88 comanche easy engine swap?

[abehuyser]

So I am new to this forum and the question I am trying to find an answer to is which engine would be the best to use for engine swap.  I currently have a 1988 jeep comanche with 4.0 manual 5 speed and 4wd.  I would like to have a little more power and gain some mpgs.  I was thinking of swapping with the HO 4.0  Which years are these engines available with ease of swapping the engine.  I understand there might be some harness changes I may have to make, but wasnt sure if there were a few years of engines that were easier than others.  Thanks in advance for the help. 

[cruiser54]

So I am new to this forum and the question I am trying to find an answer to is which engine would be the best to use for engine swap.  I currently have a 1988 jeep comanche with 4.0 manual 5 speed and 4wd.  I would like to have a little more power and gain some mpgs.  I was thinking of swapping with the HO 4.0  Which years are these engines available with ease of swapping the engine.  I understand there might be some harness changes I may have to make, but wasnt sure if there were a few years of engines that were easier than others.  Thanks in advance for the help. 

First off:

 

HO myth buster

 

 

Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference. 

 

HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had 58 mm throttle body versus a 52 mm throttle body on a Renix and also had a better design header. See where I'm going with this?

 

The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold.

 

Put a 60mm TB from www.strokedjeep.com on your present head, eliminate the "crush" in your headpipe with proper re-routing, and go for it. 

 

HO stands for Highly Overrated.

 

Secondly, if you want to put an HO engine into your 88, here's how:

 

Cruiser’s HO into Renix Swap

 

This swap is easier than some will lead you to believe, generally those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.

 

The HO and Renix have some differences but none that can’t be overcome very easily.

 

Any HO engine from an XJ or ZJ through 1999 can be used. One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from the HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head for the sender.

 

You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use the Renix gasket. Exhaust ports are identical.

You will need to use your Renix distributor as it is different than the HO because they use different fuel management systems. The  flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.

 

The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.

 

As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.

 

 

Revised 03/28/13

 

Thirdly:

 

If you want more power, there are things you can do to your existing engine as long as it's in sound condition. 

 

Have you ever indexed your distributor? 

 

 

__________________

[64 Cheyenne]

abehuyser, you might want to put a little more info about your vehicle, tires/gears etc, and the condition of its current engine. There are other performance, mpg options besides an engine swap if your current engine is in good shape.....unknown quote: "Hands down, best bang for your buck is gears"

[abehuyser]

Thanks for the quick answers. Really appreciate it.

So that's where I was headed with the next question. I don't believe my engine is in the best shape. Getting oily residue on the air filter. Cooling system issues I don't believe it's in the radiator. I think it's in the head. Cooling system doesn't stay at operating temps. 200k miles on the engine. I don't really want to spend a bunch of $ on either rebuild or swap. This is my daily driver and used to play around in the woods. No climbing and none in the future.

 

The gearing I don't honestly know the ratios. Factory as far as I know.

 

Was thinking of just tearing engine down and doing basic rebuild. No stroker. Maybe an updated head and manifolds. What's your guys opinions?

 

I like the throttle body upgrade. Seems fairly inexpensive.

Should a updated head be installed?

 

Thanks for the help

[64 Cheyenne]

"oily residue on the air filter"... there's a write up for that.

 

"Cooling system issues I don't believe it's in the radiator."...Condition of the pressure bottle? ANY loss of pressure from the tiniest leak in the pressure bottle and cooling system will cause problems with cooling, if the pressure bottle does not look new, I'd suggest replacing it or convert to closed cooling system, and yes there are write ups for that also.

[Pete M]

yeah, oil in the airfilter is EXTREMELY common on the Jeep engines and usually because of a clogged up or broken CCV line.  in worse scenarios the late model valve cover can fix it.  some of us have 4.0s that are beyond even that and I use a catch bottle inline to the air filter.  the engine still works well enough to drive 3000 miles out to Moab and back with wheeling in UT, CO and IL along the way.  blow by is certainly not a deal killer. :thumbsup:

[cruiser54]

Thanks for the quick answers. Really appreciate it.

So that's where I was headed with the next question. I don't believe my engine is in the best shape. Getting oily residue on the air filter. Cooling system issues I don't believe it's in the radiator. I think it's in the head. Cooling system doesn't stay at operating temps. 200k miles on the engine. I don't really want to spend a bunch of $ on either rebuild or swap. This is my daily driver and used to play around in the woods. No climbing and none in the future.

 

The gearing I don't honestly know the ratios. Factory as far as I know.

 

Was thinking of just tearing engine down and doing basic rebuild. No stroker. Maybe an updated head and manifolds. What's your guys opinions?

 

I like the throttle body upgrade. Seems fairly inexpensive.

Should a updated head be installed?

 

Thanks for the help

I think you're nuts to take that approach. Your unfamiliarity with these engines is trumping the good advice you're being given.

 

A factory thermostat would solve the underheating issue.

 

The tip I gave you for oil in the air filter came from Jeep Engineering..........

[abehuyser]

I tried factory thermostat.

[cruiser54]

I tried factory thermostat.

Mopar, from the dealer?