boost question

[starsthensun]

I know this has been beaten to death, and I've been searching but haven't really found the answer. I have a 16g turbo and full 3" turbo back exhaust with a ball and spring mbc. I can't control boost at all. I have the controller ran from the bov line and the wastgate. No matter where I set the boost control at, it boosts to around 23 psi. If I put the plug in on the end of the exhaust it regulates to about 15 psi, but as soon as I take it out it goes right back to 23 psi or so. Adjust wastegate, try a different mbc?

 

[Backinajiffy12]

boost solenoid? < can't spell

 

[jrohner]

By plug in the exhaust you mean the baffle for the muffler? If so you are getting boost creep, which those turbo's are known for. I would recommend to just get the supporting mods to run the boost at 23. Once you get your car to have a lot of power, your turbo probably won't go up to 23psi anymore anyways.

If you want to get the boost down, just take the exhaust manifold off and port the turbo to make exhaust flow to the wastegate easier. Mine only creeps to 17 after doing that; I'm not sure if you can get it much lower than that. Once you get the supporting mods to run 20+, you will never want to run under 20 again. From 17 to 20 makes a huge difference in power on these turbos.

Also, make sure your boost controller is hooked up right. Take off your MBC and run the line straight to the wastegate, if your psi is lower at higher rpms, your MBC was not hooked up right. I don't run a MBC at all on my talon and can pretty much run any amount of boost I want just by using a different T fitting that flows more and run the hose to the air intake without the boost solenoid in between.

 

[starsthensun]

Do you think I could just get away with installing a 190 fuel pump and porting the exhaust side of the turbo? I keep blowing the head gasket too, I need to install head studs. When using headstuds, will a oem head gasket hold up to 25 psi? Am I blowing head gaskets because I'm running a little lean when I get into higher boost, or because I'm not using head studs?

 

[LandoAWD]

Am I blowing head gaskets because I'm running a little lean when I get into higher boos

By asking this question, you've earned yourself the penalty of buying a logger.


Wait, penalty? NECESSITY.

 

[starsthensun]

Yeah I know. I have the logger itself, but I don't have the cables or software. I think it's time to download the software and buy some cables.

 

[No_Skillz]

Lets nip this thread in the bud before it turns into a huge cluster####...

First off, you need to have an uninterrupted line from your BOV to intake manifold. The boost source line for your MBC needs to come from a pressure source as close to the turbo as possible. Compressor cover or IC pipe right after the compressor cover.

Second, is your problem with boost symptomatic of spiking, creeping, or unregulation? Spiking would be hitting 23psi as soon as boost builds, then dropping just as fast (all before ~4k rpms on a 16g). Creeping would be hitting 15psi, then slowly building up to 23psi as you reach redline. Unregulated would be similar to spike, but without the corresponding drop.

Third, are you sure you have your MBC oriented the correct way? Is it a ball and spring type? Bleeder types are crap. There is only 1 input and 1 output. Make sure you didn't switch the two. If it is all peachy, take it apart and give it a good cleaning.

Fourth, no you can't just throw on some fuel mods because you have no way of telling you ECU (which controlls the injectors) that you have done so... so it'd be kind of useless and probably cause a host of other problems (such as inconsistent lean/rich conditions).

Fifth, you're plugging up your exhaust to control boost, which is basically castrating your car of any power. It's safe to do now (as a matter of fact I recommend it) since you shouldn't be running 23psi on stock injectors nor on stock headstuds. You are most likely knocking a shitload and blowing headgaskets.

Sixth, you don't need the headstuds right now. Get your shit controlled for 15psi first. When you want to go above 20psi (and you have the right mods for it), then you can consider ARPs with a stock headgasket, which will let you reach ~30psi with the right tune.

Seventh, get a logger so you can watch stuff like knock and timing so you stop blowing headgaskets.

Eighth, do a BLT.

 

[viperlp01]

ebay 16g??? you have to adjust wategate. it will make you hold boost forever

 

[starsthensun]

Lets nip this thread in the bud before it turns into a huge cluster####...

First off, you need to have an uninterrupted line from your BOV to intake manifold. The boost source line for your MBC needs to come from a pressure source as close to the turbo as possible. Compressor cover or IC pipe right after the compressor cover.

Second, is your problem with boost symptomatic of spiking, creeping, or unregulation? Spiking would be hitting 23psi as soon as boost builds, then dropping just as fast (all before ~4k rpms on a 16g). Creeping would be hitting 15psi, then slowly building up to 23psi as you reach redline. Unregulated would be similar to spike, but without the corresponding drop.

Third, are you sure you have your MBC oriented the correct way? Is it a ball and spring type? Bleeder types are crap. There is only 1 input and 1 output. Make sure you didn't switch the two. If it is all peachy, take it apart and give it a good cleaning.

Fourth, no you can't just throw on some fuel mods because you have no way of telling you ECU (which controlls the injectors) that you have done so... so it'd be kind of useless and probably cause a host of other problems (such as inconsistent lean/rich conditions).

Fifth, you're plugging up your exhaust to control boost, which is basically castrating your car of any power. It's safe to do now (as a matter of fact I recommend it) since you shouldn't be running 23psi on stock injectors nor on stock headstuds. You are most likely knocking a shitload and blowing headgaskets.

Sixth, you don't need the headstuds right now. Get your shit controlled for 15psi first. When you want to go above 20psi (and you have the right mods for it), then you can consider ARPs with a stock headgasket, which will let you reach ~30psi with the right tune.

Seventh, get a logger so you can watch stuff like knock and timing so you stop blowing headgaskets.

Eighth, do a BLT.

I have hooked up the mbc a couple different ways, nothing seems to work. Yes, the mbc is hooked up properly. It is a ball and spring type, brand new.The boost is unregulated. goes way too high and stays there. Yes it is a ebay 16g.

 

[No_Skillz]

In that case it sounds like your MBC and wastegate aren't talking to each other. Is the flapper opening? Try to test it with an air compressor going straight to it and see what psi it opens at.

 

[Defiant]

try a different mbc?

Yes. Get or build an MBC that isn't crap.

 

[No_Skillz]

Yes. Get or build an MBC that isn't crap.

C'mon D. MBC is just a spring, a ball, and a casing. Even e-bay can't screw that one up.

Starsthensun, if you don't have an air compressor handy you can:
Tap a boost source and re-route your vacuum lines like I described originally,
Connect the boost source directly to the wastegate,
Observe boosting characteristics.

You might get some boost creep but it should initially keep the boost nice and low to let us know how your wastegate is doing. We'll tackle the issue of boost creep after we clear the first hurdle.

 

[LandoAWD]

C'mon D. MBC is just a spring, a ball, and a casing. Even e-bay can't screw that one up.

I wholeheartedly disagree. Different springs, ball weights, etc.

Why do you think the quality Hallman units boast a ceramic ball?

 

[No_Skillz]

I wholeheartedly disagree. Different springs, ball weights, etc.

Why do you think the quality Hallman units boast a ceramic ball?

Damn. Schooled. Never thought of that... I bought a Hallman just cause I was a ricer and liked the color. I'm assuming lighter ball is always better?

 

[Defiant]

I always thought it was a gimmick. With the amount of spring an MBC is using against its working load, the weight of the ball will be inconsequential.

 

[starsthensun]

I will have some free time this weekend to do a couple tests. I will let you know what happens.

 

[starsthensun]

I adjusted the arm a little bit. It opens at around 10-15 psi, but not fully. I put the baffle in the exhaust and it still goes uncontrollably high. I will try to find another mbc to see if the one I have is junk. when adjusting the arm, should you be able to slide the arm up and down on the flapper?

 

[dsm-onster]

I wholeheartedly disagree. Different springs, ball weights, etc.

Why do you think the quality Hallman units boast a ceramic ball?

Balls are balls . But, I built my own MBC from homedepot parts and it is still working to day. . . Been through, 1, 2, 3, 4, cars. . . But still boosting reliable and very little spike. I should sell them, I suppose.

. . .But, yea, I can see how an ebay mbc could have the wrong spring or improper diameter bleader hole. It's not like they actually put the thing on a car and turn the boost up to test it's spike characteristics. He!! there arnt real turbos from China anyhow .

 

[starsthensun]

At what psi should the flapper fully open at?