Which vacuum sensor for data logging?

[drdano]

For you data loggers, I have a question.  I have an Innovate LM-2 that has capacity for a few inputs for analog data.  In addition to the wideband O2 AFR and RPM inputs I have now, I'd like to add a manifold vacuum input as I think it could be useful.  I need a sensor/transducer that is 12v and 0-5 output to the logger.  Does anyone have a recommendation that is on the affordable side?  Thanks.

[jayb]

A standard GM style MAP sensor will work, although I think it requires 5V for the power supply, not 12V.  A lot of the Innovate stuff has a 5V supply available for running sensors like that.  If you just get a 1 bar MAP sensor I'm sure you can make it work; I have one on my Galaxie for measuring crankcase vacuum.

[drdano]

5v input?  Hmm...so a resistor from an old coil may be needed here.  I didn't notice that.  I'll have to check the documentation that came with my LM-2, it does have capacity for 2 linear analog outputs.  If I could configure one for 5v out, power the MAP with that. 

My main reason for wanting to log the manifold vacuum is to aid in tuning the carb.  Would it be as useful as I think, or is RPM and AFR going to be good enough?

[jayb]

I guess I've never looked at MAP when doing carb tuning; AFR is far and away the most important parameter.  But having MAP data would be good anyway.  Here's a link to how to wire it up:

http://www.hondata.com/tech3barmap.html