Throttle body spacers

[Highway Man]

After reading the input on air foils and the impact or lack thereof I am curious to hear if anyone has had any experience with throttle body spacers that they would like to share or just vent your opinion.

 

[vetteoz]

Save your $$$
With MPFI you are not dealing with raw fuel in suspension in the intake like on a TBI or carb engine;
the fuel is sprayed straight in the head intake port at back of the valve where it atomizes so anything that affects airflow turbulence up stream is irrelevant




Only spacer that works

 

[boomdriver]

After reading the input on air foils and the impact or lack thereof I am curious to hear if anyone has had any experience with throttle body spacers that they would like to share or just vent your opinion.

IMHO the TB spacer is not about turbulance or fuel atomization, its about air & vacuum.
Adding a spacer causes the air flowing thru the TB and spacer to accellerate very slightly because it now has to travel a greater distance to get where the source of the vacuum actually is. It increases the vacuum, thus thinning and speeding up the air charge. This has the effect of 'shooting' the air into the open intake valve and trying to get more in the cylinder from the speed of the moving air.

The downside to this is that the air is thinner because the accelleration of air speed is caused by a vacuum, NOT accelleration from being pressurized and released like a charger or turbo. So the result is a slight benefit in low speeds, but at higher RPM the motor starves for air. If the motor fell flat at 5500 before, with a spacer plate it'll fall off at 4500. Thats the secret to runner length, diameter and the distance air has to travel between where it was measured and where it ends up. Vacuum helps low end, but kills top end.:ugh

Remember why NASCAR uses a restrictor plate,...to slow top speeds down. Although a restrictor is a smaller opening, it does basically the same thing, alters the air speed which effects the volume of air. Thin air comes from vacuum and thick air comes from compression.

The airfoil has good theory behind it but it has problems in reality not being a part made and engineered for that specific engine. They also break and get throttles stuck wide open. I've seen them crack. Wonder where the fragments went???

Spacers can make a slight difference in low end but you will feel the engine struggle to rev at higher rpm. So the benefit is nearly 100% in the pocket of the guy selling the things.

Power just ain;t that cheap, or easy. The 'placebo' effect is easy...

 

[Schrade]

I posted up on that foil/snake oil gig once, took a stab a a POTENTIAL application for that foil, and Joe (user 'anesthes', who DOES know his stuff), backed it up, to my surprise...

See post 8.

I got no clue on spacers (or much else sometimes here...)

 

[Marv02]

If you want a spacer I build you one how thick do you want it I have a waterjet.

Just kiding save your money.

There alot BS products out there that claim it give you 10 or 20 More bolt H/P all they do is take you'r money and add weight to your car.

 

[vetteoz]

Adding a spacer causes the air flowing thru the TB and spacer to accellerate very slightly because it now has to travel a greater distance So the result is a slight benefit in low speeds, but at higher RPM the motor starves for air. If the motor fell flat at 5500 before, with a spacer plate it'll fall off at 4500.

Lots of miss-information there.
Read
Carburetor Spacers - Review & Comparison - Tech - Hot Rod Magazine

Adding a spacer on a EFI engine can give " some " benefit by increasing plenum volume on engines that run at the top end

Remember why NASCAR uses a restrictor plate,.. Although a restrictor is a smaller opening, it does basically the same thing, alters the air speed which effects the volume of air. Thin air comes from vacuum and thick air comes from compression.

NASCAR's restrictor plate is just that, a physical restriction to limit flow .
It has no depth like a spacer plate to change plenum volume or raise carb highe from intake floor

Spacers can make a slight difference in low end but you will feel the engine struggle to rev at higher rpm.

1" spacer on my engine is really killing the top end

 

[Highway Man]

Good input

Well, there's a lot of good input on this one and I appreciate everyone who has chimed in to share their opinion. I have seen similiar thoughts on other threads that may affect some who still have old school thinking about what works on different engine setups. Thanks everybody!

 

[Schrade]

Everybody's got an opinion, just like what needs wipin' :booty.

Usually tho', it just "Won't work; you're wrong", and no explanation. At least some folks know to post up both sides...

 

[boomdriver]

Lots of miss-information there.
Read
Carburetor Spacers - Review & Comparison - Tech - Hot Rod Magazine

Adding a spacer on a EFI engine can give " some " benefit by increasing plenum volume on engines that run at the top end


NASCAR's restrictor plate is just that, a physical restriction to limit flow .
It has no depth like a spacer plate to change plenum volume or raise carb highe from intake floor


1" spacer on my engine is really killing the top end

Where is the "mis-information" ?

You quote an article about carb motors. Completely different animal when fuel IN the airstream is involved.

Spacers don;t add enough plenum volume to make any difference. Certainly not 1"...its basically extending the TB bore, thats all.

A naturally aspirated motor requires vac at specific points in the process to help get air when it needs it. Thats what a spacer tries to do, a simple way to add some speed to the airflow, or decrease the pressure right behind the TB plates so it moves faster.
Increasing vac tries to accellerate the incoming air. Because 99% of the people that bolt on a spacer looking for more power never match the bores in the TB, its almost pointless. If more mid to top end were the goal, shorter runners, larger diameter would be the solution, with the understanding that there would be a low-end trade.
(in an engine where everything else stayed the same)

Went back and read some of the claims of the people selling spacer blocks...Here is what they have to say about their own product...

"The GMC throttle body spacer does this by increasing the distance between the factory throttle body and the intake manifold to create a higher air velocity, which mixes the air with the fuel more thoroughly as it passes the injectors."

another from Airraid

IRAID POWERAID THROTTLE BODY SPACER, 6061-T6 ALUMINUM -- 50-state legal; Provides additional power between 800 to 3,000 RPM; 1 in. spacer thickness; Includes power plate, gaskets, bolts, washers, and linkage plate; Made of aircraft grade billet 6061-T6 aluminum; Developed to enhance mid-range power, torque, and fuel efficiency; Has the unique dyno-proven helix bore.

So. they say themselves that they are a midrange to low end boost...not much else that I can add to that. They help, probably help alot depending on the motor.. Not everyone will get the barn burning results that someone here did.