Post 3-Improving the Vacuum System

This is part 3 in a series. If you haven’t started at the beginning, please go to Post-1 and start your training at the beginning, and do it NOW!

Where does all the energy in your gasoline go? This graphic was borrowed from the EPA website as a confession of sorts, as they admit here for the world to see that at least 60% of the energy in your fuel is lost in your exhaust. That means that over 60 cents of EVERY dollar you put in the tank is spit right out the tailpipe.

Engine Energy Losses EPA 60 percent

Look closely at this! As the EPA is willing to admit that 60% of your fuel burns in your tailpipe, how bad do you think it REALLY is?

(According to my numbers, based on mileage increases in Grooved vehicles, this number is probably closer to 90-95% loss.)

As our challenge is to glean every ounce of energy in the fuel to deliver power to the piston, from the above graphic you can see that if we are able to get ALL the fuel to burn inside the engine, we could at LEAST double the mileage of every car in the nation.

(We have known vehicles to gain as much as 600% with The Groove and other adjustments.)

Because engines are terribly inefficient (what else would you call 60% of your fuel burning in the tailpipe?), and we are working to increase that efficiency, The Groove will many times reveal overlooked maintenance issues. It’s not that The Groove CAUSES them, it is only they become more apparent after The Gadgetman Groove is added.

The most common deficiencies are found in the vacuum system. There are sometimes hundreds of locations where a vacuum leak can occur. This can make diagnosis a little time-consuming. Fortunately, most leaks will present little issue. It’s the really BIG ones we’re going to be looking for as they represent the greatest threat to your obtaining maximum efficiency.

The most common places vacuum leaks are located are in the hoses. These are relatively easy to locate and identify. It’s the ones that are most difficult to locate that we’re going to look for. First, I want to explain EXACTLY why vacuum leaks are so bad for combustion in general.

Here’s what a small leak can look like:

Notice the small crack. Easy to overlook. Important to repair!


Here’s what a larger one will look like:

You better not miss one like this!


The Gadgetman Groove modification is vacuum-based, so the entire intake system needs to have its full integrity. ANY opening in the intake manifold can cause a vacuum leak. The reason for this can be found when you start thinking in PRESSURES and FLOWS.

Just think about it like this. Take a garden hose and poke a hole with a straight pin and put 5psi pressure on it. It will drip a little. Now, apply 50 psi to the same hole. It will shoot a stream of water 30 feet into the air. As this applies to vacuum leaks (pressure differentials), consider that The Gadgetman Groove increases the magnitude of the pressure wave that is created by the motion of the piston as is draws in the air and fuel.

As the pressure drops during the first half of the downstroke, the low pressure is vastly lower, allowing the outside air to enter at VASTLY higher rates than would occur normally. This means that ALL openings (including mechanical parts) will let in more air than usual.

Under normal conditions, the ECU can adapt to this, effectively masking the leaks. After The Gadgetman Groove is installed, the ECU cannot compensate, and the symptoms of a leak become greater as the airflow into the intake is increased. Additionally, as the wave hits its enhanced lows (which we depend on to effect the vaporization of the fuel) the leak allows more air in, effectively deflating the effects The Groove creates.

The good news is that these leaks are usually easy to identify and correct.

The Crankcase Ventilation System is one component that is an engineered flaw in the system. In the interest of reducing HC emissions caused by friction and heat on the motor oil as well as the blow-by gases entering the crankcase, this system was designed to evacuate these gases into the intake manifold so they may be burned in the combustion chamber.

Vacuum is harnessed to effect this evacuation, in direct contradiction to all principles of engine efficiency. Applying a reduced pressure to your crankcase actually causes more blow-by to be sucked into the crankcase. It also forces the lighter components of your oil to vaporize, leaving your oil thicker and less able to flow through the system.

Conversely, when you elevate the pressure in your intake (which is what letting air in DOES) you reduce the quantity of fuel that is in vapor state. And it’s GOT to be in vapor state to mix with the Oxygen, and it has GOT to mix with Oxygen before it can burn.

All in all, this is engineering overkill.

So, we simply cap off the vacuum port(s) that supply the vacuum. This will then reverse the flow through the system, allowing the crankcase to vent naturally through the breather tube which is before the throttle plate, thus enhancing the level of vacuum available to the combustion chamber, and increasing the vaporization rate of the fuel.

Capping off the vacuum port to the PCV alone has yielded increases of from 2-5 mpg’s and MORE. So, consider doing this to your own engines and just watch what happens, with or without The Groove.

It’ll run better, I promise!

Here’s what it looks like on a late 90’s GM V-8. The PCV Valve is circled in black.

Taken from the front of the vehicle, Drivers Side Valve Cover


We will go into the vacuum system in earnest in the next post. For now, you have an understanding of just how important the intake manifold is, and why great care should be taken to ensure integrity of all areas of the intake manifold.

Here’s a video that shows how Eric the Car Guy does his tests. This is a really good way to find leaks at the intake manifold. (notice this is the 3200 series of GM engines)

Many mechanics swear by smoke testing. But The Truth is that is NOT an effective test to determine if a system is holding or not holding a vacuum. The ONLY way to know if a system can hold a vacuum is to APPLY a vacuum. For that, you are going to need a hand-held vacuum pump. The one I use is the MityVac 8000, which is used also to make bleeding your brakes a one-man job.

The testing is really a very simple procedure. I cannot stress strongly enough how important thorough testing is when faced with a fuel efficiency issue, to say nothing about the effects of a leak on your Gadgetman Groove modification.

So, learn to master this testing procedure and add many many miles to every tank of gas!

If you’ve done all this, and STILL suspect a vacuum leak, then you will want to visit Post 5. It deals with a commonly overlooked source for reduced vacuum, Valve Operations.

Next up: Post 4-An Average Installation

If you would like to learn this amazing fuel efficiency technology, we want to hear about it! Email myself, the developer of The Gadgetman Groove and we’ll see what we can do about that.

Post 1-Basic Flows in a Gasoline Engine

Post 2-Intake Flows and Wave-Form Technology

Post 4-An Average Installation

Post 5-Varnish and Vacuum

Post 6-Hidden Weaknesses

Post 7-Diagnosing Error Codes

Post 8-The Role of Sensors in Fuel Delivery

Post 9-Adjusting Your Spark Plug for Maximum Efficiency

One Response to Post 3-Improving the Vacuum System

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