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Old 03-28-2016, 09:36 AM   #8 (permalink)
gumby79
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Join Date: Dec 2014
Location: Butte, Montana
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little jona - '91 Dodge D 250 first gen cummins LE
Team Streamliner
90 day: 23.4 mpg (US)

Little Jona airo modded - '91 Dodge RAM 3/4 TON D 250 2×4 AUTO
Pickups
Team Cummins
90 day: 18.5 mpg (US)

The Salted Hound Jenny. - '87 Dodge Ram 50/D-50 5sp 4X4
90 day: 20.24 mpg (US)

Jona Allison aero - '91 Dodge Ram D-250 Le
90 day: 20.76 mpg (US)
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Sources for Vss ( vehicle speed sensor)

Quote:
Originally Posted by johnbullas View Post
In the case of the tachometer (rpm) a 0/12v pulse exists for the Mega to monitor

In the case of the vacuum gauge a custom pressure/vacuum measurement device is required

In the case of speed the rotation of the speedometer cable needs to be monitored (and a turns per mile value used to convert to speed) else a hall effect transducer will need to be used !
The VSS senders I linked will provide this at a much higher resolution than 1pulse per tire revolutio. I used this one SPEED SENSOR, MECH TO ELEC, GM & CHRYSLER, 7/8"-18 THREAD, HALL EFFECT, 16 PULSE
On my 79 K-20(3/4ton 4X4 Chevy). When I custom built the dash all electronic. Something like 32000 pulses per mi on 33"s and 4.10's. Its been 9 years and no longer have the truck. As a bonus your stock mechanical speedo can be retained this just plugs inbetween your cable and Trans.
Gumby stay flexible
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