which boost gauge is the right reading

[no rice]

I have an aftermarket boost gage on my 87 TR. It seems that the stock gauge is about 2-3psi off the the aftermarket one.
Is this normal. How accurate is the stock gauge?

Because to I bolted a TA 61 turbo ysterday. Running low boost test and the gauge was reading 12psi and my stock gauge is reading 15psi.
I was scared that the after market was wrong. i replaced it with another one and it's the same reading.


With the big turbo i don't want to take the chance of over boosting.


Lue

 

[UNGN]

The stock tach and boost gage are not accurate in the least. Some peoples boost gages show 1 lb at idle (must be a cam ) and the tach on my 24K mile GN says 3300 RPM when turbolink says 2200 Rpm.

A $15 boost gage I bought at a swap meet is dead nuts with what my turbolink boost sensing says, so I would tend to go with the aftermarket gage.

 

[no rice]

i was thinking the same thing.

 

[GNSCOTT]

A FAST system doesn't lie. I had a VDO and a liquidfiled ( forgot the manu) and both were wrong.Both read the boost 2#'s lower than actual.

 

[salvageV6]

Yup, I got a very expensive calbrated mirrored scale Omega gauge from work and found I was running 1.5 more psi. than I thought. Varied throughout the range too.

I calibrated my electronic DPS unit and display and that is well within .5 psi. from 10-25 psi. where I calibrated it.

Various analog gauges I used for testing all read diferent up to 3-4 psi. all non-calibrated some aircraft some automotive.

I trust the Omega one and now the electronic one.

 

[UNGN]

Originally posted by GNSCOTT
A FAST system doesn't lie. I had a VDO and a liquidfiled ( forgot the manu) and both were wrong.Both read the boost 2#'s lower than actual.

Doesn't a FAST system use a GM 3 bar MAP sensor? That's what turbolink boost sensing uses and I've noticed it is very accurate (if you make sure it is zeroed properly)