4.0 to 4.0 swap...

Not sure if this belongs here, or in the OEM category, but here goes.

I am building a Jeepspeed XJ, and we are starting with an 87 4.0, with AW4 tranny.
I am told that the 94ish 4.0 block, and head, along with a 99.5 - 2002 intake is the ideal setup.
I am about to order a 94 longblock, 2001 intake, and put it in... The question is, what else should I expect to have to change to make this work?
Will the 87 distributor work?
Will the computer work? Wiring harness? Injector wiring? (Plan on useing the new injectors out of 2001, or even 24# Ford ones)

Basically besides the longblock, and intake will I need to to replace to make this work?
I figure instead of re-inventing the wheel and figuring it out as it pops up, I'd get some knowledgeable people like the members involved because I doubt I'm the first person to do this.
If there is another thread that already covers this, please let me know, I was unable to find anything that answered all of these questions.

Thank you for your time!

Jeremy
Austin Texas, Bombshell Racing

It's the 99+ grand chero with 4.0 intake you want. Then you need to modify the intake (adaptors) to get the renix throtle body on. If you use the h.o. throtle body, then the sensores in it need to be modified to work. Or you need to get the pcm for either an auto or stick h.o. (which ever you are running) and the wire harness. Injectors are fine, the 24# will run rich and faul out the 02. The 94 wont have a knock sensor and your pcm will be looking for it.

I thought all 99+ intake mani's worked?

99+ XJ intake will work the same as well.

87 is renix and you are attempting to swap to a pretty much totally different setup.

You're probably gonna have to search for each individual problem/issue you encounter.

http://jeephorizons.com/tech/xjstockspecs.html

for a JeepSpeed vehicle, i'd look under the "body" section of that link. I'd go with a model with a stronger body from the get-go.

Thanks for the info guys.
We are starting with the 87 because that's what we were given as a platform.

I really don't know what the HO, or Renix systems are to be honest.

I was hoping that the stock 87 computer would work, but it sounds like that might not be the case?
Just trying to figure out what all it will take to make this thing work, before we start buying parts, I was about to order the engine today, but after reading this I might hold off until I get some more feedback.
Or as was stated, might cost less, to start with a newer model, but we haven't been able to find a 95+ for less then 2-3k!

Just follow Mike's advice: either adapt the renix(87) tb to fit on the 99+ intake or modify the renix sensors to fit on the 91+ tb. Whichever one you decide to go with, get a bigger bore tb while you're at it (60-63mm).

Ohh, so Renix / HO just refers to the thottle body! That doesn't sound so bad! I was thinking entire motor setup was different or something.

jerds19 said:

Ohh, so Renix / HO just refers to the thottle body! That doesn't sound so bad! I was thinking entire motor setup was different or something.

Click to expand...

nope. HO is a general term for the engine setup for 91+. renix is 90-. in addition, there are numerous changes in sensors, computers, wiring, and parts throughout all 14 years of production.

as JNickel said, you're gonna have to search for each issue independently, as each one is dependent on the year of the vehicle as well as the year of the part.

if you use the renix computer(ecu), you will need to use the dizzy and flywheel/flexplate/cps from the 87 or the ecu will not get the correct timing signal. you can use the renix throttle body if you drill and tap holes in the intake to mount it or use an HO throttle body and modify the renix tps. if you use the 87ecu, you need to use the renix sensors, althought you may have to relocated them.

Thanks again for the info.

I would ideally like to use the computer/wiring that the 87 has in it now, for money, and simplicity sake as well.
Since all we are getting is a long block from the 94, and intake from the 2000, I will be re-using as much of the 87 stuff as possible.
If there is a good reason (IE: horsepower gains) to upgrade any of the sensors, or other parts, I'm not opposed to doing that. But if it's a matter of just adapting what we have, vs buying new, I'd rather adapt.

if you use the renix ecu, there is no sensor upgrade. why not use the 87 block and just upgrade the head and intake.

have you looked into building this as a stroker?

jerds19 said:

Thanks again for the info.

I would ideally like to use the computer/wiring that the 87 has in it now, for money, and simplicity sake as well.
Since all we are getting is a long block from the 94, and intake from the 2000, I will be re-using as much of the 87 stuff as possible.
If there is a good reason (IE: horsepower gains) to upgrade any of the sensors, or other parts, I'm not opposed to doing that. But if it's a matter of just adapting what we have, vs buying new, I'd rather adapt.

Click to expand...

There is no simplicity either way..... You are either going to have to dump the 99+ intake or go ahead and swap in a HO wire harness. Your taking this swap far to light...
The flywheel from the Renix 4.0 is needed to swap in the 94 so you CPS can read correctly, the throttle body sensors are far different. Older ones have a different wire count then the new ones. Not to mention EGR.

89xj said:

if you use the renix ecu, there is no sensor upgrade. why not use the 87 block and just upgrade the head and intake.

have you looked into building this as a stroker?

Click to expand...

I don't know what the difference between an 87, and an HO motor is, or how it gets the extra high output. If it's just the head and intake, I woulda done that, but since the whole thing needed to be rebuilt anyways, I figure the 94 longblock is the way to go right?

Jeepspeed limits you to 250 cubic inches, IE: a 4.0 bored .060 is max, so stroking would be simple, and very effective, but not allowed

You're dealing with parts from Renix, OBDI, and OBDII systems.
You probably want to keep the renix system, its easier (no wiring swaps), you can diagnose the entire system with a multimeter, and it has no rev limiter.
you need all the renix sensors to be transferred to the new engine. There may or may not be a hole for the knock sensor, but theres at least a spot for it.
you need the Renix flywheel or flexplate so it will "talk" to the Renix crank sensor.
You want tou use the newer TB and the newer intake. The renix TPS will need to be adapted to the new TB. it must be adapted in such a way that it can be adjusted properly.
The renix's exhaust manifold has a hole for the EGR system, while the newer intake does not. The exhaust mani hole needs to be plugged, or you need to use headers made for the HO. toss the EGR valve.

Thats all i can think of. I have a 93 motor running on Renix, wasn't too difficult, I'm glad I didn't try to swap the entire wire harness to switch to OBDI.

if i ever need to rebuild/stroke my 89, i plan on using a HO intake, head and exhaust but would use the renix throttle body. i would bore out the throttle body to, i believe, 59mm. if i have problems with the renix throttle body not being large enough, than i would concider using the HO throttle body and modifying the tps to make it work.

Re: 4.0 to 4.0 swap...AGAIN ?? YES HELP PLEASE

Bought it this way

so I have an obdI engine in a renix XJ 5 speed....

I must get a flywheel fro a renix and put it in

what us significant about this flywheel... will a flywheel from an auto renix

work???


and swap the sensors

thanks for any help pm me please

No the flywheel you need for the 5 speed is a real flywheel not a flexplate. So they of course won't interchange. The Renix flywheel has the right sensor pickups for the CPS to "talk" to the ECM. They are year specific. Prior to 91 stuff will not exchange for 91 and up stuff. Apples and Oranges.

mikeforte said:

No the flywheel you need for the 5 speed is a real flywheel not a flexplate. So they of course won't interchange. The Renix flywheel has the right sensor pickups for the CPS to "talk" to the ECM. They are year specific. Prior to 91 stuff will not exchange for 91 and up stuff. Apples and Oranges.

Click to expand...

thanks i figured that

so any renix flywheel (5 sp) should work :helpme:

*Mundane* said:

thanks i figured that

so any renix flywheel (5 sp) should work :helpme:

Click to expand...

if it runs at all, you have the correct flywheel.

jerds19 said:

Ohh, so Renix / HO just refers to the thottle body! That doesn't sound so bad! I was thinking entire motor setup was different or something.

Click to expand...

There are three generations of control systems for the AMC242/4.0L engine...

1987-1990 was known as "RENIX." It's a robust pre-OBD system designed and spec'd by AMC/Renault, and built by Bendix/King. REN for Renault, IX for Bendix - RENIX. Few mods are available for it.

1991-1995 was Chrysler-built and spec'd OBD-I controls. Since it's a more common system (the ChryCo controls were essentially the same across various models, just the programming was different,) there are more mods available.

1996-2007 was also Chrysler-built, but they're OBD-II. More or less the same deal, but there are more differences between models and engines in the programming.

1991-2007 is collectively referred to as "HO" - Chrysler decided that their power output was sufficiently higher than AMCs as to warrant the descriptor (I honestly don't think so - as I recall, the difference was less than 10BHP and 15 pound-feet at peak, and they moved the peak higher in the RPM band. I prefer RENIX...) but HO can then be divided into OBD-I and OBD-II using the brackets given above.

OBD-II can be further divided - 1996-1999 (XJ) and 1996-1998 (WJ/TJ) still had the distributor, while 2000-2001 (XJ) and 2000-2008 (WJ/WK/TJ) had the COP/DIS (Coil On Plug/Distributorless Ignition System) with the #0331 head. Stay away from the #0331 head on models made before 2002 - if you want to know why, search up <0331 club> here and you'll see what I mean. Early variations on that head are prone to cracking between the #3 and #4 cylinders, and I don't know how to tell the difference between the early casting and the later "revised" casting (they solved the problem, but they didn't admit to it.)

My ideal stroker would be built around a RENIX block (heavier casting, can often be bored out to 4.000" safely - check the cylinder walls to make sure!) and OBD-I (#7120) head, add the OBD-II main bearing brace, and use a 12-cw AMC258/4.2L crankshaft. Sounds like a crazy quilt, but that's the way I'd go (if throttle response is important to you, use the later cranks - fewer counterweights and they're a few pounds lighter. I drive a stick, and the 12-cw crank saves me having to get an inertia ring made for the flywheel.)

The HO throttle body is more of a "standard" part than the RENIX (I've heard of people using late Ford V8 throttle bodies on 1991-up 4.0L) so you can get away with more. The RENIX is a chunky three-screw affair that isn't very easy to adapt to anything - it can be done, but it takes a little work.

@Mundane - a "flywheel" is significantly different from a "flexplate." In any engine, a "flywheel" (using the term in a generic fashion) is used to smooth out the power impulses from firing events. A "flywheel" (generic, again) is a heavy rotating mass that uses its inertia to accomplish the given purpose.

In an automotive sense, a "flywheel" is a heavy cast iron disc to which the clutch is bolted - not only does the mass of the flywheel/clutch assembly accomplish the generic purpose of the flywheel, but the added mass increases the heat absorbtion capacity of the thing for when you're taking off (it gets rather warm. Friction, you know...)

A "flexplate" is much simpler in design - it's a rigid coupling between the crankshaft and the torque converter in an automatic transmission. The torque converter is fairly heavy - and holds about a gallon of fluid. The full torque converter tends to weigh rather more than a flywheel/clutch assembly, but will accomplish the same purpose.

Speaking at construction, a flywheel is cast as a single part, and is about an inch thick. It's then machined to size, the clutch surface is ground, and it is then balanced. The "trigger ring" (CPS teeth) is integral, and the ring gear (for the starter motor pinion to engage) is pressed on and can be replaced.

A flexplate is stamped from heavy-gage sheet steel, and the "trigger ring" and ring gear are welded to it. It is then balanced. If the ring gear gets wrecked, the whole unit is replaced.

While a flywheel and a flexplate perform much the same function (rigid power coupling between the engine and the transmission, with a selective engagement device,) they're built rather differently - and you can't swap them back and forth. If you have a manual, you must have a flywheel. If you have an automatic, you must have a flexplate. No two ways about it (you can get a lightweight flywheel, but you still need mass and bulk - if not for inertia between firing impulses, you'll need it to dissipate heat from clutch engagement.)