Inliners International Forums General Discussion Hi Performance Anyone build a Jeep 4.0? Just finished a mild one

2001 Cherokee 4.0

CR from 8.8:1 to 9.5:1
Mild custom cam
Mild port work
Relocated intake air temp sensor to air box tube
Muffler bypass (bypasses factory muffler when intake vacuum goes away, then through a cherry bomb)

Just drove it to town for the second time. It runs smooth but thus far I'm underwhelmed. Not the kind of throttle response and power I was expecting. Some say I should try bigger injectors and throttle body. And reprogram the ECU. I'm probably close to the point where I need the injectors.

Did not get a chance to really monitor O2 sensor data, the little I tried, it did not seem to lean out under moderate acceleration.

Still have some minor things to finish.

The Nova 230 project has not made any progress, it runs ok, I drive it once in a while, but next steps would be HEI and adapting a 2bbl on a stock intake. Need to make an adapter, I have a spare intake/exhaust manifold to work with.
That engine too seems less powerful than expected, but some of it comes from the single barrel bottleneck, as well as stock torque converter.

Probably not the response your looking for but..

Consider the cost of the injectors ( $200??) + tune ($200??) + will you be happy with it? ($$$$ >> ?????)

I get quite a few Jeep guys asking if the 4200 drive train will fit... A few years ago I did a quick test fit into a TJ and the 4200 engine, 4l60 + xfer case fits, I would think it would fit into a Cherokee as its longer.

In stock form the early 4200 make 275hp the later ones 290HP

With a little bit of head work this jumps by 30+ HP.

Quite a few people are adding a turbo to a bone stock 4200 engine and getting 400 RWHP with a tune ( to keep the engine alive as they are 10.2:1 CR).

Something to consider.

If I ever take the next step with the Jeep engine, it will be a 4.7-4.9 stroker..... maybe a turbo too. You can punch it out to 5.0 but then the cylinder walls will be pretty thin.
The last two production years (00-01) have an ECU that really does not like changes in manifold pressure, this cam had to be custom made to work around it and produce close to stock vacuum signal.
I want to stay with the original 4.0 engine and ECU. The 4.0 is arguably one of the best sixes ever made, with of course, a couple of shortcomings... nothing too bad.

Jeep tuner can adjust a lot of things in a matter of minutes, including speedometer correction etc... and I think that's what I'd do. I could change between economy and power programs in minutes, myself, any time, for one time investment of around $300 for the programmer. And I could always go back to stock program too.

I like the 4.0. I have owned 3. I never modified one though.

It's your project and goals, but to modify the engine and run a stock ECU just seems very limiting to me, even with re-programming it's usually just a crutch, especially if you are considering a turbo.

The difference between a power and economy tune with EFI is the right foot.

Just dump an LS into it...

{runs and hides}

Seriously, though, have you tried the Jeep forums? They might be a better help than us.

http://www.jeepforum.com/

I used to post on there when I had a WJ V8.

Edit: For kicks I tried looking up my transfer case thread but couldn't find it. Instead I found this thread that has my transfer case pics in it: http://www.jeepforum.com/forum/f310/so-my-babysitter-blew-up-my-wj-1176379/

Quite amusing...

How does that even happen to a t-case??? wow

I wanted to stay with the stock ECU for THIS stage, it is a very mildly modified engine. The cam was carefully tailored to run with everything else being stock. I gave it more compression and the cam grinder said that's fine, but I may need to step up to slightly bigger injectors. I can do that. On top of that I don't mind further tweaking it with a programmer, to see what it can do.
A distant possibility is a bigger throttle body. That's it.

Anything beyond that point would be kind of a waste, might as well go all the way and start a stroker build, which would be a whole different animal.

But just like with my Nova, I want to stay with the stock six as my base engine.

Just because.

Transfer case: The rear seal went out when we were driving it to Indiana about midway through Ohio. Didn't know anything was wrong until I went to fill up the car and noticed oil all over the rear. It was around midnight and I figured we did the damage already so I continued on to Indiana.

Had a new seal put in while out there. TC had a slight whine but nothing too bad. Drove it like that while topping it off for another 50k miles (it was a spare vehicle at this point so I wasn't throwing money into it).

At around 180k miles we were driving it to Lowes in town to get some yard stuff for springtime. My wife was 7 months pregnant. There's a highway that cuts through town so we were on that when I heard a loud bang. Looked in the rearview and saw a 3" chunk of metal fly out from under the truck. She still drove and we were getting off the next exit anyway so I went with it. Got out at Lowes and looked underneith it. Saw where that missing hunk of metal fell out: a nice 3" hole in the transfer case.

...yet she still drove. So we decided to risk it through town on 30mph roads. Made it halfway and there was a stoplight. as we were slowing down another loud BANG and this time the back of the truck jumped up in the air a good foot.

...yet she still drove.

I figured I'd already done the damage so we kept going. Got about another 1,000 feet when there was yet another BANG and this time i could hear something dragging. Hit the gas and...

...she didn't go.

So we coasted into a Costco parking lot, called a friend, towed it home and put it in the garage.

The next week I found a 249 TC, bought a new front drive shaft and slapped it in. All in I was out $500.

Greatest damn vehicle I've ever owned.

You brought this up when I asked here about doing a supercharger on my Cherokee...
The GM engine is too tall and won't clear the front axle in a XJ unless it's got a lift kit .An XJ has a smaller engine bay than the TJ.. And it also requires two reworked driveshafts,floor and crossmember modifications It is not like you buy and engine for 500 bucks ,drop it in an go. Its a full on engine swap. And some of us want to retain the 5 speed manual and the non electronic reliable transfer case.
Not impossible of course and while the GM engine can make a lot more HP than the pushrod 4.0, not everyone wants or needs 400 hp.

I just want to keep the old engine and see what it could do with some tweaks, kind of release the performance that may lurk in there, choked down by emissions crap or sacrificed for some other reason. That's what I've done all my life. I know I could have dropped a V8 in the Nova for $500 and have twice the power I have now with my 230.... which by the way is still super slow But it is an immediate conversion starter. And I plan to do more to it, a complete waste of time and money. I just installed a HEI distributor, have not timed it yet. HUGE improvement on how it starts. As quick as a new car and sounds like it too.

The Jeep is already showing improvement across the range with the mild cam and higher compression, and today I will try tuning the ECU with a Banks tuner. (Refurb on Ebay for $225) It offers 3 different pre-programmed tunes, and those with either 87 or 91 octane optimization. I'll go with 91 oct "Sport" for best performance. No hitch, I never tow anything. I don't off road either. No lift. Might go with a 2" lift at some point, maybe not. No more. No insane mud tires.