I'm all for research, but spending hours testing a $75 sensor that isn't even designed for the task at hand is poor use of my valuable time

 

That was never the discussion. The discussion was whether or not the stock map sensor ould read 17 PSI, and the answer was then, and still is now, yes.

As I said before:

 

for some, yes, for others, no...as demonstrated by maxcooper

and it also depends on the atmospheric pressure where the measurement is made and how accurate the $50 gauge is you are using to do the measurement

so again it's not a cut and dried answer

 

It's not a cut and dry NO either.

 

Maxcooper's read out is from the PFC, which as I've stated now 3 times doesn't read out the actual psi from the turbos.

If you only used the PFC to tell you boost and everything then yes it appears it is 16psi, but if you take an actual boost gauge or Mity vac. and test what the pressure REALLY is, then it is 17-17.5psi.

 

the bottom line is the stock sensor was likely designed with a "buffer" or "window" of surplus pressure quantification to keep morons from blowing their engines by misusing it and being a bit off in their expected max boost

however, to make a blanket statement that "x" is the absolute hairy edge and you can always go to "x" and be safe is foolish

again, the big picture is why risk it for a $75 sensor, why not use the sensor actually designed for the job (what a concept)? that's the real issue here, not essay length novels about the stock boost sensor that no one will bother to read

 

according to your test with your gauge, which is statistically irrelevant

 

But it IS more relevent than the test you have done on it.

Here I'll help you out, not that you are going to read it and LEARN something but hey can't say I didn't try. If you don't believe what Chuck says about tuning and the PFC you don't need to believe anything anyone says:
https://www.rx7club.com/showthread.p...ght=MAP+SENSOR

This is just an interesting thread to read that has to do with this:
https://www.rx7club.com/showthread.p...ght=MAP+SENSOR

 

How did you calibrate your 3 bar sensor?

Nobody seems to care about calibrating their MAP sensor correctly? If you don't get the correct absolute pressure from the given PIM voltage then that's ok huh? You can still tune it with the wrong pressure readings. You could use the default PIM scale and offset for your 3 bar MAP sensor and tune it so that it works. The boost readings, boost settings, and P-Rows would be way off but it should work for a little while. If you use a boost controller and never use boost data then you might get away with it. The default PowerFC maps work fine with the wrong PIM scale. It's certainly not a necessity but I believe one should either correctly calibrate or understand the problems caused by reading incorrect absolute pressures.

If you didn't understand any of the above then please understand that you can't trust your PowerFC boost readings or settings. Please use a boost controller to reduce your chances of a blow motor.

I really don't have a problem with you using a 3 bar MAP sensor. It's a good idea if your going to go single. If you were a little more open minded you might learn something here.

 

basically what I get from that is the stock sensor is flaky, something I've known for years, which is why I pitched it

 

atmospheric pressure in beautiful North Carolina

it works fine and has for two years, you'd have to ask Brian Cain how the various PFC settings were adjusted

I still use the Commander to monitor max boost because I know for a fact the Autometer pos gauge I have is off, which is a major reason I blew my previous motor

I'm sure I could spend countless hours on the PFC subforum and learn alot of stuff, but it's not all that important to me, that's why I paid a tuner, I'd rather be driving

 

I agree with the above 100%. If someone wants to run up to around 17psi (or even slightly more) and their tune is reasonable, the stock MAP sensor is sufficient.

Wade

 

ask Brian Cain or Steve Kan's opinion, they tune these cars for a living, everyone else is just spouting random opinions based on very limited experience, usually their own cars and that's it

over 1 bar gauge, you need the GM sensor, no one except those two guys are going to change my mind

 

i just think the 3 bar map sensor is a cheap piece of mind for any build i will now do if im going to up the boost past 14psi.. weither its right or wrong i dont care whats 100 dollars when you spend thousands on motors and performance parts..


If you own a FD you should now know not to go cheap or you will pop a motor.. do everything you can to save your motor.. thats my motto at least!

 

amen brother

 

yes straight mid.. no. why chance it. By the way. Damn this thread blew up..Your set-up up is only as good as its tune, fuel..and the beat goes on.

 

dont be a tool. theres a line between buying good parts that make a difference, and buying anything availible that *could help. esp. if your only running 14 lbs.

the fact that all you anti-stock map sensor people ignore is: no matter what, if your car ain't tuned for past 17 lbs you're screwed either way, don't matter if you had a 25k gold plated 10 bar sensor - your ***** gonna blow same as a stock sensor.

 

I've been on this forum for quite a while. I even spent about a year or so just watching and reading before I ever registered. I've seen people spend a ton of money on their car and pop their engine within a few thousand miles.

It's not how much money you spend, it's spending what you do spend wisely.

 

Your Autometer gauge is very likely more accurate than your Commander boost reading. Most professional RX-7 tuners do not know how to calibrate the MAP sensor so the boost reading will usually be off except at one pressure. Don't trust the Commander Boost reading to be correct! You can use it as a reference to see if something has changed but don't interpret anything from the value.

 

no kidding sherlock! of course the car must be tuned for the boost you're running

 

I know it's off, trust me

and what is so difficult about calibrating the MAP sensor?

 

just get the feeling people think if a hose 'pops' off and they boost 20 that the 3 bar will cushion their ***.

 

+1, first doing research before you do anything is very important. Arguing without the proper research and experience is pointless and is one reason everyone is afraid of touching these cars so much.

+2, Why spend extra money on something you don't need. I could buy the best everything and still blow my engine at 10psi. Tuning is where it is at, not the equipment, that is unless you pass the performace capabilites of the equipment, which in this case is 17-17.5psi. Running 16-17psi the stock map sensor if fine, anything about that I could see getting a 3bar but for 16-17psi it isn't worth the money, whether $1 or $1000.

 

How do you know it is off?? Did you test with a gauge you know is correct?? or against more than one other gauge?? Thats as good of an argument as saying the stock map sensor only reads 14.7psi without testing it.

Here is how to calibrate a map sensor:
https://www.rx7club.com/showpost.php...83&postcount=3

 

thta's great, but how many people actually do this? and how many people use a $10 pressure gauge from Grainger or McMaster Carr as their "standard"