MBC Options and opinions

[noone]

I've bought myself a MBC with the idea of using it inline with the N75 to hold a little boost before the N75.

My idea is to aleviate the action of the N75 in the low boost (will see what works best, but only looking to hold the first 5-10 psi with MBC) and then let the N75 do the rest.

Why: help the turbo build boost quicker than the ECU wants by restricting the flow to the N75, thus stopping the N75 opening the wastegate.

How: As desicribed above (likely MBC between charge pipe and N75), coupled with removing the N249 (already done).

This has been discussed a lot of Vortex, but I wanted to know if anyone here has tried or has opinions on this.

There is a new option to me I have not seen, in this thread.

Here is a pic from the thread:


Don't really understand how diverting boost back to the manifold would help, or if this setup requires a specific MBC... Looks like the vac is being used to help open the MBC (simiar to how the Diverter works).

Time and testing will tell, my main concern is not stopping the operation of the wastegate once reasonable boost has built (thus not bypassing the N75 all togeather).

[noone]

No one?

ok, well, i put it on last night and did a little driving. with the MBC on a soft setting there was pretty much no percievable difference.
I wound it up tighter and boost is coming on like a brick wall. There can be a little jerkyness coming off partial throttle and a little part-throttle surging, but overall, pretty good.

Have done some scan / logging, no codes from this. When I can do some propper logging, I'll post again.

[vwthunder]

I have a manual boost controller which i got a few months and haven't got around to putting it on

I was going to run it to bypass the N75, I have read to just leave it plugged in and use the MBC instead, I dont know about using both of them

I only have a spike of about 18psi, would like to see about 22 like it was when i got the car with the "bunnings tap"

[noone]

Have a read on Vortex, there are a lot of discussions about the options.

The main issue with MBC only, is that boost is either on or off, making slow boost impossible and overboost common.

[vwthunder]

I will have a try of both when i have the time

Can you get some pics of your setup

[Catfish]

X2. Love some pics if possible.

[Guy_H]

This is the only one I have personally seen work really will with the stock N75 valve:

Modshack | Stage 3 Boost Machine

[noone]

Looks pretty swish.. I'll have to get my head around how that one works.

i think using the MBC to hold the first 5-10 psi is a good idea as this brings the boost on like I've not heard before in my car, but its not going to hold the boost any better at the top end. This was not my goal, I like using the Mid range torque rather than high revs.

will post some photos and maybe logs over the weekend.

[noone]

On the right is the MBC (I bought an ebay spring / ball type MBC).

I've been playing with it to get it to hold a reasonable amount of boost without making the throttle response jerky. Quite happy with the increased boost, I'd say it comes on 30% faster.

Pretty basic setup.

There are some other photos coming but are destined for the SAI bypass thread.

[Dscott]

Hey man,

How is this setup going for you?

Does this help maintain boost after the intial peak? i havent got a boost gauge yet, but after the revo tune, i feel my boost comes on hard probably 13psi until like 4000rpm then tappers off to like 8... Could the MBC also, hold the intial boost of 13psi all the way to readline?

D

[noone]

There are many ways to run the MBC, i'd recommend some reading in the 1.8t section on Vortex.

My setup is great for me, boost comes on strong and fast, but after the initial surge is regulated by the N75 as per stock.

Doing it this way I am not controlling peak boost. The problem with running a BMC only is the throttle response can become very jerky, if I wind my MBC too high, the car is uncomfortable for normal driving.

Lots of options, cheap to test, just go slow as you will change parameters the ECU is not initially expecting.

A MBC won't be much help with holding the boost into higher revs, that is an issue with the turbo's flow. My boost is probably at 90% by 3k rpm, so I don't feel the need to redline it, if anything the Bmc in this configuration probably makes the boost roll off earlier.

On the up side, the torque at 3k has never been stronger.