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Davezj
01-04-2009, 09:22 PM
Has anyone tested there MBC before fitting it?

i Have just bought an MBC i know how to connect them up and i have a boost gauge to tweek it on the car, so that is not a problem.

The one i have bought is a 2 pipe valve with a small hole in the boddy of the valve to release pressure.
It is a ball and spring type, take the screw valve end bit off, you then have a ball, spring, metal coller round the spring, ball at the bottom, is the normal?

me being me i thought i would bench test it before i fit it.

Testing:-

setup is a compressor with a regualetor controling the pressure with gauge to show boost pressure going up and down (i will call the Inlet Pressure=IP), connected to the MBC, then into a gauge to show what waste gate actuator pressure is (i will call this Wastegate Pressure=WP). all stated pressures will be in PSI

what happened would you expect to happen?

did an inital setup by setting the IP=12 and adjusted MBC to give WP=7.

IP=1,WP=0
IP=2,WP=0
IP=3,WP=0
IP=4,WP=0
IP=5,WP=0, Slight leak from hole in valve.
IP=6,WP=1, slightly more of a leak from hole.
IP=7,WP=2, slightly more of a leak from hole.
IP=8,WP=3, Leak inreases evry time the IP is increased.
IP=9,WP=4
IP=10,WP=5
IP=11,WP=6
IP=12,WP=7
IP=13,WP=8
IP=14,WP=9
IP=15,WP=10
IP=16,WP=11
IP=17,WP=12
IP=18,WP=13
IP=19,WP=14

exactly the reverse occurs when IP is reduced.

1. with the valve starting to open at IP=5 this will this make the turbo's to spool quicker will it not.

2. seams to be a linear response. But the air being released by the hole in the valve body is massive, or seams to be.

3. Now i presume that if the MBC was fitted to a turbo with a wastegate, when the wastegate opening pressure is reached (7psi ish) the inlet pressure would not have risen any more. with WP=7 would have given IP=12.

does this seam resonable, and how does it compare to others that have been tested.

MPBVr4
01-04-2009, 10:47 PM
I have tested one in a similar way but didn't tabulate any results. Interesting findings. I was a bit concerned by the leakage through the pilot hole as well:inquisiti.

Mark 4
01-04-2009, 10:53 PM
I have tested one in a similar way but didn't tabulate any results. Interesting findings. I was a bit concerned by the leakage through the pilot hole as well:inquisiti.

Hi Malc, did you post this up, do you have a link /

I am thinking that this is a bit like Hi Fi in the 80'S.

Buy the best individual components, connect them together and what do you have ?

A Mess !

Davezj
01-04-2009, 11:16 PM
did you get similar results?

what do you think to my test method, i don't see i have done anything obviously wrong in my test setup. but all comment are welcome.

this is how they are supposed to work isn't it.?

What would happen if i changed the spring for a slightly higher/lower spring rate. could get it to open later at say 10psi and still get the wastegate to fully open by 14psi

I was after doing some kind of in cabin boost control, what is the down side of putting the valve on long tubes in to the cabin. i would imagine response time would be fractionally slower. but all that air coming out of the vent hole and it would be so noisey. i might just set it in the cabin for setup. then relocate it back under the bonet. i am going to add some solenoid valve sto make the boost selectable.max boost standard boost and might even try and do a eco setting no boost.