Topic: 4.0 tb conversion?....(sorry)

[melbill]

I have a '95 YJ and I have the intake on the left (looking at the picture). I am in the process of cleaning it up right now and will be opening it up for a 64mm tb this week. I guess '95s got lots of different parts some YJ some TJ depending on the line and the day it came off.  

[Jeffy]

I have a '95 YJ and I have the intake on the left (looking at the picture). I am in the process of cleaning it up right now and will be opening it up for a 64mm tb this week. I guess '95s got lots of different parts some YJ some TJ depending on the line and the day it came off. 

Well, TJ's use a intake then the YJ's as there is no port for the MAP.  Most of the weird YJ's were '95.5's and not '95's as the '95's carried over into 1996.  That's when you start seeing stuff like the dual diaphragm boosters, pucks on the hoods and upgraded tailgate hinges among other things.

Anyone have a '93 or '94 and can confirm?

[oldjeep]

Well, TJ's use a intake then the YJ's as there is no port for the MAP.  Most of the weird YJ's were '95.5's and not '95's as the '95's carried over into 1996.  That's when you start seeing stuff like the dual diaphragm boosters, pucks on the hoods and upgraded tailgate hinges among other things.

Anyone have a '93 or '94 and can confirm?

I've got a 94 and my Map is on the firewall.

[FourbangerYJ]

this is off two different yj's 4 cylinders 

Mine was made in Oct. 95. I have the non square style intake (the one on the right looking at the pic). I have the TJ rubber pucks on the hood, and TJ style tailgate hinges. But I missed out on the brake booster.

[melbill]

They get weird. I believe mine is a  95.5 it  has the square intake, pucks on the hood, and a plugged MAP port on the tb.

[Jeffy]

They get weird. I believe mine is a  95.5 it  has the square intake, pucks on the hood, and a plugged MAP port on the tb.

Might just be a 1995.5 thing.  Some 1995.5's don't have everything but rather have some things that are older depending on when exactly it was made.

[Jeffy]

I've got a 94 and my Map is on the firewall.

Was your intake the square or the round one?  They should all have the MAP on the firewall.

[sharpxmen]

I have been reading alot about 4.0 tb upgrade but thought the intake was the only opening to be enlarged. Do both the intake and lower tb opening need to be enlarged to 64mm??

the 4.0L tb is 60mm at the top and 56mm at the bottom. you can bore out the bottom side of the t/b to 60 mm but not with a dremel or holesaw - it has to be done on a lathe or milling machine. The 62, 63 and 64mm throttle bodies are machined and enlarged from top to bottom, they require a larger butterfly to match the new diameter.

[Bounty Hunter]

My spare '94 engine and my '95.5 both have the rounded base for the TB, FWIW.

I wouldn't waste your time with a 4.0L TB, go with an overbore like a 62mm for the large increase in throttle response and airflow.

[sharpxmen]

Was your intake the square or the round one?  They should all have the MAP on the firewall.

my 95 is the rounded one, same with a '94 intake that i have as a spare.

all YJs had the MAP on the firewall, would probably work with either one but the wiring would be in a different location and the plug is different also, so my guess is that's why there was no YJ with a MAP on the t/b when they start mixing them up.

[Jeffy]

my 95 is the rounded one, same with a '94 intake that i have as a spare.

all YJs had the MAP on the firewall, would probably work with either one but the wiring would be in a different location and the plug is different also, so my guess is that's why there was no YJ with a MAP on the t/b when they start mixing them up.

They moved the MAP for 1996 XJ's and 1997 TJ's.

Seems strange that they would implement a new intake design at teh end unless they were seeing if they could lighten it or maybe cut cost on it so they could see if it would work on the TJ's before they came out.

[Bounty Hunter]

My 95.5 YJ stock 2.5L TB had the MAP port on the TB, with a vacuum cap.  Also had a goofy crossbreed of a mainshaft in the transfer case, didn't use caged bearings like earlier YJ's, the sprocket spun straight on the shaft like TJ's and SYE's, yet the rest of the mainshaft was pure YJ.

[sharpxmen]

Speaking of throttle bodies. wth am i supposed to do about my 1990 2.5? there isnt shizzzle for em!!

i have one that i cannot test so i don't know how and if it works but if you're up for some testing send me a PM - have a look here http://4bangerjp.com/forums/index.php/topic,8142.msg64698.html#msg64698

[Eucalypta]

I have a '94 2.5 YJ with the manifold on the left.

Today I swapped my TB with one of a 4.0L.
The flange opening in the manifold is about 56mm and the outlet of the 4.0L TB is 56mm.
By only swapping the TB's I increase the minimum air intake diameter from 48mm (outlet opening from the 2.5L TB) to 56mm.

I drove just a bit along the countryside today so cannot yet tell if it is a big improvement on the highway with a strong head wind. 

I guess if you go to a full bore without changing the injectors, fuelpressure valve and possible O2 sensor, you might not gain extra power? 

[xjaz]

Speaking of throttle bodies. wth am i supposed to do about my 1990 2.5? there isnt shizzzle for em!!

Sure there is, just do the MPI conversion like this http://www.naxja.org/forum/showthread.php?t=950222&highlight=multi+port+injection.  Not an easy swap, and in hindsight, not really worth it.