I think this entire thing is an effort in futility.

Because this ^^^ goes against some pretty basic fundamentals of engine efficiency.

I used this source for a different thread just yesterday.

SOURCE.

One of the biggest sources of inefficiency in a gasoline engine is pumping losses. That's because engine output is controlled by a throttle plate that functions by restricting flow of air into the engine, creating a manifold vacuum. It's this lower pressure going into the cylinders that permits the injection of less gasoline, and less power is made. The problem with this is that when at part throttle your engine is sucking air through a VERY small straw, which is the throttle plate. It takes work to suck air past this restrictive opening, and that work is bought and paid for with your fuel dollars.

If this weren't the case overdrive transmissions would never even exist, because they put the engine under a higher load and less vacuum. To demonstrate that, you should hook up a vacuum gauge and go down the interstate in overdrive, and then disable overdrive and compare vacuum readings. You'll be running much less vacuum in 3rd gear, but fuel economy would be MUCH less. The same principle applies when climbing a hill; the most efficient thing is to open the throttle as much as possible while staying in overdrive. This brings energy-wasting manifold vacuum to almost nothing but keeps engine RPMs down. The end result is cresting the hill at a slower speed because less power is produced...but what power is produced is made much more efficiently.

Making less power isn't the answer to fuel economy. Making the power you need most efficiently is.

Why do you guys think the most efficient cars on the road have some of the smallest engines? They cruise down the interstate at nearly full load which makes these little engines extremely efficient. If high manifold vacuums were more efficient my V8-powered Lincoln Town car would be the most efficient thing on the road, because that thing will cruse at low engine load all day long because of how big the engine is. But alas, that's not the case. She's a thirsty girl, and in the winter time I can't get more than 20 MPG on my mostly-highway commute. V6-powered cars of the same size routinely get 24-25 for the same duty.

 

With that being said, driving style is by far the most important thing to improve fuel economy. Sean's post above is correct because driving a vehicle is an exercise in energy management.

It takes energy to push your car through the air, and because wind resistance increases much faster than linear speed faster speeds are more wasteful. Likewise every time you press the brake pedal you are wasting energy. That forward motion that you bought and paid for with your fuel dollars is being bled off into the atmosphere as heat from your brake rotors.

 

So I already have the gauge and A-pillar mount. Also, I understand the principle of cutting the vacuum line and installing the T. My problem is, I don't know what the vacuum line looks like or where it is. Does anyone have a photo of their 5.4 and where they tied into it?

 

Anybody have a photo or diagram?

 

I just tee'd into the brake booster vacuum hose, like this:




Here's what the fitting arrangement looks like. I had trouble with the rubber piece on top and replaced it with a compression fitting. Its all detailed in my gauge writeup:
http://www.frontiernet.net/~jmray/F250QuadGauge.htm

 

Awesome. Thank you. So when I open up the hood of my truck, what will this look like. That's the problem, I don't know exactly what I'm looking for under there or where it's located geographically.

 

You can see it in the upper right corner of this pic...

 

Thanks for all your help guys. The photos are definitely helpful. I just need to get to the auto parts store to get the hose and fittings.

Tom, I need a gauge to help me find that thin line between making power most efficiently and the transmission kicking down a gear! Oh I wish I had a manual transmission, or at least manual control on the 5 speed Torqshift.

 

A good source for vacuum gauges are on older medium duty trucks that had hydraulic brakes. Most of them had gauges from the factory (2" dash mounted), and had reserve tanks for the brake booster. Old school buses are a good source, also. They are usually still in real good shape. I've got one in my tool box to use for testing---works great for adjusting the air/fuel mixture on older vehicles.