Very slow spool up

[TSIkw]

I installed an EVOIII 16G, front mount, and GM Maf and translator running a blowthrough setup. I've calibrated the MAFT too.

The problem is the turbo will spool up to 10psi by around 3000rpm's and it stops there. Then around 4500rpm it will slowly start to build more pressure. It takes all the way to around 6000rpm to get it up to 16psi where is have it set.

I've done multiple boost leak tests and can't find any leaks. Even sprayed soapy water all over and I don't see any bubbles.

Any thoughts on how to fix this or what else to look for? I'm lost.

My Setup:
EvoIII 16G
FMIC
3" GM MAF and Translator
Denso 660's
DSM Link

 

[linksys42]

Are you sure you have it set to 16 psi? Or do you have it set to 10psi and when it gets in the upper rev’s its creeping up to 16? That's what it sounds like to me.

 

[MountainDew]

Are you sure you have it set to 16 psi? Or do you have it set to 10psi and when it gets in the upper rev’s its creeping up to 16? That's what it sounds like to me.

He didn't mention an MBC. Aren't the Evo 16g's wastegate set at like 16-17psi?

 

[linksys42]

He didn't mention an MBC. Aren't the Evo 16g's wastegate set at like 16-17psi?

Its in his profile.

 

[oldman]

Are you sure you have it set to 16 psi? Or do you have it set to 10psi and when it gets in the upper rev's its creeping up to 16? That's what it sounds like to me.

Bingo.

He didn't mention an MBC. Aren't the Evo 16g's wastegate set at like 16-17psi?

Nope, they are about the same as stock 14b actuators of 10-12 psi. Furthermore, you can't lower boost levels lower than the wastegate spring with a MBC even if you wanted to.

 

[MountainDew]

Its in his profile.

Sorry about that, my mistake.

Edit - Gotcha oldman. Perhaps the 3" turbo back is causing some of this boost creep.

Time to do some porting!

 

[linksys42]

What I would do if I was the OP is just tighten the MBC a little more to up the psi slowly to your desired psi since you have the 660’s and the fmic you should be safe. But do it slowly, up the boost pressure a little at a time and watch knock on link. And make sure that when you up the boost on the MBC that the creep doesn’t get higher. What im saying is if you up it to lets say 12psi the creep doesn’t go up any higher than the original 16psi at 6000rpms. Once you get up past 18-20 psi you shouldn’t see the creep at all because that’s what that turbo was designed to run at anyway. Just be careful.

 

[oldman]

Edit - Gotcha oldman. Perhaps the 3" turbo back is causing some of this boost creep.

It's the turbo, free flowing exhaust just helps with uncovering it. Most MHI turbos have the same problem due to the poorly designed wastegate path/actuator/flapper, this includes 14b, s16g, b16g and EVO3 16g (the worst one of them all). My old setup of s16g with 2.5" exhaust/hi flow cat was creeping to 23psi prior to porting.

 

[TSIkw]

I do have a manual boost controller. I had my 14b set to 16psi and i didn't change the MBC from that setup. I turned the MBC 1 full turn to up the psi but it didn't change anything. Still spooled to 10psi then creeped.

Also the turbo was ported by Slowboy and the O2 housing is ported.

 

[oldman]

I do have a manual boost controller. I had my 14b set to 16psi and i didn't change the MBC from that setup. I turned the MBC 1 full turn to up the psi but it didn't change anything. Still spooled to 10psi then creeped.

Turn it 5 turns and post back results. BTW, is it a ball and spring or bleeder MBC?

Also the turbo was ported by Slowboy and the O2 housing is ported.

Complete waste of money, a SBR port job is a 5 min port job consists of opening the inlet flange to match a 7cm^2 gasket (if that) and does nothing for boost creep. Almost every person I have helped with boost creep almost always starts with a SBR ported EVO3 and an exchange much like the one you and I are having. Just ask the author of this tech article. http://www.dsmtuners.com/forums/showthread.php?t=186525

 

[TSIkw]

I'll do that in the morning.

Good to know about the SBR porting...I didn't pay for it though. Bought the turbo from my friend who upgraded.

 

[talon187]

ive got the same problem by 4500 rmps mine would be at 15ish psi im on stock injectors so yeah it blows but ive got an external gate and a 2g ported manifold im geting the flange welded so my prolem should be fixed. my problem is even with the a mbc and the externalgate i can run anything lower the 14psi is that to much for stock injectors?

 

[TSIkw]

oh yeah and its a ball and spring MBC which was leaking but i fixed that.

 

[linksys42]

It's the turbo, free flowing exhaust just helps with uncovering it. Most MHI turbos have the same problem due to the poorly designed wastegate path/actuator/flapper, this includes 14b, s16g, b16g and EVO3 16g (the worst one of them all). My old setup of s16g with 2.5" exhaust/hi flow cat was creeping to 23psi prior to porting.

I see what your saying oldman, but I didn’t port anything on my set up I even bought the 7cm sealing gasket that goes between the exhaust mani and the turbine housing. I did it like that on purpose, I believe its inefficient to open up the exhaust turbine housing after the exhaust manifold to force it back thru a small 7cm^2 opening. To combat the creep I put on a tubular o2 housing. My exhaust goes from the 2.5” tubular o2 housing to 2.5” down pipe till the flex section on the down pipe then it opens up to 3”. My spool up to 16-psi gets there at 3000rpms and holds solid till 7000rpms.

Quote: shapegsx
All that exhaust still has to go through a 7cm^2 opening, regardless of how wide you make the inlet to the turbine housing. If you make the inlet wider, all you are doing is letting the exhaust expand before it has to compress and accelerate through that small opening that leads to the turbine wheel. Porting the turbine inlet actually makes it less efficient. Chances are that it will actually slow down the spool of the turbo. There is no reason to make the exhaust expand before it enters the throat of the housing.

He was the first Evo III 16g in the 11’s, flowing 44.1lb/min!!!! He is the reason why I second-guessed about porting and his method worked.

 

[oldman]

Quote: shapegsx
All that exhaust still has to go through a 7cm^2 opening, regardless of how wide you make the inlet to the turbine housing. If you make the inlet wider, all you are doing is letting the exhaust expand before it has to compress and accelerate through that small opening that leads to the turbine wheel. Porting the turbine inlet actually makes it less efficient. Chances are that it will actually slow down the spool of the turbo. There is no reason to make the exhaust expand before it enters the throat of the housing.

He was the first Evo III 16g in the 11's, flowing 44.1lb/min!!!! He is the reason why I second-guessed about porting and his method worked.

It's game of give and take, someone like shapegsx doesn't need to to worry about boost creep because he's not running low boost.

As for slower spool, I would have to disagree, what he said is based on theory where as proper 3 piece porting has been proven over the years to help spool with real life results. Porting is an art, it's not just about making it bigger, and if you're looking for 11's, EVO3 16g would be a terrible choice to begin with anyway.

How much boost are you running anyway? Are you able to run 12 psi to redline? I suspect the tubular O2 (what I had on my old setup) is not what cured your boost creep, the combination of the 2.5" DP and running decent boost level is what did it.

 

[TSIkw]

Ok I turned the MBC up 5 turns and it did nothing. Still spools to 10-11psi by 3K and peak at 17psi near redline.

It is a turbo xs boost controller and there was air leaking out of the O-rings so I put RTV around them to seal it up. Is some air supposed to leak out of those? Could this be causing a problem?

 

[oldman]

Ok I turned the MBC up 5 turns and it did nothing. Still spools to 10-11psi by 3K and peak at 17psi near redline.

It is a turbo xs boost controller and there was air leaking out of the O-rings so I put RTV around them to seal it up. Is some air supposed to leak out of those? Could this be causing a problem?

Which TurboXS? Standard or Hi performance?

 

[TSIkw]

Its a standard single stage and it looks just like one of the ones in this link

http://www.extremepsi.com/store/customer/product.php?productid=18861&cat=276&page=1

 

[oldman]

Its a standard single stage and it looks just like one of the ones in this link

http://www.extremepsi.com/store/customer/product.php?productid=18861&cat=276&page=1

The standard version is a bleeder MBC, not a ball and spring. Which fitting do you have going to the wastegate and which to the J-pipe? (Better not be hooked up to the BOV line like their instructions say) Which direction are you turning the adjustment knob? CW or CCW?

Let's make sure this is the one you have. http://www.extremepsi.com/store/customer/product.php?productid=16134&cat=276&page=1

 

[TSIkw]

Well it looks like it is hooked up wrong and it is going to the bov line. My new J pipe I used when put the front mount on doesn't have a nipple on it to put the vaccuum line so i went to the bov.

Set up is....WGA to bottom of the MBC and BOV Line to the side outlet of the MBC.

 

[TSIkw]

I've been turnig it CCW too.

 

[TSIkw]

Before I did the turbo swap I had the hose from the WGA to the bottom of the MBC though and it worked fine. The only thing I changed was running it to bov line.

 

[oldman]

1. Tap a fitting on your new j-pipe and move your pressure source away from the BOV line to avoid an open BOV under boost, BOV flutter/compressor surge after letting off and vacuum leak during idle and part throttle.

2. Which direction are you turning the knob? CW is to decrease boost and CCW is to increase boost.

3. Do you see any bleeder hole other than the air leak through o-ring you mentioned above? This is a bleeder type mbc and it works by regulating amount of air bleed and reduce the pressure that the actuator sees. If the above mentioned leak is the only leak you see, you have just disabled the MBC by sealing the leak.

4. If all else fail, test run with the actuator fitting open and see if boost shoot right past 10psi, if so, the problem is clearly the MBC. The expected result is infinite boost so make sure to use your other manual boost controller wisely, your right foot.

 

[TSIkw]

I will route it through the J pipe as soon as i can and I don't see any bleeder valve on the MBC it looks just like blue ones in the other link with the o-rings...same color too., but it is set up like this one here.

link.http://www.extremepsi.com/store/customer/product.php?productid=18861&cat=276&page=1

 

[oldman]

Trust me, you have the white one but in blue. It's a bleeder type because,

1. The bottom fitting goes to the wastegate where as a ball/spring goes to pressure source.

2. CCW to increase boost, the looser the knob, the more air is bled off, the less pressure the wastegate sees, the higher the boost level. Where as a ball and spring is completely the opposite.

Was the sealing of the o-ring done before or after the turbo swap, I suspect that is the problem. No air being bleed off, the wastegate always sees actual pressure, wastegate opens at 10psi (actuator spring pressure).