Low Boost, Catback questions

[J-Rat]

Low end power is a wide argument.. I make 400 ft/lbs of torque, which is stump pulling power. Its more a question of how usable the available power is.

Chances are if its a stock turbo and its not spooling then the twin scroll is not working or the turbo itself is malfunctioning. A 2.5 inch system wont choke a stock turbo, nor will it choke a big single, since I am still on a 2.5 inch catback.

Rat

[Phoenix7]

Originally Posted by J-Rat

Low end power is a wide argument.. I make 400 ft/lbs of torque, which is stump pulling power. Its more a question of how usable the available power is.

Chances are if its a stock turbo and its not spooling then the twin scroll is not working or the turbo itself is malfunctioning. A 2.5 inch system wont choke a stock turbo, nor will it choke a big single, since I am still on a 2.5 inch catback.

Rat

I noticed my boost go down to 10psi on a 2.5" catback (now on our NA) mated to my 3" DP and midpipe from 12psi (with the 3" open cat-back single).

[Boostmaniac]

I was leading more towards the twin scroll not working or the turbo malfunctioning, which sucks seeing as that turbo doesn't leak any oil.

Is there any way to test the twin scroll outside of the car or do you have to actually remove the turbo to do it? I've never really thought about messing around with it before lol.

I do believe that piping was 2.5 on the catback system. I will be removing the turbo either today or tomorrow depending on my situation when I get home. I'll run it through some tests and take some pics.

[djmtsu]

I edited the title of the thread so it is easier for members to see what is in it. Also, it will make a search easier for someone.

[Boostmaniac]

Originally Posted by djmtsu

I edited the title of the thread so it is easier for members to see what is in it. Also, it will make a search easier for someone.

Thank you kind sir. I did the title mainly to just get some laughs. I didn't think it would go this long.

[J-Rat]

Originally Posted by phoenix7

I noticed my boost go down to 10psi on a 2.5" catback (now on our NA) mated to my 3" DP and midpipe from 12psi (with the 3" open cat-back single).

Did you re-adjust the boost controller to compensate for the difference in pressure differential? As with anything else on this and other forums, its all up to personal experience. I can hold 25 PSI all day long to the redline on my 2.5 inch catback. Is it optimal? HELL NO! At my HP level I should be more on a 4 inch exhaust.


The thing that bothers me is that the car is STOCK. Even a stock turbo with a pre-cat, main cat, and crappy stock exhaust system should spool faster then that. All things being considered, I am not entirely convinced its the exhaust. It sounds like how my car ran years ago when I thought I would be smart and wire the Twin Scroll open.

[Phoenix7]

You're most likely right since he's not boosting when he should be.

No, I didn't change anything, I swapped that catback in to pass visual and have a "modified exhaust" ticket written off.

[J-Rat]

Could be a crappy turbo too.. I am not there to check shaft play, etc.. Course there would be an appreciable increase in oily residue/smoke.

[Phoenix7]

crappy and/or old (high mileage toasty turbo)

[Boostmaniac]

Originally Posted by J-Rat

Did you re-adjust the boost controller to compensate for the difference in pressure differential? As with anything else on this and other forums, its all up to personal experience. I can hold 25 PSI all day long to the redline on my 2.5 inch catback. Is it optimal? HELL NO! At my HP level I should be more on a 4 inch exhaust.


The thing that bothers me is that the car is STOCK. Even a stock turbo with a pre-cat, main cat, and crappy stock exhaust system should spool faster then that. All things being considered, I am not entirely convinced its the exhaust. It sounds like how my car ran years ago when I thought I would be smart and wire the Twin Scroll open.

That made me laugh.

Ok, during my general overhaul of my braking system yesterday, we got to the turbo to start removing it and swapping it out with the S5 unit and I made a few notable discoveries.

There seems to be no oil coming out of the turbo, shaft play is minimal to none that I can tell. I'll be able to make a better assessment once it is removed from the car. I did notice something on the compressor wheel, but I need to get a pic to show you, I can't quite explain it on here adequately.

I did see the twin scroll rod and it does seem normal. Maybe it is malfunctioning, maybe it is wired open and I just can't see it. Again, upon further removal, I'll be able to give you all the down low.

If it isn't the exhaust (which should help me out a little bit) then it is either the turbo or my engine. I am praying it is the turbo, I don't want to rebuild just yet. I just want ONE GOOD PULL the way my car is supposed to pull.

The pics should be high quality also, my buddy that is helping me has been bringing over his incredibly awesome camera.

Edit:

Don't laugh at this. I believe in doing baseline pulls on a dead stock car to see where any improvements I make can be found and to also give accurate reports back. This is my baseline pull, dead stock, crappy catback exhaust.



The car was at WOT at 2500, the target window started at 3000. Boost on this pull didn't really hit positive (maybe 1 psi max) till about 3500 - 3800. Yes I know the AFR is pig rich, that is getting fixed very soon. Yes I also know my power peak is 1k higher than it is supposed to be and I can't explain that at all. Also worth noting, this car has NO acceleration until it gets into boost and it still makes power to 8k or higher and it will hold boost the entire way.

Next time, I'll see if I can datalog boost if I am still having the same problem. There ya go, tell me what you think.

-Maniac

[RETed]

If that black, jagged line is your AFR, it's all over the place...
Fix issues like that first, cause that can cause low boost and low power problems.


-Ted

[Boostmaniac]

Originally Posted by RETed

If that black, jagged line is your AFR, it's all over the place...
Fix issues like that first, cause that can cause low boost and low power problems.


-Ted

Oh yeah, that is definitely getting fixed. On one of my runs, it dropped into the NINES. I swapped out the 02 sensor and discovered that someone had been kind enough to have never changed it in 20 years. I have seen thousands of 02 sensors, but never one this bad. It literally came apart in my hands. So I have a new one on there and I am watching it with a narrowband at the moment. I'll be getting the Rtek 2.1 and pull some fuel out while using a real wideband and try to smooth it out all around.

On the low end though, it is sitting around the 13's pre boost which isn't half bad. So unless my timing maps are messed up also then I have no idea.

I'll continue tearing into it today. I'll see if I can get some pics up to let you all see this craptastic issue.

[Boostmaniac]

Ok, after tearing into it and removing the turbo, this is what I found. The turbo was like this when I bought the car.




Yeah, that can't be good in any way.

But the good news is that I already have a replacement.

S5 is on the left.



So, you all think that might have been what was causing me issues?

[Phoenix7]

Take it apart and tell us or send it to BNR and have him tell you

[Boostmaniac]

I'll take the compressor housing off and try to get another pic.

Look at how eaten up the blades are though.

I have no idea how they got bent that way at all.