Need help with MBC setup

[Deathmug]

Hey guys.
I'm about to put my new turbo on & I wanted to make sure I've got this MBC setup correct.
It's an external wastegate by the way.

Check it out. Is this right?

<img src="http://i9.photobucket.com/albums/a65/mugofdoom/MBCsetup.jpg" alt="Image hosted by Photobucket.com">

 

[h3o]

Hey guys.
I'm about to put my new turbo on & I wanted to make sure I've got this MBC setup correct.
It's an external wastegate by the way.

Check it out. Is this right?

<img src="http://i9.photobucket.com/albums/a65/mugofdoom/MBCsetup.jpg" alt="Image hosted by Photobucket.com">

i wouldnt use the compressor housing as a boost source tee it off with the bov

 

[Deathmug]

I've seen setups using the BOV.
What's the advantage of using the BOV vs the compressor housing?

I would think you'd get a faster wastegate responce using the comp housing.

 

[Quasimondo]

No, you don't want to tee it off of the line that goes to the BOV. That's too long of a hose to use and you don't want any possible leaks to intefere with the operation of your BOV. Keep those hoses as short as possible to avoid boost spikes.

What kind of wastegate are you using, and what is that lower nipple for? If it's not doing anything, just bypass it and run directly from the compressor outlet to the wastegate nipple with the MBC in-between.

 

[oldman]

Keep it on the compressor housing, it will help reduce the chance of boost spike due to short route pipping and help prevent over spinning the turbo in the case of boost leak. There isn't anything to gain from the BOV line.

 

[h3o]

No, you don't want to tee it off of the line that goes to the BOV. That's too long of a hose to use and you don't want any possible leaks to intefere with the operation of your BOV. Keep those hoses as short as possible to avoid boost spikes.

What kind of wastegate are you using, and what is that lower nipple for? If it's not doing anything, just bypass it and run directly from the compressor outlet to the wastegate nipple with the MBC in-between.

??? the bov is more consistent source to tee it off of and its not a long way, on top of the the bov operates just fine teed off with the mbc ask most people on here they have it setup that way. i would be worried about your compressor housing not giving you a good enough boost source and then your boost will spike

 

[oldman]

??? the bov is more consistent source to tee it off of and ,

What makes the bov source more consistent than the compressor?

its not a long way

How is going through the entire intake track then out of the intake manifold to the BOV not a long way?

on top of the the bov operates just fine teed off with the mbc ask most people on here they have it setup that way.

Just because most people say so doesn't make it so.

i would be worried about your compressor housing not giving you a good enough boost source and then your boost will spike

Please explain.

 

[h3o]

What makes the bov source more consistent than the compressor?


How is going through the entire intake track then out of the intake manifold to the BOV not a long way?


Just because most people say so doesn't make it so.


Please explain.

directly from the tech guide

You HAVE to use the intake manifold is you want proper boost control. Why is that? The manual boost controller regulates the amount the wastegate is open based on the pressure at its source. Since you want to control manifold pressure, you want the MBC and the WGA to be recieving pressure directly from there.

Using a source off the turbo or intercooler pipe can cause you to have boost that changes with weather, load, and engine speed, and can also slow down boost response. By comparison, a manifold source will be fairly steady, solid, and reliable.

 

[oldman]

directly from the tech guide

You HAVE to use the intake manifold is you want proper boost control. Why is that? The manual boost controller regulates the amount the wastegate is open based on the pressure at its source. Since you want to control manifold pressure, you want the MBC and the WGA to be recieving pressure directly from there.

Just because one tech guide said so doesn't mean it's right. If your boost gauge is tapped to the intake manifold, changing the location of your boost source does not change the fact that the boost gauge is still tapped to the manifold. The only difference between the two boost sources is that the bov line will result in a slightly higher boost setting due to the pressure drop after IC, this can easily be solved by a little adjustment on the mbc

Using a source off the turbo or intercooler pipe can cause you to have boost that changes with weather, load, and engine speed, and can also slow down boost response. By comparison, a manifold source will be fairly steady, solid, and reliable.

Slight change with the temperature I can see because it's before the IC but you or someone will need to explain to me how load and speed will slow down boost respones, what makes a manifold pressure more steady, solid and reliable.

 

[h3o]

Just because one tech guide said so doesn't mean it's right. If your boost gauge is tapped to the intake manifold, changing the location your boost source does not change the fact that the boost gauge is still tapped to the manifold. The only difference between the two boost sources is that the bov line will result in a slightly higher boost setting due to the pressure drop after IC, this can easily be solved by a little adjustment on the mbc

okay since i have time im going outside right now to test this ill be back in 10 mins to see what the difference in boost source there is.

Slight change with the temperature I can see because it's before the IC but you or someone will need to explain to me how load and speed will slow down boost respones, what makes a manifold pressure more steady, solid and reliable.

think about it when the compressor blows out the air the load and speed changes as the psi is increased so it will be a bigger increase/decrease when getting on the throttle. but agian im going outside right now to test this

 

[h3o]

dammit forgot i pulled my engine this morning

okay this test will be done on a 96 eclipse with a t3 50 trim with delta wastegate and joe p mbc

be right back again

 

[oldman]

okay this test will be done on a 96 eclipse with a t3 50 trim with delta wastegate and joe p mbc

What exactly are you testing for that will prove anything?

 

[h3o]

okay first test

this is with the car up on jack stands so the test can be exact

outside temp 82*
car running 0.7 bar on the boost gauge (0.6 spring in the wastegate)
car ran for 2 mins of idling to warm the engine up
boost source is teed off with the bov at the manifold
boost gauge will remain at same source which is the manifold

after idling we reved the engine till we could dial in the mbc at 0.7 we ran it for a few seconds at 5500 so it reached full boost, boost stayed consistent the whole time

now we are letting the car cool down see we can test exact same at a different boost source

the boost controller will not be moved and no adjustment will be made, only thing will change is the boost source

 

[h3o]

okay second test

outside temp 82*
boost controller left at same pressure level from last test
only thing changed is the boost source

let the car idle for 2 mins

again reved the car up to 5500 to get full boost, as soon as we got on the throttle boost spiked to 0.9 and dropped to 0.75-.8 stayed consistent after that at .8

now you guys can draw up your own conclusions but this is just a simple research thing cause i didnt know what was right and what was wrong. either way i think it would be okay to go either boost source but from what i seen the teed from the mani makes the boost rise smoother and and more consistent. now could this be because we didnt change the source of the boost gauge? could be but im too lazy to wait and try again as i am in the process of changing out my rod bearings and need to get the crank to the machinist. so make your own conclusions

 

[Quasimondo]

??? the bov is more consistent source to tee it off of and its not a long way, on top of the the bov operates just fine teed off with the mbc ask most people on here they have it setup that way. i would be worried about your compressor housing not giving you a good enough boost source and then your boost will spike

In all honesty, how much more of a good source can you get than the nipple coming directly off of the turbocharger?

 

[oldman]

While you're waiting, mind sharing exactly what you're testing for and how will it prove or disprove your statements? What is this thing about revving in neutral? I can't even build 1psi free revving it.

 

[h3o]

While you're waiting, mind sharing exactly what you're testing for and how will it prove or disprove your statements? What is this thing about revving in neutral? I can't even build 1psi free revving it.

never said it was reving in neutral this is why i said we had it on jackstands to give the engine some load. also it was done in 2nd gear and i was just testing if i seen a boost spikes from either source

 

[h3o]

o and look oldman im not trying to argue or debate with you, i dont care for confrontation. its just that ive always had my mbc hooked up teed to the bov and when you guys say that this is wrong i got some question in my head about my setup. so i went back and read the tech article cause maybe i read something wrong or misunderstood the article, well then i also took what you said into consideration thats why i did this little test. i found that the manifold is a more consistent source so thats what im going to keep it at and thats still what im going to recommend people doing, now am i saying the way you guys do it is wrong? no, you all have your own opinions and im not going to argue with you or get into any little debate game that i know alot of forum people like to play.

 

[Deathmug]

What kind of wastegate are you using, and what is that lower nipple for? If it's not doing anything, just bypass it and run directly from the compressor outlet to the wastegate nipple with the MBC in-between.

The lower nipple is called the "compressor reference port".

 

[oldman]

First off I would like to say "YOU GOT BALLS DOING 2ND GEAR WOT PULLS ON JACKSTANDS".

I didn't look at it as an argument at all rather a technical discussion, you did a good job not allowing it to spin out of control. I'm fully aware of the fact that most run their boost source from the BOV line but that is because most mbc installation instruction suggest doing so. I do not know what happen to your test, I will not comment on it since I was not there with you. I can say this though, I have helped out countless boost spike threads where in some cases, changing boost source to the compressor housing solved it and here's an example.

I was not saying at all that tapping from the BOV line is wrong, it will work fine in most cases. I am saying this:

it will help reduce the chance of boost spike due to short route pipping and help prevent over spinning the turbo in the case of boost leak.

 

[97EclipseGS-T]

I dunno, every side of this seems right. But, the intake manifold is the pressure before it goes into the pistons....so wouldnt it be more consistant? Its the last place boost is.

 

[h3o]

First off I would like to say "YOU GOT BALLS DOING 2ND GEAR WOT PULLS ON JACKSTANDS".

I didn't look at it as an argument at all rather a technical discussion, you did a good job not allowing it to spin out of control. I'm fully aware of the fact that most run their boost source from the BOV line but that is because most mbc installation instruction suggest doing so. I do not know what happen to your test, I will not comment on it since I was not there with you. I can say this though, I have helped out countless boost spike threads where in some cases, changing boost source to the compressor housing solved it and here's an example.

I was not saying at all that tapping from the BOV line is wrong, it will work fine in most cases. I am saying this:

ah i do all my tuning with jackstands usually do it in 3rd gear though and then fine tune it on the way to the track. and like i said everyone can make there own conclusions to my test i did it for the sake of getting the question of my mind. but then again im sure most people that come to the newbie section and ask for this help arent running big huge turbos. if you want the best boost source do what the pros do and use nitrogen

 

[oldman]

I dunno, every side of this seems right. But, the intake manifold is the pressure before it goes into the pistons....so wouldnt it be more consistant? Its the last place boost is.

When all things are working as they should (no leaks, spikes...etc.), there should be no inconsistencies between the compressor and the intake manifold because it's a closed system, only difference is the normal pressure drop due to cooling by IC. It is when things don't operate as they should, the advantages of the compressor kicks in, especially in the case of boost leaks.

 

[Deathmug]

Thank you, everyone, for your input.

Correct me if I’m wrong here:
If I’ve got my boost gauge source from the manifold (the last place to measure boost before it enters the cylinders), and the MBC source at the compressor housing (shortest root for tubing to reduce chance of boost spike), than inconsistencies in boost pressure due to pressure drop or whatever wont really matter. I say that because I’ll still be reading accurate boost on my gauge. I'll still be able to achieve desired boost by adjusting the MBC.

I could see how it would matter on an electronic boost controller, but not a MBC.

Am I right?

 

[oldman]

I could see how it would matter on an electronic boost controller, but not a MBC.

It shouldn't make a difference between EBC or MBC.

Am I right?

That is the common wisdom and exactly what I was trying to say however obviously h3o disagrees. Keep it on the compressor for now and try the BOV line if you run into any boost inconsistencies, keep us posted.