what are the things to install in order to boost HP and MPG (mostly MPG) in a jeep cherokee sport 1999 ?

 

I have the exact same question. Only things I can think of that are in my price range (not sure what kinda price range you're working with) is doing proper maintenance (changing air filter, plugs, wires, o2 sensor, etc etc all on schedule and not let them get too old), changing from 10W 30 to 5W 30 (5 weight is easier for engine, it's winter as well anyway), I ran some seafoam through the brake booster cable, keep wheels at right psi. I get around 20 ish mpg (more on highway). Other than that, you can run higher octane gas, gets you farther per tank (but costs more), put in some sort of super charger (not the $40 electric ones lol), oversize exhaust or chromed. I heard chrome intake and polished valves and ports allow for better air flow because of the slick surface of chrome but I'm not 100% about that. Better injectors, or clean your injectors. Well I think that's about all I can think of. I'm sure others will chime in with some more suggestions

 

This is a very common topic on this forum. A search will find you more info than you know what to do with.

 

True that, a search for injectors will give you a plethora of information as well

 

sorry my question was general as to what i could do because i dont know where to start. thank you for the better help though to the first comment.

 

exhaust, better flowing filter, injector swap (i dont know what years, or cars for your 99 but there are posts) tune up in general, all will help. Some more than others some less than they are worth. I have a spectre filter instead of k&n like $25 autozone, catback $69 after rebate (wait for it as dynomax seems to have it every year from what i saw) and magnaflow cat $90 off ebay. I think that it does well but i didnt expect to gain something crazy like 5mpg or add 20hp either so there is no dissapointment if all said and done if i didnt gain anything ya know. Although i did check just the filter originally and i was sure i drove the same way and definitely picked up 1.5mpg but i had also replaced a reg paper filter that wasn't clean but not clogged either. Course i may have subconsciously driven a little better too so you can't be for sure it was that much of a gain.

 

how many miles, if over 100k replace ps pump. Very interesing, but it works. Guess old pump causes alot of paristic drainon the system, also, put jy electric fans on, that will free up power and a tad bit mpg. All the other suggestions above applie also.

 

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Higher octane gas has less energy per gallon than lower octane. Octane reduces pre-ignition allowing higher compression ratio, higher boost (turbos/superchargers), or more advance on the timing. All of these will produce more power and the all can lead to improved mileage if driven with moderation.

Best bang for the buck is free flowing exhaust and intake

 

kool somebody else that was paying attenion when learning automotive

 

Yeah, started early working on small engines. Dad worked on his own vehicles, read Hot Rod, and kept performance books where I could reach them. I could tell you at age ten how to light and set an acetylene touch for brazing even though I never saw one.

Now I work for a large tier 1 OEM as a test engineer testing diesel injectors.

 

me two at that age dad had me changing oil cause he did not have to jack the car up i just slid under lol been doing it 38 years now

 

It burns better, more complete combustion, it's better for the environment too lol if anyone cares...
also- I don't know where you got "has less energy per gallon than lower octane gas" That's contradictory to more complete combustion. you're wrong, I'm sorry
If the same amount of gas burns more completely, it has more measurable energy, which is also why it helps gas mileage.

 

You guys are making me feel entirely too young now. ._.

 

Really? Because All I get in a search is people telling others to Search.