I am installing a vacuum gage and need to know a good location to tap into manifold vacuum.

Thanks for the help...

 

how about a tee in the brake booster line?

 

Only if one is an exceptional mechanic, loose your brakes and

There should be a plugged port on the intake manifold. It would give far better response. If there are several choose on furthest away from the intake port.

 

i got it. there is a line going into the intake right on top. I just wasnt sure if it was a good source.

I agree though, I never tap in to the brake booster. Too risky.

 

what r u puttin it in for??
here is a better idea put a s/c on it and use the boost/vac gauge
sorry about the brake line i wasnt thinkin but you wouldnt lose the brakes they would just get hard as hell and the engine would stall

 

I use a vacuum gage to drive as efficiently as possible. The higher the pressure the better the mileage. Sometimes I wonder where the "sweet spot" is. On the freeway under 3,000 rpm or shift to 6th and go down to 2400 rpm. Seems to lug at the lower so I can use the vacuum gage to really know.

I have used them on most of my trucks, which I have used to tow heavy boats and trailers, etc.

I think this will be a better efficiency measurer than the computers that seem to not be that accurate anyway, and besides I don't have the 'puter.

 

I'll be interested to see what you find... I often feel that 6th gear is too much, especially for the relatively low (60-65) highway speeds around here. That is, if you can get out of traffic long enough to maintain 60!

 

wow thats neat i never heard or thought about that
do tell on the findings
also would temp/elevation have anything to do with that or would this test work anywhere
thanks

 

About 50% of the torque range is the place to start. On a short trip ~20 miles each way I did 3k one way 2.5K the other mileage jumped 1.5mpg easy.

If your gearing and tire sizes are in sync you should be able to shift each gear between the 2-2.5 mark and cruise around 2.4 or so. That with my gears is still over 65 if I remember correctly. I also use cruise control to eliminate my heavy foot.

I just did ~600 miles and got roughly between 17.5 and 18.2 at 80MPH 90% of the time.

Post your results and testing used. I'd be interested due to the PID Loop used by the computer to recalc driving styles. It will take repeating the same test three times or more to ensure that the computer is still not adjusting/recalculating.

 

Humidity, temp and altitude all play a part, as does fuel octane.

The test would work anywhere results vary by area factors.