Topic: 4.0 Throttle Body on the 2.5

[Dan Marino]

Guys,

I've read about the modification of grabbing a 4.0 throttle body and bolting it onto the 2.5 engine.  This is supposed to make the throttle response better and seems to increase horsepower somewhat.  What effect does installing the 4.0 throttle body have on gas mileage?

Thanks,

This place is way better than jeepforum.  Over there, JeeperDon and the gang slams anyone with a 2.5.

[Jeffy]

Did you start with this: http://www.4bangerjp.com/forums/viewtopic.php?t=8 ?

[low output 2.5]

thanks for the write up on this upgrade iam doing it as we speak  i bored out underneath throttle plate also got a airraid tb spacer for the 4.0 it was way smaller and restricted so i devained it and it matches and so does the intake but  my question is do i need to space the throttle pull linkage up a inch or will it be fine it looks fine to me but i know some of you guys have done this o yeah gotta get that darn safety screws out tools are at work   :x

[Krod]

did mine over the weekend.  I installed the TB first (no spacer, no port matching) and drove it like that for a day and a half, decided to port match the intake, but i didn't notice much of a difference really.  I'm not running a spacer at the moment, but i can certainly feel a difference on the lower RPM range from about 1200-2600 and it seems to be "smoother" overall.  

Definately a must do.  
Cost...FREE  (helps to have friends with parts jeeps    :wink: )

[jaszon]

ok,new here to the site and must say thanks for the info but im a little confused on the tb swap,this wont work on a 1990 will it,it looks like 91 and up or am i wrong.I have a 90 and would like a little more power and wanted to try this.thanks again.

[Jeffy]

ok,new here to the site and must say thanks for the info but im a little confused on the tb swap,this wont work on a 1990 will it,it looks like 91 and up or am i wrong.I have a 90 and would like a little more power and wanted to try this.thanks again.

Read this: http://www.4bangerjp.com/forums/viewtopic.php?t=8.  Your engine is TBI and not MPFI.  If you could swap the TB, you would be left with no injectors.  Some people once said that a S-10 TB might work but I'm not certain since I've never tried it nor have I hear from anyone who could confirm it.