new boost gauge
Turbo Mini Forums

I got my new boost gauge installed and now it reads in the minus area all the time. I've taken the advice to plug up all the hoses that were open and the car seems to run fine but the boost gauge always reads on the minus side. What could be wrong? Slobo

"Stick your foot in it"

i hope you have fitted the gauge to the ""pressure"" side of the turbo

if this is the case, then the gauge must be faulty
even new ones can be!

but please check your work again my friend

Have you done what i did and joined it ontop of the inlet after the one way valve? mine always read under 0 when i did that.

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

You need to tap it in to the inlet maniford so the gauge reads on and off the boost

1293 Turbo mini

Is it a Mocal one? I've had a faulty one myself.

Yes it is a Mocal one and I just plumbed it in exactly as the old one was. The old one always was in negative when idling but went to the plus side when going through the gears but this one never goes plus. But I did plug up two hoses that were open but went nowhere, The last one I plugged came out of the turbo right behind the carb on the drivers side(rhd) and went over toward the brake servo but not connected at the end to anything.Could that be the problem? Like I said, the car seems to run fine.

"Stick your foot in it"

When I fitted the old one back everything was fine...
Take a good blow at it with your mouth, I tried this, but still no boost.. Isn't Mocal supposed to be a good brand?
I'm sending mine back to Demon Tweeks...

Does it look like this:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...AMEWN%3AIT&rd=1

I just bougth this one to see if I've done something wrong.

Edited by Vegard on 26th Apr, 2006.

Yep, mine's exactly like that except white face and I paid Avonbar 25 UK pounds for it. Wish I had thought of Ebay. Hopefully this is not too stupid of a question but which is the "pressure" side of the turbo? This is all new to me.

"Stick your foot in it"

I must add, Avonbar gave me some extra advice along with the gauge so to me it was worth the extra few dollars. Slobo

"Stick your foot in it"

When the engine is running at low revs, say 2000rpm with the throttle wide open, it is sucking air into the engine. Therefore it creates a vacuum. By connecting your gauge to the inlet manifold, you can see this vacuum (NEGATIVE pressure) at this time. When the revs get high enough and the turbo comes on boost, the engine is now having air FORCED into it under pressure. So say at 4000rpm at full throttle you should be able to see the gauge read POSITIVE pressure.

Are you sure that the gauge is plumbed in directly to the inlet manifold? Make sure it is not connected to the one way valve sometimes fitted here to stop the turbocharger pressuring the brake servo.

If you don't have one I recommend the "HAYNES SERVICE AND REPAIR MANUAL" this has a good schematic diagram of how the turbo and intake system works.

Edited by Tom Fenton on 26th Apr, 2006.

Ok, it looks like it is plumbed into the top front of the carb and the hose goes to a tee with one side going to the gauge and one side going to a vacuum thing on the distributor. Is that wrong?

"Stick your foot in it"

Yes it will work from the vac pipe off the carb

1293 Turbo mini

So do you think it's a faulty gauge? And how about all these hoses that lead to nothing? Should they all be plugged up? Why have them just to plug them up?

"Stick your foot in it"

i tried plubing my dump valve trigger into the vac advance pipe before and it wouldn't work as its the wrong side of the butterfly.
Might be worth shifting your boost gauge take off onto the inlet manifold instead to know for sure if its a gauge or plumbing problem.

[quote=Tom Fenton,26/04/2006 15:18:31]
When the engine is running at low revs, say 2000rpm with the throttle wide open, it is sucking air into the engine. Therefore it creates a vacuum. By connecting your gauge to the inlet manifold, you can see this vacuum (NEGATIVE pressure)


blimey ,ive got about 3 psi boost at 2000rpm with the throttle wide open ..if you run it at 2000 rpm at neutral just holding the throttle open just enough you ll DEFINATELY get a good vacuum. regards robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM