Need GM 2 Bar / Greddy Pressure Sensor Conversion - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


E-Manage Post your questions about greddy e-manage installation and tuning here.

Reply
 
 
 
LinkBack Thread Tools
Old 09-24-2007, 10:06 PM   #1
Junior Member
Thread Starter
 
Join Date: Jul 2006
Posts: 88
Total Cats: 0
Default Need GM 2 Bar / Greddy Pressure Sensor Conversion

It's been a while since I have done any tuning and I can't find a conversion table that translates the voltage output for both the GM 2 bar and Greddy Sensor. There was an old thread that had it here but it appears to be gone.

I have the pressure-to-voltage for my GM 2 bar MAP sensor (source robbietherobot.com). I need the same for the Greddy sensor, so that I can convert the PSI that the EMU is logging into volts then back to the correct PSI.

I know that you can tune the maps in volts, but the data logger will only show PSI.

I am using Emanage Ultimate v 2.13. I also noticed that there are several versions of "Factory Pressure Sensors" available. Anyone find an option that matches the 2 bar map sensor?
retro is offline   Reply With Quote
Old 09-24-2007, 11:53 PM   #2
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

My first instinct was to be a wiseass and tell you to search, but you already covered that. Looks like the conversion document was lost in the Great Purge.

I've re-attached it to an existing sticky thread. Last message here: https://www.miataturbo.net/showthrea...818#post155818
Joe Perez is offline   Reply With Quote
Old 09-25-2007, 09:53 PM   #3
Junior Member
Thread Starter
 
Join Date: Jul 2006
Posts: 88
Total Cats: 0
Default

Thanks for adding to the sticky. That's the exact file I remember.

-Keith
retro is offline   Reply With Quote
Old 12-19-2007, 08:12 AM   #4
Newb
 
Join Date: Jul 2007
Location: Hampshire UK
Posts: 32
Total Cats: 0
Default

Quote:
Originally Posted by Joe Perez View Post
My first instinct was to be a wiseass and tell you to search, but you already covered that. Looks like the conversion document was lost in the Great Purge.

I've re-attached it to an existing sticky thread. Last message here: https://www.miataturbo.net/showthrea...818#post155818
Link not working, I need this! Can anybody help?

Thanks

Nick
RSNick is offline   Reply With Quote
Old 12-19-2007, 09:10 AM   #5
Senior Member
iTrader: (3)
 
Join Date: Dec 2007
Location: Fayetteville NC
Posts: 828
Total Cats: 0
Default

On a similar note, I am about to install an EMU on my mazdaspeed miata. Should the EMU pick up a signal through my factory ECU from the factory map sensor?
msydnor is offline   Reply With Quote
Old 12-19-2007, 09:28 AM   #6
AFM Crusader
iTrader: (18)
 
olderguy's Avatar
 
Join Date: Oct 2004
Location: Wayne, NJ
Posts: 4,438
Total Cats: 84
Default

Does this help?
Attached Files
File Type: doc Pressure Conversion.doc (61.5 KB, 41 views)
olderguy is offline   Reply With Quote
Old 12-19-2007, 09:53 AM   #7
Newb
 
Join Date: Jul 2007
Location: Hampshire UK
Posts: 32
Total Cats: 0
Default

Thanks buddy, I can't get to it here at work but I'll try later at home on a pc
RSNick is offline   Reply With Quote
Old 12-19-2007, 12:52 PM   #8
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by msydnor View Post
On a similar note, I am about to install an EMU on my mazdaspeed miata. Should the EMU pick up a signal through my factory ECU from the factory map sensor?
I guess you could try it, though I have no idea what the conversion would be for that sensor. As a baseline you could try measuring the voltage at atmospheric (engine off) and that would put us in the ballpark.
Joe Perez is offline   Reply With Quote
Old 12-19-2007, 01:24 PM   #9
Senior Member
iTrader: (3)
 
Join Date: Dec 2007
Location: Fayetteville NC
Posts: 828
Total Cats: 0
Default

Quote:
Originally Posted by Joe Perez View Post
I guess you could try it, though I have no idea what the conversion would be for that sensor. As a baseline you could try measuring the voltage at atmospheric (engine off) and that would put us in the ballpark.
Thanks, I'll give it a shot
msydnor is offline   Reply With Quote
Old 12-19-2007, 04:35 PM   #10
Newb
 
Join Date: Jul 2007
Location: Hampshire UK
Posts: 32
Total Cats: 0
Default

Ok, got it. Interesting and helpful chart.

So even though I have a 2-bar sensor it will max out at 14.5psi?
RSNick is offline   Reply With Quote
Old 12-19-2007, 04:47 PM   #11
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

A 2 bar (absolute) sensor will max out at 14.5 PSI relative.

People get hung up on the idea of relative pressure vs. absolute pressure.

When we speak of boost, we are usually speaking of relative pressure, that is, pressure in addition to ambient atmospheric pressure. On earth, at sea level, ambient pressure is appx. 14.5 PSI. That is by way of comparison to a total vacuum. We call that amount of pressure 1 bar.

So if you are running 10 PSI of boost, that's 14.5 PSI + 10 PSI, or a total of 24.5 PSI absolute.

A MAP sensor, by its very name, measures absolute pressure. It can measure not only boost above atmospheric, but also vacuum below atmospheric. A 2 bar sensor can thus measure 14.5 PSI below atmo, and 14.5 PSI above atmo.
Joe Perez is offline   Reply With Quote
Old 12-19-2007, 05:01 PM   #12
Newb
 
Join Date: Jul 2007
Location: Hampshire UK
Posts: 32
Total Cats: 0
Default

Thanks Joe, that is a good clear explanation; I am approaching all this from a position of absolute ignorance.

Nick
RSNick is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 05:59 AM.