Boost Creep Problem after 2 changes

[rn240sx]

Here is the story.I had the revhard manifold with the wastegate dumping to atmosphere..!! All was GOOD..!!!Now i have got rid of the revhard and using an equal length manifold, new downpipe (same everything else) and now im dumping the wastegate BACK into the exhaust stream at the downpipe. (to be quiet on WOT)They designed the manifold with a Deltagate wastegate, I have a Tial 35mm which is a direct swap. Now for some reason, my boost is creeping past 7 psi. It will spike from vacuum to 7 psi FAST, then come to a drastic slow down, but it doesnt stop, it will then slowly creep past 7 psi and keep on going till i let off at 10 psi.

I know its not the manifold cause i have spoken to 4 other 240 owners with this same setup and they use the deltagate, BUT they run open dump to atmosphere, and it holds solid at 7 psi..My setup has the Tial 35mm wastegate, dumping BACK into the downpipe cause its TOO loud under wot..I know its not the manifold cause i inspected the wastegate hole on the collector and it matches the diameter of the feeding pipe, so i know enough gas pressure is getting thruplus the deltagate is holding up fine with it..The only difference is that im dumping back to the exhaust stream.. I have NO boost controller, my line runs FROM the compressor DIRECT to the side of the Tial 35mm via a BRAND NEW 6mm line that has been inspected.!!Something is not letting the gas pressure exit the wastegate fast enough to hold my boost at a constant level..And i dont know what...Any clue's..??

thanksRobert

[TrunkMonkey]

have you run it with an open wastegate to see if it stays at 7 psi?

-demetrius

[rn240sx]

No, cause i absolutely HATE that sound of open dump. Its so damn annoying. I went with open dump for 6 months and hated every second of it.

[TrunkMonkey]

this is just for testing purposes only. if it holds at 7psi with an open wastegate, then you might want to reroute your dump tube into your downpipe a different way.

-demetrius

[IvoryJ30t]

why not just get a small muffler for the dump??

[IvoryJ30t]

i would definately suspect the replumbed dump pipe. especially if your exhaust is smaller. when you climb up in the revs, the exhaust volume increases, and could impede the flow of the wastegate gasses, causing boost creep.

[rn240sx]

Smaller muffler for the dump..?? Are you kidding me..?? Do u even know what the dump pipe looks like or how big or small it is..??

[IvoryJ30t]

ok. i work on cars for a living. i was giving you a suggestion. and YES, I HAVE DONE THAT BEFORE. you use a small [12 inch or so] muffler on the dump pipe.

you said it yourself- the creep started after you rerouted the dump. GEE, I WONDER WHAT THE PROBLEM COULD BE??

you probably have the dump pipe welded to the exhaust at a 90 degree angle, causing restriction to the wastegates gas flow.

why dont you try to make the flow as smooth as possible, or use a bigger pipe for the dump.

hell, why dont you just reroute the exhaust into the cabin and go for a long drive.

[C-Kwik]

i would definately suspect the replumbed dump pipe. especially if your exhaust is smaller. when you climb up in the revs, the exhaust volume increases, and could impede the flow of the wastegate gasses, causing boost creep.

This should not be of any significant concern. The same restriction would be passed onto the turbine as well.

I'd test out the wastegate to make sure it's working properly.

[IvoryJ30t]

the wastegate was working fine with the open dump.

[C-Kwik]

He is also using a new manifold. But that's not the point I was making. You said that gas flow from the dumppipe would be restircted. Yes, you are right, but I'm saying that so will the gas exiting the turbine. So it tends to balance out. The restriction is to the entire system. Thus, it should not be of much concern.

My XS kit had no issues from routing the waste gas back into the downpipe.

[IvoryJ30t]

theres another thread about it where demcj points out exactly what i said as being the problem. the dump is plumbed into the downpipe at a 90 degree angle.

demcj went on his site and saw his downpipe. its funny how i called it before demcj even saw it.

[IvoryJ30t]

no, its not the return that the problem, its that the flow of the exhaust is causing a restriction to the wastegate flow that hes forcing into the downpipe at a 90 degree angle.

if he would have done it properly and blended in at like a 30 degree angle, there wouldnt be a problem.

see, i just wasnt being clear when i said the exhaust is restricting the wastegate flow.

[C-Kwik]

i would definately suspect the replumbed dump pipe. especially if your exhaust is smaller. when you climb up in the revs, the exhaust volume increases, and could impede the flow of the wastegate gasses, causing boost creep.

This does not say or even imply anything about how the dump pipe is plumbed back in. My argument is to the fact that routing the dump pipe back into the exhaust stream, in that of itself, does not cause boost creep. Which is what your original post seems to be saying.

Even with the 90 degree entry, I'd still make sure the wastegate is operating correctly. While it might still be a good idea to plumb it back in at a more narrow angle for performance purposes, I'd hate for him to end up redoing the pipe only to find out the wastegate, or something else for that matter, is the cause.

[IvoryJ30t]

you probably have the dump pipe welded to the exhaust at a 90 degree angle, causing restriction to the wastegates gas flow.

why dont you try to make the flow as smooth as possible, or use a bigger pipe for the dump.

he also said the wastegate was working properly before he rerouted it back into the downpipe, since the open dump was annoying.

[IvoryJ30t]

i know that the dump being routed into the downpipe wont cause boost creep WHEN DONE PROPERLY.

restriction- atmosphere < narrow angle entry < 90 degrees

when you have the engine flowing more and more exhaust gasses into the exhaust system as the revs climb, then you have the wastegate dump forcing more exhaust into the downpipe in an extremely turbulent manner [high angle of entry] its gonna cause a signifigant restriction of the wastegate flow.

[rn240sx]

IvoryJ30t and Demcj:

I just wanted to thank both of u guys for your "knowledgeable" help in such a sarcastic way..!!

Im obviously not ASE certified and i dont know it all. I just didnt expect to encounter this problem by just re-routing the dump back to the exhaust stream. Maybe it was done wrong, and thats why i have boost creep. Maybe it was done right and my boost creep is being caused by something else...I was hoping to get some replies with simple SUGGESTIONS on what i MAY have done wrong and things to do to see if that was the problem.But instead, I get the opposite..!!

I'll definitly ask u questions in the future

[TrunkMonkey]

IvoryJ30t and Demcj:

I just wanted to thank both of u guys for your "knowledgeable" help in such a sarcastic way..!!

what the?!

I was hoping to get some replies with simple SUGGESTIONS on what i MAY have done wrong and things to do to see if that was the problem.But instead, I get the opposite..!!

the opposite? how? i suggested that you run with an open wastegate to see if it stays at 7psi. if it stays, then i suspect the 90 degree merge that your dump tube enters the downpipe. if it doesn't stay at 7psi with an open wastegate, then check your wastegate as C-Kwick suggested.

did you check it at all? if so, what were the results?

-demetrius

[C-Kwik]

i know that the dump being routed into the downpipe wont cause boost creep WHEN DONE PROPERLY.

restriction- atmosphere < narrow angle entry < 90 degrees

when you have the engine flowing more and more exhaust gasses into the exhaust system as the revs climb, then you have the wastegate dump forcing more exhaust into the downpipe in an extremely turbulent manner [high angle of entry] its gonna cause a signifigant restriction of the wastegate flow.

I'm not arguing about whether or not a 90 degree entry is the problem or not. I was merely correcting a poor statement you made. I don't make assumptions that you either know what your talking about or that others will know what you are talking about.

And as far as a 90 degree entry, it does cause a restriction, but it does so to both the turbine and the wastegate. To what extent each sees is dependent on a number of factors. I'm not convinced this is the problem, but it is suspect. But I would not rule everything out just yet. I think testing the wastegate is quite easy so I'd start there myself. For me to remocve my dump pipe, I'd have to cut it off. I'd rather not pay to have something cut off and rewelded only to find it's not the problem.

[TrunkMonkey]

For me to remocve my dump pipe, I'd have to cut it off. I'd rather not pay to have something cut off and rewelded only to find it's not the problem.

his dump tube is flanged on both ends .

-demetrius

[rn240sx]

My dump is not flanged on both ends..

On the wastegate side, i have the pipe welded to the output flange on the wastegate (dump flange) and on the downpipe side, the pipe is welded DIRECTLY to the downpipe with NO flange..!! So if i do this, the wastegate will be fine for atmosphere dumping, but id have to cut the pipe off at the downpipe and have it sealed to prevent ex gas leak... I just dont have anything to seal off a 1.5 inch hole on that downpipe... I have a welder but what can i use to seal it off..??

P.S. If i came on hard to you 2 guys, I apologize, but i got the feeling that u were telling me that my dump routing was WRONG and that I should have known this from the start.I just didnt understand the theory behind the dump return routing, if i would have known that it needed to be returned at an angle to the downpipe, i would have done it..This is just another one of those technical aspects that your "average" tuner doesnt know..

[TrunkMonkey]

so this is not your downpipe?



-demetrius

[vadem]

rn240sx hey man, I was talking to you at the orlando meet, last night. Anyway I was reading some article on a celica turbo some shop was doing. And they had the same problem, they kept getting boost creep because their dumpipe was routed in at an angle, and it was stopping flow drasticly, so they redid it and made it enter smoothly, and problem solved. From what It sounds like its definatly your wastgate plumbing. Later

Vadem

[rn240sx]

YES that is my downpipe..!! At 1st you said that my dump pipe was at a 90 degree turn.. ITS NOT..!! After thinking about what u said, Now i see your point to the 90 degree turn. Its not in the pipe itslef...But what u failed to explain to me was that the gas pressure was entering the downpipe THEN making a 90 turn down which is essentially causing the restriction in the wastegate flow... thus causing the boost creep..Hope this clears things up..

[TurboKA37]

wasnt there someone else using the IAP manifold with boost creep problems? id definatley find something to plug the dump pipe and run it to the atmosphere to see whether the problem is with the wastegate or manifold. since the wastegate was running perfect on your previous set-up im beting that the problem is with the manifold if not the angle at which the dump pipe return is at.

[TurboKA37]

my bad rn240sx, i just noticed you were the problem with the boost leak problem in the other thread

[rn240sx]

CORRECTION to turboka37:IAP does NOT route the dump back to the downpipe. They run OPEN DUMP on their setup..

[TurboKA37]

yea, i understand the IAP manifold doesnt route the wastegate gasses back into the downpipe. i was wondering whether the design of the manifold was the reason for boost creep

[rn240sx]

I seriously doubt it cause i have spoken to 4 other 240 members with this same manifold but they use the deltagate with open dump and they claim it holds at 7 psi solid all the time..!!I know its not my Tial wastegate cause of how it reacts.

[j-z]

then its gotta be the angle of the dump. you can put a bike muffler and run open dump. that wouldnt be that much of a hassle. or you could take a chance and redo it to enter the dp further down at more of angle. i understand when youre talking about open dump sounding annoying, cause it is.