NITROUS OXIDE ( nos / n2o ) advice forum

I'm still having difficulty with a buzzing boost gauge, particularly at idle/off-boost.

I've been told a damper/restriction should sort the buzzing so I tried that and it did sort of work slightly but not enough - anyone know how small a bore I need? The gauge inlet is tiny already.

Update, removed both MBC and gauge, brought them indoors and fed them a battery powered air pump. Result? They both behaved admirably. Must be user error

mike, a small restrictor orifice works if you get the right size for the type/size gauge and pipework, go too small and you get lag that masks initial boost spikes,
before boost gauges were readily available we used 30psi bourdon gauges from a local refrigeration firm, if you just plummed them in they buzzed and the needle looked blurred,
i found using a fuel filter from a vauxhall cav sri inline with the gauge did the trick of damping the needle vibration without hurting the response of the gauges, still use one to this day on my old mityvac, not pretty but it works for me and it helps keep crud out of the gauge,

you could try moving your restrictor close to where its tapped into the intake to maximise volume after the restrictor.

i thought the Ts that come with the gauges usually have a restrictor built in?
the greddy, blitz and hks boost gauges ive used all have them in the T

i like the unorthodox filter mod bob using things for purposes for which they arnt designed should always be applauded

I'm so cheap I didn't get any hose or T's.
I've relocated the take-off to a post-IC hose instead of taking off the turbo compressor but it's made little difference. Next test is a small connector which I've filled with chemical putty and, when I get some micro drills, will experiment with different bore sizes.

you should really have the boost gauge connected to the manifold plenium

AFAIK, there's two schools of thought on this - those that want to know the turbo isn't exceeding it's specs and those that want to know how much boost is getting to the manifold. I originally went for the safe option but it's now getting the same signal the fuel pump is getting - which is just prior to the manifold.

but wont that mean the fuel pressure regulator isnt actually setting the fuel correctly?
its giving a rich mixture as it will always see turbo boost, even when the the throttle is closed?
but as i seem to be saying lots lately, what do i know??

As it's an IDI diesel there's no fuel regulator, just one big clever bosch mechanical fuel injection pump.

And also no throttle to be closed

dammit how am i supposed to know what everyone drives!
my bad bloody oil burners

LOL

i had that problem once.. bought a geddy that has a electronic map sensor so no tube inside the cabin.