Throttle Body Spacer

I have a 95 5.7 TBI with approx. 1000 miles on it. Can anyone tell me what the advantage, if any of using a Throttle Body Spacer Spacer?? Thanks for your help.

I’ve had one for many years and I love it. Now it’ll improve gas mileage really but only on the highway.
I made 3 trips to the same place and that was also with a tow. The first two times I didn’t have it. By the third time I made the trip, it was already installed. I noticed a good increase in gas mileage then. I’m told it adds additional torque but I really don’t feel it.


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A spacer gives you a little more volume of space inside of the intake manifold for air fuel mixture. All the hipe says, it spins the air, it does this or that. I bought one for my vortec. It slowed the truck down. Vortec engines do not mix air and fuel inside of the intake, so all the spacer did was make more air space. On a tbi it should help a little, but dont expect to much. There are a lot more effective things you can do to your truck to add power, but there is no one thing that will give you a lot of power all by it self.

I think the jury's still out whether there's any real benefit of these spacers. They make several types. Of course the price goes up with each.

Trans Dapt Smooth Bore TBI Spacer 1992-95 Chevy/GMC Truck/S10/SUV 4.3L V6 & 5.0L/5.7L V8

Trans Dapt Swirl Torque TBI Spacer 1986-91 Chevy/GMC Trucks/S10/SUV 4.3L V6 & 5.0L/5.7L V8

JET Performance Power-Flo TBI Spacer

Airaid PowerAid Throttle Body Spacer 1987-1995 GM 5.7L

I'd really like to know myself, when I was researching them it seemed for every one that said they saw a difference there was another that saw no difference. I don't know if they were looking for a huge HP increase or fuel increase.

I agree with others, if anything it'll be minimal fuel increase and very very minimal HP increase

All I can say is it worked for me. Ran the same trip 3x with the same tow and on cruise control. Third time I ran that trip, it was installed. My fuel needle moved half of what it did the first two times. It’s been in my truck since 2002. Its the one with the swirl in it. Just my experience with it.


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I have had one for a few years. It went on with the ultimate TBI mods and a few other random air cleaner doodads. I didn't really notice any overwhelming differences power wise. It does make sort of a cool swooshy sound, and it gives you an extra inch of clearance if you are running a different air cleaner or ditching that plastic ring.

The “swirl” does nothing. The air rushes over the ridges/valleys of the swirl so fast that the air in them is literally trapped and the rushing air goes right past as if they weren’t there. What they actually do, is add plenum volume. And this does give you a little bump in hp/tq.

Last spring I had a 350 tbi motor dynoed. Not a stock engine, but a pretty well stock 350tbi with 454 injectors, roller cam running .488 lift but stock type dished pistons to keep the compression down to 9.5:1, anyway, after several runs once we got her dialed in, added the spacer. It added 8hp, 10ft-lbs over all. (311hp/385ft-lbs)

So a long story short yes they work, but not for the reasons some of them claim, and on a completely stock engine I wouldn’t be surprised if the gain was only a couple hp if that.

Gramps said:

Last spring I had a 350 tbi motor dynoed. Not a stock engine, but a pretty well stock 350tbi with 454 injectors, roller cam running .488 lift but stock type dished pistons to keep the compression down to 9.5:1, anyway, after several runs once we got her dialed in, added the spacer. It added 8hp, 10ft-lbs over all. (311hp/385ft-lbs)

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Good piece of real world information. I put one on my stroker just because, plus it provided a little more fuel line clearance. Makes me feel a little better that it might be doing something.

CrustyJunker said:

Good piece of real world information. I put one on my stroker just because, plus it provided a little more fuel line clearance. Makes me feel a little better that it might be doing something.

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Was never a believer myself, but happened to pick this one up on a parts truck and since we were already paying for the dyno session why not give it a try? Like I said though, it’s not the “swirl” or vortex or whatever buzzword is on the label, it’s the added plenum volume.

Yeah, I just put a regular two hole non-swirl one on mine. I was curious about cutting it like those "wide open," spacers. Only thing that stopped me is I thought it might become turbulent when it hit the intake face between the throttle bores...I'd probably have to just notch and taper it to the separate bores.