I am looking into possibly fabricating a throttle body spacer for my '92 4.0L HO and am wondering about the dimensions. Three main questions...

1. How does the height affect the power gain? 1" better that 3/4"? 1.5" better than 1"?

2. Does the inside of the cylinder shape matter? Twisted compared to smooth?

3. How wide is the square both ways?

 

They are a waste of money. I wouldn't even waste your time fabing one because they do absolutely nothing, except whistle when you shift if you have a 5 speed. Haha.

 

^x2

TB spacers where 1st made for carb'ed engine where the point of it was to better mix the fuel and air. They do nothing but make someone else money and your jeep whistle

 

I'm not going to fab one of the ones that whistle, but I've heard with a bigger throttle body (63mm) which is what I have, they help with air flow a bit creating not much, but a little extra power.

 

Larger throttle body or not... they do nothing for a direct injected engine.

I am not convinced that the throttle body itself is worth it either...

 

if you could fab one about two inchs tall it would give more top end power like the old high rise intake bu because of hood clearence it wont work

 

but he has the log style intake so it wouldnt really do much cause the point of high rise intakes is to have long straight intake runners to increase the speed of the incoming air

 

i have one on my rig, could rlly tell you if i gained anything from it. makes a noise that kinda sounds like a turbo took a little while to get use to it. if i did gain anything its very little, i got it for free so idc

 

Isn't it atleast worth it for better air flow and performance of the motor if I'm getting them for basically nothing? I don't mind as long as long as it's good for the engine. Or is this really not even worth the time?

 

Why do you think it would increase the air flow? Air still has to make a 90 degree turn into the TB and then 2 more 90 degree turns in the manifold before entering the cylinder. Adding 1-2" under the TB doesnt change the fact it needs to make those turns.

Id say its a waste of time, which could be better spent on a nice intake system or a 99+ intake manifold. (everyone has opinions on this upgrade but i totally love mine, with a header to match of course, and its worth it just for the fact is so much easier to remove or tighten my belt)

 

I agree TB spacers do nothing....in some cases have caused an actual loss of power on the dyno in some vehicles.

Even if you have a larger TB...unless you port/polish or bore out the intake manifold. This is just what I have learned from past vehicles.

 

Not because of the height, but because of the larger inlet for air to be sucked in. But from all the negative feedback, I don't think I'll be doing this anyways.

I've never heard of the 99+ intake manifold though. Are they larger or...?

 

Yeah and ported better for smoother airflow. Opening up your throttle body (to 62mm for example) will give you a noticably better throttle response but you're not going to gain any HP. The throttle body and intake are already well suited for a 4.0L, anything above that with the intent of gaining horsepower would be futile; you'd have to increase the engine capacity as well.

 

slap a sticker on the side of your jeep if you want an e-***** extension. TB spacers do nothing.