn't hold pressure. therefore a spike.
exhaust back pressure has nothing to do with how much the wastegate opens and closes, which is the only thing that has control over boost pressure.....

**poormansporsche** · 03-10-2010, 02:03 AM

Hmmm yeah, not it's not that problem. Though I'm not entirely familiar with that problem either.

It seems to me that a cracked wastegate line would do something different. But like I said I'm not familiar. In my mind the cracked wastegate line would mean the car is just going to run at wastegate pressure. I ran my car in with that hose pulled completely off. Now I could see the wastegate hose being cracked and causing inconsistent boost. Such as the car is under full throttle, the hose starts leaking so it's only at 7 or 8 PSI when it should be at 12 or 13 PSI then for whatever reason it spikes up to 14 as the leak slows.

Maybe the ECU tries to compensate for the leak and thusly opens the taps on the turbo then suddenly the leak slows and it spikes?

But please explain more.

cheers

poorman

squidmaster · 03-10-2010, 02:05 AM

funny. he didn't say anything about over-boost. he said the boost control will be all over the place.... probably from opening and shutting the wastegate more than it would have without that higher flowing exhaust because not it doesn't have to open or shut as much. Boost is still SOLELY controlled by wastegate. Until you get to 20psi on a stock super restricted exhaust where there's more coming from the engine than can escape from the muffler...

**Smezmerz** · 03-10-2010, 02:08 AM

That sounds beastly!

squidmaster · 03-10-2010, 02:08 AM

I'm not 100% sure exactly how it's working with the wastegate solenoid, but it happened to my STi. Was boosting at 14.8 without a tune and with a TBE. Line cracked started to spike at 17 and 18. Replaced line went back to 14.8. Same thing happened to two of my buddies that have WRX's. With or without stock exhausts.

RSblood · 03-10-2010, 10:14 AM

I was tuned on a straight pipe, I don't think removing the axleback is gonna cause it to overboost

**poormansporsche** · 03-10-2010, 10:30 AM

Whatever you say guys.

Everything you need to know about boost creep - NASIOC

cheers

poorman

**poormansporsche** · 03-10-2010, 10:35 AM

I also had a discussion about this recently with my tuner, William Knose of Crawford.

But I'm sure you guys are right.

cheers

poorman

03-10-2010, 01:46 AM	#11 (permalink)
poormansporsche Premium Member Car: RSTI Fav Mod: Launch control My: Subaru Parts Join Date: Mar 2005 Trader Rating: (2) Posts: 5,589	Not sure I'm following. cheers poorman __________________ "STIs are serious business." - Dr. Drew Pinsky

03-10-2010, 01:55 AM	#12 (permalink)
poormansporsche Premium Member Car: RSTI Fav Mod: Launch control My: Subaru Parts Join Date: Mar 2005 Trader Rating: (2) Posts: 5,589	[/QUOTE] Guy from MRT seems to know what what I'm talking about. Last 1/4 of the video he mentions tuning in regards to restriction. Start at 3:00 min in. And as he points out there used to be a clip on their website about the dangers of running aftermarket exhaust without tuning properly. cheers poorman __________________ "STIs are serious business." - Dr. Drew Pinsky Last edited by poormansporsche; 03-10-2010 at 01:57 AM..

03-10-2010, 01:56 AM	#13 (permalink)
squidmaster 3.3L Car: 2000 2.5ReallySlow & 91 Miata Fav Mod: Was my access port :[ My: Subaru Parts Join Date: Aug 2008 Location: Orlando, FL Trader Rating: (1) Posts: 538	wrx has extremely common problem where the pressure hose from the wastegate cracks and doesn't hold pressure. therefore a spike. exhaust back pressure has nothing to do with how much the wastegate opens and closes, which is the only thing that has control over boost pressure..... __________________ http://squidmaster.net

03-10-2010, 02:03 AM	#14 (permalink)
poormansporsche Premium Member Car: RSTI Fav Mod: Launch control My: Subaru Parts Join Date: Mar 2005 Trader Rating: (2) Posts: 5,589	Hmmm yeah, not it's not that problem. Though I'm not entirely familiar with that problem either. It seems to me that a cracked wastegate line would do something different. But like I said I'm not familiar. In my mind the cracked wastegate line would mean the car is just going to run at wastegate pressure. I ran my car in with that hose pulled completely off. Now I could see the wastegate hose being cracked and causing inconsistent boost. Such as the car is under full throttle, the hose starts leaking so it's only at 7 or 8 PSI when it should be at 12 or 13 PSI then for whatever reason it spikes up to 14 as the leak slows. Maybe the ECU tries to compensate for the leak and thusly opens the taps on the turbo then suddenly the leak slows and it spikes? But please explain more. cheers poorman __________________ "STIs are serious business." - Dr. Drew Pinsky

03-10-2010, 02:05 AM	#15 (permalink)
squidmaster 3.3L Car: 2000 2.5ReallySlow & 91 Miata Fav Mod: Was my access port :[ My: Subaru Parts Join Date: Aug 2008 Location: Orlando, FL Trader Rating: (1) Posts: 538	funny. he didn't say anything about over-boost. he said the boost control will be all over the place.... probably from opening and shutting the wastegate more than it would have without that higher flowing exhaust because not it doesn't have to open or shut as much. Boost is still SOLELY controlled by wastegate. Until you get to 20psi on a stock super restricted exhaust where there's more coming from the engine than can escape from the muffler... __________________ http://squidmaster.net

03-10-2010, 02:08 AM	#16 (permalink)
Smezmerz Premium Member Car: 2004 Acura RSX type S My: Subaru Parts My: Subaru Blog Join Date: Jun 2009 Location: Okinawa Japan, but in Minot ND right now Trader Rating: (5) Posts: 1,238	That sounds beastly! __________________ You just have to not take teh interwebz so serious- Eloheem

03-10-2010, 02:08 AM	#17 (permalink)
squidmaster 3.3L Car: 2000 2.5ReallySlow & 91 Miata Fav Mod: Was my access port :[ My: Subaru Parts Join Date: Aug 2008 Location: Orlando, FL Trader Rating: (1) Posts: 538	I'm not 100% sure exactly how it's working with the wastegate solenoid, but it happened to my STi. Was boosting at 14.8 without a tune and with a TBE. Line cracked started to spike at 17 and 18. Replaced line went back to 14.8. Same thing happened to two of my buddies that have WRX's. With or without stock exhausts. __________________ http://squidmaster.net

03-10-2010, 10:14 AM	#18 (permalink)
RSblood 3.3L Car: 2001.5 Audi S4 Vast stage 2 Fav Mod: Turbo Power! My: Subaru Parts Join Date: Mar 2005 Location: Needham,MA Trader Rating: (11) Posts: 878	I was tuned on a straight pipe, I don't think removing the axleback is gonna cause it to overboost __________________ Goodbye ol' white Subaru

03-10-2010, 10:30 AM	#19 (permalink)
poormansporsche Premium Member Car: RSTI Fav Mod: Launch control My: Subaru Parts Join Date: Mar 2005 Trader Rating: (2) Posts: 5,589	Whatever you say guys. Everything you need to know about boost creep - NASIOC cheers poorman __________________ "STIs are serious business." - Dr. Drew Pinsky

03-10-2010, 10:35 AM	#20 (permalink)
poormansporsche Premium Member Car: RSTI Fav Mod: Launch control My: Subaru Parts Join Date: Mar 2005 Trader Rating: (2) Posts: 5,589	I also had a discussion about this recently with my tuner, William Knose of Crawford. But I'm sure you guys are right. cheers poorman __________________ "STIs are serious business." - Dr. Drew Pinsky

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