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Engine Specific Info and Questions => IDI Engine => Topic started by: AAZTristar on May 19, 2015, 11:50:33 am

Title: Best type of MBC for K-14 turbo/AAZ engine
Post by: AAZTristar on May 19, 2015, 11:50:33 am
I want to add a manual boost controller to my AAZ converted Vanagon Tristar truck. I bought a nice ball and spring type boost controller, but while reading some other posts came across a reference that the older KKK K-14 type turbos should use a bleed type MBC. (something about the waste gate needing a flow of air for cooling vs being totally blocked by ball/spring?)
Is this correct? And what would happen if I did use the ball/spring type MBC?

I currently have a Giles super pump, external oil cooler setup, the BOV is blocked, and have a boost gauge that shows the truck running at 11-12 psi max. I would like to bring it up to 15psi for now until I build an air/water intercooler setup.
Also, the truck still has the JX intake manifold from the original engine. Will I be able to use a AAZ intake and still use the JX turbo and exhaust setup?
Any help on these questions will be greatly appreciated!
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: 745 turbogreasel on May 19, 2015, 11:44:52 pm
On my ball and spring controller,I put a dent in the  ball seat for the cooling air to leak by.  It worked as intended on the first try.
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: jmaddocks on May 20, 2015, 07:03:32 am
The bleed isn't for cooling air - it simply enables air to escape the WG diaphragm.  Without it, air gets trapped in the diaphragm even as boost decreases, causing your WG to stay open.   ;)

I ran a Dawes MBC for a while on one of my cars.  It has the bleed valve.  www.3barracing.com
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: vanbcguy on May 20, 2015, 07:22:53 am
The K24 does actually have a bleed built in to the wastegate can which is supposed to be for cooling. The K24 also has the wastegate actuator mounted directly to the turbo hot side. Theoretically using a ball and spring style controller with a K24 isn't the best idea, but I ran mine like that for a long time.

The K14 however has its wastegate actuator remotely mounted I believe. That makes the whole thing moot, no cooling is required nor does the actuator have a bleed built in.
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: libbydiesel on May 20, 2015, 08:19:36 am
The VW K14s have the same wastegate actuator design as the K24.
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: vanbcguy on May 20, 2015, 09:47:39 am
Gotcha.  So then yep, it likely has the same bleed setup.
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: 745 turbogreasel on May 20, 2015, 12:48:33 pm
My VAG T3 on  the Volvo has the  same "KKK" design.  Boost control was erratic and spiky till I 'engineered'  the  leak into it.
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: jmaddocks on May 21, 2015, 06:00:17 am
Hmm...I'd never heard about the cooling air before.  Learn something new every day I guess.   :)
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: AAZTristar on May 21, 2015, 09:40:46 pm
Been camping. Thanks for the replies.
So…., to create a bleed path through a ball/spring type MBC I just make an indent in the face of the ball seat? How large?

Any help on the intake question?
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: 745 turbogreasel on May 22, 2015, 02:34:12 am
didnt take much, maybe like the  lead of a mechanical pencil.
Title: Re: Best type of MBC for K-14 turbo/AAZ engine
Post by: RabbitJockey on May 22, 2015, 04:52:04 am
u can also drill a tiny hole, theres lots of info for it online.