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H.O. swap

L

lsc910

NAXJA Forum User
Location
New Jersey
Just wondering whoi has done one and how hard is it. If you have done one do you have pics on what has to be done. I have an 88 with the renix in it and I also have a 93 that the floor is pretty rotted and I redid the front floor but the back is all messed up and I don't know if I want to get into replacing it all. The 88 has a blown motor and every thing else seems to be sound on it. I'm just wondering about the wiring and how bad it will be to swap. Thanks for all the info.
 
Go for it. Strip the 93 down to a long block and transfer your manifolds, distributor, flexplate or flywheel, sensors, and accessories over. You'll have to remove a coolant plug on the driver's side to install your coolant temp sensor. The back of the head on the 93 should be tapped for your temp sender. If not, there's an easy solution. Use an intake exhaust gasket from an 88 motor. Any questions during the swap, post them up.
 
i'm going to be doing the same swap over the next couple weeks. i'm swapping everything from an 94 to an 88 model. good luck to you.
 
cruiser54 said:
Go for it. Strip the 93 down to a long block and transfer your manifolds, distributor, flexplate or flywheel, sensors, and accessories over. You'll have to remove a coolant plug on the driver's side to install your coolant temp sensor. The back of the head on the 93 should be tapped for your temp sender. If not, there's an easy solution. Use an intake exhaust gasket from an 88 motor. Any questions during the swap, post them up.
Click to expand...



uh. NO.



he wants to replace A BLOWN RENIX motor with everything from a '93 H.O.


on top of that, the manifolds don't simply switch over. the porting is wrong.




anyways, to do a H.O. swap, you have to swap each and every bit of wiring over. if you want just the motor, you can always eliminate the EGR system and make the H.O. tps wiring together.
 
I want to swap everything over, the wiring and motor. The 93 has a few things wrong and I'm kinda getting tired of trying to fix the floor when I have one with a good floor.
 
So, you want to convert your 88 renix to a 93 H.O. OBDI system.

While you could try and "patch" the engine management of the OBDI into the renix harness, unless you are REALLY good with electrical and reading wiring diagrams you shouldn't try it.

Gut the ENTIRE harness from the 93--from the headlights to the taillights and everything in between including the PDC and fuse block. Make sure you take digital photos and label everything.

While the engine is out of the 88--easier that way--start at the headlights and start replacing the entire harness.

You are going to need the instrument panel of the 93 too.

Use all of the 93 sensors and flexplate/flywheel/crank sensor.

It's been done before. Having both vehicles next to each other makes the job easier.

Good luck.

PS--check with your local friendly governmental body regarding inspection/emissions issues BEFORE you start doing this.
 
jeepcomj said:
uh. NO.



he wants to replace A BLOWN RENIX motor with everything from a '93 H.O.


on top of that, the manifolds don't simply switch over. the porting is wrong.




anyways, to do a H.O. swap, you have to swap each and every bit of wiring over. if you want just the motor, you can always eliminate the EGR system and make the H.O. tps wiring together.
Click to expand...

I have done just what I described with a 92 HO motor to an 88 Renix. It works perfectly. The intake ports are off by less that 1/8". This is typical of responses to questions about these swaps. Tons of negative info from those who have not performed the swap, poo-pooing those of us who have performed it successfully.

If you want to keep all the 93 stuff and put it in your 88, you're in for a huge job. If you decide to do it, follow Joe's direction.........My way is super simple.
 
Last edited:
Cruiser54--which intake gasket did you use on your swap--the one for the intake or for the head?

I have read of people relocating the dowels to improve the intake/head match up.
 
I use the gasket for the intake manifold. The mis-match is absolutely minimal, maybe something a hot-rodder would port match for more power. It's hardly an eighth of an inch on the bottom of the port. Not worth relocating the dowels IMHO.
 
alright.


so theoretically, I have a complete running '93 H.O.

and I have a complete '88.

I pull the motor and trans from the '93.

seperate them.

remove every single accessory bracket, plus the intake and exhaust.

I put the renix intake manifold on (which restricts airflow more than an H.O. intake, and MUCH more than a '99+ intake), with the renix exhaust manifold.

while I'm in there, I dick around for anywhere between a half hour to a couple hours trying to get the damned coolant plug out of it, that has neither a 1/4", 3/8", nor 1/2" square to it...so I grind down the next size up extension, and *try* to get it out without bringing out the torch.

then, once I'm finally done, I swap the renix flywheel on, I swap the renix distributor in, the renix gauge temp sensor on, the INFERIOR renix closed system t-stat manifold on, all of the renix bracketry and accessories on it...

and then I put it in.


While there is mild, extremely mild power increase, I have still essentially wasted my time, and robbed a H.O. motor of the extra power it *could have* had, had I done the full swap.



or, switch the situation, and I just strip the '88 down to absolutely nothing...which, since I don't care about it's wiring as it's not worth money anyways, shouldn't take me more than about 2 hours. 3.5 to 5 hours first time through, having never done it before, and including pulling the engine and trans after draining their fluids.


then, I take the experience I just had on the '88, apply it to stripping the '93, spend around 2 hours less pulling the '93 apart. and, while I'm pulling it apart, I lay each part of the harness right back into the '88 body.

so, spend 20 or more hours effing around and keeping the crappy renix operating system that's a pain in the butt to diagnose, or spend 15 to 20 hours netting MORE gain with LESS issues.


and, at the same time, when I go to the parts store, every part I order is then for a '93...rather than a clusterf**k of parts.



yeah, that's a no brainer cruiser. I'll opt with the latter option every time.
 
Last edited:
side note. it took me 2 hours, 15 min to do a complete '95 high output wiring swap on my '87 comanche. add an hour to that for figuring out the crossover harness between the xj dash harness and mj rear harness, and a further 2 hours to swap the engine and trans in.


granted, I had several months to prep the mopar reman with all of the mods I did to it...so add another 20 to 25 hours spent in the shop somewhat working on the motor, mostly jibber-jabbering with my buddies.


either way, a complete H.O. swap will only take a weekend to do, if you're not resealing the motor (which I suggest doing while it's out).


pulling a dash takes no more than an hour. and once you've done it once, it takes under 20 minutes every time afterwards.
 
jeepcomj said:
alright.


so theoretically, I have a complete running '93 H.O.

and I have a complete '88.

I pull the motor and trans from the '93.

seperate them.

remove every single accessory bracket, plus the intake and exhaust.

I put the renix intake manifold on (which restricts airflow more than an H.O. intake, and MUCH more than a '99+ intake), with the renix exhaust manifold.

while I'm in there, I dick around for anywhere between a half hour to a couple hours trying to get the damned coolant plug out of it, that has neither a 1/4", 3/8", nor 1/2" square to it...so I grind down the next size up extension, and *try* to get it out without bringing out the torch.

then, once I'm finally done, I swap the renix flywheel on, I swap the renix distributor in, the renix gauge temp sensor on, the INFERIOR renix closed system t-stat manifold on, all of the renix bracketry and accessories on it...

and then I put it in.


While there is mild, extremely mild power increase, I have still essentially wasted my time, and robbed a H.O. motor of the extra power it *could have* had, had I done the full swap.



or, switch the situation, and I just strip the '88 down to absolutely nothing...which, since I don't care about it's wiring as it's not worth money anyways, shouldn't take me more than about 2 hours. 3.5 to 5 hours first time through, having never done it before, and including pulling the engine and trans after draining their fluids.


then, I take the experience I just had on the '88, apply it to stripping the '93, spend around 2 hours less pulling the '93 apart. and, while I'm pulling it apart, I lay each part of the harness right back into the '88 body.

so, spend 20 or more hours effing around and keeping the crappy renix operating system that's a pain in the butt to diagnose, or spend 15 to 20 hours netting MORE gain with LESS issues.


and, at the same time, when I go to the parts store, every part I order is then for a '93...rather than a clusterf**k of parts.



yeah, that's a no brainer cruiser. I'll opt with the latter option every time.
Click to expand...

4.0 MYTH that the 99+ intake will net you MUCH, IF ANY HP gain; it resulted in a NET LOSS of HP when JP Magazine did it and dyno'ed the results--search 4.0 MYTHS on jpmagazine.com

The block plug is 5/16" for those that want to know. You could figure that out with a measuring device and take the mystery out of it.

To the OP--pick a method and go for it, you will learn a lot no matter which path you choose.
 
no, the newer intake won't help on a stock 4.0.


bored, with a mild cam, preferably a stroker, with a high flow exhaust manifold and muffler, it nets HUGE gains.



but yes, the motor can only intake so much air. having twice the volume of air sitting there won't net any gain if there's not twice the volume of exhaust, and twice the volume of fuel.


although, one thing I have to point out is that JPmagazine is wrong about alot of things, and IIRC they also lifted and put bigger tires on the vehicle when they installed the intake, without doing gears. that may be another one I'm thinking of, but of course it would have less RWHP in that situation.
 
as far as the 99+ intake, I have one here with a new exhaust manifold that I am installing on my '98 xj (97 running 98 systems). it's a stock motor. I'm installing them because mine are dirty, these are clean, and I have a 62mm TB for it. I'm also installing mustang 5.0 injectors, with an adjustable fuel pressure regulator. We will indeed find out if there's more of a "seat of the pants" feel to it. I'll also be able to determine if there are any immediate loss/gains to fuel economy.


sorry that this is off topic. a few posts up someone said to do whichever way you want. I agree. just posting my opinion of it.
 
jeepcomj said:
side note. it took me 2 hours, 15 min to do a complete '95 high output wiring swap on my '87 comanche. add an hour to that for figuring out the crossover harness between the xj dash harness and mj rear harness, and a further 2 hours to swap the engine and trans in.


granted, I had several months to prep the mopar reman with all of the mods I did to it...so add another 20 to 25 hours spent in the shop somewhat working on the motor, mostly jibber-jabbering with my buddies.


either way, a complete H.O. swap will only take a weekend to do, if you're not resealing the motor (which I suggest doing while it's out).

I'm trying to keep in mind the OPs experience level. Asking for photos was my first clue to his possible skill level. Obviously you have alot of experience swapping with the wiring. He may not. I offered the simple solution for him.

pulling a dash takes no more than an hour. and once you've done it once, it takes under 20 minutes every time afterwards.
Click to expand...
 
I don't know how the above post ended up with my response intermingled with your quote, so let me clarify. I'm trying to keep in mind the OPs experience level. He asked for photos and that was my first clue that a rewiring job may not be something he would necessarily enjoy, unlike you or I who would like doing it. Nor did he indicate a desire for additional power or performance. OP, and others on the forum, need to be aware that the swap does not necessarily have to be complicated nor do they need to possess more than a basic mechanical skillset to perform the swap. I try to offer a positive and encouraging solution to people who may be in need of a simple, cheap and effective solution to their transportation problems.
 
There's nothing complicated about unplugginh connectors, pulling interior panels, and swapping wiring.
 
*shrug*

there was nothing complicated about it the first time I did it, by myself.


I don't understand how it could be complicated, since it's not complicated for me *shrug*
 
jeepcomj said:
*shrug*

there was nothing complicated about it the first time I did it, by myself.


I don't understand how it could be complicated, since it's not complicated for me *shrug*
Click to expand...

Obviously not complicated for such a fine young fellow as yourself--just don't A**ume that its the same for everyone else residing within the borders of the continental U.S. of A. :D
 
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