Which TBS should I get?

[Sparky-Watts]

I've come to the point where I'm ready to buy a Throttle Body Spacer for the YJ, but don't know which one I want. Poweraid now makes one for both the 2.5 and the 4.0. I have been reading on another forum that the TBS for 4.0 engines works just as well on the 2.5 because of the diameter of the intake opening, but now that one is offered for the 2.5, I guess I could use that. Here are the 4 I'm considering:

http://www.4wd.com/shop/productdetail.asp?productsku=310510
http://www.4wd.com/shop/productdetail.asp?productsku=310511
http://www.4wd.com/shop/productdetail.asp?productsku=6211
http://www.4wd.com/shop/productdetail.asp?productsku=40005

I'm leaning more toward the Poweraid model for the 2.5, simply because I've heard the name more often than the other two brands. It's about $20 more, but I figure probably worth it for the notoriety.

I notice they all have some type of "threading" inside the intake to make the air spin.....is it just me, or wouldn't it be a better design to keep that smooth, less air drag and all?

One has a tight group of grooves cut into it, another a fairly loose group of grooves (for less spin). Is this even going to be an issue?

Lastly, of those of you that have added a TBS to your rigs, is there much noticeable difference in HP or mileage? I think I'm at the upper limit of mileage, but any little bit of HP gain would help right now.

 

[TwistedCU]

Unless you want to change the throttle body to one for a 4.0L (which you may want to consider if you're looking for more power) I would go with the Poweraid spacer for the 2.5L.

 

[Sparky-Watts]

Eventually I will go with the 4.0 TB, so I figured I might as well go with the 4.0 TBS for now....but what difference will that make while I still have the stock 2.5 TB on it? I've heard that the intake diameter is the same on the 2.5 as the 4.0, and many folks have been using the 4.0 TBS with the stock 2.5 TB and still getting good gains from it. Only recently has anyone even begun making the TBS for a 2.5. If the 2.5 TBS is a smaller diameter than the 4.0, I'm thinking the 4.0 TBS is still a better deal since the airflow will be greater. What do you all think on this?

 

[TwistedCU]

Putting a larger diameter spacer won't open up the throttle body, so I don't see how it would work any better then the 2.5 spacer, but if the intake is the same diameter I can't see what it would hurt. So, yeah, if you plan on getting the bigger TB down the road the 4.0 spacer is a no-brainer.

 

[Junkpile]

I'm not convinced that the inner designs of any of the spacers is such a big deal. The companies need a way to distinguish their product from the next guys, and I think that is the main reason for all of the helix and grooved stuff. It's a dry flow log type manifold. The biggest factor with the spacer is that it distances the TB from the intake floor, therefore smoothing flow as it makes that turn towards the engine. The whole concept of disrupting the intake charge with some type of helix or grooved intake floor is more for a wet flow intake, such as with a carb or TBI where you would want to increase fuel atomization, and often that doesn't work as it should and you end up with fuel puddling in the intake. I'm just speaking on theory here, but it seems like a big old fat gimmick. Besides, why spin the intake charge just to have it then slam into the intake floor and then make another 90 degree turn into the individual runner?

I'd bet that the gains will be similar for any of them when tested on the same engine. The height of the spacer and how well it matches the intake throat and TB would be the more important factors in my opinion.

 

[Sparky-Watts]

Besides, why spin the intake charge just to have it then slam into the intake floor and then make another 90 degree turn into the individual runner?

I'd bet that the gains will be similar for any of them when tested on the same engine. The height of the spacer and how well it matches the intake throat and TB would be the more important factors in my opinion.

That has been my thought all along.