Boost Gauge

[1stRaven]

Originally Posted by gpl1968

Surely that would only be true for a 'bleed valve' type mbc.
With a 'ball & spring' type mbc, it is effectively a pressure relief valve, only opening above a set pressure. It also works as a non-return valve when the boost pressure drops below it's threshold. For the return air to pass back into the turbine housing, there would be an open circuit, rendering the mbc useless, unless the return line incorporated a one way valve.
My first mbc had a pinhole on the 'actuator' side of the valve.
My current mbc is more sophisticated and only vents (again on the 'actuator' side) when the valve is closed, so not wasting boost pressure.

As I said, it does depend on the type of valve.

I would say most of the valves on ebay will be a type of bleed valve, either without a ball and spring (basically a hole in which air escapes, meaning more boost is required to overcome this 'leak' and kick in the actuator), or with a ball and spring, blocking the hole until the boost pressure pushes the ball back past it, releasing some pressure through the hole. The second type of valve is better as it allows boost to build quicker but has a return/release valve built in.

I've not used a straight ball and spring valve so cant really comment on those.

[Profpriv]

Thats it exactly, GPL, except that they sent me a nice length of YELLOW silicone hose!!


Any way, I wish I could get the hang of posting images like this.It cant be that difficult- can it??



But i was pointed in this direction by Des, CTC Network.Surely he cant be wrong??


And there is definitely no hole in it that I can see.
Shaun

[gpl1968]

If you are posting a pic from another website, right click on the pic and select 'copy image address' from the pop-up menu. In the message pane, when you want to use the pic, click on the picture icon and paste the image address when prompted. Voila

If you want to post your own pics upload first to Photobucket or similar. You can then paste the provided image code directly onto the message pane.

[Profpriv]

Thanks GPL.

Now back to the MBC??

[gpl1968]

Originally Posted by Profpriv

Thats it exactly, GPL


And there is definitely no hole in it that I can see.
Shaun

As it is a bleed valve, it doesn't need a hole as it is constantly bleeding air to the atmosphere anyway(the pipe in the pic leading to 'engine bay').

As opposed to the ball & spring type of mbc that I have, with which you choose the pressure at which the valve opens and consequentially the maximum boost pressure, with the bleed valve set up as per the diagram, you are controlling the rate at which air is leaking from the system.
The faster you allow the air to bleed out, the greater the difference between the actual boost pressure and the pressure at the actuator and the higher the maximum will be.

When I was researching this subject prior to buying an MBC, the majority of information I could find suggested that the 'ball & spring' pressure relief valve type of MBC was the safest and easiest to set-up, type of MBC.
There is plenty of discussion on the Turbobricks forum on the subject.

[Profpriv]

Yes there is, and I thought I was buying a ball and spring type mbc.

[740T]

Sounds good, I'm looking for a decent guage, would you mind posting a link?

Cheers,
C

[Profpriv]

Hi 740 T. these TIM gauges are currently listed on Ebay at £25.99- one or two bar depending on your requirements.

To have the inlet manifold nipple in the box has to be worth it!!



300421998687 Ebay - One bar gauge




380229060918 - Two bar gauge

[1stRaven]

Just merged all of the boost gauge threads together so all of the info is in one location.

[rabbitwoman1977]

can anyone suggest where i can purchase a boost gauge and pillar pod to fit my 1997 v70r?
thanks