KAT: BOV adjustment needed or Boost controller settings? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

GTS · 07-14-2008, 10:37 AM

Hi guys

I've had these 2 issues for a long time and I only have some ideas of the problem, but can't really confirm so I was wondering if anyone could provide more insight.

Turbo: TD06 20G
BOV: Greddy Type RS
Controller: AEM Tru Boost

Duty cycle: 55%
Spring pressure: 5-6psi (depending on how hard I want boost to kick in)
BOV: left it as it came from the factory

1st Issue: When I lift at less than 7psi of boost, it vents followed by the flutter sound. When I lift at anything higher than 8psi, there's a straight wooshing venting sound (assumed to the way the RS is suppose to sound).

Resolution?
I can't be sure if the flutter sound is being caused by the not being opened all the way OR if it's actually compression surge because the BOV isn't opening at all. Keep in mind that it does vent but it also has the flutter sound. I believe that if I tighten the BOV, it will eliminte the flutter sound, but then I have apprehensions about the BOV being too tight and causing too much pressure. Your thoughts?

2nd Issue: Increasing the crack/spring pressure on the controller causes me to have erratic boost readings. When I set the crack pressure at 3psi, the turbo spools slower (running on stock WG) but it holds the pressure more consistently. When I increase the crack pressure, it spools much faster (with erratic spikes) then it fluctuates all across the board (5-9psi), eventually, it settles to 7psi.

Resolution?
I believe it's related to the BOV. I think the BOV is releasing early, causing the controller to NOT hold pressure.

What are your thoughts?

Z33dori · 07-14-2008, 11:11 AM

loossen the spring on your bov to get rid of the compressor surge

GTS · 07-14-2008, 11:40 AM

From what I guess...if I loosen, then it'll make my second problem worse.

!Zar! · 07-14-2008, 11:41 AM

Is this the Greddy turbo kit?

Are you using that shitty internal wastegate that comes attached to the 20g?

If so, that's why your car is boosting all fucked up, and it is compressor surge.

Compressor surge under light boost really isn't problematic.

GTS · 07-14-2008, 11:54 AM

The turbo is internally gated. Anyway to remedy this without using an external gate?

Z33dori · 07-14-2008, 11:58 AM

hks wastegate actuator

best money can buy .... internally anyways

GTS · 07-14-2008, 12:09 PM

So in summary....

the BOV needs to be loosened to address issue #1.

But issue 2 is caused by the internal wastegate on the 20g. It is opening too early. Switching to an HKS will effectively increase the wastegate pressure so that it holds higher pressure.

Is this right?

***S14DB*** · 07-14-2008, 12:12 PM

The flutter sound is normal at low boost let off.

!Zar! · 07-14-2008, 03:28 PM

What you are supposed to do is weld the flapper shut and buy an external wastegate. It's more than just the wastegate I believe.

So unless you want to bore out the wastegate hole and weld on a bigger flapper, your best bet is to go external.

20g internal setup is notorious for boost creep.

Don't loosen your bov, it's fine.

Z33dori · 07-14-2008, 03:38 PM

i know 2 sr running 20gs and are not having any problems running a 20g with KS waste gate

and my friend had a internal 20g on his srt4 and has no problem with it leaking.. its on a hans wastegate

so imma say its the greddy wastegate and not the 20g flapper

07-14-2008, 11:11 AM	#2
Z33dori Post Whore! Join Date: Dec 2006 Location: Riverview, FL Age: 36 Posts: 5,557 Trader Rating: (12) Feedback Score: 12 reviews	loossen the spring on your bov to get rid of the compressor surge __________________

07-14-2008, 11:41 AM	#4
!Zar! Post Whore! Join Date: Nov 2004 Location: North Korea Posts: 14,579 Trader Rating: (27) Feedback Score: 27 reviews	Is this the Greddy turbo kit? Are you using that shitty internal wastegate that comes attached to the 20g? If so, that's why your car is boosting all fucked up, and it is compressor surge. Compressor surge under light boost really isn't problematic. __________________

07-14-2008, 11:58 AM	#6
Z33dori Post Whore! Join Date: Dec 2006 Location: Riverview, FL Age: 36 Posts: 5,557 Trader Rating: (12) Feedback Score: 12 reviews	hks wastegate actuator best money can buy .... internally anyways __________________

07-14-2008, 12:12 PM	#8
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	The flutter sound is normal at low boost let off. __________________ Comments should be taken as Opinions not as Statements of Fact

07-14-2008, 03:28 PM	#9
!Zar! Post Whore! Join Date: Nov 2004 Location: North Korea Posts: 14,579 Trader Rating: (27) Feedback Score: 27 reviews	What you are supposed to do is weld the flapper shut and buy an external wastegate. It's more than just the wastegate I believe. So unless you want to bore out the wastegate hole and weld on a bigger flapper, your best bet is to go external. 20g internal setup is notorious for boost creep. Don't loosen your bov, it's fine. __________________

07-14-2008, 10:37 AM	#1
GTS Leaky Injector Join Date: Sep 2005 Location: Ontario Posts: 115 Trader Rating: (0) Feedback Score: 0 reviews	KAT: BOV adjustment needed or Boost controller settings? Hi guys I've had these 2 issues for a long time and I only have some ideas of the problem, but can't really confirm so I was wondering if anyone could provide more insight. Turbo: TD06 20G BOV: Greddy Type RS Controller: AEM Tru Boost Duty cycle: 55% Spring pressure: 5-6psi (depending on how hard I want boost to kick in) BOV: left it as it came from the factory 1st Issue: When I lift at less than 7psi of boost, it vents followed by the flutter sound. When I lift at anything higher than 8psi, there's a straight wooshing venting sound (assumed to the way the RS is suppose to sound). Resolution? I can't be sure if the flutter sound is being caused by the not being opened all the way OR if it's actually compression surge because the BOV isn't opening at all. Keep in mind that it does vent but it also has the flutter sound. I believe that if I tighten the BOV, it will eliminte the flutter sound, but then I have apprehensions about the BOV being too tight and causing too much pressure. Your thoughts? 2nd Issue: Increasing the crack/spring pressure on the controller causes me to have erratic boost readings. When I set the crack pressure at 3psi, the turbo spools slower (running on stock WG) but it holds the pressure more consistently. When I increase the crack pressure, it spools much faster (with erratic spikes) then it fluctuates all across the board (5-9psi), eventually, it settles to 7psi. Resolution? I believe it's related to the BOV. I think the BOV is releasing early, causing the controller to NOT hold pressure. What are your thoughts?

07-14-2008, 11:40 AM	#3
GTS Leaky Injector Join Date: Sep 2005 Location: Ontario Posts: 115 Trader Rating: (0) Feedback Score: 0 reviews	From what I guess...if I loosen, then it'll make my second problem worse.

07-14-2008, 11:54 AM	#5
GTS Leaky Injector Join Date: Sep 2005 Location: Ontario Posts: 115 Trader Rating: (0) Feedback Score: 0 reviews	The turbo is internally gated. Anyway to remedy this without using an external gate?

07-14-2008, 12:09 PM	#7
GTS Leaky Injector Join Date: Sep 2005 Location: Ontario Posts: 115 Trader Rating: (0) Feedback Score: 0 reviews	So in summary.... the BOV needs to be loosened to address issue #1. But issue 2 is caused by the internal wastegate on the 20g. It is opening too early. Switching to an HKS will effectively increase the wastegate pressure so that it holds higher pressure. Is this right?

07-14-2008, 03:38 PM	#10
Z33dori Post Whore! Join Date: Dec 2006 Location: Riverview, FL Age: 36 Posts: 5,557 Trader Rating: (12) Feedback Score: 12 reviews	i know 2 sr running 20gs and are not having any problems running a 20g with KS waste gate and my friend had a internal 20g on his srt4 and has no problem with it leaking.. its on a hans wastegate so imma say its the greddy wastegate and not the 20g flapper __________________