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Old 08-14-2009, 02:49 PM   #1
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Default Begi 7psi adjustable short bent arm turbo actuator

Has anyone been able to get the 7psi actuator from BEGi to hold more then 12 psi up to red line? I've tried a couple of boost controllers now (Gizzmo MS-IBC and AEM EMS Boost Controller [GM Solenoid]) with no luck. It'll carry 14psi to about 4500 rpm, and then drop to less then 12 up around the 6000rpm point. I know with my friends Greddy setup he couldn't get the stock one past 9psi (would mad boost spike early, and then drop off), and the only way he fixed it was to mount a HKS wastegate to it and then he pretty much had full control with his boost controller.

Thanks folks
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Old 08-14-2009, 02:56 PM   #2
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It has nothing to do with external boost control. The spring in the can is too weak to hold the pressure in the turbine housing from blowing open. You should never run more than 2x the boost of the spring in the can. Same applies to ewg as well.
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Old 08-14-2009, 02:57 PM   #3
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I assume you have connected your boost controller's inlet terminal to the stock nipple on the compressor? Remove it, put a cap on that nipple, and install a new nipple in the pipe between the intercooler and the throttle body.

The dropoff in boost you are experiencing is likely caused by the fact that the pressure drop across the intercooler increases as flow (volumes per unit time) increases. IOW, for a given MAP, flow (and therefore pressure drop) across the intercooler increases with RPM. You are regulating the pressure before the intercooler instead of after it.

I run 15 PSI on a 6 PSI can. Rock solid.
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Old 08-14-2009, 02:59 PM   #4
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Joe, do you have a helper spring?
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Old 08-14-2009, 05:19 PM   #5
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Quote:
Originally Posted by Joe Perez View Post
I assume you have connected your boost controller's inlet terminal to the stock nipple on the compressor? Remove it, put a cap on that nipple, and install a new nipple in the pipe between the intercooler and the throttle body.

The dropoff in boost you are experiencing is likely caused by the fact that the pressure drop across the intercooler increases as flow (volumes per unit time) increases. IOW, for a given MAP, flow (and therefore pressure drop) across the intercooler increases with RPM. You are regulating the pressure before the intercooler instead of after it.

I run 15 PSI on a 6 PSI can. Rock solid.
Hmmm, that makes a ton of sense. It's a small turbo, with 2.5" intercooler piping and of course the intercooler. I'll drill and tap a new nipple on the cold side pipes.

Thanks folks, will keep updated with results.
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Old 08-15-2009, 07:02 PM   #6
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Ok well I installed a new reference in the other side of the charge pipes (after intercooler), and there was no difference except it spiked a bit. Then I suddenly realized I'm an idiot, and that the only thing I moved was the point for the solenoid. My AEM uses the MAP sensor to run the car and measure the boost, and it's plugged into the back of the intake manifold.

Anyways, I think it's just a weak wastegate. I changed my boost settings in the AEM to be by TPS/RPM, told it to run max boost in the higher RPM where it was dropping off, and then increased the wastegate duty in that area as well. All in all, it appears to be functioning quite well now, but sort of sketchy in my mind.

NOW, does anyone know what a good replacement for the short bent arm actuator would be? I'm trying to figure out what turbos/cars came equipped with this actuator so I can track down a few.
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Old 08-15-2009, 07:06 PM   #7
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Quote:
Originally Posted by dustinb View Post
Then I suddenly realized I'm an idiot, and that the only thing I moved was the point for the solenoid. My AEM uses the MAP sensor to run the car and measure the boost, and it's plugged into the back of the intake manifold.
Sorry, didn't realize you were still running EBC. Before you do anything else drastic, why not try an MBC, sourced from the new nipple you installed?


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Joe, do you have a helper spring?
No. I tried that first, and all it did was raise the baseline pressure. It still had the same dropoff. In my case, this was not caused by a weak wastegate can, but simply by taking the boost reference from a stupid place. (And by a cheap tube-n-fin IC that probably has a higher ΔP than most of y'alls.)
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Old 08-15-2009, 07:07 PM   #8
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BEGI sells a 15psi one, thats what you need if you are running that much or more.
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Old 08-15-2009, 07:21 PM   #9
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Thus far, it just hasn't been a problem for me ever since I relocated the signal source. I'm rock-solid at 15 PSI with a MBC and a 6 PSI can.
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