jigly

I've had a few jeeps and have rebuilt the motors top to bottom. Have replaced everything at one point or another. Maybe I never heard the question because I was buying parts for the specific year/body/motor and not messing with different year parts, but what the hell is the HO motor you all keep referring to?

Andrew0257

High output

kohlers89XJ

its jeeps more beefy motor has more hp and torque

jigly

And more importantly; does my 2000 have one?


Since threads get pushed off the first page so quickly here, we'll make this a two-parter... While we're here discussing 2000's, I've read that there has issues. What's this about?

rich

yes it does

jigly

Well, I assumed it stood for high output. What's different? How do I tell what mine is?

rich

Yes the head are prone to cracking between cylinders #3-4,so after market heads have fixed this issue by beefing up between those two cylinders just like jeep began doing after 2001.(Head casting is 0331 for 2000 up)

rich

Really the big differance is 10 to 15 more hp/torque and better flowing intake runners and head, also the coil on plug ignition knot motor related I think the unibody also was beef up,Also higher fuel pressure to help burn better. Most likely some other small things maybe someone else can chime in if I missed anything. I think from 97 on are all ho motors I think its 97.

CodeXJ

I believe the HO was introduced in '91 and was offered until '99. It was a refinement of the previous version of the 4.0L and offered 190HP and 235ft/lbs of torque, and improvement of 17hp and 11ft/lbs.

In 2000 the HO motor was replaced with the PowerTech motor, which was really the same motor with a different intake manifold. The PowerTech produced 193HP and 243ft/lbs of torque, HO motors can be brought up to this by bolting the newer manifold on. The PowerTech got a different head casting as well, probably as a cost saving measure since from what I've heard it doesn't flow any better. Unfortunately this casting is more prone to cracking when overheated than the older version. I'm not sure but I believe the pre-00 head will fit on the PowerTech block just fine, so if the head does crack that's an option.

I believe they stopped putting the "High Output" badges on them in '96, but I'm guessing at that. In the 90s (in the USA at least) only the 2.5L 4-cylinder and 4.0L 6-cylinder were offered, and all the 4.0Ls were HOs.

jigly

Well, she aint leaking yet!

jigly

Awesome. Thank you.

rich

The heads are differant in 99 they dont have the bolt holes for the coil pack yes all heads will bolt on all motors and 2000 up are still the h o motor the only problem with bolting up the intake from a 00-01 to 99 and ealier motors is the runners dont line up just right thus reducing flow slightly but its still better then factory flow.But like I said Im not sure what year they started the ho and Im still not.

rich

Well thats good you wanted to know and I told YOU!!!!!!