4.0L HO Jeep Engine Build
Now on to my goals for this engine. It will be for a daily driver so mileage and useable power are top on the list. It won't be a high rpm screamer, nor will it be turbo'd or supercharged. :) I just want the most power I can get for the lowest price with the least mileage penalty. I know that these engines can be stroked to 4.5L, 4.6L or even 4.7L fairly easily, but that is out of the scope of this build. Maybe later as I still have the early block. :)
Here's the mods as planned:
1. .030 overbore, always worth a couple of ponys.
2. Later block with thinner ring pack coated piston, less friction.
3. Decking the block for .040" quench, more compression and less chance of detonation. Compression is always worth power, as is quench.
4. Set my bearing clearances to .0025, less friction.
5. Using the early ('92) head. It has larger ports than the late head and also did some home porting and had my machinist bring the valve seat out to very outer diameter of the intake valve but the left the ex valve pretty much in the middle to maintain longevity.
6. I'll be using the late intake manifold. Much better design. It was originally engineered to to pick the HP back up after using the smaller port head and cam on the later models to reduce emissions.
7. I'll be using the early throttle body (it's bigger than the late model).
8. Swapping out to mustang style 24 lb injectors. They are the 4 hole disc type and should give better atomization.
9. Aftermarket SS header. It give better flow and solve the cracking issue that plagues the 4.0L HO.
10. Cat back exhaust. Less flow restriction.
11. Early style ('92) cam, more lift and duration than the late model cam.
12. New, high flow cat.
Pic 1, the new header. It was cheap. There are better headers than this but they are very expensive. This header was less than $150 shipped.
Pic 2 Here you can see the difference from the old vs. new style intake.
Pic 3&4 Nice shiny new pistons. They give me a nice warm fuzzy feeling deep in my heart. :) These rods are press fit so this was done at my machinists place. Note the very narrow ring grooves.
Now on to my goals for this engine. It will be for a daily driver so mileage and useable power are top on the list. It won't be a high rpm screamer, nor will it be turbo'd or supercharged. :) I just want the most power I can get for the lowest price with the least mileage penalty. I know that these engines can be stroked to 4.5L, 4.6L or even 4.7L fairly easily, but that is out of the scope of this build. Maybe later as I still have the early block. :)
Here's the mods as planned:
1. .030 overbore, always worth a couple of ponys.
2. Later block with thinner ring pack coated piston, less friction.
3. Decking the block for .040" quench, more compression and less chance of detonation. Compression is always worth power, as is quench.
4. Set my bearing clearances to .0025, less friction.
5. Using the early ('92) head. It has larger ports than the late head and also did some home porting and had my machinist bring the valve seat out to very outer diameter of the intake valve but the left the ex valve pretty much in the middle to maintain longevity.
6. I'll be using the late intake manifold. Much better design. It was originally engineered to to pick the HP back up after using the smaller port head and cam on the later models to reduce emissions.
7. I'll be using the early throttle body (it's bigger than the late model).
8. Swapping out to mustang style 24 lb injectors. They are the 4 hole disc type and should give better atomization.
9. Aftermarket SS header. It give better flow and solve the cracking issue that plagues the 4.0L HO.
10. Cat back exhaust. Less flow restriction.
11. Early style ('92) cam, more lift and duration than the late model cam.
12. New, high flow cat.
Pic 1, the new header. It was cheap. There are better headers than this but they are very expensive. This header was less than $150 shipped.
Pic 2 Here you can see the difference from the old vs. new style intake.
Pic 3&4 Nice shiny new pistons. They give me a nice warm fuzzy feeling deep in my heart. :) These rods are press fit so this was done at my machinists place. Note the very narrow ring grooves.
