Throttle Body Injection Spacers

I have read alot of hype regarding the spacers for throttle body injections. My question is do they really increase horsepower/torque or fuel mileage? If so, then how do they work?

As part of an overall program of opening up an engine’s intake and exhaust systems, a throttle body spacer may have a very small effect, but alone there will be no effect. If they really did improve performance, don’t you think the automakers would have already made that very simple modification?

a spacer can improve the torque a bit but it won’t be anything you will notice. that’s one of those things that is best used in conjunction with a dozen other little items.

should have added that what it does is increase the air velocity ehich in turn aids torque.
the best example of this is the old chrysler “long ram” intake manifolds. these worked very well but this is a different situation.

The key word is “hype”.

Your question is far too general to give a reasonable answer. In wet TB applications where the fuel/air mix makes a 90 deg turn to flow into the manifold, these spacers are often used to increase the turning distance. This allows a bit more time for the fuel to mix and not impinge on the manifold “floor” quite so hard and “rain out”. The spacers are often made of thermally insulating materials like phenolic to reduce the effects of temperature on the TB. They were far more common on carburetor applications for the last benefit alone. On a grocery getter you’re not likely to notice any difference. Where you’re trying to eek out every last bit of performance, they do have benefits. This is in regards to spacers only, If you’re talking about something that alters the velocity of the air, that’s a different animal. So why not provide some more details about what you’re trying to do and on what platform?

I am trying to increase towing power for my 1994 Ford F150 2x4 for towing an 18ft. pontoon boat and hopefully increase mileage, it has the 5.8l motor and still runs very good even with 194,000 miles. Any advice? I would greatly appreciate it.

the first you have to do is decide if you are willing to spend some serious dollars to gain power and economy.

adding a throttle body spacer is not going to produce anything noticeable, nor will the addition of something like a cold air intake kit.
if you want noticeable gains it is going to require things like camshaft changes, cylinder head flow work, opened up exhaust, etc. and this is far from cheap.