engine swap

[gayle m]

I have a 1988 comanche with a 4.0. I am putting a rebuilt 4.0 with a newer head, can I put a 95 intake manifold and throttle body on. If so , will the sensors and computer work this combination? What changes would I have to make?

[Pete M]

the link in my signature might have info on that.  there are several swap threads down in "Systems conversions"

[gayle m]

Thanks for the reply, I do not have enough information, whether to go with the stock manifold or a newer one with the better throttle body. any ideas would be a great help. I do not want to get into a lot of wiring changes,

[Pete M]

what's the end goal?

[gayle m]

I am doing a complete restoration, its in the body & paint shop now. I wanted to do the engine swap before paint. It will be my every day driver. I have a new 2020 for longer trips. I will put a hitch on it to tow behind my motorhome,

[Smokeyyank]

It can be done but if you want easy keep the old manifold and TB. Swapping to the HO stuff is doable but takes some time and mechanical knowledge. 

[gayle m]

thank you, I found a tps adaptor. I think I can make it all work using all the original sensors. If you have any suggestions to make it easier, it would be much appreciated.

[cruiser54]

Don't bother with the intake swap. Not worth it. Better results can be had with a bored Renix throttle body which is bigger than a stock HO one. 

 

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 a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this? 

It’s only a 4% horsepower increase…..

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 manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it. 

HO stands for Highly Overrated.
__________________

 

 

[Smokeyyank]

19 hours ago, gayle m said:

thank you, I found a tps adaptor. I think I can make it all work using all the original sensors. If you have any suggestions to make it easier, it would be much appreciated.

 

Nickintimes has a YouTube film documenting the process. It's not just a few sensors. You'll also need a newer power steering pump since the renix won't bolt up new exhaust manifold and other odds and ends. My project MJ had this swap. Honestly I'd go with what Cruiser is saying. He's probably forgot more about jeeps than most will ever know 

[ghetdjc320]

On 5/4/2022 at 7:32 AM, cruiser54 said:

Don't bother with the intake swap. Not worth it. Better results can be had with a bored Renix throttle body which is bigger than a stock HO one. 

 

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 a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this? 

It’s only a 4% horsepower increase…..

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 manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it. 

HO stands for Highly Overrated.
__________________

 

 

I would speculate though that even more power can be made overall with a complete HO running on a Renix efi system with its active knock sensors. It would seem that the HO is mechanically superior as several of its parts were redesigned for better airflow (including the head) throughout the entire rpm range but the sbec2 ecu does seem like a downgrade or at least a very conservative tune. The base timing on the sbec is definitely not going to be a power adder. Just curious of the actual specs on running a rebuilt pure Renix vs running a rebuilt HO engine on late model Renix ecu. 
 

It seems through the years that there were many modifications to the 4.0 post amc that should have achieved higher power numbers but instead were detuned. 
 

 

[cruiser54]

I can't think of anything they did on the HO was a power adder except bigger throttle body and better flowing header. 

 

I ran an HO on Renix and it didn't run any better than my Renix on Renix Jeep with almost identical mods. The HO on Renix had the later header but the Renix on Renix did not.

Both ran 60mm throttle bodies. 

 

Everyone wants the great magic of the HO, but Chryco didn't deliver. Well, except the liftgate emblem...and they gave us breaking pistons and incompletely drilled engine mount bracket holes. That was a disaster. Not to mention the 0331 head. Even their redesigned and improved header cracked with the same frequency as the HO versions. 

[ghetdjc320]

13 hours ago, cruiser54 said:

I can't think of anything they did on the HO was a power adder except bigger throttle body and better flowing header. 

 

I ran an HO on Renix and it didn't run any better than my Renix on Renix Jeep with almost identical mods. The HO on Renix had the later header but the Renix on Renix did not.

Both ran 60mm throttle bodies. 

 

Everyone wants the great magic of the HO, but Chryco didn't deliver. Well, except the liftgate emblem...and they gave us breaking pistons and incompletely drilled engine mount bracket holes. That was a disaster. Not to mention the 0331 head. Even their redesigned and improved header cracked with the same frequency as the HO versions. 

 

All versions of the 91+ heads flow better than the renix hands down. 

The 60mm TB

Exhaust header 

96 Block revisions for NVH and the addition of a crank girdle

96 belt tensioner design was a much better than the renix or early HO years

99+ equal length runner intake

99+ wasted spark system (this one had its issues but they were headed in the right direction).

 

The 0331 head was a problem that was addressed with the “Tuppy”revision. As for the efi system, Chrysler had been running SBEC for some time at that point and given the amount of vehicles they already had running on it, it was only logical that they would keep using it on the 91-95 obd1 years. That’s not saying that Renix wasn’t a great system. It was well advanced for its time. But Renix is just an efi system. I’m referring to the engines mechanical systems. A well tuned modern efi would outperform a stock Renix, Sbec or Jtec system. 
 

Mechanically this engine was evolving from its early years as well it should. Who knows what amc would have done with the engine going forward but the fact that Chrysler gave them another 16 years life span is what has contributed tremendously with the current support we see for the 4.0. 
 

 

 

 

 

[cruiser54]

All versions of the 91+ heads flow better than the renix hands down. 

The 60mm TB

Exhaust header 

96 Block revisions for NVH and the addition of a crank girdle

96 belt tensioner design was a much better than the renix or early HO years

99+ equal length runner intake

99+ wasted spark system (this one had its issues but they were headed in the right direction).

 

I agree with all of the above. But, the flow only helped at higher RPMs. Torque was no better. The HOs up to 95 used the same cam as Renix. 

 

The changes in accessories etc were nice to have. Can't dispute that. 

But still, the engine itself, longblocks compared were not night and day. Barely discernable.

I worked at a Jeep dealer from 1980 through 1992. I got to order myself a new Comanche every 6 months beginning in 1986 and continuing through 92.  

When the 91s came out, myself and others at the dealership were disappointed. Couldn't feel any more power. I had 3 or 4 with the HO. 

[ghetdjc320]

Very true. All I’m getting at is Chrysler did some nice improvements to the 4.0 over the years and some are worth pursuing depending on one’s end goals.  

[cruiser54]

Yes. My point is if you have a Renix, don't ditch it in favor of an HO and think you will be amazed. 

[ghetdjc320]

1 minute ago, cruiser54 said:

Yes. My point is if you have a Renix, don't ditch it in favor of an HO and think you will be amazed. 

I have yet to be amazed by a 4.0 

I’ve built many 4.0’s and 4.0 based strokers, you definitely don’t get much bang for buck with most “upgrades” 

[cruiser54]

They were quite good right out of the gate. 

I drove this one a lot. 4.6 with a Paxton supercharger and programmable fuel injection. Belonged to Jeep Racing.

 

 

[Pete M]

gear, gears, gears.    best bang for your buck.

[89 MJ]

If I were you, I’d buy a bored Renix throttle body and a high altitude crankshaft position sensor. Both of those woke my truck up quite a bit. 

[ghetdjc320]

10 hours ago, cruiser54 said:

They were quite good right out of the gate. 

I drove this one a lot. 4.6 with a Paxton supercharger and programmable fuel injection. Belonged to Jeep Racing.

 

 

Beautiful truck! That should have been a production model

[cruiser54]

It almost got crushed!!

[Tex06]

A big plus to the renix system is the ability to hook up a REM from nickintime and see what's going on. 

 

Us with the HO setup are left with cranking the key and counting flashes 🤣

 

Biggest difference I've felt was the 99+ intake on my motor. Pulls more smoothly thru the entire rpm range.