when did the H.O 4.0 come around??

Well I was out looking at parts Jeeps, and I found this 89. I looked under the hood, and sure enough it had a H.O engine. If I remember right, the H.O didn't come out until 91, and for a few years the Renix was still offered as the base I6. Annother funny thing I read the other day was that the H.O got a Sequential Fuel Injection in 1993 or around there. This seems kind of funny to me because, as far as I know, the performance specs for the H.O never changed from when it was introduced in 91.

The HO had Chrysler sequential EFI from the outset in 1991. That '89 Jeep might have had a HO engine transplant.

The HO came out in 1991, and there was no overlap with the Renix. The Chrysler system replaced the Renix system.

And the HO was sequential injection from the outset, this was not something that was "added" in 1993.

Where do people come up with "information" like this?

Dunno - but if you want to see what's going on, find the head casting number and the block casting number.

2686 is the casting number for RENIX (1987-1990) heads - 7120(1991-95), 0630 (1996-98), and 0331(1999-2005) were the later castings.

Engine blocks may be dated thus:
8933002665 - 1987-1990 (have to check this one - I think I've got an extra zero...)
53008405 - 1991-1995 (Knock sensor boss unmachined.)
53020569 - 1996-1996 (Introduction of "Main Cradle" brace)
53010449 - 1999-2005 (Don't know what they changed here... Yet.)

It's also possible that, instead of a full transplant, the RENIX block was left in place and the HO top end bolted in - the parts will swap readily - as long as the manifolds are brought across as well. The HO heads made more power by way of a more direct shot past the intake valve - the corner going down was not as sharp as it was in the 2686 head. The bolt patterns and sizes are the same, so putting the later head on an early stroker is doable. With the 7120 head, the RENIX system may be retained (except for the EGR setup,) which allows keeping the knock sensor feedback in addition to everything else.

Oh - and, as I recall (Eagle, you'll tell me if I'm wrong, won't you? :wave: ) the fuel injection setups used from RENIX forward were SEFI - no "batch fire" or anything like that. There was always a SYNC sensor - and BFFI doesn't need it - while it's important for SEFI to know where cylinder #1 is...

5-90

Could be just a HO valve cover? Some say it helps with blowby.

Also a possibility - but you didn't mention that... That's why I gave you the list of casting numbers.

I forgot one tho - 530053535. 1987-1990 RENIX. There, that should be all of them (no-one's asked for crank/rod numbers, so I'm not going to bother...)

5-90

the_bandit87 said:

Well I was out looking at parts Jeeps, and I found this 89. I looked under the hood, and sure enough it had a H.O engine. If I remember right, the H.O didn't come out until 91, and for a few years the Renix was still offered as the base I6. Annother funny thing I read the other day was that the H.O got a Sequential Fuel Injection in 1993 or around there. This seems kind of funny to me because, as far as I know, the performance specs for the H.O never changed from when it was introduced in 91.

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HO came out 8th month of '90 and is easily spotted by the computer under the hood and no EGR valve.

Carnuck is on the money. That is when the factory began producing "1991" models. If you go by model year, the HO was introduced with the 1991 models but, as with most automobiles, the model year went into production and on sale a few months before the end of the previous year.

That's also when Jeep went from 21 spline to 23 spline (I bought an '07/90 hoping it was 23, but it wasn't. Then I pulled an '08/90 and it was)

5-90 said:

Dunno - but if you want to see what's going on, find the head casting number and the block casting number.

2686 is the casting number for RENIX (1987-1990) heads - 7120(1991-95), 0630 (1996-98), and 0331(1999-2005) were the later castings.

Engine blocks may be dated thus:
8933002665 - 1987-1990 (have to check this one - I think I've got an extra zero...)
53008405 - 1991-1995 (Knock sensor boss unmachined.)
53020569 - 1996-1996 (Introduction of "Main Cradle" brace)
53010449 - 1999-2005 (Don't know what they changed here... Yet.)

It's also possible that, instead of a full transplant, the RENIX block was left in place and the HO top end bolted in - the parts will swap readily - as long as the manifolds are brought across as well. The HO heads made more power by way of a more direct shot past the intake valve - the corner going down was not as sharp as it was in the 2686 head. The bolt patterns and sizes are the same, so putting the later head on an early stroker is doable. With the 7120 head, the RENIX system may be retained (except for the EGR setup,) which allows keeping the knock sensor feedback in addition to everything else.

Oh - and, as I recall (Eagle, you'll tell me if I'm wrong, won't you? :wave: ) the fuel injection setups used from RENIX forward were SEFI - no "batch fire" or anything like that. There was always a SYNC sensor - and BFFI doesn't need it - while it's important for SEFI to know where cylinder #1 is...

5-90

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Not to question you or your knowledge anything, but I have a 99 with the 0630 head on it. September 99 build date too. I think it was the extreme late 99 models that were the first to have the 0331's in them....big difference on reliability from what I've been reading on here.

99XJSPORT06 said:

Not to question you or your knowledge anything, but I have a 99 with the 0630 head on it. September 99 build date too. I think it was the extreme late 99 models that were the first to have the 0331's in them....big difference on reliability from what I've been reading on here.

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'99 was something of a crossover year for the heads. All the '99 WJ's have the 0331 head but it seems only the very late '99 TJ's & XJ's have that head.
The 0331 head has been known to crack and strangely enough, the negative reports that I've heard concerned heads made in 2000.

Well I got my information on H.Os from a book on the history of Jeeps. I don't have the book with me and I forget the name of it, but it mentions the club. The book covers the Jeep from the first Bantom design all the way to the Liberty and Commander concept (the fuel cell powered one). The other thing that gave me the idea that the H.O was optional was that I did hear it mentioned some where, and the first few years it was out, Jeep had the 4.0 High Output decal on the back. As this wasn't on every Jeep, it sort of made it look like the H.O was optional.

I could be wrong, but I though the 4.0 High Output (like the one on the back of mine) came on every jeep that was equipped w/ a 4.0 after 90- hence an "HO" design 4.0 until late models 97? when that was no longer used on the badges. XJs without a 4.0 HO badge on the back were are the ones equipped w/ the 4 bager option.

that would explain it, I wasn't thinking about the 4 cyl. Well I'm off to another junkyard today, and I was wondering, what is the year that they strengthened the block of the 4.0 to respond to some NVH complaint. I've yet to get my 87 Renix running again (need to reinstall the tank and pump) but I've basically desided to start throwing a stroker together bit by bit. I don't even know for sure that there's a whole lot wrong with my Renix, so I'm going to take my sweet time. But I figured if I was going to do it, I should start with the best block/head combination. I understand that the 91-95 head has the best flow, and that in the mid to late 90s they strengthened the engine block. Annother thing I should ask is, which intake manifold is the best for the 4.0. I'm not positive, but I remember a few months back looking at a WJ 4.0 and I remember reading that they had a new redesigned intake. Anyway, the other thing I should ask is, can I keep the Renix ECU system with these new parts ( H.O head, NVH block, H.O intake manifold ect.). The first thinks that jump out at me is that maybe some sensors would be different and not be supported by the newer block ect. and that I could have fuel rail problems with the newer intake. Would it be possible to keep the renix intake (since I wouldn't have to throw together a TPS or IAC to work with a H.O intake) and bolt it up to the H.O head. I know that the Renix isn't the best system for power, but I don't want to start converting over the engine control system. The wireing in my XJ is 99.9% perfect (there is electrical tape wrapped around one wire under the hood) and I don't want to start mucking around with my wires.

Just got back from the Junkyards. I keep trying to tell you guys how slow things are out here in the great Canadian east, maybe you guys will belive me now. I just came back from the biggest Junkyard around here for a good few hundred miles, and damn was I suprised. I had been there about last October, right before the leaves start to fall and things start to cool off, well any way, I got some parts off an old burnt 85 XJ that was in decent shape, and I noticed a burnt 01 WJ powered by a 4.0 there. It was burnt from the back forward, but the engine looked alright, the PCV hoses on the valve cover had melted off, but other wise it looked ok. Well I just went back there today, looking for a spare 5 spoke rim, and didn't I find both Jeeps there, and its been almost a year. I priced the WJ motor last fall and they wanted somthing like $1000 for it then, and refused to part it out, but maybe they'll change their minds now. The other thing I found at a different junk yard was a 91 XJ sport with a H.O motor. They want $100 canadian for the head, do you guys think this is a fair price?

the_bandit87 said:

. The other thing I found at a different junk yard was a 91 XJ sport with a H.O motor. They want $100 canadian for the head, do you guys think this is a fair price?

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in canadian...hell yeah thats a decent price. And I work in the business. My shop asks $125.00 US...but some of the poeple here aren't good at priceing...thats why we have a few lying around

Thanks for the fast responce, I'll probably pick the head up tomorow. I forgot to mention to you guys that the Jeep book I got the information is called JEEP by Steve Statham, he mentions Jeff Vaech of the for "taking the time to give me the scoop on the state of affairs among the XJ Cherokee crowd." He also mentions that "In 1989 the 4.0 was tweeked to deliver 190 HP and 224 f-lbs of torque" I miss read the part about sequential fuel injection. It was given to the 4 cylinder in 1993 not the H.O\

By the way, what do you guys think is a good price on the WJ block and maybe the intake Manifold? I'll try to get them to let me part it out.

sounds good to me! I just sold 2 of them for $150 US apiece for rebuild!

the_bandit87 said:

Thanks for the fast responce, I'll probably pick the head up tomorow. I forgot to mention to you guys that the Jeep book I got the information is called JEEP by Steve Statham, he mentions Jeff Vaech of the for "taking the time to give me the scoop on the state of affairs among the XJ Cherokee crowd." He also mentions that "In 1989 the 4.0 was tweeked to deliver 190 HP and 224 f-lbs of torque" I miss read the part about sequential fuel injection. It was given to the 4 cylinder in 1993 not the H.O\

By the way, what do you guys think is a good price on the WJ block and maybe the intake Manifold? I'll try to get them to let me part it out.

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if you have to machine the bolck ? $100-150.00 if it is easily accessible, if it is more work than a few unbolts..you end up paying for TIME..thats what most people DON'T understnad about a wrecking yard..TIME is costly...and say 75-100 for the intake.

if they tell you more than that for the block...let it sit for another 3 weeks, then go back.

Eventually if they don't sell it...they will throw it out and then you have your most effective tool..."hey don't throw it out...I'll give ya $50.00"...which is probably as much as they'd make scraping out the rig by itself.

Well the WJ that the engine is inside of is scortched all the way to the front fenders. The motor is a bit crispy on top hoses burnt off ect, and its been there all winter. I would say that everything like the trans and electronics is all burnt out, but it looks like the engine is worth getting, since the fire was not engine related. Then again, you never know, maybe his WJ broke down, and the owner got mad and took a match to it. How much time would it take them to get the engine out of the hulk? I know it would have to be unhooked from the trans and motor mounts ect, but wouldn't they let me do the work, and then just get an engine crane out to lift it?