Dual MBC

[GhostMercury]

Well it came to me in a dream last night. But if i got 2 MBC's and put them both on the same line. (strait from manifold to wastegate) Set them at exactly the same boost level. Would i in turn be able to have a more steady boost with less to no boost spike. I would set them the same by counting the amount of threads on the screw "thing-a-ma-bob".

 

[Dpwhitehead1]

Well it came to me in a dream last night. But if i got 2 MBC's and put them both on the same line. (strait from manifold to wastegate) Set them at exactly the same boost level. Would i in turn be able to have a more steady boost with less to no boost spike. I would set them the same by counting the amount of threads on the screw "thing-a-ma-bob".

yeah that's a good idea.. subin for ideas.

 

[MSpeed2397]

Wouldn't that make the vac line longer though as to make response slower?

 

[Drumfreak]

Wouldn't that make the vac line longer though as to make response slower?

Doesn't a slower response usually equal less spike?

 

[MSpeed2397]

I dunno, I guess we'd have to look into what causes spiking. I'd assume quicker response = less spike. The reason people get an EBC is that there is less of a spike because of its quick response time. Or at least I would assume that this is the reason. If there is more of a delay then I would assume the boost would spike more than if the response time was quicker. I know that the amt. of boost is dependent on the vac pressure to the WGA. So if the vacuum pressure changed more quickly, then the WGA would respond more quickly (less spike).

 

[Drumfreak]

I dunno, I guess we'd have to look into what causes spiking. I'd assume quicker response = less spike. The reason people get an EBC is that there is less of a spike because of its quick response time. Or at least I would assume that this is the reason. If there is more of a delay then I would assume the boost would spike more than if the response time was quicker. I know that the amt. of boost is dependent on the vac pressure to the WGA. So if the vacuum pressure changed more quickly, then the WGA would respond more quickly (less spike).

I use response differently. To me response is lag. Less lag = better response. Thus more lag = less spike. That's my wierd thinking though. It's solely based on my experience. When my WG was f'ed and not fully closing the flapper there was a lot of lag but absolutely no spike. It went right to the set boost level and stuck there. As soon as I fixed my WG the spike was back because there was less lag or to me better respoonse from the turbo but bad response from the WG which isn't opening fast enough causing the spike. Wouldn't two MBC's cause a highly increased boost level. The turbo would have to push twice as hard to open the WG. I don't think it's a good idea but I would love someone to try it out to see what happens. Not it.

 

[djarkitek]

what is the biggest difference between this and some of the dual stage mbcs that are already out there? sorry not to sure on this subject...

 

[Drumfreak]

what is the biggest difference between this and some of the dual stage mbcs that are already out there? sorry not to sure on this subject...

Because there would be two seperate cut ins to the vacuum line from the mani to the WGA.

 

[GhostMercury]

Well i want to try this. but there is alot of technical words being thrown around. so, would this be a bad idea in general? or is it something that hasn't been tried?

 

[Drumfreak]

Well i want to try this. but there is alot of technical words being thrown around. so, would this be a bad idea in general? or is it something that hasn't been tried?

If your main goal is to get rid of spike then just find a used EBC for cheap or use a different MBC if yours spikes too much. I personally wouldn't want to be the guinea pig for an experiment like that. I'm not sure anyone has done this before.

 

[Kansei]

I really think this is exactly what a dual stage MBC entails.. I'd try it but to buy another one of my MBCs.. I could have just bought an EBC.

 

[MSpeed2397]

A dual stage MBC is basically 2 MBC, but not configured in this way. A dual stage is just 2 separate MBC's that you can switch between. Paint diagram on the way...

 

[MSpeed2397]

Essentially what a dual stage MBC is

Basically it will be like this for a dual stage MBC made of 2 MBCs (which is probably not a cost effective way of doing things btw)

 

[djarkitek]

well from what I've read i thought a dual mbc was sort of like the ebc's that have different boosts for different shifts so that you could get better traction in the first and second gears for things such as drag racing. Basically off the line you would hit about 7psi and then by 2nd gear you'd hit like 15 psi and then not just spin out. no??

 

[Kansei]

no, the dual mbc is controlled by an electronic switch, you'd have to flip a switch in 3rd gear to get the higher boost levels.

 

[BOOSTR]

You can flip the switch in any gear to activate the second stage of boost. I like my TXS unit. Making sure that your pressure and wastegate lines are free of kinks and as short as necessary can lessen the spike. My boost goes right to were I have it set at in each stage and holds it. Look at the tuning with Unichip, its got a built in spike. My point being that a spike is not necessarily bad. You just don't want any crazy spikes that will cause excessive force on the rods and bolts.

 

[Drumfreak]

You can flip the switch in any gear to activate the second stage of boost. I like my TXS unit. Making sure that your pressure and wastegate lines are free of kinks and as short as necessary can lessen the spike. My boost goes right to were I have it set at in each stage and holds it. Look at the tuning with Unichip, its got a built in spike. My point being that a spike is not necessarily bad. You just don't want any crazy spikes that will cause excessive force on the rods and bolts.

Spikes really mess up fuel curves. Mine is horrendous cuz it spikes to 12 psi while running 9 lbs. My overall hp number would be higher without the spike and the car would rev quicker. The spike causes a huge dump in fuel. Off the chart rich and it takes a while to lean out again. Unichip may compensate for it since it's built in but is the spike necessary or does their boost control module just suck?

 

[Blake]

Running it this way would cause MORE BOOST. It would not cause less spike. A boost controller works in this way. It leaks air causeing the wastegate to be fooled into thinking that full boost has not yet been reached. If you put two mbcs on and turn them both the same it would give you more boost. The only way to rid yourself of spike is to get an EBC that has spike control on it. Do not do this it is a bad idea and a waste of money.

 

[jeffmsp]

or to adjust your wastegate to desired boost levels. Its free and takes 5 mins. Or tap the intercooler piping before the intercooler for you wastegate vac source, then put the mbc on that line, should have very little spike if none.

 

[Drumfreak]

or to adjust your wastegate to desired boost levels. Its free and takes 5 mins. Or tap the intercooler piping before the intercooler for you wastegate vac source, then put the mbc on that line, should have very little spike if none.

Have you tried this method with success? And if yes how is turbo lag? More or less or same?