Turbo 95 Mustang GT

[Spammy36]

Hey all, I’ve recently turbo’s my 1995 Mustang GT on a blow thru carb setup. I’m running into a pretty serious problem. I hear the turbo spooling, and can physically feel the difference in power, yet my boost gauge reads 0. I’ve already tested my boost gauge with an air compressor so I guess that rules that out, my boost reference line in coming out of the turbo compressor. I’m totally clueless to how it’s still reading 0.
Here’s the link to my cheapo boost gauge, maybe I’m missing something. LEVANLIGHT 2" 52mm Red Digital LED 30 PSI Turbo Boost Gauge with Boost Sensor Hose/T- Fitting for Boat Truck Car Modificine 2-1/16" 52mm https://a.co/d/0rm07ZJ

 

[pmuller9]

The gauge description say it reads from 14 to 29 psi.
I would take that to mean it won't start reading until 14 psi of boost?

What pressure was it reading with the air compressor?

 

[Spammy36]

The gauge description say it reads from 14 to 29 psi.
I would take that to mean it won't start reading until 14 psi of boost?

What pressure was it reading with the air compressor?

Holy crap how did I not see that, why would they make such a gauge??? With the air compressor it read around 30. On a couple super hard pulls it flashed to 6 so I’m very confused.. Thanks for your reply!!

 

[jgregg13]

I believe the pressure range claimed is a miss print and should be -14 to 29 so it will show vacumn as negative PSI. And the gauge should be plumbed to the intake manifold (after the carb or throttle body). Measuring at the compressor will never show vaccumn and could be subject to surge pressure when the throttle is closed. I assume you have a blow-off valve between the compressor and the throttle. If the gauge sending unit was subject to surge pressure, then the sending unit could be damaged. If you have a vaccumn / fuel pressure diagnostic gauge, you can connect it to the intake manifold and see what it says. These gauges only go up to about 15 psi so don't exceed 15psi

 

[powerband]

.
. Manifold Vac/Boost - AFR - Charge Tube (compressor) Vac/Boost



..
at most driving there is no boost unless enough load on a turbo and RPM on a supercharger, then you should see it on the gauge from intake manifold ...

carb's charge tube' gauge probably only fluctuates off atmosphere at no boost light driving and cruise, and unless WOT the BOV still dumps most charge pressure.

the '74 / 250 Maverick has a V2 Vortech supercharger for boost. Gauges are on charge tube from compressor to carb and the intake manifold after carburetor. (also a carb port for fuel pressure reference on fuel bowl.) The Bypass/Blow-Off valve on charge tube simply reacts to intake manifold vac/pressure - opening under vacuum to dump boost and closing with boost transition. When throttle opens charge tube pressure rises slightly as manifold pressure quickly builds until WOT - only then the charge tube pressurizes toward manifold ( and we go ... )



hav e fun

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[aussie7mains]

You need one of these, manifold absolute pressure.

 

[jgregg13]

You need one of these, manifold absolute pressure. View attachment 18706

Also handy for predicting the weather. ;-)

 

[aussie7mains]

Also handy for pricting the weather.

Yep, that it does. Ive got a draw through blower, the instrument has two needles, so I have one on the suction side and one on discharge side. Its an old ww2 bomber gauge I happened upon at at junk sale for $20. Its interesting to watch the goings on while driving. The movement is beautifully smooth, its fluid damped. New ones are easy to get, but expensive.