Manual BC function; questions ??

[raf702]

I'm a bit confused on the manual boost controller function. Say the stock wastegate on the T25 is preset to ~7-9psi. Then adding an MBC to increase boost, how does it allow the wastegate to accept more psi?

Cause I'm currently using a ball and spring type MBC(homemade). As I turn the knob of course, it tightens the spring towards the steel ball, which closes up the channel of airflow. As it get's tighter I know it'll increase more boost. And loosening it to decrease boost, but how does the air flow create more boost then the preset psi? When going through the MBC and to the wastegate.

And what about adjustable wastegate actuators. Such as the HKS version when set to the minimum or max psi. Could using an MBC still override the amount of psi that is already set when adjustments are already made with the actuator rod?

Thanks for everyones input/opinions.

[HYPNOTIK]

I'm a bit confused as to what you're asking? Are you trying to run less boost than your wastegate spring? The boost controller only restricts the flow of air to the wastegate so it "sees" less boost and opens later. You can't run less boost than the spring in your wastegate. With a adjustable wastegate actuater you can, but not with the MBC.

[Sileighty_85]

YEAH OKINAWA!!!

But yeah hypnotik said it

more air going to W/G= Less boost (less spring pressure on ball bearing)
Less Airl going to W/G = More Boost (lstrong spring pressure on ball bearing)

I didnt really read the thread so im hopeing im on the right tack
mmmm Beeru...

[raf702]

Sorry if I confused any of you. I'm trying to run more boost then the wastegate spring. I assume that I just keep tightening it so that it increases pressure to the ball bearing?

[lightsource]

YEAH OKINAWA!!!

But yeah hypnotik said it

more air going to W/G= Less boost (less spring pressure on ball bearing)
Less Airl going to W/G = More Boost (lstrong spring pressure on ball bearing)

I didnt really read the thread so im hopeing im on the right tack
mmmm Beeru...

wow... i had no idea, that makes sense though.

[drifter_for_life06]

Sorry if I confused any of you. I'm trying to run more boost then the wastegate spring. I assume that I just keep tightening it so that it increases pressure to the ball bearing?

you are correct

[s14_mike]

on my mbc it has a + and - and than an arrow for rotation.
+ = letting more air through to the wastegate which means less boost.
- = letting less air through to the wastegate, in sense restricting air flow, which means more boost.

[sirfallsalot243]

Hate to bring back an old thread, but this is what I found most closely related to what I searched.

I understand that the wastegate setting is your minimum boost, and boost can be raised with either an MBC or an HKS actuator. My question is, what are the pro's and cons of each? It seems like they basically do the same job, the HKS is just able to raise and lower the boost as you want, where as an MBC can only raise it higher than the stock (or current) wastegate setting. So by and large, the vast majority of us are trying to raise the boost. So why is the HKS actuator in such higher demand than an MBC? Or why would people pay $100 for the HKS actuator when a $20 MBC does the same job?

Thanks for any help.

[fliprayzin240sx]

Its all a matter of preference...

[jspaeth]

Hate to bring back an old thread, but this is what I found most closely related to what I searched.

I understand that the wastegate setting is your minimum boost, and boost can be raised with either an MBC or an HKS actuator. My question is, what are the pro's and cons of each? It seems like they basically do the same job, the HKS is just able to raise and lower the boost as you want, where as an MBC can only raise it higher than the stock (or current) wastegate setting. So by and large, the vast majority of us are trying to raise the boost. So why is the HKS actuator in such higher demand than an MBC? Or why would people pay $100 for the HKS actuator when a $20 MBC does the same job?

Thanks for any help.


No no no no no.

You cannot run less boost than the wastegate spring itself.

[sirfallsalot243]

No no no no no.

You cannot run less boost than the wastegate spring itself.

Right- thats what I'm saying. Not sure where the "no's" are coming from since were in agreement... The wastegate setting is the LOWEST boost you can run. If your wastegate is set at 7psi, you cannot run 4psi. But with an MBC, you can run 10psi if your wastegate is set at 7.

So basically, the HKS actuator can RAISE AND LOWER boost, whereas an MBC can only RAISE boost. Correct? Are there any other differences that warrant the $80 difference in price?

So again I ask, when one is attempting to run any boost level other than stock, which is preferred- the HKS actuator or an MBC and why?

fliprayzin240sx says its a matter of preference- preferences are usually based on personal opinion after learning the pro's and con's of each. I'd like to learn the pro's and con's so i can make an educated decision on which to go with. Just saying "its personal preference" does me no good... If i wanted to take a shot in the dark and just pick one, I wouldnt have asked to begin with.

Edit.. i think i misunderstood. After rereading, i feel like youre saying the HKS actuator cant lower boost below factory wastegate settings? If thats the case, than an MBC does the exact same thing as the HKS? Then I REALLY dont understand why people would spend the money on the HKS actuator. The do the same job... one costs 5x as much. There have got to be pro's and con's of each...

[jspaeth]

Right- thats what I'm saying. Not sure where the "no's" are coming from since were in agreement... The wastegate setting is the LOWEST boost you can run. If your wastegate is set at 7psi, you cannot run 4psi. But with an MBC, you can run 10psi if your wastegate is set at 7.

So basically, the HKS actuator can RAISE AND LOWER boost, whereas an MBC can only RAISE boost. Correct? Are there any other differences that warrant the $80 difference in price?

So again I ask, when one is attempting to run any boost level other than stock, which is preferred- the HKS actuator or an MBC and why?

fliprayzin240sx says its a matter of preference- preferences are usually based on personal opinion after learning the pro's and con's of each. I'd like to learn the pro's and con's so i can make an educated decision on which to go with. Just saying "its personal preference" does me no good... If i wanted to take a shot in the dark and just pick one, I wouldnt have asked to begin with.

Edit.. i think i misunderstood. After rereading, i feel like youre saying the HKS actuator cant lower boost below factory wastegate settings? If thats the case, than an MBC does the exact same thing as the HKS? Then I REALLY dont understand why people would spend the money on the HKS actuator. The do the same job... one costs 5x as much. There have got to be pro's and con's of each...

Hate to bring back an old thread, but this is what I found most closely related to what I searched.

I understand that the wastegate setting is your minimum boost, and boost can be raised with either an MBC or an HKS actuator. My question is, what are the pro's and cons of each? It seems like they basically do the same job, the HKS is just able to raise and lower the boost as you want, where as an MBC can only raise it higher than the stock (or current) wastegate setting. So by and large, the vast majority of us are trying to raise the boost. So why is the HKS actuator in such higher demand than an MBC? Or why would people pay $100 for the HKS actuator when a $20 MBC does the same job?

Thanks for any help.


The way that you wrote that made it sound like the MBC can only raise the boost above the wastegate pressure whereas the HKS can either raise OR lower it compared to the wastegate pressure.

The fact is, you cannot lower the boost below the pressure dictated by the wastegate alone.

[sirfallsalot243]

The way that you wrote that made it sound like the MBC can only raise the boost above the wastegate pressure whereas the HKS can either raise OR lower it compared to the wastegate pressure.

The fact is, you cannot lower the boost below the pressure dictated by the wastegate alone.

Yeah, thats what I thought until i edited my last post. I thought the HKS allowed you to set your wastegate pressure at whatever you wanted, but i understand now.

Okay. Now were on the same page. So with just an HKS actuator i can run a minimum of stock 7psi, but can be turned up until the turbo is running out of air. And the same can be done for an MBC.

So essentially, they DO do the same job. So now that we've cleared up the functions of each, what about the pro's and con's? Which is better and why? One adjusts the boost from the turbo itself, the other via a vacuum line... does it not matter which is used? Is one considered more "legitimate" than the other?

[jspaeth]

Yeah, thats what I thought until i edited my last post. I thought the HKS allowed you to set your wastegate pressure at whatever you wanted, but i understand now.

Okay. Now were on the same page. So with just an HKS actuator i can run a minimum of stock 7psi, but can be turned up until the turbo is running out of air. And the same can be done for an MBC.

So essentially, they DO do the same job. So now that we've cleared up the functions of each, what about the pro's and con's? Which is better and why? One adjusts the boost from the turbo itself, the other via a vacuum line... does it not matter which is used? Is one considered more "legitimate" than the other?


Um....kind of.

Even with an EBC or good MBC (still kinda shitty), there is a limit to how reliably you can control boost at very high levels.


You want a wastegate spring that is at least in the ballpark of what boost you actually want so that you aren't asking so much from the boost controller.

[sirfallsalot243]

Alright. Im planning on running a redtop with a gt28r and a rom tune. Not really sure what kind of power im gonna be looking for, but ill probably be only running around 10lbs for now. So an MBC is considered kinda shitty... would I be wasting my money on the HKS actuator to be only running 10lbs? Im sure Ill end up turning up the boost eventually, but for now even stock 7lbs with the t25 would be a huge improvement over my bone stock KA. Whats the ideal way to raise the boost to higher levels?

I've got my motorset and I'm currently gathering parts to complete the swap before I install it. Im getting the gt28r for $200, so its really tough to decide whether i should get the tune, injectors, and maf, and do that straight from the get go, or if i should put it in with the t25 and stock ecu first. I'd like to "do it once do it right" but it seems like its gonna be a race against the clock, as my main seal is leaking like a siv on my KA, and Im praying itll last me long enough to get the SR in.

[DALAZ_68]

every MBC ive dealt with has leaked horribly...boost creep is something i wouldnt want to deal with...just sayin

personally im just gonna be crazy and run my HKS EBC, and HKS Actuator...im only running 12psi, but, safer than sorry is now my game...

[g6civcx]

I'm a bit confused on the manual boost controller function. Say the stock wastegate on the T25 is preset to ~7-9psi. Then adding an MBC to increase boost, how does it allow the wastegate to accept more psi?

Cause I'm currently using a ball and spring type MBC(homemade). As I turn the knob of course, it tightens the spring towards the steel ball, which closes up the channel of airflow. As it get's tighter I know it'll increase more boost. And loosening it to decrease boost, but how does the air flow create more boost then the preset psi? When going through the MBC and to the wastegate.

And what about adjustable wastegate actuators. Such as the HKS version when set to the minimum or max psi. Could using an MBC still override the amount of psi that is already set when adjustments are already made with the actuator rod?

Thanks for everyones input/opinions.

The wastegate is a mechanical actuator. The stock wastegate is designed to operate on boost pressure. When the turbo hits a certain pressure, the wastegate opens and exhaust gas is diverted around the turbine so you don't have overboost.

Since the wastegate is a mechanical device, theoretically as long as you supply the threshold boost pressure to the wastegate pressure port it should activate and bypass exhaust around the turbine.

This is pure theory. You can have an electronic wastegate activator, or you can even have an air pump to supply pressurised air to the wastegate when you want to stop boost. As long as the wastegate sees the boost it will open.

In practise though it's not as simple. It's very hard to realy control bost at the precise leel you're looking to do. Read the comments above and ask if you have questions.

[lazysk8er2]

i dunno about your preference guys but i enjoy my hallman mbc its been pretty good to me so far.

[!Zar!]

There is a difference between running a MBC and an actual wastegate like the HKS one, is that the MBC seems to boost creep more so than an adjustable HKS unit.

The HKS unit holds a lot better than a MBC could with increased boost.

Because if the logic of them both being the same would result in no need to buy an aftermarket wastegate, and everyone would just run a MBC.

Best bet is to run both really. A wastegate, and something like an avcr.

[jspaeth]

MBC generally are substantially sub-optimal.


If you want to hit a certain "max boost", you dial it in at a certain level, which sometimes leaves your spool up (3000-4500 RPM range) sub-optimal.

If you try to set it so that you get the optimal spool up characteristics, you will probably overboost on the topend.

Thus, the beauty of EBC (and particularly, those that have RPM-based solenoid duty), so that you can effectively achieve whatever boost you want at any RPM.