Any mechanical gauges scaled in ABS vs Vac + Boost?
 

For no particular reason, except for a single scale and units: Are there any commercially available "Boost" gauges that are scaled, like 0 - 270kPa, which would be at about 100kPa at engine off; rather than -30" Hg to "0" to 25 psi?

It would be the same physical gauge, just scaled to correspond to the values we see on Tuner Studio.

Obviously, there is not enough action on MT.net to satisfy my addiction, so I pose this question.

DNM

AutoMeter is one brand that does.

AutoMeter boost gauges

Edit: Sorry, now see you want kPa instead of PSI. The ones I could find were either 0-200kPa or 0-1000kPa [Defi brand]

Interesting request DNM lol. A style of gauge I've never thought of. It seems there are no actual off the shelf options of that in my super quick search.

Closest thing I found was this https://www.extremepsi.com/store/pro...roductid=19825 but it's not quite as detailed as I assume you are desiring. Only goes up to 200 kpa as well, so not for a ton of boost.

Looks like you just need to make a digital dash so you can have it in kpa right in front of you :)

Actually, it wouldn't be the same physical gauge. Cheap mechanical boost/vacuum gauges measure relative pressure (or "gauge pressure"), with the reference being the ambient atmospheric pressure, while the Tuner Studio value is absolute pressure. If you were to rescale it at sea level and then go up 500 feet in altitude, it'd show 100 kpa MAP when it's actually 80-ish.

I've never seen a mechanical absolute pressure gauge. I'm sure it's possible (perhaps by having a reference chamber that's in a vacuum), but probably expensive/unreliable.

--Ian

https://www.auberins.com/index.php?m...roducts_id=504

https://www.auberins.com/index.php?m...dex&cPath=5_21

In my mind it would be the same gauge, but you make the correct point that it would not be accurate. I guess the gauges that now exist will always show boost vs ambient, which are also incorrect vs the MAP reading in boost that is true absolute. If I have my EBC set at 15 psi equivalent ((202 kPa), then at high altitude, my Boost gauge will show like 18 psi, and the re-scaled one I mention would show 222 kPa. Both equally inaccurate vs the true MAP.

DNM

"boost" is inherently a relative (or "gauge") measurement (so is "vacuum"). MAP is inherently an absolute measurement. They are not the same thing and you cannot convert one into another without referring to a particular ambient pressure.

The boost gauge is telling you the truth when shows 18 psi for a 200 kpa MAP at altitude. Technically it should probably have "psig" (g for gauge) on the face instead of just psi, but that's implicit.

--Ian

Ian, great answer. Technically, I am asking for an incorrect device.

Thank you you to everyone who participated.

DNM

There are a few to choose from. One from Apexi and one from HKS. Also there is a DIY on here from a member. I'm sure there are more, these are just the first I found.

https://www.miataturbo.net/diy-turbo...e-53870/page2/

https://www.extremepsi.com/store/pro...roductid=19825

https://www.kseriesparts.com/HKS-44004-AK002.html

Plenty of gauges are scaled in BAR.

I don't know if it is helpful to you but I run the perfect tuning universal gauge with my ms3 via canbus and I have a gauge on there that tells me my KPA at all times. It does a lot more than just that but it would tell you your readout you are looking for. It also isn't mechanical so it doesn't really answer your posed question but I thought the info would be helpful.

https://perfecttuning.net/en/gauge/5...uge&results=52

They ones I posted were configurable for kPa, either absolute or gauge.

Six. Yep, those would certainly work. Electronic gauges that work right off a MAP Sensor. Not sure how one would run them as gauge pressure with a single sensor, however.

They might take & remember a reading at power-up (before the car starts), or they might have a second sensor mounted in the gauge body that's open to atmosphere.

--Ian

Further complicating this is that many sensors that are labeled as psig are what is known as "sealed gage" pressure (and a lot of what's used for fluid pressure in cars), which ends up just reading out absolute pressure minus a fixed offset. I imagine a lot of the gage gauges are the same way.

A fun option would be to get a custom MAP gauge face for a cheap mechanical vac/boost gauge from Revlimiter or somewhere. You could even DIY RTV seal the case at sea level if you really care about how absolute your pressure is :)