Hello everyone, I'm planning on doing some mods to my 91 cherokee. I've heard that you can exchange the intake manifold from the '99-'02 editions to previous models, and the end result is a 15 hp gain. In addition if you swap for a Hesco fuel pressure regulator and 99 injectors, it can show up to 27 hp and 20 rear wheel torque at the rear wheels. Now can anyone tell me if this info is credible?

 

I haven't done it but this guy has.
http://www.go.jeep-xj.info/HowtoIntakeManifold1.htm
I have done some of his other mods and they work.

 

The intake mod will had some HP and Torque.. It flows better then the older ones. The injectors will add some better performance simply because you get better fuel flow. The fuel pressure reg mod IMHO is a waste of money unless you have a stroker since your engine likely can't handle the added fuel pressure. The primary reason for adjustable fuel pressure regulators is when you build a stroker you need to be able to tweak it to fit the engine. So do the intake mod and maybe some new better injectors, but I wouldn't waste the money on the fuel pressure regulator.

 

Yes it credible. On a 91 you'll have to do some rewiring to upgrade to 96+ style harness. The reasoning behind the horsepower gain is that the manifold is larger. In 99 Jeep had higher exhuast restrictions put in place and this cost horsepower. So Jeep designed a new manifold that produced more horsepower to make up for the difference. That's why 99+ XJ's make 193 horsepower. Put the 99+ on a 98 or older and you'll see a nice change in power. The link 01xjsport provided is probably the best.

 

x2

 

Shouldn't need to do this. Everything should bolt right to the manifold off the 91.. Only real issue is getting the power steering pump bracket so it will fit.

 

is it the Non Ho's that need the new P/s bracket?? or does any 4.0 that isnt 99+ have to have it to run this manifold.?

 

Thanks for the info, I'll let you know how it goes once Ive found one to change on mine. So there shouldn't be any big issue with my 91 jeep, just maybee the power sterring bracket...