Differences between 91/92 HO vs 93+ HO

[WahooSteeler]

Got my eye on a 92 MJ rust bucket but with very low miles. My interest would be the motor and all that would be needed to go with it to swap my 88 to an HO motor, plenty of other good parts to sell off and recover some of the purchase cost. My question is, are there any reasons a later model HO from an XJ etc would be more desirable if/when I do the swap? I don't see myself ever doing any serious mods to the motor, my main interest in this particular one is it's got <100k on it and the HO's hopefully will continue to have parts available for years to come. 

[Smokeyyank]

The advantage of going with a 96+ is OBDII. Prior to that you had OBDI, nothing else. It's a debate on whether OBDI is an upgrade over Renix. Personally, I think it is not, but that's just me. If I was to do the swap to a HO I'd find a 99. Last year of distributor and has the better intake manifold. 

[FrankTheDog]

91 HO has same pilot bushing size as renix. 92 and up have all the same size.

If you want to use later model transmissions you need 92 and up.

96-98 seemed the most powerful by the seat of my pants than all others. 

But not all of them. I had 2 98’s and 1 96 that felt like they had 15 or more hp than identically equipped 92-00 XJ’s.

[Dzimm]

13 hours ago, FrankTheDog said:

91 HO has same pilot bushing size as renix. 92 and up have all the same size.

If you want to use later model transmissions you need 92 and up.

96-98 seemed the most powerful by the seat of my pants than all others. 

But not all of them. I had 2 98’s and 1 96 that felt like they had 15 or more hp than identically equipped 92-00 XJ’s.

A lot of that "power" difference you feel may be in the gearing.  My 98 xj (runs great) has 3.07 gears and is super sluggish, while my 95 xj (runs like crap), and 97+ swapped MJ have 3.55 gears and are quite noticeably quicker and seem to have more power.  All of them have the 4.0, AW4, NP231, D30, and C8.25, only difference is gearing. 

[FrankTheDog]

These were all stock geared automatics.

[Dzimm]

32 minutes ago, FrankTheDog said:

These were all stock geared automatics.

XJs came with 3.07 and 3.55 from the factory in the C8.25.  It was possible to get 3.73 on a D35 for a while. 

 

I also want to say that contrary to what you find online, XJs with the auto tranny did come with 3.07 gears, at leasy my 98 XJ SE 2-door has an AW4 and came with 3.07 gears.  Hence why it feels so much slower.  Potentially special order possibility? 

[FrankTheDog]

These all said 3.55 on the rears. 

The 96 and 98 with abs had D35’s.

The 98 without had a C8.25.