If you were building a jeep for speed pit, mud racing only. Would you build a stroker xj or a 5.2 zj? My wife loves the whole mud racing and she's won a few times. I told her I would make her faster this winter because she has to run against v-8's alot of the time. Not that she isn't competative I just want to make her better. But I'm wondering if it wouldn't be better to just get her a 5.2 grand...Help me out guy'sssss cause a strokers gonna cost me...Here's a pic of the xj

 

I'm betting you could sup up that 4.0 without stroking it and costing yourself a whole lot of money. Between a stroker and a v8 out of a grand, i'm not sure the grand 8 is that powerful, look at the torque it puts out and see where to go. More torque=more power to launch.

 

your not going to get alot of power out of the 4.0 without stroking it. if you are thinking about just doing aftermarket upgrades forget about it. it would need to be stroked to compete with the v-8. now if you put the 5.2 or 350 in the cherokee you really would be going somewhere. the xj is lighter than the zj thats why i would stick with it, and i bet there is a kit to swap a 350 in. those engines are a dime a dozen. put out good power and you can get alot of power out of them very easy. i guess it all depends on how much time you want to put into it. but if your really looking for power the 4.0 stock is not the way to go

 

id take a 318 the power to weight ratio is insane and its still keepin it in the mopar family

 

I would work the 4.0:
cams
bore
shaving heads and valves
SUPERCHARGER!!!
5.0 stroker kit
chip it
dyno tune and you got some BALLZZZ

 

you are soo lucky to have a wife that loves offroad

 

I forgot to mention that she runs the "stock" or "street legal" class. which rules say the motor has to have came stock in that vehicle and pull 17 pounds of vacume. She does so well because of the weight of the jeep against the full sizes. There killing us off the line though, and I am lucky but she eats up alot of the jeep funds...LOL

 

If you are going to race the V8s, take those stock gears out and put in some low gears. That will be the cheapest way to take care of your off the line starts. Also, exhaust in a 4.0 is very restrictive. Put some good exhaust on it behind a good set of headers. Then do some head work. Get a HO head, port it and polish the combustion chambers and put some mustang fuel injectors in the rail. I used to race myself. There were two guys that stood out. One had a 225 cu in V6 that was top notch and smoked the V8s consistently. The other ran an AMC 360 and took top eliminator at the Pacific Northwest regional meet against supercharged big block, glass bodied Chevys. One trick they both had outside of finely tuned motors was tires and suspensions. I would change those swampers out for some iroks or boggers. They look like they get lots of traction, but there is too much rubber in the middle.

 

something i would do is raise the front a .5 inch above the rear, to lose the plowand it will cause your heep to wanna stay up above the mud, not bogged down in it, you can probably gain a good three seconds on your average time with a half inch

 

all I have to say is.... NOS

 

Turbo the 4.0

 

x2

 

Interesting, cause I swear she did better last year on 33 BFG MT's. Not alot of info on the net about mud racing....Her jeep does sit one inch lower in the back and sorry no turbo's or NOS...

 

BFGs have more traction in the center of the tire. I have both and the BFGs get better traction. The Swampers, although you would think they are for mud, are rally more of a rock tire. The IROKs would do much better due to the open center. And of course, the boggers will throw lots of mud. She will gain more from the right tires than horsepower. What kind of mud racing is she doing?

 

15in of mud or less and 150ft pit. It's usually very sticky thick mud and the pit usually have two distincts tracks by the time she runs. She does better if the pit is alittle deeper and without tracks. She is the only women in are area running her own rig and actually winning a few in the 4/6 class and seriously competing in the stock/street legal class. I put the 33/1250 boggers on her jeep in the beginning of the fair season but she couldn't hit the limiter with them on and that seems to be where her jeep is fastest. I bought the 34/10.50's for her to get the diffs out of the mud to keep down drag and so the skinny tire is staying in the center of the tracks and not dragging her down. Didn't seem to help though.