KPA values
I want to see if I understand this correctly I am sure its posted in "Come in for a free tune" but I couldn't find it in there. When tuning with KPA does, 0 mean lots of vacuum and the higher the KPA number equal less vacuum? 0= tons of vacuum like at closed throttle
100KPA No vacuum like at full throttle going up a massive incline.

Also if Im running out of fuel with a mildly cammed TBI above 3500RPM can I bump up the fuel pressure which is presently stock to make it richer as long as the injectors dont go static? Presently When its floored I can't seem to get it any richer than 14-15 on the WB at or above 3500. Im thinking bumping up the pressure with an "jet adjustable regulator" a little would cure this, and get me to the 13 range where I want it.

 

100kpa is full atmospheric pressure at sea level. 0 kpa is full vacuum. you might see 100kpa or 100 MAP at WOT assuming no restriction in intake tract disallowing the 100. Key on engine off you might see 100 MAP reading atospheric pressure

Quote: No vacuum like at full throttle going up a massive incline.

I agree. Steady throttle and going up incline the MAP will increase.

If you live high elevation key on engine off may show 95 MAP.

you may benefit with higher fuel pressure.

 

Thanks for the reply; essentially what your saying is the higher the kpa number equals a lower vacuum reading, or the harder i press the pedal it equates to a higher kpa number.

 

Yes.

Max vac or minimal MAP is when let off throttle at higher MPH. You can go from 60 MAP(40VAC) rignt down to 0 MAP 100 MAP in log. I think min value is 20 MAP in log. Conversley if you are cruising say 45 mph in 4th gear and wack throttle chances are you will see 95-100 MAP.

 

FWIW
Two years ago I took a typical 1 BAR GM MAP sensor (460) and run some applied vacuum (in-Hg) vs. Output voltage (Vmap) tests:

kPa | in-Hg Vac | Vmap<460-9004>
100.| .0.0...........| 4.90
95..| -1.5..........| 4.62
90..| -3.0..........| 4.35
85..| -4.4..........| 4.08
80..| -5.9..........| 3.80
75..|-7.4...........| 3.53
70..| -8.9..........| 3.26
65..| -10.3........| 2.98
60..| -11.8........| 2.71
55..| -13.3........| 2.44
50..| -14.8........| 2.16
45..| -16.2........| 1.89
40..| -17.7........| 1.62
35..| -19.2........| 1.34
30..| -20.7........| 1.07
25..| -22.1........| 0.80
20..| -23.6........| 0.52

 

There you go! MAP sensor being a 0-5V devise. That shows it will never see 0 nor 5V.

My WB logs with Innovate show the same. I think most I see is 4.8 V (1250 ft sea level) and .5 V. Follows exactly. My WU-EBL reads in MAP.