I have a 96 Grand Cherokee... It's at about 130,000 miles... It has the 4.0 straight 6 in it... It is a gutless wonder, Seem like the gearing is too high, My sister has a 98 cherokee sport with the same engine and it might be geared lower but has alot of power... Is there any cheap do it your self tricks to inprove power??? I put a cold air intake on it, did not improve much, but make the engine sound like a vacume cleaner when idleing..... I know like the ford 300-6s you could pull the egr valve off and put a plate in between with a smaller diameter hole on it and bolt it back up, put 302 injectors and run the twin exsaust manifold for a little increase of power... just looking for tips and tricks like that.....


Thanks

The Grand Cherokee weighs a lot (like 600lbs) more than the Cherokee so there would be some power difference. The 4.0 usually makes ample power for the Grand though, it sounds like you have a problem with the engine or your expectations are too high. The Cherokee's with Auto trans all run 3.55 gear ratio. The Grands run 3.73:1 to help compensate for the extra weight.
You can do a few things, how much money do you want to spend and do you live in California? You can install a Banks Header and power tube. The inlet of the Cat is 2.5" and the outlet is 2.25" (so the rest of the exhaust is also 2.25"). You can replace the CAT with a low restriction CATCO 2.5" in/out and replace the exhaust with a 2.5" low restriction setup. You can change out your intake manifold for a '99 or newer unit (7-10hp). Hypertech makes a programmer for it +7hp for regular fuel, +13hp for premium. All of these together should get you from the stock 190hp to about 225hp. If you need more, you can add a turbo kit (about $3500-$4000) or you can pull the engine down and install a stroker kit (increase to 4.5l-4.7l). The cheapest kit also increases your compression ratio to 9.7:1 so you must use premium fuel. The stroker setup should get you into the 250hp range, a turbo or supercharger on the 4.0 would get you into the 270hp range. At this point you are to the limit of what the auto trans can take.