Engine swap options? Help me decide

[JRappleguy]

Sup y’all, so I’m playing around with what to do to my 1991 4.0HO 5-speed Short Bed 2wd.  I want to keep it Mopar so no Chevy or Ford swaps.  
 

I’m not against keeping the 4.0HO and building it as a stroker but I came from a Hemi in my Ram and would strongly consider going back to a V8.  I plan on also keeping it RWD and would like to keep it 5-speed as I enjoy driving stick.  
 

So here is my questions.  
 

1st, if I go to a V8, which would be better,  a 5.9L or do a Gen3 Hemi swap?
 

2nd, what is the strongest rear to use outside of going to a Ford 8.8?

 

3rd, can the AX15 be strengthened or should I swap it to a different manual trans?  
 

Please don’t hesitate to let me know if there is something better out there but keep in mind I am not swapping to Chevy or Ford products.  
 

if there are links to write-ups I will be happy to check them out.  
 

Thanks in advance.

[JZLAJeep]

13 minutes ago, JRappleguy said:

Sup y’all, so I’m playing around with what to do to my 1991 4.0HO 5-speed Short Bed 2wd.  I want to keep it Mopar so no Chevy or Ford swaps.  

You've already got the best drivetrain. Keep it.

[ghetdjc320]

I agree, keep it as-is. But to address some of your questions:

 

Assuming you want to keep things all Jeep,

The AX15 can handle quite a bit. Wouldn't be concerned at all until over maybe 400lbft of torque but it can be upgraded to handle a decent bit more. Th ax15 is basically a Toyota R150/151 transmission. Marlin Crawler offers bot only rebuilds of the AX15 but also two crucial power handling upgrades: first gear thrust bearing and rear bearing retainer plater. They have a few other items they offer as well but the actual ax15 gear set is plenty stout and able to handle a lot of torque. Also, use good fluid in it such as Redline MT90, Amsoil MTF or similar. NO GL5 oils though.

 

The "strongest" rear axle is really subjective but if your wanting to stick with oem or at least the oem theme, go with either an original Dana 44 or an 8.25 from a later model XJ or KJ liberty. The liberty is a nice swap as it's wider than stock and actually fits the MJ remarkably well. Also has decent disk brakes. The KJ 8.25 has a ton of extra brackets that need to be removed.

 

As for links and write-ups, browse through the members builds and also the epic build section and you'll come across a lot of different build to gather ideas from. 

 

 

 

[Pete M]

gears gears geats.  nothing gives a kick in the pants like a big bump in ratio.  

[Smokeyyank]

Keep the 4.0 and ax15. Only V8 swap worthwhile is a LS. Others can be done but there's a reason LS swap are popular. Dollar per HP nothing comes close. Strongest jeep rear would be a d44 but they aren't cheap. 8.25 is a solid choice. Gears will give you a nice little pep. You could get a rear from an auto that will bump to 3.55.

[howeitsdone]

Where there's a will, there's a way. And a lot of money to be spent.

 

 

https://rocksolidfab.com/manny-the-manche

[pizzaman09]

I'm all for a cool swap, I know nothing of any of the American V8s.  Anything is possible and not everything has to land on the logical LS, K series or rotary swap that so much of the automotive build world lands on.

 

Personally, I want to swap in an early 2000s BMW M3 S54 inline 6.  Lightweight, high revving, makes more power and torque than any stock 4.0L.

[Armyvet25]

What about building an AMC 304/360, or source the 390/401. Dodge Dakota RT Magnum 318/360 would also be nice. Never mentioned budget, and Hemi is going to consume quite a bit. I've got a 2.8L GM I'll sell ya