TB vs TB Spacer?

Would like to get a little more out of my '90 model 3.9 Dak. and the most common suggestion that I see on the WEB is change out the TB to either an improved V6 or a V8. When I start Shopping around (EBay etc.) I see a lot of TB Spacers but no TBs. They are not the same thing are they? What difference?

Thanks

Reply to
Bob
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No, they are not the same thing. The TB or throttle body controls the amount of air entering the intake manifold. A TB spacer fits between the throttle body and the manifold with the idea of smoothing out the airflow into the intake for better fuel atomization and allowing more air to get into the cylinders.

Reply to
TBone

Yup.

Perhaps, but more likely its to add length to the intake tract in an effort to get more low end torque. Not that it always works thta way. Smoothing air flow by adding a second mating point seems a bit odd. Better idea is to use something that will produce laminar air flow, which could be added with the spacer, but usually is not.

Atomization, perhaps yes. More air into the cylinders? Nope. As you just said, the TB regulates that, not the spacer.

Ultimately, the spacer is a debatable add on, but a cheap experiment.

Reply to
Max Dodge

While the TB regulates air flow, that flow is ultimately limited by the efficiency of the intake system as well. The spacer as you said, increases the length which should, but not always, increase air speed and reduce turbulence which should get more air into the cylinders. Why do you think that they are said to increase lower end torque, debatable or not?

Agreed.

Reply to
TBone

The op stated he had a '90 3.9l engine. IIRC this motor used the barrel shaped intake manifold. If you take this manifold off and take the bottom plate off, you'll see that as the air comes thru the t/b it enters a chamber roughly the size of a gallon milk jug. The intake runners start at the bottom of this cavern and go up and over the top of the manifold to the opposite bank of cyls. I fail to see how adding a half inch spacer at the top of this cavern would make didly squat difference in the airflow thru the manifold. I could see how a spacer could work on a single or double plane manifold but this???? Take a look at hughesengines.com and read how they modify the manifold for higher flow. Notice they don't sell spacers but they do sell other performance enhancing items. This tells me they probably know more about these engines than J.C. Whitney.

Denny

Reply to
Denny

so the law of 'negative entropy ' kicks in and longer piping = less resistance ?

it's a proven fact that longer intake runners increase low-end torque

just as 3 % / 2 % = 150 %

Reply to
TranSurgeon

By the time the air flow gets to the cylinder runners in the typical Mopar manifold, the TB is long past being the cause of turbulance. Too much has happened to the air by that point to blame the TB for the turbulance. However, inducing a laminar flow at that point can ease some of the rough trip ahead.

The volume of air in the cylinder will always be the same. Again, the TB spacer is so far upstream as to have little effect on the engine itself. Changing the TB may have an effect, but from what I've seen, read, heard, etc, most times a larger TB drops low end torque and boosts HP.

Money is better spent on intake manifolds, be it a better one or simply porting and port matching on the stock one.

Reply to
Max Dodge

Bingo.

Reply to
Max Dodge

THe spacer increases the phlenum effect under the TB which can improve throttle responce and power some and the theory is that you want to also stir the mixture up more (more turbulance or swirl) to increase atomization of fuel mixture for better power and burn.

Reply to
SnoMan

reduce

That is where you have it wrong. A larger phlenum has long been a trick to enhance flow from the old carb days at midrange on upper RPM?s. It works on the theory of increased airmass and better fuel mixing and how it interacts with the suction pulses as the base of the carb or TBI unit and increases the flow efficency so that less "flow" is needed (throttle plate does not need to be open as much) to fill cylinders properly at the desired intake pressure in cylinders. (there is less over all pressure drop between base of TBI and intake port so overall flow is improved) Spacers are worthless on multi point injection becauce they truely have nothing more than a air valvle on their intake and most multi point system have pretty well tuned intakes as well unlike most TBI engines that are not tuned properly.

Reply to
SnoMan

True. In theory.

Reply to
Max Dodge

We shall see.....

Not exactly..... Larger plenum made the runners appear longer and thus improved performance due to increased signal in a low vacuum environment.

Which is where you go into the woods. A larger airmass below the TB or carb kills the sharpness of "signal" (in reality its the accuracy of the vacuum drop). If its muted (as it would be wih a large airmass), the carb is slow to respond in allowing more fuel into the stream, a throttle body system doesn't have this sensitivity because you are no longer depending on vacuum alone to induce fuel flow.

And you are completely wrong here. Better flow depends on two things: 1) smooth passageways, and 2) larger pressure/vacuum differential between orifice (TB) and container (cylinder). If you drop the difference to nil, NO flow is the result, and the engine will stall. (Hint: vacuum leaks are a bad thing)

Yup, thats because TBI is a carb in disguise.

Reply to
Max Dodge

Plane??? WTF are you talking about? This is supposed to be about a spacer! Now your confusing the issue with planes, not just a single plane, but your also talking about a couple of them. Looking back at your post, I see you are also talking about joggers, and milk jugs, caverns and being over the top. I also see you mentioned taking a plate off. Now that is something I'm sure you have expertise in, taking a dinner plate off the table. I'm just throughly confused by your explanation, do you think you could clear it up a bit?

I'm glad somebody is paying attention and trying to correct some of the misinformation that has been tossed out here recently, keep up the good work.

Roy

Reply to
Roy

LOL, perhaps you need to do a little research there buddy. There is more than one resistance going on here and a slight increase in one resistance can be more than made up for by overcomming another one.

I never said different but do you know how? I realise that this is another flow question so you may once again be baffled.

Hey, did you figure out the fluid flow in that TC yet, Mr. Trans expert?????

Reply to
TBone

Well hot damm!!!!! Ole Pudge of the East looks like he's trying to think again. Stand up there Pudge, it'll go better for ya..

I told you to stand up before you try thinking. Or maybe you're just thinking bout another pack of Twinkys.

I'll leave that up to 'bone. He has more time than I do.

Great Brownies Made For Gobbling????? Roy, please quit dwelling on food all the time. If not for Sue, for the dog.....

Have fun friend.. Got a meet tomorrow am, maybe I'll get lucky and finish higher than next to last....

Denny

Reply to
Denny

Hey! I can't help it if I get confused when you take a thread from a truck to airplanes! Geeeeze

Twinky's??? Do they still make those things? I liked the 2 things that had cocanut on them.

Not bad fur face, not bad at all.

Best of luck Mr Hathcock.

Roy

Reply to
Roy

A TBI spacer is not like putting a taranula intake on your engine with a open phlenum under all bores (which by the whay does well above 3500 RPM or so with the correct carb because I have used them). The TBI spacer allows a little more precharge room under the TBI for better flow resposce to flow requests and the two planes of the manifold are still seperated too for good throttle responce

"Max Dodge" wrote:

between

Smooth passageways can be a bust for low end to mid range responce with a carb or TBI because some roughness and turbulance is needed for good mixing and atomization of fuel for a better burn. Porting can help top end but it can murder it too if not done properly. ANd again the larger phlenum allow for less pressure drop because of more precharge volume that is avaible under the TBI unit. Flow through a TBI of carb is not constant, it is a series of pulses that increase in frequency as RPM increases and the phlenum smooths thes pulses out a bit because it allows the velocity and mass of the air to continue flow into eare under TBI/carb a few milliseconds longer at impluse minimum, precharge the enlarger phlenum while waiting for the next intake pulse cycle from a cylinder. As RPM increase the mass of the air and its velocity can because a factor in "ramming" the mixture into phlenum for next cycle.

Reply to
SnoMan

Ok, I'll repeat myself. TB systems do not depend on vacuum signal like carbed engines do, since the fuel is introduced by a different means. Furthermore, more airmass does NOT allow a quicker response, since the MAF is not inside the intake, but is upstream considerably. Thus it does not register the flow as quickly when put further from the vacuum source.

Reply to
Max Dodge

You do know that this is not always true, right? Turbulence tends to be cumulative and amplified in it's travels so the sooner you can reduce or eliminate it, the better off you are. Now I am not saying that it will work for his manifold but they do work well for some and that is the reason why their effectiveness is so arguable, pretty much like the performance increase claims of a K&N filter.

No, the volume of the cylinders will always be the same. The volume of air in those cylinders is always changing or there would be no need for the TB.

While not always true, it may very well be the case of the current run of DC engines.

Which probably is not the best idea for a truck.

Agreed but that wasn't his question.

Reply to
TBone

You are not going to gat an argument out of me. I simply answered his question as to what a spacer was, not how effective it would be on his engine.

Reply to
TBone

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