Throttle Body spacers

[HeepJr]

I keep seeing Throttle Body spacers on Xj's What is the purpose, or the benefits what exactly does it do. (sorry dont know much about engines)

[Mudderoy]

I keep seeing Throttle Body spacers on Xj's What is the purpose, or the benefits what exactly does it do. (sorry dont know much about engines)

I say nothing, but we have at least one member here that says it increased his MPG, no measured mpg, just able to drive farther on a tank of fuel.

[HeepJr]

so its more for show then anything else

[OrangeXJ]

There are believer's and non believer's. Most say there is no benifit on fuel injected engines. I put one on a 1996 Bronco the last year they made the full size one. It had a 351 cid and gas milage went from 8 to 12 mpg. I put one on my 97 TJ (4.0) that I did not do a base line mpg but I could go about 10-15 miles more on a tank of gas than before. And has more low end throttle responce. I just recently put one on my 2006 C6 Corvette LS2 and it also inproved the low end throttle responce ( like it really needed it )

[XJ Wheeler]

I put a Poweraid on mine several years ago and also noticed more low end grunt. I didn't do fuel mileage on it though. If you're wanting one, check ebay. There's usually a couple on there used for much cheaper. There's not much to mess up on them so going used shouldn't be a problem. Just make sure it comes with the longer bolts and spacers.

[cantab27]

For show

[NW99XJ]

Some throttle body spacers have what look like "threads" on the inside, or even curved veins. The theory here with this style of design, is that it creates a whirlwind effect to the air, making it travel faster, and with more density. With the addition of more available air in the system, the fuel is better "combusted".
I have installed many throttle body spacers on various vehicles, from tuners to trucks, and everything in between... Everyone was happy with the results... I think with every throttle body spacer, its going to change the torque curve a little, which ALWAYS will be measured by the "Seat-o-your-pants-o-meter"
Bottom line... if its something you want to add to your Jeep... go for it. It;s certainly not going to hurt anything, and yes... regardless of performance or mileage claims... they DO look cool. :cool:

[Cheromaniac]

I say nothing, but we have at least one member here that says it increased his MPG

I'm one of them. I installed my TB nearly 15 years ago and at the time, it did yield a near 1mpg gain in gas mileage and a small SOTP performance gain mainly at lower rpm.
I believe the reason why the TB spacer works is that it raises the TB further away from the floor of the intake manifold plenum and reduces turbulence. The threaded helix inside the spacer is a marketing gimmick and I had mine bored away when I increased the size of my TB to 62mm (and later 65mm).

[Mudderoy]

I've been measuring my MPG for YEARS, literally, YEARS. If anyone wants to send me a throttle body spacer I'll run it, report the MPG results and ship it back to you.

I'm assuming it's just a bolt on and no other modifications need to be made.

[autotech98]

I have to agree with you Josh on the principle of way spacer works it decreases turbulence in the air flow and allows the mixture to flow more smoothly into the cylinders that's also why the 99 and up intakes give you a performance gain and in a vehicle that has a TBI or carburetor it also increases the fuel atomization

[autotech98]

If I recall correctly that's also the principle behind porting and gasket matching your cylinder head by taking the sharp edges off the transition between the intake and the cylinders it decreases turbulence:cool:

[GetRstuck]

Port matching is to remove restricting turbulence. TB spacers are meant to allow the fuel to air mix more consistence. It’s like pouring a 2lt coke bottle upside-down and it splash out or spin the coke around and then let the coke come out, same amount better flow.

[prerunner1982]

Port matching is to remove restricting turbulence. TB spacers are meant to allow the fuel to air mix more consistence. It’s like pouring a 2lt coke bottle upside-down and it splash out or spin the coke around and then let the coke come out, same amount better flow.

The only problem is that on a 4.0 XJ the fuel is injected into the cylinder. A carb/throttle body spacer works well in a vehicle where the fuel is injected into the carb/throttle body which as mentioned above would allow for better atomization. (air/fuel to mix better).

[autotech98]

I agree but i would think it would help with the less turbulance / better airflow

[4.3LXJ]

I agree but i would think it would help with the less turbulance / better airflow

This is one of the issues at the core of the debate in my opinion. In the 80s and 90s, with head design that was current at that time, the idea was to increase the length of the intake runner to reduce turbulence. This was done because the fuel for combustion was sprayed on the intake valve. A less turbulent air flow would sweep the fuel into the combustion chamber and allow better mixture in the combustion chamber. This is one reason that in 99, in order to meet emissions requirements the intake runners on the new manifold had longer center runners and larger, to reduce turbulence in the middle of the 4.0 intake. So I question any device that increases turbulence. However I think there MIGHT and I want to use that word cautiously, that there might be a benefit in reducing turbulence generated by the butterfly in the throttle body by some increased distance given by a spacer