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Old 05-07-2002, 09:08 PM   #1
ac_gohan
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Member#: 1903
Join Date: Jul 2000
Location: Bay Area, I-Speed Tech
Vehicle:
2000 2.5 RS-T coupe
T3/04 Link'd 2 10 PSI

Default MBC suggestions

and yes, i did a search and all that came up was WRX crap. Im in the market right now for a MBC. The psi rating on my wastegate is about 5 right now, and i need more! Inexpensive and reliable are the 2 key words here. Thanks

Andy
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Old 05-07-2002, 09:18 PM   #2
kastle
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Do not use a MBC on a low boost application. You will blow up your engine.

You have been warned.
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Old 05-07-2002, 09:24 PM   #3
ac_gohan
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T3/04 Link'd 2 10 PSI

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why is that?
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Old 05-07-2002, 09:31 PM   #4
kastle
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The MBC is designed for higher boost applications. Like 12psi or above. Controlling 5 to 7 psi isn't very efficient with it. Then, while trying to tune it, you adjust it 1/100 of a turn, and your little 5psi application is 15psi and now your #3 piston is destroyed.

Ask Aaronb....

It's just bad news on a RS-T.... WRX, it's perfect
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Old 05-09-2002, 01:44 PM   #5
92SE-R
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Umm...no. MBC's are very reliable for even low boost applications. He must've gotten a ****ty one. You have one guy's experience with a MBC. Me and my friends, and thousands of DSM owners have had no problems with MBC's. So how do you figure? For 2 very good manual boost controllers, try Hallman or Joe P. www.boostcontroller.com



Terrin
92 SE-R
13.3@104 <--- 8 psi with Hallman
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Old 05-09-2002, 02:11 PM   #6
Jewbaru
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DSMs don't strike me as low boost applications.

8psi is a little touchy with a MBC, but they'll work, anything under 7psi it's recommended you use an EBC over an MBC.
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Old 05-09-2002, 05:11 PM   #7
subachad
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If you are going with a MBC, check out the Dawes Devices one. I've used it for a while and the only problem I have is the cheap hose that he sends with it. Put some real vacuum line on it instead and you should be fine. It is real touchy to set, but once it's set you are fine. Also, it will help a lot to set it so it doesn't raise boost at all, but it will allow the boost to come on much stronger. Check out Dabblers post as well.

Chad
93 1.8T
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Old 05-09-2002, 06:50 PM   #8
the Dabbler
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As subachad said, the Dawes Boost Controller seems to be working fine for me so far (5-6psi). And, as has been mentioned, it's not a traditional kind of MBC. It doesn't bleed -- it has a spring-actuated valve that functions much like the mechanical wastegate itself.
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Old 05-09-2002, 08:51 PM   #9
Graham
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How much does this unit cost compared to an EBC (AVC-R or Blitz SBC-ID...etc..)

Dabbler, what is your wategate spring spring set for and what is your MBC set for? This sounds like a good alternative to expensive EBC's.


Graham
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Old 05-09-2002, 09:04 PM   #10
92SE-R
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Both boost controllers in the link I provided are ball and spring boost controllers. Bleeder valve type boost controllers suck.

www.boostcontroller.com
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Old 05-10-2002, 02:52 AM   #11
AaronB
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I am not the only one who has had a bad experience with a MBC on a 5psi turbo setup. Scooby South and some of the others don't post much (if at all) anymore.

In the RS-T world we consider low boost to be 3-6psi typically. Manual boost controllers are too sensitive at these levels to be used with our incredibly fragile stock pistons. A few good pings (which can easily occur from just a 1 lb increase on our 9.7:1 or 10:1 motors) and your piston looses an ich or two from the outer perimeter, down to the ring land. We have far too many pictures we could show to demonstrate this.

Mine was a JoeP boost controller. When I bought mine I spoke with Joe via email and he wasn't sure if it would work well in a low boost setting (4-5psi). He thought it would. It turned out to be too sensitive to be of any use in this application. I believe that this is a good product, and Joe is a good guy. I don't blame him in any way for blowing up my motor. I took a chance that it would work and learned a tough lesson that it would not. It works great for those who run higher boost levels, as can be seen from the 1000's of DSM cars and the many WRX guys who use them. I even sold mine to a WRX guy who hasn't had a problem with it.

So IMHO I would NEVER use a MBC on an internally stock 2.5 RS-T. If you want to mess with the boost get a nice EBC, or just get a new wastegate spring.

Regards,

Aaron
http://www.AzScooby.com
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Old 05-10-2002, 12:50 PM   #12
the Dabbler
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AaronB --

I don't doubt your experience. I sincerely hope that I don't become a repeat of this.

But here is why I feel at least some level of confidence:

Similar to your response from JoeP, in an email, Darren Dawes expressed some confidence that his part would work for low-boost applications. He was, of course, not willing to guarantee that (and I would be very suspicious if he had).

The Dawes Device perhaps is different than the JoeP device, for whatever reason. My boost controller, for what it's worth, seemed to have a very fine boost level adjustment in the range I was looking at. That is, large turns of the barrel resulted in only very small differences in peak boost level (I have a peak hold gauge).

My testing so far has consisted of full-throttle runs, uphill, in every gear, plus two weeks of California highway commuting (typically 80+mph, again, uphill). Under these conditions, I have not yet experienced significant boost creep or boost spiking (again, I have an electronic peak hold gauge). While I believe this to be a heavy load, it is not, of course, the same kind of abuse that one would expect on a road race track. I have a track date in a few weeks -- hopefully I won't be towing my car home. Believe me, the first few sessions, I'll be keeping a close eye on that boost gauge and knock sensor activity gauge.

A disclaimer here that probably doesn't need to be said, but here goes anyway: I do not advocate the Dawes Device for any application. I'm using it in my vehicle, and so far have had good results. If anyone has a contrary opinion or experience, I certainly respect that.

My wastegate is a Deltagate, with a 5-7lb spring, set to the minimum level (which in my case is actually around 4psi). The MBC is currently set to 5psi.
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Old 05-10-2002, 03:26 PM   #13
92SE-R
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Aaron, please do not tell me you have a Deltagate wastegate. If so, therein lies your problem. Deltagates are notorious for boost spikes. A few SE-R guys have blown up their motors from these crappy wastegates.

Also, if you are blowing up your motor with 9.7:1 or 10:1 compression at less than 10 psi, you REALLY need to get some better fuel management. That is not that high of compression and VERY low boost pressure. It is all about TUNING. 9.5:1 compression SR20DE motors with stock internals(cast pistons) can run up to 15 psi on 91 octane California piss water with no detonation at all. With race gas and water injection, people have run 24 psi and gotten 400+ whp. STOCK INTERNALS. 9.7:1 is not that much more compression, and for that matter, neither is 10:1. 10 psi of boost SHOULD not be a problem for your motor, given you have the fuel to support it. TUNING.

Just because you had a Joe P MBC does not automatically mean that is what caused your motor to blow. Also, if you overadjusted the Joe P, that is not the fault of the MBC. Yes, me and my friend have had experience with the JoeP. It is very sensitive to little adjustments and is not linear. BUT, it is VERY reliable and never spikes. IMO, the Joe P and the Hallman are made out of the same unit that can be bought from Mcmaster Carr with the only difference being the adjustment valve. I have had absolutely no problems boosting only 2 or 3 extra PSI from my Hallman. Stock wastegate actuator is set at 6.5 psi. I am running 8 psi now. I will not hesitate at all to run 10 psi of boost.



Terrin
92 SE-R <--- stock internals, 141,000 original miles
13.3@104
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Old 05-10-2002, 03:36 PM   #14
kastle
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Aaron was using an internal wastegate at the time. He now has a Tial 35mm installed. It was 10.0:1 compression (MY00)
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Old 05-10-2002, 05:02 PM   #15
92SE-R
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What exactly blew the motor up? Did Aaron set the adjustment screw ALL the way down when he first put it on? I mean, if the Hallman works for me, there's no reason why it didn't work for Aaron considering its the same regulator valve as the Joe P one.



Terrin
92 SE-R
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