Stock motor/what cam? 96xj sport

[muchos189]

the time has come for me to rebuild the engine in my 96. I have made arrangements to drop the engine off at the machine shop next saturday. I figure while I have the chance I want to go ahead and install an aftermarket cam but I have very little knowledge on the 4.0l HO motor.

I am doing a stock no frills rebuild.

can someone offer a choice or 2 on what cam is gonna suit my needs best and not give me fitment/computer issues.

I'm thinking something that brings alot more TQ then HP is fine with me.

I am fine with a having to purchase a full cam/lifter/valve spring combo as long as its a drop in set.


Vehicle info -

Not a daily driver
6in of lift and 36in tires and soon to have high 4 or low 5 gear ratio
around here we crawl alot when we go wheeling

thanks in advance

[muchos189]

quick add in - the jeep is gonna gain some weight with the front and read nates4x4 bumpers I just bought. I'm also gonna add full underbody skid plates and I was thinking about a c-rok exocage.

[Bouncy]

My buddy is running a stage 2 mopar performance cam in his and likes it. Said it wakes it up.

Above that, look into comp cams for a cam to fit your needs. Just keep in mind...A bigger cam doesn't always help, with a bigger cam, you have to see if you can put enough FUEL and AIR through it. Meaning bigger injectors, cold air intake, ported head especially on the exhaust side. Maybe ported throttle body to get more air in.

Then after that...IF you did all those upgrades, you may look at adjustable fuel pressure regulator and adjustable map sensor so your computer doesn't freak out from the extra fuel/air.

The MP stage 2 probably doesn't need any of the extra work...But you get smaller gains with it than the 2nd option.

[muchos189]

Yeah, I'm not concerned with max gains if it includes modification of the computer. I don't mind things like a larger t-body and other minor upgrades ect.

I'm looking for more of a drop in to keep things simple.

BTW I Comp cams website is the suck right now I can't get half of the links to work right now.

[Dr. Dyno]

Your stock '96 cam is already pretty good so I'd leave it well alone. Since you're going to add more weight and bigger tires, I think you're much better off regearing the axles. With 36" tires you're going to need 4.88 axle gears.

[muchos189]

Dr Dyno I apprecate the reply. I can't say that I'm not unhappy with the power the engine is making now. I wah just hoping for a little more grunt on the bottom end while I have this chance with the engine out for the rebuild and all. Thanks for the suggestion on gears as well. I'm pretty new to jeeps and wheeling in general (I come from a mustang drag racing background) so advice like that is golden to me.

So what suggestions do you offer other then a cam swap that would "wake up" the motor, but still keep things from getting out of control. I'm really wanting things simple because 2 projects that require constant tuning and maintainence in something I want nothing to do with.

Thank You

[Dr. Dyno]

Here's a list:

K&N FIPK or copy my homebrew version
Bored 62mm TB
Bored 62mm TB spacer
Insulate underside of intake manifold (see my site http://www.jeep4.0performance.4mg.com/diary.html )
Header
Custom 2.5" downpipe, 2.5" high-flow cat
2.5" performance cat-back

All these mods will collectively add about 25-30hp and 25-30lbft, make the engine much more responsive to throttle inputs, and make the Jeep more fun to drive.

[j99xj]

Insulate underside of intake manifold

I actually tried this one and it really does make a difference, especially off road when I'm traveling walking speed in low range. I also noticed a faster throttle response after sitting in traffic or a light for several mintues.

You said the gains from this mod are 4lbft at 1000rpm, 2.5lbft at 1500rpm, 1.5lbft at 2000rpm, and 1lbft at 2500rpm. I totally believe these numbers.

I actually think the numbers could be slightly higher in my case because I have the 99 intake with more metal and plenum volume (and thus heat capacity).

[Flash]

You said you wanted lots more torq then HP.

there is always the stroker way!
The only thing that its going to add to the cost of the rebuild, is the price of a good used crank and rods out of a 258!

http://www.jeep4.0performance.4mg.com/photo3.html

A "stroker" is going to give a a lot more torq over any thing els!......as the the saying go's THERE IS NO SUBSTITUTE FOR CUBIC INCHES(OR LITER IN THIS CASE):passgas:


Flash.

[Dr. Dyno]

Yup. I have a 4.6L version of the "poor man's" stroker in my '92 XJ. Today it dyno'd 210hp@4900rpm and 250lbft@3500-4000rpm at the rear wheels. With a 17% drivetrain loss for the AX15, that's 253hp and 301lbft at the crank with at least 90% of maximum torque available from 1700-4900rpm.

[Flash]

Yup. I have a 4.6L version of the "poor man's" stroker in my '92 XJ. Today it dyno'd 210hp@4900rpm and 250lbft@3500-4000rpm at the rear wheels. With a 17% drivetrain loss for the AX15, that's 253hp and 301lbft at the crank with at least 90% of maximum torque available from 1700-4900rpm.

:party: :party: :party:

now go and look up your stock HP and torq spec. of you 4.0 and then you will be vary impressed!



Flash.

[Dr. Dyno]

I am, but my HP/TQ numbers would have been even higher if my Crane 753905 cam hadn't pooped the bed 3000 miles ago forcing me to put the old stock cam back in.

[MudDawg]

I'm with Dino....if you want low rpm grunt, leave the stock cam in it.

[Dr. Dyno]

How do you like these dyno curves? Just got them today.

http://www.angelfire.com/my/fan/HP_TQ.jpg

[SCW]

great run Dino.

Do you expect your stock cam to last? What are the differences in performance from the Crane cam and the stock cam? All the cam trouble makes me nervous about running a stroker, not that I'm very close yet.

[Dr. Dyno]

I certainly hope the stock cam will last. I'm using stock valve springs instead of the Mopar Performance springs (40% higher spring pressure than stock) that I used previously with the Crane cam so they'll be easier on the cam lobes. I'm also using SL rated semi-synthetic oil rather than Mobil 1 full synthetic so it should have enough ZDDP to protect the cam from wear.
According to my Dyno 2000 program, the Crane cam should make 10hp/17lbft more than the stock '92 cam in a stroker and my performance numbers seem to bear that out. The stock cam does make more torque though from idle to about 1500rpm and the torque curve is flatter. The Crane 753905 in a stroker is very strong in the 2000-4500rpm range.

[jeepinwi]

Dino-
You gotta love that flat torque curve.:) Did you figure out what was causing your rev limiter to kick in at 4500 rpm's? Apparently you have that fixed. Was it the Jet chip?

[MudDawg]

The recent run of cam problems have nothing to do with being installed in a stroker engine....they are either manufacturing problems, installation problems, incorrect break-in, or lubricant issues.

[Dr. Dyno]

Dino-
You gotta love that flat torque curve.:) Did you figure out what was causing your rev limiter to kick in at 4500 rpm's? Apparently you have that fixed. Was it the Jet chip?

Yes it was. I removed it and the engine ran exactly the same as before except the rev limiter returned to normal.
MudDawg, I'd done 34000 miles on the Crane cam before removing it so the mileage was way too high for it to be an installation or break-in problem. If it was a lubrication issue, the cam would surely have had more than just one worn lobe. The other 11 were perfect. I'm more inclined to believe that the cam and lifters were poor quality.

[Flash]

Yes it was. I removed it and the engine ran exactly the same as before except the rev limiter returned to normal.
MudDawg, I'd done 34000 miles on the Crane cam before removing it so the mileage was way too high for it to be an installation or break-in problem. If it was a lubrication issue, the cam would surely have had more than just one worn lobe. The other 11 were perfect. I'm more inclined to believe that the cam and lifters were poor quality.

I had a mopar cam in my cuda tha i ran for the last 6 of the 11 year of it rebuilt life.
lifter started clattering, then nocking
remove the cam and had 2 lobes, missing all the rest still looked good!

liked the cam to much! put the same one back in

I thing the lifter was at fault on my cam but was to be expected with the time and mileage that i got.
Just my .02

[j99xj]

I removed it and the engine ran exactly the same as before except

One more piece of evidence that the jet chip is a piece of crap.

[Dr. Dyno]

Yeah, it's just a shame I only found out after I bought it 8-1/2 years ago but I did run the engine for 122,000 miles with it and it never gave me any trouble until the recent 4550rpm rev-limiter shenanigans.

[MudDawg]

Way back in the day when I had hair and all my own teeth, I almost exclusively used Erson cams....never had a minute's problem from those....I had one motor (SBC) go 270,000 miles with their hydraulic version of the old 20/20 Duntov cam....I wore out two sets of rockers, 2 sets of valve guides and 3 sets or springs....but the cam and lifters never gave up....I fed it Castrol GTX and EOS.....