Exhaust leak causing slow spool?

[dsmcoder]

I have a 1g dsm with 16g turbo and 2g exhaust manifold and 2.5" cat bypassing downpipe with the rest of the exhaust stock. I have an ets street intercooler kit and I'm running speed density and all supporting fuel mods.

I'm not building full boost which is 20psi until 5000rpm. I've read that I should be building that at least by 3500rpm and probably sooner with me since I have a cyclone intake. In link it shows that I'm only building two psi by 3500rpm. I have an automatic transmission and I'm using first gear for the tests.

I seafoamed my car to see if I have any leaks and I noticed that it's leaking the worst at back part of the gasket that connects the turbo to the manifold. It's also leaking a small amount at the o2 sensor and in it looks like it's leaking a little bit in that area I marked red in the pic on the turbo.

Now would these leaks cause my turbo to build full boost this late? These leaks are not huge either

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[JusMX141]

You're losing pressurized pre-turbine exhaust energy out of the leak spot....it's basically a boost leak on your exhaust system.

So, yes. Your stock exhaust isn't helping matters much, either.

 

[Clutch450]

Exhaust leaks definitely do not help spool up.

Replace the gaskets that are leaking. And when replacing the turbo manifold gasket use a straight edge or file to see if you turbo hotside face is warped and check the exhaust manifold too.

Having an uneven warped mounting surface will not help with proper sealing. And you could blow another gasket. I went through two good gaskets for this reason. Manifold surface was very warped

 

[dsmcoder]

Alright, what do you think it should spool at with the stock portion of my exhaust with no leaks?

Also how would I go about fixing the leak that's on the exhaust side of the turbo?

 

[Clutch450]

Do you mean between the hotside of the turbo and cold side? Wear the v-band is at?

You should be building full boost on a 16g before 4k rpms. Lower depending on your mods: cams, exhaust, compression and such

 

[dsmcoder]

Do you mean between the hotside of the turbo and cold side? Wear the v-band is at?

You should be building full boost on a 16g before 4k rpms. Lower depending on your mods: cams, exhaust, compression and such

Yes by the v-band where the arrow is. I have delta 264 hks style cams so I shouldn't lose any spool with those. My compression is 150 across the board.

 

[ricktb]

yea, the thing about exhaust leaks and I know from personal experience.. if a little exhaust runs past a gasket for long enough, it will melt or destroy a chunk of the gasket and the piece flys out and the leak gets bigger. Your gonna want to dismantle the sections, clean the mating surfaces and inspect them.. they should be flat clean and smooth, then put in the new gasket. I think I also used a thin coat of red high temp rtv on both sides of the gaskets to ensure a tight seal. Exhaust in these areas are basically a flame thrower so you want to contain it in the pipe.

 

[dsmcoder]

Is there a gasket on the v-band?

 

[Clutch450]

No gasket in the v-band. Just basically two metal rings being pulled tightly together by the band. I prefer v-bands over plain gaskets in the exhaust area

 

[T is for TURBO]

It looks as if you are missing the gasket between the turbo and O2 housing.

 

[Bud92gsx]

Make sure all manifold bolts are tight,manifold to turbo bolts, and turbo to o2 housing are tight.Also I don't see a gasket from turbine housing to o2.That could be another problem as well.

Did you make sure to butt the turbine housing up with compressor before putting the clamp on.It's very simple to do.

You should be about 3.5k at the most for boost, not 5k.

 

[dsmcoder]

Make sure all manifold bolts are tight,manifold to turbo bolts, and turbo to o2 housing are tight.Also I don't see a gasket from turbine housing to o2.That could be another problem as well.

Did you make sure to butt the turbine housing up with compressor before putting the clamp on.It's very simple to do.

You should be about 3.5k at the most for boost, not 5k.

There is a gasket between the wastegate housing and the o2 housing you just can't see it in the picture and it wasn't leaking in that area when I seafoamed it.

I have no clue it if turbo housing was butted up with the compressor because I never put it together. Im actually not sure how to remove the v band? Is it difficult? Do I need to replace it if I remove it, if so where would I buy one?

 

[T is for TURBO]

There is a gasket between the wastegate housing and the o2 housing you just can't see it in the picture and it wasn't leaking in that area when I seafoamed it.

I have no clue it if turbo housing was butted up with the compressor because I never put it together. Im actually not sure how to remove the v band? Is it difficult? Do I need to replace it if I remove it, if so where would I buy one?

No, removing a V-band is not difficult, though it should be done with the turbo off the car, as it will be easier. However, with that said, I find it unlikely that the vband is your problem. If your leaking a lot from a blown gasket, then that might be your problem. But is sounds more like a nasty exhaust restriction. Do you have a CAT? If so, it could be clogged. Also, if you have collapsed flex section in your down pipe.

But than again, you said it was leaking a "little". Define a "little"
I've had some pretty big pre-turbo exhaust leaks caused by a two very lose turbo bolts and and a very blown manifold to turbo gasket, yet my spool wasn't affected all that much. Maybe 200-300 rpm.

 

[dsmcoder]

No, removing a V-band is not difficult, though it should be done with the turbo off the car, as it will be easier. However, with that said, I find it unlikely that the vband is your problem. If your leaking a lot from a blown gasket, then that might be your problem. But is sounds more like a nasty exhaust restriction. Do you have a CAT? If so, it could be clogged. Also, if you have collapsed flex section in your down pipe.

No I don't have a cat but I do have stock exhaust after the downpipe, Now how do I check the flex section in my downpipe?

 

[T is for TURBO]

Take it off and look down the pipe, it would look like this

Another to check would be your wastegate function. Is it closeing all the way. If it's partially open, it would cause some seriousy lag.

 

[dsmcoder]

I checked that wastegate and it is functioning and closing properly. I will however have to check the flex section by taking the downpipe off and shinning a flashlight down it. If it is the flex section can that be replaced?

 

[T is for TURBO]

I checked that wastegate and it is functioning and closing properly. I will however have to check the flex section by taking the downpipe off and shinning a flashlight down it. If it is the flex section can that be replaced?

You can cut it out and weld a new piece in. How did you check the waste gate? did you pull the o2 housing off?

 

[dsmcoder]

You can cut it out and weld a new piece in. How did you check the waste gate? did you pull the o2 housing off?

No not yet I just verified that the actuator was closing the wastegate all the way.

 

[dsmcoder]

I took everything apart and the wastegate seating surface has no crack at all and the gaskets didn't look bad. Due to the bends of my down pipe I can't see inside the flex section, is there anyway to tell if it's collapsed by looking at the outside of the downpipe?

Is there anything else that would cause this slow of a spool?

 

[T is for TURBO]

I took everything apart and the wastegate seating surface has no crack at all and the gaskets didn't look bad. Due to the bends of my down pipe I can't see inside the flex section, is there anyway to tell if it's collapsed by looking at the outside of the downpipe?

Is there anything else that would cause this slow of a spool?

Take it off and try to roll a ball down the pipe the is just a little smaller than the diameter of the pipe? If it goes through, then it's not plugged.

What are you tuning with? Have you checked for boost leaks? When did this problem start? Did the problem start after you installed something?

 

[dsmcoder]

Take it off and try to roll a ball down the pipe the is just a little smaller than the diameter of the pipe? If it goes through, then it's not plugged.

What are you tuning with? Have you checked for boost leaks? When did this problem start? Did the problem start after you installed something?

I tried rolling a ball down the pipe and it went all the way through so it's not plugged.

I'm tuning with ECMlink v3 with lc-1 wideband and speed density and I have checked for boost leaks and have none.

I have had this problem ever sense I bought the car when everything was stock but the evo3 16g turbo. I just thought it was normal until I did some reasearch and found out I should be spooling at 3500rpm or better.

 

[Mr PopUps]

There are so many 'wrong' posts i wont bother to quote them all to correct them.

Post turbine leaks dont hurt spool. The faster you get the exhaust through the turbo, the faster it will spool. Also you really should test for spool in higher gears, theres a bit more load and its more of a controllable environment. Might be a bit harder with an auto to keep it from kicking down a gear though.

Without seeing the inside of you exhaust side, im willing to bet none of it is ported which will help IMMENSELY, more so than compression/cams/superchargers what have you.

However YOUR specific problem is the stock catback. You have this "huge" downpipe which is like a storm drain to water, then put a McD's straw at the end of it and expect to run off all your rain, or in this case, build any boost.

This type of port job can get you full boost by 2800 (in 4th on a manual) on a 14b @ 18 psi. (sorry for the crappier ex-man/turbine housing pics, they are all i have as i didnt have a digital camera back then)

Full gasket port on the inlet side, 70mm on the exit

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56mm~ on the WG inlet, full 60mm nearly all the way through inlet to outlet

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This was an early housing where i was seeing how far they could be opened up, which is a lot more than i got to do on this one. Also later on i was able to port enough material away to allow the flapper to open 90 degrees to the housing, just to make sure there was nothing in the way. The turbine outlet was ported in a taper from just past the ex-wheel to 60mm at the exit. This helps in exhaust gas evacuation as it expands, so having your pieces 'stepped' smaller to bigger helps with spool as well since the gasses cant ever go backwards or they will compress. Simple science.

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[romeen]

Without seeing the inside of you exhaust side, im willing to bet none of it is ported which will help IMMENSELY, more so than compression/cams/superchargers what have you.

Are you saying that porting the exhaust manifold, turbine inlet and O2 housing will give better performance gains than increasing compression, installing performance cams, or supercharging a motor? If so, that is a bold statement. Do you have any actual data to back this up?

This type of port job can get you full boost by 2800 (in 4th on a manual) on a 14b @ 18 psi. (sorry for the crappier ex-man/turbine housing pics, they are all i have as i didnt have a digital camera back then)

Full gasket port on the inlet side, 70mm on the exit

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Theoretically, porting the exhaust runners will decrease the velocity of the exhaust gases thereby hurting spool. You could argue that the decreased back pressure makes doing this worthwhile but I don't know if this is true or not. In the end, I'm not sure if anyone has hard numbers to back up one or the other.

 

[Mr PopUps]

How about .4-.5 and 1-2 mph gain in the 1/4"? And no im sorry i do not know where those time slips are at this time. I was able to recreate this on a friends 98 AWD with a brand new Big16G and he got the same results.

I took over TRE's porting way back when, after Jon stopped porting, so i was good enough for him to send customers to me. I had to stop when i herniated a disc in my lower back and unfortunately pissed off a couple customers by not being able to do the work and taking a decent amount of time to send them their parts back. (if i admit this, do you think i would be making this up? )

You do need at least a 2.5" t-back exhaust to match the 60mm outlet or no, it wont work. When i first got my Frank 1 (20G with a Garrett 50 trim comp wheel and 10 degree clip on the exhaust wheel) i didnt have a 7cm housing so i used my 6cm housing that i hand ported and was able to hit 18psi around 3500 with a 10 degree clip on the exhaust wheel. If you know anything about what i just said then that should be enough proof.

I did find the email excerpt Shawn sent me after a visit to the track after installing his newly ported pieces. He gained .3 in 35 degree hotter weather too.

------------------------------------------------------------

From my friend Shawn P Re: porting
"A.J., I picked up 2 MPH over the 1320. I ran the 13.2 @ 50 degrees while I ran the 12.9 at 85 degrees."
This was from porting his stock 2G ex-man and O2 housing, and his 7cm 16G ex-housing. It also reflects the .4-.5 and 1-2mph I picked up when I ported my stock 1G stuff.

(edit: i said what i did about the comp/cams/supercharger with tongue in cheek to make a point, but adding cams to the mix without a good port job wont give you the increase you would expect from a major purchase)

 

[romeen]

I was referring to porting only the exhaust runners and it's correlation with exhaust gas velocity (as stated in my post). The OP is asking specifically about the late spool up of his turbo. In this context, porting the runners might make the spool up worse. But since I have no data for or against doing this I started it off by saying "Theoretically."

Thanks for providing the 1/4 mile results though. I have no doubt that porting post-turbine (if properly done) gives gains. Both theory and real world results support this.

On a side note, I herniated a disc at L5-S1 a few years back. That pain was worse than what I had with multiple broken bones. So I can definitely understand what you mean when you say that you weren't able to work.