Physical Differences 4.0 - 4.0 HO

[Yoke]

I was wonderign what are the physical differences in the two engines? Blocks, heads, intakes, etc.... I have been able to search and find out that the heads are slightly different and the injection system is different but no mention about the block differences if there are any.

 

Yoke

[jeepthing07]

The head and exhaust manifold is different, fuel injection is different. The block is the same but its supposed to be stronger than the HO block. Renix has a knock sensor and the temp sensor screwed into the side of the block. The end of the crank on the HO crank is machined out deeper on the HO's.. so HO's with a manual trans use a spacer in the crank that the pilot bearing is pressed into. i think thats about it

[pingpong]

I did a HO head swap on an XJ once.. the exhaust manifold won't work... and neither will the intake... I suppose you could modify the intake to accept the non-ho throttle body.. but I am not sure. THe exhaust has no provision for the egr tube.. Also the valve cover is different between the two

[jeephack]

This intrigues and also puzzles me. I did the swap about a year ago,except in the other direction. I swapped the entire engine

(89 renix) into a 93 XJ. The intake and exhaust manifolds both bolted

in with no problems or modifications. Also swapped the HO valve cover

onto the '89 so that the hoses would fit without modification. Jeep's

been running great for over a year now. It's my son's DD. What gives???

Maybe I just got lucky!!!

 

Jeephack

[jeepthing07]

This intrigues and also puzzles me. I did the swap about a year ago,except in the other direction. I swapped the entire engine

(89 renix) into a 93 XJ. The intake and exhaust manifolds both bolted

in with no problems or modifications. Also swapped the HO valve cover

onto the '89 so that the hoses would fit without modification. Jeep's

been running great for over a year now. It's my son's DD. What gives???

Maybe I just got lucky!!!

 

Jeephack

 

I swaped a 89 renix block into a 97 and used the 97's head. When i went to put the new intake/exhaust gasket on that i bought as a set from the dealer the exhaust ports lined up fine but when i looked at the intake the holes in the gasket were way to low and shaped slightly differently.

 

The HO head has higher ports for better airflow. the exhaust manifold will bolt on but the collecter is further back than a HO manifold. A renix intake on a HO head would sit probably 3/8" lower and the ports wouldent be aligned but as long as the gasket sealed up on it i guess it would run. I sure wouldent do it

[87manche]

when chryco deleted the EGR system they changed the cam durations and overlaps to compensate for emissions. The HO head is a better flowing head.

 

When putting an HO motor in a renix rig I think the best option would be to use the HO manifolds, delete the EGR system, and adapt the renix TPS sensor to the HO throttle body.

Otherwise you could make a simple spacer plate to adapt the renix TB mounting pattern to the square pattern on the Ho intake.

[jeepthing07]

when chryco deleted the EGR system they changed the cam durations and overlaps to compensate for emissions.

 

I have allways seen 4.0 cams were the same form 87-95 then it changed 96-06 :dunno:

 

www.angelfire.com/my/fan/Jeep4.0Camshafts.htm