Throttle Body Spacer Question

[diablosjeep]

I was thinking about getting a throttle body spacer (Airaid to match the cold air intake) and was wondering if anyone has used one before. The new Jp magazine said it won't make much difference on an injected engine, and causes a whistleing sound. I was just wondering if this was true?

 

[Bounty__Hunter]

I think they make a slight difference, and to me every little bit helps. Can't say much on the whistling, I attribute most of that to the airtube and conical filter.

 

[droopey]

I read some where that it was the spiraling in the bore of the spacer that made the whistling but the smooth bore did not. I am only quoting what I read.

 

[lethaldose]

i have a smooth bore spacer on my 4.0 ... before the K&N i was clocking about 19MPG... no whistling sound but i landed mine on ebay for i think 30 bucks couldn't see paying 70 bones for a block of aluminum with a hole in it haha

 

[Gsx31337]

I got an Air raid one, Noticed no MPG change however I felt a lil more umph in the mid RPM range. It makes a bit of a hissing sound, kinda like a turbo at first a lil annoying however I got used to it fast, dosnt bother me anymore.

 

[jfrabat]

Well, first of all, let me say that I have a Helix spacer (I got mine from eBay) on mine, so bear that in mind...

But on theory, according to the manufacturers, the way these things improve efficiency (ie. power and fuel consuption) is by better mixing the fuel and air by means of the vortex created. If you have a fuel injection model (except for a TB Fuel Injection), then the vortex will not affect your mixture at all. In fact, because of the fins, you would be restricting the flow of air when the throttle is fully open because the fins are thinner than the throttle body spacer. Besides, the air moves faster in laminar flow than with turbulence, so any smooth bore is preferable to a turbulence inducing bore. However, on the other hand, the spacer will give you a bigger "storage" of air BEHIND the TB, which COULD improve efficiency.

Now, having said that, I chose to install a 63mm spacer on mine because with the new 4.0L TB I am about to install, I would still get better flow than before, and I am still not putting any restrictions on the total air flow going in (although I may be adding unwanted turbulence). But, I am not 100% possitive that it DOES NOT improve the engine performance, and for that, I am willing to shell out $20 (although I would not invest more than that, but that's just me); hey, just the new gaskets and getting rid of those tamper proof torx screws was worth the $20!

This is just my logical analysis of what is actually happening, and I am sure many people out there disagree. But if you have a 2.5L, I would recomend changing the TB for a 4.0L, and if you have a 4.0L, maybe you are better off investing in a 62mm TB (2mm does not sound like much, but keep in mind that the AREA increase is significant because it goes all the way around!).

Felipe