Boost not staying the same.

[2002SL1]

Okay im having a weird issue right now. My boost isint staying the same from day to day, one day it will hit 30 like a champ and then other days its only hitting 24-25. Ive done a boost leak test and I dont have any. I have an internal waste gate that is bloted closed and dosent even have a line running to it so it dosent open. The only major difference from the boost differences is that it is cooler out when it acctually gets up to 30psi. I dont know if that would make a difference. If you have a thought let me know.

I could also try welding the waste gate flapper shut. It might be getting some exhaust coming around that but thats the only thing I can think of.

All of my mods are in my profile.

 

[justin_5585]

just trying to get this all straight. So you are not running any type of wastegate? Simply letting the turbo spool as high as it will go before redline? There are a number of reasons you could be losing pressure. Is it spooling to 30 then dropping off to 24 at x rpm? Was it really cold on days you hit 30, and hot as hell on days your boost was lower? Air temp affects density, which in turn affects how efficiently a turbo can compress air. Any additional info would help for sure.

-justin

 

[vc_wannabe]

Well you may as well throw out our EBC and Turbo timer as they are doing you absolutely no good if you are running with the waste gate blocked off/not opening. You won't be able to adjust boost pressure. There is no reason to have a turbo timer if your having the turbo go out of its effective range all the time, it will end up damaging it.

The reason it will varey boost pressure would be the ambient air temperature, and the heat created by the turbo itself once it gets outside of its range.

 

[2002SL1]

Okay thats what I was thinking that it was the tempature of the outside air that was affecting it. I dont have my EBC hookup right now but im gonna hold on to it for when I get my GT35R in the car. The effective pressure for my turbo is 28psi so im not really running it outside of that and the car isint my DD so even if it is damaging the turbo its still gonna last me a long time.

Its not spiking to 30 and then dropping off to 24 it just goes straight to 25-26 and then dropps off to 24 or it will go straigt to 30 and hold there. But yeah im not using any kind of wastegate on my car.
It was cold on the days it was hitting 30 and a hell of alot hotter outside on days it was only hitting 24.

 

[dsm-onster]

What do you mean "bloted closed"? Blocked closed? as in welded?

The wastegate is there to maintain consistant boost.

You'll certainly run a wastgate when you get your GT35R correct?

 

[2002SL1]

What do you mean "bloted closed"? Blocked closed? as in welded?

The wastegate is there to maintain consistant boost.

You'll certainly run a wastgate when you get your GT35R correct?

The rod that is attached to the waste gate is bloted all the way down so it wont open (its an internal gated turbo)

And Yes I Will be running a wastegate with a GT35R. Im Crazy but im not the Crazy.

 

[nightspeed87]

Are you running race gas or really low timing on forged internals or something because 30 psi is a lot of boost on pump gas especially if you are running something around a 16g size. With that much boost, I smell trouble unless youve done the works on your tune as far as timing and a/f ratio goes and problems also unless you built that engines bottom end have a fmic intercooler, meth or water injection, with mls head gasket/arps etc. or something. and your avatar shows your only running 14s? Whats up with that considering your running that much boost...

 

[2002SL1]

Are you running race gas or really low timing on forged internals or something because 30 psi is a lot of boost on pump gas especially if you are running something around a 16g size. With that much boost, I smell trouble unless youve done the works on your tune as far as timing and a/f ratio goes and problems also unless you built that engines bottom end have a fmic intercooler, meth or water injection, with mls head gasket/arps etc. or something. and your avatar shows your only running 14s? Whats up with that considering your running that much boost...

Stock Bottom End, Rebuild head, FMIC, Tuned it to 10.7:1 on E85, 26 degress of time with Water/Methnol Injecton, Running an RS49T (50Trim), MLS Headgasket, 950cc injectors (running at 91% IDC).

The 14s was back when that car was running 10psi. I havent had time to take it out to the track with the new setup.

Ive been running the car like this for the last 5000 miles and its been running just fine. Considering I own 2 cars and between the two of them I only drive 4500 miles a year that 5000 is alot for me. Usually my Talon is only driven to the track and back and on a rare day durning the week, so im not going to break it anytime soon if there is a problem.

 

[nightspeed87]

Just askin for your sake, good to see you know what your doing.

 

[dsm-onster]

The rod that is attached to the waste gate is bloted all the way down so it wont open (its an internal gated turbo)

And Yes I Will be running a wastegate with a GT35R. Im Crazy but im not the Crazy.

Hmmm, you have the rs49. So you have a BEP turbine housing and a 38mm wastegate flapper that you've not been able to keep closed to get to higher boost. So you screwed it down tight. Nothing happened, so then you disconnected the boost reference.

Is it possible that the wastegate is still blowing open. Or that it wasn't and now it is? It hasn't been welded shut I suppose. Many guys w/ the rs49 and rs60 turbos. . . Especially 49T & 60T (has the t3 stage3 turbine wheel) have screwed their wastegate arms all the way down and even disconnected their boost reference, yet the flapper still opens. Sometimes it helps then it stops working. . .

Mine did this. I did everything to get the higher boosts and nothing worked. The flapper just kept blowing open. So I disconnected the reference source entirely and eased into the throttle it held to 26 psi just fine... So I "experimented" a little more and found that it held good to 30 psi and was relatively consistant. Well, my wastegate actuator arm contacts the actuator bracket when connected to the flapper arm (manufacturing flaw). Later i realized that the wastegate actuator arm was grinding away where it contacted the wastegate actuator bracket and soon it wouldn't boost nearly as high (the flapper was opening up again). The bracket was helping the actuator hold the flapper shut. It became insonsistant. Sometimes it would "grab the actuator arm enough to keep the flapper from blowing open. Sometimes it would not... I suspect it running higher boost in cold weather is a coincidence.

The 38mm flapper is great for boost creep issues related to the 14b, 16g, 20 turbos. And BEP is attempting to make a "universal housing". So the mitsu guys are happy they don't creep at 20 psi. But even they get mad when the flapper opens at 28 when they're really trying to get into that 20g compressor wheel.

I eventually extended the wastegate flapper arm (not the actuator arm).

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In extending it, three things were accomplished:

1. It angled the wastegate actuator arm to a more tangental line to the wastegate flapper arm arc. This gave the wastegate actuator a more "direct shot" at keeping the wastegate flapper closed at high exhaust manifold pressures.
2. The extension brought the wastegate actuator arm away from contacting the wastegate actator bracket.
3. It lengthed the lever arm the actuator has over the flapper. This is equivelant to placing a stronger spring in the agp actuator. There is more leverage to keep the flapper closed.

I need to clean up my mod and do a write up, I know. But for now, that's a probable explanation from someone who has your same series turbo.

 

[2002SL1]

You Know that helps out alot when you get a picture and from someone with the same setup. I didnt think about extending the are any to fix the angle it was at. I dont have any lines hooked up to my wastegate eather. I'll try extending that are like you did to see if the extra levarage (sp?) helps out and if that doesnt work im gonna pull the O2 Housing off and weld the darn thing closed.

You know I just thought about something, It might be my BOV too. I only have the Yellow spring in it and when I goto the track or am doing tuning I'm changing it out for a stronger one. That could be an issue if its blowing open on me and since I have a blow through setup nothing will show up on my wideband or inside of DSMLink since the Air would be getting out before my Air Sensor. I'll try that and the Gate thing before I start ripping stuff apart to weld it.

 

[2002SL1]

Just askin for your sake, good to see you know what your doing.

Lol, I know what you mean there are alot of people here that think that No Mods and a Higher boost pressure makes your car go faster. I always tell that that you need to do this and that, but they never listen and the 2 weeks later BOOM!!! and they wonder why.

 

[dsm-onster]

You Know that helps out alot when you get a picture and from someone with the same setup. I didnt think about extending the are any to fix the angle it was at. I dont have any lines hooked up to my wastegate eather. I'll try extending that are like you did to see if the extra levarage (sp?) helps out and if that doesnt work im gonna pull the O2 Housing off and weld the darn thing closed.

You know I just thought about something, It might be my BOV too. I only have the Yellow spring in it and when I goto the track or am doing tuning I'm changing it out for a stronger one. That could be an issue if its blowing open on me and since I have a blow through setup nothing will show up on my wideband or inside of DSMLink since the Air would be getting out before my Air Sensor. I'll try that and the Gate thing before I start ripping stuff apart to weld it.

FREEZE! just put the arc welder down, Son. Just put it down!

The BOV spring sure looks like a possibility!!!

Seriously don't weld it shut if nothing works.

Options if extending the flapper arm doesn't work:
1. Get an external gate exhaust mani and external gate and weld the flapper shut
2. get an external gate o2 housing and external gate and take the flapper off
3. get a t3 flanged exhaust mani and a .63 a/r turbine housing (or any a/r you would prefer) w/ a smaller internal gate flapper.

 

[2002SL1]

I changed out my BOV spring and that didnt fix the problem. I still have on more spring for my BOV I can try.

I just got done adding a second spring inside of the wastegate. It was a pain in the ass to do but I got it done. I'll take the car out later tonight and let you know how that works. If that doesnt fix it im going to extend that wastegate arm and if that doenst work im just going to blame it on the fact that its the tempature outside that is effecting the ammount of boost. I might just have to give into science on this one.

 

[2002SL1]

Looks like adding that second spring inside of the wastegate did the trick its holding 30 like a champ now, it boost up to about 31 and then settles at 30 for the rest of the RPM range.

 

[dsm-onster]

Where did you get the spring? You have the AGP actuator correct? I'm interested as I have the same basic setup just a bit more compressor wheel diameter . I'd like to take a look at it. MY mod looks trashy . I'll not have to figure out a way to clean it up if I can grab a spring and hid it all. Compiling a few fixes for this will really make things easy for researchers.

 

[2002SL1]

Where did you get the spring? You have the AGP actuator correct? I'm interested as I have the same basic setup just a bit more compressor wheel diameter . I'd like to take a look at it. MY mod looks trashy . I'll not have to figure out a way to clean it up if I can grab a spring and hid it all. Compiling a few fixes for this will really make things easy for researchers.

The Spring came out of my old 1G BOV, It was a pain in the ass to get the AGP actuator apart and then get that spring in there with the other one and get it put back together, used my vice and some clamps the hold the thing together so I could get the C-Clip back in there. It looks just like the stock acuator except where it ended up getting scratch to hell and back. In total it to me about an hour to do the whole thing.

The other spring is inside the actuator, I basicaly doubled up the springs inside of the actuator.