MBC users... Drawbacks of increasing boost using an MBC?

[bast525]

Been considering putting a boost controller, boost gauge and boost cut defender in my car, but had a concern or two.

My last car was also factory turbocharged with a relatively small turbo, and one of the first things I did for more power was install a means to turn up the boost (actually a wastegate actuator with a much tighter spring than stock). It was initially set up like the MS3... stock wastegate actuator had a weak spring, but then a solenoid would bleed off some of the boost pressure signal going to it to raise and control the boost.

the big drawback I found after installing the new WGA was that, since the turbo was so small, once I took control away from the computer, the turbo would spool way too easily... at low RPM and low throttle opening, which would cause it to go into surge. This was audible as a 'flutter' sound and also the car and boost gauge needle would shake. I had to learn to drive around this by either driving with very light throttle, or full wide open throttle. Also i could not floor the throttle until at least 3000 rpm. It sucked, and after a short time I decided it wasn't worth the power and went back to stock.

So... since the speed also has a small turbo I was guessing that the same thing would happen. But i haven't seen anyone here talk about this. So for anyone running an mbc, can you tell me if there is any similiar sort of problem with the MS, getting too much boost too soon and getting any kind of flutter, surging or other odd behavior?

Any info would be appreciated!

 

[laloosh]

subscribing cause i am in the same boat as you

 

[bast525]

man don't think it will do you any good....

Kinda hard to get good answers here for some stuff no?

 

[ssinstaller]

There really isn't any need ofr a boost controller on this engine, as you open up the intake and exaust you will run higher boost levels. I don't have an aftermarket boost controller, but I spike to about 20 psi and hold almost 17~18 psi to 6000 rpm...

If you really have to have some form of direct boost control just order the Standback from CP-E, you tell it what boost you want to run (in actual PSI) and it gets you there as fast as possible and holds it there..

 

[speedi3]

Been considering putting a boost controller, boost gauge and boost cut defender in my car, but had a concern or two.

My last car was also factory turbocharged with a relatively small turbo, and one of the first things I did for more power was install a means to turn up the boost (actually a wastegate actuator with a much tighter spring than stock). It was initially set up like the MS3... stock wastegate actuator had a weak spring, but then a solenoid would bleed off some of the boost pressure signal going to it to raise and control the boost.

the big drawback I found after installing the new WGA was that, since the turbo was so small, once I took control away from the computer, the turbo would spool way too easily... at low RPM and low throttle opening, which would cause it to go into surge. This was audible as a 'flutter' sound and also the car and boost gauge needle would shake. I had to learn to drive around this by either driving with very light throttle, or full wide open throttle. Also i could not floor the throttle until at least 3000 rpm. It sucked, and after a short time I decided it wasn't worth the power and went back to stock.

So... since the speed also has a small turbo I was guessing that the same thing would happen. But i haven't seen anyone here talk about this. So for anyone running an mbc, can you tell me if there is any similiar sort of problem with the MS, getting too much boost too soon and getting any kind of flutter, surging or other odd behavior?

Any info would be appreciated!

I'm subscribing too.. I just ordered the MBC and hadn't heard about the concerns. I hope that we don't have that problem.

 

[crashkelly]

MBCs are pretty much crap all the way around...there are very few reliable ones that do not spike. EBC is the way to go if you want to turn up the boost and even if you go that route dont get too boost happy or you shoot a rod through the block. Personally I think its a waste to turn the boost up with little or no mods. Get some supporting mods first then start messing with the boost...remember that jacking up the boost isnt always a instant source of power...in fact you can run into fuel/spark cuts, hesitation, and you could ruin your AFRs. Make power on stock boost and then you get the satisfaction of knowing what kind of power your other upgrades make and then if you determine you need more boostdo it the right way.

 

[pHeeL tHiZ ViBe]

lol...no a manual boost controller will not cause any flutter, nor will it cause it to spool up any 'easier'.

the MBC does not replace your WGA, which is what your problem was with your other car. nor did your problem have anything to do with it being a small turbo.

the MBC will 'deceive' your stock wastegate into opening at the desired boost level. it does so by altering the amount of vacuum in the vacuum line that connects directly to your stock wastegate.

it will spool, and sound as it did before..only with more boost.

you will not be able to pull more than 17psi efficiently with a stock turbo, but you can get more boost than 17 if you want. the stock turbo is just pushing its efficiency around 17psi, +/-1psi of course.

 

[laloosh]

My boost guage comes in tomorrow. Once i get it working properly the mbc is going in. I simply refuse to believe that an extra 2lbs of boost will harm anything lol. Af ratios going to hell? We run sub 10s stock. I would love for them to be leaner, but it most likly will not happen. MBC and atp fuel cut defender is the route im going. 17-18psi with whatever it spikes too. I see this being no different than poeple running bad mazdaspeed cais and spiking with downpipe mods. Some poeple are reporting 21-22 psi spikes on stock boost cause their intake a pos.

 

[BoostedSpd6]

i trust MBC'S but not for my speed 6 im waiting till CP-E comes out with the PnP and then hopefully i get good A/F's with the boost at 17 on the big turbo..along with my other mods that are going to help support the upgrade.. MBC is to risky for me id rather see it on the computer..

 

[laloosh]

why would you call a MBC risky. As long as you have self control it should be fine. But i guess im the opposite cuase i love mechanical things and hate electrical things lol

 

[pHeeL tHiZ ViBe]

i agree lol, this is my first car with any computer/electronics at all..and its so regulated, I'd almost prefer no ECU and a carburetor for some raw power lol.. almost ah haha.

 

[bast525]

First off, I have used MBC's a few times on other cars and never had a problem with them. A good ball-and-spring MBC will have minimal spiking and hold boost very nicely. I ran a ball-and-spring on my turbocharged 240z for over a year and had ZERO problems from it, and it only spiked about 1psi, it might spike as high as 2psi if I punched it in like 5th gear at a higher rpm... the turbo would spool so fast that the MBC couldn't react fast enough in those conditions.

Secondly, the issues I was talking about with spooling too soon and compressor surge had nothing to do with the wastegate actuator. That car was a Dodge SRT-4, and many people have experimented with different ways of turning up the boost on that car. Wastegate actuators with stiffer springs, manual or electronic boost controllers, putting a 'bleed' inline with the WGA signal hose to bleed off some of the boost signal... Almost all of these methods resulted in the exact same issue, which is commonly referred to as PTB or PTOB, a.k.a. Part Throttle Over Boost. Again, this happens because the turbo is so small that it will spool full boost at light throttle and low rpm without the ECU's control.

The turbo would DEFINATELY spool up faster when boost control was taken away from the computer. The computer would purposely slow turbo spool down at low throttle angles or RPM, allowing the full signal to be sent to the wastegate actuator, then once RPM or throttle got high enough, the ECU would bleed off some of the signal causing the turbo to spool to the full boost level (14-15psi in the case of a stock SRT-4).

As for the MS, we've already had one 3 owner run an MBC on a dyno and found that power 'maxed out' at 18psi... anything higher than 18 and he lost power. So there's at least a good 2 psi of extra 'headroom' for the MS3 it seems.

but this thread isn't about that... I'm just wondering if taking the boost control away from the ECU would result in PTB and compressor surge since it's a small turbo.

 

[pHeeL tHiZ ViBe]

k sorry, i must not be understanding fully.
the best solution to cure the flutter, sounds like it would be the cp-e ems though. since their standback controls the wastegate at 255 different degrees to maintain a more correct boost than any BC or even the stock ECU. no chance of flutter. just my thoughts, good luck

 

[speedi3]

First off, I have used MBC's a few times on other cars and never had a problem with them. A good ball-and-spring MBC will have minimal spiking and hold boost very nicely. I ran a ball-and-spring on my turbocharged 240z for over a year and had ZERO problems from it, and it only spiked about 1psi, it might spike as high as 2psi if I punched it in like 5th gear at a higher rpm... the turbo would spool so fast that the MBC couldn't react fast enough in those conditions.

Secondly, the issues I was talking about with spooling too soon and compressor surge had nothing to do with the wastegate actuator. That car was a Dodge SRT-4, and many people have experimented with different ways of turning up the boost on that car. Wastegate actuators with stiffer springs, manual or electronic boost controllers, putting a 'bleed' inline with the WGA signal hose to bleed off some of the boost signal... Almost all of these methods resulted in the exact same issue, which is commonly referred to as PTB or PTOB, a.k.a. Part Throttle Over Boost. Again, this happens because the turbo is so small that it will spool full boost at light throttle and low rpm without the ECU's control.

The turbo would DEFINATELY spool up faster when boost control was taken away from the computer. The computer would purposely slow turbo spool down at low throttle angles or RPM, allowing the full signal to be sent to the wastegate actuator, then once RPM or throttle got high enough, the ECU would bleed off some of the signal causing the turbo to spool to the full boost level (14-15psi in the case of a stock SRT-4).

As for the MS, we've already had one 3 owner run an MBC on a dyno and found that power 'maxed out' at 18psi... anything higher than 18 and he lost power. So there's at least a good 2 psi of extra 'headroom' for the MS3 it seems.

but this thread isn't about that... I'm just wondering if taking the boost control away from the ECU would result in PTB and compressor surge since it's a small turbo.

All that i want to do is limit the boost. Right now i spike to 20. I want to keep the boost level at say 15 until I'm convinced of the right EMS. Will a MBC do that? and hold it? I DO NOT WANT TO dial it up. I want to hold it back.

 

[bast525]

I just installed a boost gauge, but still no boost controller.

I can say that with only the MS CAI, I see spikes of 19-20 psi any time I floor the throttle in 4-6th gears. It spikes and then settles to about 16 psi.

So even on stock ECU boost control, you will see more than 15.6 psi.

I'll be installing the MBC hopefully next week and will see what happens.

And I agree, the CP-E would probably eliminate any flutter problem that was seen so commonly on the SRT-4 when people upgrade to the stiffer wastegate actuator

 

[laloosh]

its settles to 16 psi till what rpm. Mine spikes to 18-19 goes to 15-16 stays there for a little bit and then drops to 13ish

 

[speedi3]

If any of you have Auterra I can send you an acceleration run that shows: boost vs. rpm vs throttle position from 0-120 and just holding at a certain speeds. I'm not educated enough to get a proper read on what I'm seeing. I haven't gone too much over 120 since hitting fuel cut the first time.

 

[jcgemt2003]

Turning the boost up on the stock turbo 2psi wont change s***....youll never feel the difference...now if you turn it up to 20psi with an fuel cut killer than you should know a difference. The bad part about that is you dont have any controll over timing....and that is bad.

 

[bast525]

its settles to 16 psi till what rpm. Mine spikes to 18-19 goes to 15-16 stays there for a little bit and then drops to 13ish

It stays there up until pretty high RPM... around 5000 I want to say? It holds nice and steady from what I saw.

Quick spike to 19-20, hold 16 ish until at least 5k, then down to about 10psi by 6k.

 

[laloosh]

she my car comes nowhere close to running 16 psi near 5k rpm. Check out my video and tell me if you gauge does the same thing.

http://www.youtube.com/watch?v=e2AEZr3YFr8

btw my pos prosport reads -2 vac when everything is off