Homebrewed in car MBC.

[rampridersrider]

What do you guys think. I have a Hallman Pro MBC and am getting tired of having to get out of my car to change the boost in the mornings or whatever. Would it be possible to run some slightly longer vacuum lines into the cabin and run the boost controller from there. Would the lines collapse or anything like that. I wouldn't think so, but who knows. I don't see a lot of people do it to be honest. Hallman sells a kit to do this but it works off a long cable. Give me some input here.

 

[dsm-onster]

What do you guys think. I have a Hallman Pro MBC and am getting tired of having to get out of my car to change the boost in the mornings or whatever. Would it be possible to run some slightly longer vacuum lines into the cabin and run the boost controller from there. Would the lines collapse or anything like that. I wouldn't think so, but who knows. I don't see a lot of people do it to be honest. Hallman sells a kit to do this but it works off a long cable. Give me some input here.

You'll no doubt run into serious boost spiking issues. Not boost creep. Boost spike. Research boost spike remedies and you'll understand .

 

[jasteel13]

i had my mbc in my glove box with hard plastic lines. Didnt have any problem with the boost levels. Held 20+psi.

 

[heppm01]

Generally speaking, you want your pressure lines to/from your MBC to be as short as possible.

Why are you objecting to the Hallman add-on kit? You don't want to run a long cable into your cabin, but you don't mind running long vacuum lines?

Matt

 

[DiamondStarM]

Probably to save a few bucks

But it wouldnt be a good idea, the shorter the better and tap the boost source from the licp or compressor housing as well. Dont T in with the BOV line.

 

[rampridersrider]

Probably to save a few bucks

But it wouldnt be a good idea, the shorter the better and tap the boost source from the licp or compressor housing as well. Dont T in with the BOV line.

Yah just to save some money, plus it would only take like 30 minutes. I read up on it and decided against it. I was going to tap to the j-pipe or compressor housing, but there is no nipple on either of those so I gave up. Anyway I could tap a hole on my j-pipe and stick a fitting in there? I do get a little spike every now and then cause I am tapped into the bov line.

 

[siceclipse]

im just gonna ask the simple question then ill search.

Why off the boost source rather then the boost/vacume source?
ive run off of both and i didnt really see a difference, but maybe its just been so long...

 

[suicidal2af]

im just gonna ask the simple question then ill search.

Why off the boost source rather then the boost/vacume source?
ive run off of both and i didnt really see a difference, but maybe its just been so long...

Few reasons.

Your WGA is only supposed to see boost, not vac. Seeing vac can shorten its life.

And to prolong the life of the turbo. If you have a boost leak and are tapped post-leak, the shaft speed is going to increase to potentially unsafe levels.

 

[tstkl]

i was also told that the bleed on your mbc can cause your reaction time on your bov to be a little slow. I doubt it would effect it enough tho.

someone email dejon and sbr and tell them to add a boost source option to their jpipes

 

[dsm-onster]

Few reasons.

Your WGA is only supposed to see boost, not vac. Seeing vac can shorten its life.

I've run my turbo for years with boost/vacuum source to the actuator. Also for years I did this with my T-bird TC. My fathers GN. So many people run a boost/vacuum source on their turbos for countless miles that I just have to oppose your opinion. No one I know has ever had a wastegate wear out from this.

And to prolong the life of the turbo. If you have a boost leak and are tapped post-leak, the shaft speed is going to increase to potentially unsafe levels.

The only way to tap a pre-leak source is to tap a sourse before the turbo.

 

[suicidal2af]

I've run my turbo for years with boost/vacuum source to the actuator. Also for years I did this with my T-bird TC. My fathers GN. So many people run a boost/vacuum source on their turbos for countless miles that I just have to oppose your opinion. No one I know has ever had a wastegate wear out from this.

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech101.html

They know more than either of us.

Internal Wastegates are built into the turbine housing and consist of a "flapper" valve, crank arm, rod end, and pneumatic actuator. It is important to connect this actuator only to boost pressure; i.e. it is not designed to handle vacuum and as such should not be referenced to an intake manifold.

The only way to tap a pre-leak source is to tap a sourse before the turbo .

Nipple off of the compressor housing.

In fact, theoratically, tapping at a intake mani port (post throttle body) will normally aid in transient response w/ the turbo. In otherwords, it will keep it spinning faster when you shift as the wastegate actuator is seeing vacuum when you lift a little (at shift) and causes the wastegate to shut completely keeping any and all residual exhaust flow pushing the turbine wheel instead of bypassing through the wastegate itself. This probably isn't apparent until your pushing at least a midsize turbo (20G/50-trim or bigger).

Once the engine is seeing no load(read: clutch in), the amount of exhaust gas going through the turbine isn't enough to even spin it at all. It's a nice theory, but even assuming truth in it, it wouldn't be enough to matter on a small turbo, and the amount of energy needed to spin a large turbine would make the residual gasses useless.

Of course, this way also gives you more reliable boost control. I've got a total of 5 inches of vac line to my mbc, and I don't see any boost spike on the t25. Running from the IM, I would spike to 20 before it would settle down to my setting of 16.

 

[suicidal2af]

It doesn't matter what anyone says. I've NEVER had a problem . No one I've ever met or known with a MBC has ever had a problem. And I've run Garrett, Turbonetics, MHI. . . . I'm just not going to worry about that. It's rediculous to worry about it considering the track record. I suggest the same for anyone else.

Lots of people have actuators fail for unknown reasons. Search for "won't boost" and oen of the first things you'll see being suggested is to test the WGA to see if it's working. Maybe that won't cause failure, however it's putting extra load on the diaphram, which you can't deny will make it wear down faster.

So whats the difference between the compressor housing and the intercooler piping it connects to. Theres a big hole out of the housing. You know, . . . where the intecooler piping goes. Has anyone ever had a boost leak at an intercooler coupling?

People have boost leaks at intercooler couplings all the time. I've yet to hear of anyone blowing a hole through a compressor housing, couplers age and fail all the time.

Prove it.

The engine is still spinning. The engine is a huge air pump. Air is still being pushed against the turbine blades. There is still a pressure differential from the turbine housing to the o2 housing. I know that most of the force is from the heat expansion from the exhaust gasses. But only experimenting would prove anything, of course... There is a momentary spike of boost in the intercooler piping and compressor when the throttle shuts just before the BOV releases. This would also encourage the wastegate actuator to push the wastegate open even more.

Easy to prove. Route the vac lines your way. Now go do an open throttle run, and push in the clutch. Watch your boost gauge. See it drop all the way to vac? That means there's not enough air to keep the turbo spooled.

And most of the force is in the exhaust being pushed out of the cylinder by the piston. There isn't any heat expansion going on -- by the time your exhaust valve opens, the gas is already cooling. Your idea might have merit on a tiny turbo like a t25, which takes almost no gas to spool, but on a larger turbo it won't do anything.

Absolutely on a small turbo the spiking would make this too much of a hastle to be worthwhile. Besides small turbos don't have a problem w/ spool. Large turbines w/ large turbine housings do. I think that there's enough energy from the engine pumping to make a difference... I guess it is an experiment we'll have to prove or disprove. . .

So how about on a ball bearing turbo, where you have a quarter of a second difference between 5psi and 35psi? That wouldn't have issues with boost spikes with the longer vac lines?

Nevertheless, the spike is the real issue w/ running long lines to an MBC. Reliability has never been an issue with anyone I've ever known EVER. I've never heard of there being reliability issues anywhere on this forum, Turboford.org, GNTTYPE.com either. So I'm not going add another worry to my plate .

People have WGA's fail all the time. There's tons of threads on this forum alone. Vendors sell them, somebody is buying them. They show up on ebay all the time.

That said, I would trust what Garrett, the manufacturer, says over what some people's theories are. They spent the millions on R&D for it, they know more about it than any of us could hope to.

P.S. An MBC prevents the vacuum from being seen by the wastegate actuator, as the ball in the apparatus is sucked down tight. It is like a check valve with a high crack pressure.

The split second before the ball gets smacked down against the pressure source, the diaphram in the actuator goes from seeing 15-35psi of pressure to -25inhg of vacuum. That's a pretty significant pull, and undeniably *could* cause a failed diaphram over time.

 

[suicidal2af]

Yes. . . I am denying that it will make it wear down faster. Vacuum releases pressure on the spring.

So all that is in an actuator is a spring? That's news.

There's a diaphram, and pushing and pulling on it will wear it out over time.

So you actually believe that a compressor housing maintains pressure when the intercooler piping, hanging off of it, blows off or blows a hole?

If it blows off completely? No. If it is leaking, yes. The pressure behind the leak is what is forcing the air out.

I can sit in my drive way and push in my clutch at idle and rev to kingdom-come and every time I build boost.

Yeah, 1 or 2psi at 7000rpm.

Perhaps you mean let off the throttle suddenly after a WOT run?

No, that's not what I meant.

No to that too. That means the throttle is shut and the engine is sucking all the air out of the intake manifold. Why would a blow off valve blow off if the turbo stopped spinning suddenly. Further, who would care to use one, if the turbo stopped spinning suddenly. That would negate a reason to reroute the compressed air that is reversing the compressor wheel.

Does the turbo stop spinning completely? No, but it stops at a very rapid pace. Your bov doesn't stay open for the next 48 seconds -- there's a half second or so release of pressure, and then it shuts -- because your compressor isn't spinning enough to continue to compress air.

Uh, nope. Have you ever measured the EGTs in the exhaust mani and then in the downpipe? The ideal gas law: PV = nRT.

Have you? Apparently not, because the exhaust gas is hottest as it enters the manifold, and most of the heat is transferred into the turbine housing as it runs through.

Turbine Theory:

It is a common misconception that the exhaust turbine half of a turbo is driven purely by the kinetic energy of the exhaust smacking into it (like holding a kid's tow pinwheel behind your tailpipe) While the kinetic energy of the exhaust flow does contribute to the work performed by the turbo, the vast majority of the energy transferred comes from a different source.

Neat. Toss your turbo in a convection oven and see how fast it spins. After all, you've got some airflow from the fan, and a whole ton of heat. So by your theory, it'll spool, right?

Keep in mind the relationship between heat, volume, and pressure when we talk about gasses. High heat, high pressure, and low volume are all high energy states, low heat, low pressure, and large volumes are low energy states.

Exactly. The turbine doesn't care what the temperature of the exhaust is. If you have an equal amount of velocity flowing through the blades, it will act *exactly* like a pinwheel will. Because that's all it is. However, we're dealing with a set volume here. More heat means the same amount of gas will take up more space. Since our volume is a constant, in order to move the same amount of gas through our space, it needs to move at a higher velocity.

But here's the thing: given an equal velocity, the turbo doesn't care what the temperature of the gas is. Heat plays no direct role in spooling a turbo.

So our exhaust pulse exits the cylinder at high temperature and high pressure. It gets merged with other exhaust pulses, and enters the turbine inlet - a very small space. At this point, we have very high pressure and very high heat, so our gas has a very high energy level.

Yeah, and this has to do with what? Add two more cylinders of equal bore and stroke, drop the EGT by 100 degrees. It'll still spool faster on the 6 cylinder.

As it passes through the diffuser and into the turbine housing, it moves from a small space into a large one. Accordingly, it expands, cools, slows down, and dumps all that energy - into the turbine that we've so cleverly positioned in tho housing so that as the gas expands, it pushes against the turbine blades, causing it to rotate. Presto! We've just recovered some energy from the heat of the exhaust, that otherwise would have been lost

Here's the flaw in your theory: A larger exhaust housing would give more room for expansion, more cooling, and more expelled heat energy. So logically, a larger A/R housing will spool faster, right?

This is a measurable effect: Stick an EGT upstream and downstream of the turbo, and you see a tremendous difference in temperature.

Right -- and I seem to remember saying temperatures are highest immediately after combustion, and far lower after the turbo.

From Turbo Fundamentals.

Of course, it's your choice to believe this. Just like it's my choice to believe the garrett website.

I'll believe dennis grant when it comes to things in regard to handling. When it comes to things related to turbochargers, I'll believe the people that make them.

Who's denying boost spike from long MBC lines. I said that this would be good for a slow spooler. Besides, ball bearing CHRAs increase spool by up 15%. It's a great increase, but not as exaggerated as you may think. It’s the transient response that makes them so wonderful. Straight from garrett. But you don't have to believe garrett any more than I do .

They start to spool slightly sooner, however once they spool, it's a noticeably faster amount of time to go from a few pounds to full boost.

And my point was, by running off of the compressor housing, you have drastically shorter vac lines, and spike is a non-issue.

Not from vacuum. Vacuum releases pressure on the spring. Pressure on the spring makes it saggy.

Vacuum violently pulls the diaphram back, effectively pulling on the spring. There's a difference between letting a spring return on its own energy, and yanking it back.

who knows maybe they want you to buy their wastegate actuators... I'll not worry about it. and you will. So that's that .

How is directions on where to tee you pressure source from a sales pitch?

(being a little redundant, arn't we?) . . .Not from vacuum. Vacuum releases pressure on the spring. Pressure on the springs makes it saggy.

Lack of boost releases pressure on the spring. Vacuum pulls on the diaphram.

 

[GTM]

Hey, sports fans, lets knock off the peeing contest.

I'm _not_ impressed and other members do _not_ want to wade through all the he said she said and get "misinformation notices" sent to all staff.

State your position, couch your arguments (legal context).

Support URLs with citation from recognized authorities and be done with it.

................................

mrduk
mrnot
mr2
mrnot
osarcmwangs,

GTM

 

[GTM]

I apoligize. I was in the zone. I will clean up my last post at least. . .

All of you might want to consider editing those other posts to 1 liners. Sarcasm can look like an in your face attitude, being provocative, contentious does not inspire a friendly discussion. Neither does Bernoulli's laws of Physics 101 warrant this much attention.

Lets keep it civil so the original poster can grasp what is being said rather than loosing sight of why we are here. Some of us learned there "ain't no" such thing as a vacuum, ~. It's one thing to be pedantic and another to be a pedant.

Cheers,
GTN

 

[suicidal2af]

And straight from the Garrett website:

A pressure and temperature drop occurs (expansion) across the turbine (7), which harnesses the exhaust gas’ energy to provide the power necessary to drive the compressor ​

The only thing I'm going to respond to is this one, as to not beat a dead horse.

The ideal gas law is what we're dealing with here. PV=nRT, as you've said a million times.

To examine this, let's break it down.

P = pressure
V = volume(in our case, a constant)
n = number of molecules
R = universal gas constant
T = temperature

As the exhaust gas passes through the turbine housing:

Pressure changes
Volume does not change
number of molecules does not change
R does not change
Temperature changes

So yes, what Garrett said is correct. And by the nature of having pressure differentials, T will always drop as it passes through.

That said, PV is what spools our turbo. There's two indirect ways of changing PV, and one direct way.

Increasing number of molecules(adding cylinders) increases n, which will raise pressure and create a larger differential.

Increase temperature will raise pressure and create a larger differential.

Changing volume will directly affect the amount of pressure pre-turbine, and is the only direct way of affecting the side of the law that we deal with.

If the equation were PV=T, then yes, heat is what would spool a turbo. However, it's only one variable in an equation.

 

[DiamondStarM]

Why dont you exchage numbers and share in your heated coversation on the phone, the last 12 posts have nothing to do with a homebrew mbc in the cockpit, which answer has already been agreed on.

 

[dsm-onster]

I went back and either edited or deleted all my previous posts to alleviate clutter. I compiled everything I need to say to stop the spread of misinformation and started a new thread: What Spins a Turbine Wheel. The subject is merited in this forum but certainly NOT in this poor guys thread. I apologize.

 

[GTM]

Why dont you exchage numbers and share in your heated coversation on the phone, the last 12 posts have nothing to do with a homebrew mbc in the cockpit, which answer has already been agreed on.

I couldn't agree with you more.

I repeat: This has turned into a peeing contest and reeks of some other issues beyond the scope of any thread on the subject. A sign of maturity is to walk away after having presented you case. Another sign of maturity is not not try and force someone into a corner and keep slugging.

Think about it, nobody in their right mind would want to participate in this thread when there is a slug fest for fear they too would be the target of this nonsens. This crap ruins it for everyone and this is a likely candidate for the HOW NOT TO BEHAVE ON DSMtuners forum. Should that happen it sullies the original poster's name who just asked a simple question. It has reached more people than they care to guess, people are talking and it aint good.

"You can fool some of the people some of the time~"
and
Einstein said he could tell everything he knew in 15 minutes.

GtM

 

[Coup D E'Tat]

For the record, I have set up an in-car MBC without whatever kit Hallman sells, and it does not use vacuum line to reach the cabin.

If everyone plays nice, maybe I'll post some pics when everything is mounted.

I spent $7 for parts to do this.

 

[Blk95gs]

And also, for the record, in my old 93 TSi I tapped my boost source off of the BOV.

Broke 3 WGA's when the car would hit full boost at around 18psi. So there's a first hand account of that incident.

Tap the housing.

 

[Crazy91GSX]

well, i did this exact thing in my old laser.. just bought a bunch of vacuum lines.. ran them into the cab and under the center console.. drilled two holes and mounted the mbc right on the side of the console.. actually looked decent and worked effeciently. No spiking problems at all...

 

[NeEmO6]

For the record, I have set up an in-car MBC without whatever kit Hallman sells, and it does not use vacuum line to reach the cabin.

If everyone plays nice, maybe I'll post some pics when everything is mounted.

I spent $7 for parts to do this.

I would love to see what you did. Let us know when its mounted.

 

[MrBoxx]

Yah just to save some money, plus it would only take like 30 minutes. I read up on it and decided against it. I was going to tap to the j-pipe or compressor housing, but there is no nipple on either of those so I gave up. Anyway I could tap a hole on my j-pipe and stick a fitting in there? I do get a little spike every now and then cause I am tapped into the bov line.

Since some people got sidetracked, no one bothered to answer your question. I'll step up to the plate. Yes, you can buy an NPT barbed nipple with a threaded base, drill your lower intercooler pipe, tap the hole, and use that as a boost source for the MBC. RRE's L-pipe (the one that comes off the J-pipe and goes to the SMIC) is equipped with this simple solution. Whoever said dejon and SBR should do this on their J-pipes is right. I'm sure it would make a lot of DSM'ers a little happier to have a little flexibility in their setups.

 

[Ryan95tsiAWD]

2 different cars - 2 14bs - 1 16g and we have been running an evo16g for over a year now all of which were tapped off the BOV line. never had any problems.

I have also noticed that if you do tap off the turbo elbow that the boost tends to be highter which causes a lot of cheaper MBCs to open too soon therfore causing the car to "spike" to its set psi, drop down, and then climb back up to said set psi. This of course does not happen "every" time but I have seen it more than once. Like I said before, I have NEVER had any problems with spikes or actuators going bad.