Renix=slow HO=fast!

[lazyxj]

Are both engines in equal mechanical condition?
Spending a couple of hours with a compression gauge and a vacuum gauge might provide some answers.

 

[lawagoneer]

To really tell the difference you need to actually time the vehicles. The later H.O. vehicles have more power on top end and because they run better it is possible they feel a lot faster. The Renix has a better torque curve down low and less power on top but the 0-60 and 1/4 mile times are similar. Renix usually has an edge on fuel economy. Without hard data it is hard to say whether or not the late model is faster than the Renix or just feels that way.

 

[Alaskan89XJ]

Cruiser54 said the 89 ECU enhances the 88, etc.

 

[cruiser54]

Cruiser54 said the 89 ECU enhances the 88, etc.

89 and 90.

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.
__________________

 

[maybe2fast]

Basically heres my question:

If someone put you into a Renix blindfolded and same with HO, should you be able to tell a significant difference? Throttle response, Torque, ect?

Because I would be able to tell blindfolded, drunk, and half sleep. It was that big of a difference and I am not sure why.

 

[maybe2fast]

You drove a stock with some mods. You did not say what those mods were. Stock and mods really should not be used to describe the same XJ if they include the engine or drive train gearing. Do tell what those mods are so that the Renix guys could make an educated guess.

Stock powertrains, both had 3in lifts with new 31s, same wheels. Very good comparison

 

[8Mud]

To really tell the difference you need to actually time the vehicles. The later H.O. vehicles have more power on top end and because they run better it is possible they feel a lot faster. The Renix has a better torque curve down low and less power on top but the 0-60 and 1/4 mile times are similar. Renix usually has an edge on fuel economy. Without hard data it is hard to say whether or not the late model is faster than the Renix or just feels that way.

Best guess is my 96 will beat my 88 by maybe 1-2 Jeep lengths in the quarter mile. Likely equal in the eight mile. The 96 might have a better top end, maybe not.

I actually raced my son in the 96, me in my 88 and beat him handily. It was mostly knowing when to shift.

If your Renix is that anemic something is wrong.

 

[Green Mesa XJ]

Besides a tired engine, and a decent 4.0 should last a lot more miles than 149k, is the torque converter locking and unlocking correctly? This and the power/comfort switch could greatly affect the feel.

I'd check the compression and verify timing just to have the basics done.

This is the third 88 xj that has recently been bought in this forum. Was there a clearance sale I missed ?

Although the two 88 motors were not the best. One has a stuck lifter and the motor is being swapped with a 95 4.0 they got for a song.
The other melted a piston and is being repaired, it also had a newer motor from a 93 xj instead of the 88.
(Im bad with remembering forum names, I believe 90xj06's got the 5 cyl xj, the Audi xj project?, BTW hows that going?)



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[90xj06]

Besides a tired engine, and a decent 4.0 should last a lot more miles than 149k, is the torque converter locking and unlocking correctly? This and the power/comfort switch could greatly affect the feel.

I'd check the compression and verify timing just to have the basics done.

This is the third 88 xj that has recently been bought in this forum. Was there a clearance sale I missed ?

Although the two 88 motors were not the best. One has a stuck lifter and the motor is being swapped with a 95 4.0 they got for a song.
The other melted a piston and is being repaired, it also had a newer motor from a 93 xj instead of the 88.
(Im bad with remembering forum names, I believe 90xj06's got the 5 cyl xj, the Audi xj project?, BTW hows that going?)



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i did get a good price on my 88! and it was on sale got it $10 off with a coupon.:eeks1:
it is now running. im working on the interior and exhaust now. just snagged some tinted windows and leather seats.

 

[Green Mesa XJ]

i did get a good price on my 88! and it was on sale got it $10 off with a coupon.:eeks1:
it is now running. im working on the interior and exhaust now. just snagged some tinted windows and leather seats.

So that piston repair worked out, nice. Glad it's running.

I put a set of leather seats in one of our xj, and plastic wood grain dash bezel for that touch of Elegance.

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[90xj06]

i do have the wood grain bezel. im really tempted to swap it in.

 

[Ecomike]

Basically heres my question:

If someone put you into a Renix blindfolded and same with HO, should you be able to tell a significant difference? Throttle response, Torque, ect?

Because I would be able to tell blindfolded, drunk, and half sleep. It was that big of a difference and I am not sure why.

I have 3 running Renix stock rigs. One is a 4x4 with a D-44 rear end and and the NP242 TC , with 290,000 miles and me doing the service for 12 years. The second is a 2wd 89 Renix, about 200,000 miles and it can blow the doors off the 87 4x4 in 2WD mode. The third is an 87 4x4 I have no real road miles on yet, with the NP232? (I forget the NP numbers, but it is not the D-44 rear end or NP242 TC, it has the vacuum do dad on the front axle as I recall). and that 4x4 in 2WD will also blow the doors off the 87 with the D-44 rear end.

I have so far assumed it was the bad valve guides and low pressure on cyls #1 and #2 on mine. Also it does not have a knock sensor which the 89 does have.


But the 87 Wagoneer does have good power for 29 year old beast with 290,000 miles and some engine head, possibly ring issues on 2 of 6 cylinders.

have you check fuel pressure at WOT?

 

[Ecomike]

Basically heres my question:

If someone put you into a Renix blindfolded and same with HO, should you be able to tell a significant difference? Throttle response, Torque, ect?

Because I would be able to tell blindfolded, drunk, and half sleep. It was that big of a difference and I am not sure why.

I would say no. My first Jeep was a 2 year old 96, 2WD (which I miss).

I think my 89 2WD has more power than the 96 had.

 

[Ecomike]

When I bought my daughter"s 89 2WD XJ-rig, it had 124,000 miles and a blown head gasket between #3 and #4 cylinders, due to running with a bit of carbon fouling getting too hot and eating the head gasket which is very thin at that spot between those 2 cylinders. So a 4.0 can be damaged at low mileage.

I wonder if his Renix is starting out in second gear? Or has a bad TC?

He needs to compare the RPM shift points, and speed at each shift for both rigs next!!!

And make sure the parking brake is not stuck on, on the Renix LOL.

Besides a tired engine, and a decent 4.0 should last a lot more miles than 149k, is the torque converter locking and unlocking correctly? This and the power/comfort switch could greatly affect the feel.

I'd check the compression and verify timing just to have the basics done.

This is the third 88 xj that has recently been bought in this forum. Was there a clearance sale I missed ?

Although the two 88 motors were not the best. One has a stuck lifter and the motor is being swapped with a 95 4.0 they got for a song.
The other melted a piston and is being repaired, it also had a newer motor from a 93 xj instead of the 88.
(Im bad with remembering forum names, I believe 90xj06's got the 5 cyl xj, the Audi xj project?, BTW hows that going?)



Sent from my iPhone using Tapatalk

 

[cruiser54]

Okay, here we go.

I was Service Manager and shop Foreman at a small AMC/Jeep/Renult/Chrysler/VW dealership from 1980 til 1992.

I had 13 Comanche demos from the time they came out in 1986.
First was a four cylinder 4 speed model, then a 4 cylinder 5 speed model.
The 4.0 came out in 1987. I got one with a 5 speed.
After that, through til 92 I got a new Comanche every 5000 to 7000 miles.
I special ordered them with 4.0, auto trans, trac-loc rear and 4WD.

I noticed the difference in power from 87 to 88 and 88 to 89. 90 had the same power as the 89.

When the HO came out, I had a few of those also. About 4 of them.

The difference in power between the 90 Renix and 91 HO wasn't even noticeable.

And believe me, I drove every one of those Comanches like I stole them!!!

I now have an 88 XJ, 87 MJ and 90 MJ. All have 4.0s and automatics, 90 ECUs and 88 or later TCUs hard wired into the Power mode. 2 of them have 31 inch tires and one has 235/75/15s.

All run great. I now work on a few HO Cherokees for certain people.
One is a 94 with 180,000 miles and the other a 95 with only 71,000 miles.
Neither of those will out perform my Renix stuff.

 

[Ridered4583]

My 91 and 97 drive like totally different vehicles. The 91 drives like a jeep, the 97 scoots! Don't know why. When I drive the 97 though I get that taste of power and want more. I keep lobbying for a supercharger kit, but the wife says no. Stock vs stock the HP ratings aren't that different, but the 97 FEELS like a racecar to me.

 

[Ecomike]

My 91 and 97 drive like totally different vehicles. The 91 drives like a jeep, the 97 scoots! Don't know why. When I drive the 97 though I get that taste of power and want more. I keep lobbying for a supercharger kit, but the wife says no. Stock vs stock the HP ratings aren't that different, but the 97 FEELS like a racecar to me.

My 87 (2WD) also feels like a race car, power like our 96 Ford Tauris and Saturn 2001.

 

[maybe2fast]

My 91 and 97 drive like totally different vehicles. The 91 drives like a jeep, the 97 scoots! Don't know why. When I drive the 97 though I get that taste of power and want more. I keep lobbying for a supercharger kit, but the wife says no. Stock vs stock the HP ratings aren't that different, but the 97 FEELS like a racecar to me.

The pep is amazing compared! Something is very different here. I believe the Renix is running properly

 

[cruiser54]

The pep is amazing compared! Something is very different here. I believe the Renix is running properly

It's not.

 

[maybe2fast]

Alittle update here.

Took Jeep to the Dunes (MI)

figured out that the TCC was not locking on the trek up, fixed that.

Did some drag racing with the 2000 Jeep I am referring to. I pull 2 lengths on him in a 4wd sand race!

His still feels like it has so much more pep in normal, non WOT driving.

I got decent mileage, despite the TCC and wheeling it seemed ok. I have had a 96,98,99 XJ prior to this 88. It has some very different low end feel, its all I can say. No pep.