Accuracy of autometer boost gauges
 

Well since everyone thinks autometer gauges are inaccurate and suck... here are some more information...

Sir,
Our products are calibrated to +/- 2% at full deflection.
Jim

Auto Meter Sales/Ryan wrote:

> -------- Original Message --------
> From: XXXXXXX@rogers.com
> Subject: Product Question
> To: sales@autometer.com
>
> Question:
> What is the accuracy of your gauges? what is the uncertinity in your
> measurements (+/- X%).
>
> I'm currently looking at the 4803 Carbon Fibre Ultra Lite 2 5/8" boost
> guage.

I have the Phantom Series Boost & A/F, and I've already sent my boost gauge back once because of it not being calibrated. The one I got in return is a little better, but not quite good enough. I just might have to drop a little more coin for a better line.

Jimmyv13,

how do u know it is not calibrated right? did you have the autometer and another aftermarket guage hooked up and compared the readings?

Can someone please tell me how you know that the boost gauge is in accurate?
how are you able to tell if you didn't do a real experiment.

I mean by connecting an autometer gauge to a specified pressure, and comparing it to say a greddy gauge or a high precision guage used in comerical and industrial industiries...

its +/- 2% at 20 psi... not 8 psi or 6 psi... it would be negliable at that point.

Generally when a manufacturer states +/- 2% that what it is... and if its other wise their quality assurance program is shit.

With the ignition on, the gauge should read zero, or "in the little box" on the Autometer gauges. My first gauge sat at 2 or 3 lines below the box with the ignition on. The replacement gauge needle sits in the box, but I still think something is wrong. When I am sitting in my driveway in neutral, the needle should go in the box when I rev to around 4K, right? Well, it doesn't quite get into the box, but I may have been misinformed on how a boost gauge is supposed to work.

Why should the needle be in the box?

The box would indicate SEA LEVEL. I assume you car is somewhere that is above sea level. So the gauge will read below that pressure.

+/- 2% of 20lbs is . 2lbs. That aint bad.

No, as I understand it, it's supposed to be +/- vs ambient

An Autometer tech told me the needle should go in the box with the ignition on. A local mechanic told me the needle should go into the box with neutral revs. So, is my gauge ok, then?

With my first gauge, the one I sent back, when I turned the ignition on and tapped the gauge a few times, the needle moved into the box, thats kinda why I thought it was mess up.

My Autometer boost guage sits at -2. :(

I have an Apexi :) :) :)

Wait for Autometers electronic boost gauges.
Or have they already been released?

Yes, they are already released. However, the MSRP is around $240. I had a 30 minute coversation with Mr Littlefield at AutoMeter on July 3rd. He pretty much told me they are aware the mechanical boost gauges are up to 2-3 psi off. He then suggested the electronic boost gauges. They recalibrate every time power is applied (turning on your ignition). They do still retain the block for zero, but he assured me the pointer would be dead center of the box every time. He quoted the +/- 2% for all other gauges in their line.

Just FYI, Westach claims the same tolerances for their entire lineup. They are more of an aircraft gauge supplier, but the prices aren't too out there. They have electric gauges that have an output for a warning light or buzzer, also.

I'm pretty certain that if AutoMeter gauges monitor all out race motors (NASCAR & lots of drag cars), they should be accurate enough for a street driven vehicle. Well, with the exception of the mechanical boost gauge maybe.

Yes, most boost gauges read "gauge pressure" (go figure, lol) which is +/- ambient.

If you guys are really concerned about the gauge not being zeroized, then why don't you take a couple of minutes to reacalibrate it?
http://www.autometer.com/hp/instruct...tions/191y.pdf

I'm pretty sure my ultralight gauge is accurate. It reads 5.5PSI, max deflection of 35. I was surprised that it was that good. (assuming my car is doing everything right) Any gauge should be less accurate as the scale increases. (ie. max scale 100 less accurate than max 10) A gauges are also less accurate close to the two extremes.

.........With the ignition on, the gauge should read zero, or "in the little box" on the Autometer gauges.

Are you talking about a mechanical gauge or electric? If it is mech. than the ignition being on or off dosn't matter.

I really think the gauge is affected slightly by the barometric setting of the day.

James

I think that is only for the liquid filled gauge lines...

Also Greddy quoted:
Question:

What is the accuracy of your gauges? what is the uncertinity in your measurements (+/- X%) for the following gauges.

-16001212 - Boost 60 mm mechanical Black guage
-16001202 - Boost 60 mm electrical Black guage

Answer:

It varies depending on where you are drawing pressure from for the sensor, but there should be no more than 1-2% inaccuracy registering on the gauge from actual manifold pressure.

But even a lot of the high end gauges such as defi or greddy have mechanical gauges.

i thought the electronic ones were exactly the same as mechanical.... the only difference is that the pressure sensor unit is located somewhere else... such as in the engine bay, and it sends the signal with wires to the guage so that you don't have to run the vacuum hose extension. The electronic ones should also have a vacuum hose but it terminates to teh sender unit inside the engine bay.

Ah, I assumed that's what they had. I don't think that the cheapie gauges have any adjustments.

Electric gauges have a pressure transducer which sends an electrical signal through wires to the gauge, where the signal is converted to an analog display. A vacuum hose is not required, but the transducer is usually attached to a T-fitting in the existing vacuum line so that it reads the same pressure as the ECU.

but the transducer still has a mechanical part of it which will then covert the pressure to an electrical one... Probably from the deflection caused by the pressure which is attached to a potentiometer and thus the resistance changes (not sure since i've never taken one apart). THe resistance is then passed onto a circuit which will mostly cause a change in voltage, which is what gets sent to the gauge mounted into the dash.

(not sure... just my theory)

so a mechanical one has no transducer, because the deflection is actually displayed right on the gauge instead of having it be measured by a potentiohmeter.