Boost guage

[philip j]

I have recently installed this NHS boost guage, and brake booster vac hose. It accuratly measures exactly 1/2 of what the factory guage reads. When not in boost, the guage reads -0.5, and when at full boost reads 0.5. I have a 1 bar spring, and have no reason to belive the factory guage is incorrect. Whats up? thanks Philip

[1986911]

I have the same set up. The check valve in the brake booster is a little tricky to get back in. Maybe this is allowing pressure to escape?

[mooney265]

the picture shows it reading "0" - - when does it do that?

[philip j]

0 in the pic, when the car is turned off.

[mooney265]

when you rev engine to 2-3k [while sitting still] does the boost gauge go to "0"? or, stay at -0.5?

Also, you could test the unit with a mitey-vac/pressure...

[philip j]

The guage moves with RPM, and when in boost, only half the reading as the factory guage, all the way up the scale to full boost. Of course the factory guage does not register vacuum, what should the vacuum reading be at idle?

[GradyM]

I just bought the same gauge but mine goes to 2 bar and starts at 0,it doesnt have a scale for vacuum.When I'm on full boost my gauge reads .9 bar.Seems way more accurate than the factory tach one.I connected it the same way as well.Bit of a ***** getting in there for the connections though.

[GradyM]

I have a feeling btw that your gauge could have accidentally had the guts for my gauge but the face of yours that also reads vacuum.
I'd give them a call.

[Miguel Antonett]

I would check the gauge or just recalibrate it - first.

[philip j]

I don't have anything that will measure such a low reading. How would you go about re-calibrating it? Any home made contraptions I not thinking of ? Philip

[Miguel Antonett]

I was thinking more Palo Alto - cheap money.

[BlkBird]

Mine came from NHS too. Must admit the stock gauge in the tachometer shows me using boost far more than this vacuum powered version.