Jeep Cherokee Aeromods

[JeepNmpg2]

Originally Posted by sdconcepts

Has anyone tried a header and a cat back exhaust? i'm curious to see if that will add any efficiency to the 4.0 since the exhaust is pretty restrictive. i have a 99 cherokee with a 4.0 and would like some real world feed back on this mod before i do it.

SD - I have done both stages on my exhaust, first with the high flow cat-back system, which was a huge improvement over stock. I did it at the same time I did the custom air intake, so the combination was very noticable and no torque loss. Some months later, I had the cat switched out for a high flow model from Magnaflow which gives more overall power, but I noticed a tiny bit less in the low-midrange. I had flash new maps to my computer to make up that difference, but if you just want cat-back, it's a great upgrade! Sounds nice too! I recomend Flowmaster 40 series (or 50 series if you like it more stock sounding), which is not very loud, but is noticable. I've gotten a few looks from others thinking I have a V8 under the hood from the lower rumble it makes. Hope this helps you! I noticed a little better mileage when cruising the freeway, maybe 1 or 2 MPG but you have to fight the urge to put your foot in it every once in a while (which defeats the purpose of the economy of the mod)

[winkosmosis]

Those higher flow cats don't catalyze as well. Why bother eco modding and whatnot if you're going to increase your emissions?

[sdconcepts]

how do you reflash a jeep a computer? i think there is alot of tuning that can be adjusted to get better MPG and overall efficiency. i'm still debating on which header to get, some say the stainless steel is the way to go but me personally i'm thinking the full length pace setter header is the way to go.

[JeepNmpg2]

Originally Posted by sdconcepts

how do you reflash a jeep a computer?

I'm purchasing a UNICHIP setup for my cherokee, and it holds up to five seperate programs (ecu maps, shift points, torque converter lockup, etc). Obviously I'd have one for highway ecomony on 87 octane, one for high horsepower, one for high torque both on 92 octane, one for highway towing, and one bone stock (for emissions purposes).

Originally Posted by sdconcepts

i'm still debating on which header to get, some say the stainless steel is the way to go but me personally i'm thinking the full length pace setter header is the way to go.

I would highly recomend you go with the set by Doug Thorley. They are extremely well tuned and they are coated so that they push A LOT of heat out of the engine compartment instead of letting it build up from/around the exhaust manifold. Cherokees run hot as it is before any aeromodding that might cut off airflow even more, so any help to rid your engine bay of that destructively high heat is good.

[FastPlastic]

Ok, so the weather is starting to get colder, so I've started to get the Cherokee all buttoned up to keep it warm over the winter. I decided to try something new this year and install what I call the "Partial" warm air intake. The reason I'm calling it a partial warm air intake is because I didn't want to cut any holes in my air box to do it. So I found a smaller 1-1/2" aluminum flex hose that would reach to the exhaust manifolds from the opening in the air box. My guess is this hose is about 1/3 the size of the opening on the air box. So far I have noticed the Intake air temps up about 10-20F from a cold start. Then after sitting for about an hour or so it pulls a good 100F out of the warm spot by the exhaust making re-warming the engine faster.

Flex hose is the silver tube in the center of the picture


Outside view of the hose placed in the opening of the airbox.


Inside view

[JeepNmpg2]

Fastplastic - Great idea, I like it!

How does it do with the belt mounted fan blowing air around the compartment - any movement? How do you have it secured?

As much a recent (albeit slow) convert to ecomodding (mostly because I do it primarily for MPG reasons, but I like reducing my impact on the environment too!), I'm going to remove my shroud from my cold air intake for winter driving and try that out for a season (once I'm back to the states and all). I don't know if you are up to this, but I'm seriously considering converting over to an all electric engine fan vice the belt driven one that NEVER shuts off. I've heard wonderful things about that helping warm up time and taking some load off of the engine when you don't need cooling (ie, anytime below 30 degrees driving on level ground). Based on almost everything I've read, the fan and shroud out of a 95 year Ford Taurus is the best replacement (just takes some minor modification to the Ford fan-shroud for fitment) as it's the only one that can pull the 4000 CFM that the stock fan was capable of.

Man, I hate being away from my Jeep when I have all of these things I want to try! When I'm back, I'll be sure to post some pics!

[FastPlastic]

Originally Posted by JeepNmpg2

Fastplastic - Great idea, I like it!

How does it do with the belt mounted fan blowing air around the compartment - any movement? How do you have it secured?

If you look closely the top turn of the flex hose to the left there was a hose near the air box. I just have the flex tube snug between the air box and that hose. Otherwise the tube is small enough to hold it's shape, so it won't really move.

The belt driven fan does affect it some as I will see the intake air temps rise when sitting at a light for a few seconds. But I think in all it's definitely helping.

Originally Posted by JeepNmpg2

As much a recent (albeit slow) convert to ecomodding (mostly because I do it primarily for MPG reasons, but I like reducing my impact on the environment too!), I'm going to remove my shroud from my cold air intake for winter driving and try that out for a season (once I'm back to the states and all). I don't know if you are up to this, but I'm seriously considering converting over to an all electric engine fan vice the belt driven one that NEVER shuts off. I've heard wonderful things about that helping warm up time and taking some load off of the engine when you don't need cooling (ie, anytime below 30 degrees driving on level ground). Based on almost everything I've read, the fan and shroud out of a 95 year Ford Taurus is the best replacement (just takes some minor modification to the Ford fan-shroud for fitment) as it's the only one that can pull the 4000 CFM that the stock fan was capable of.

Man, I hate being away from my Jeep when I have all of these things I want to try! When I'm back, I'll be sure to post some pics!

I'm afraid I'm probably not up to the challenge of putting in the Taurus electric fan. I was however looking at the possibility of replacing the standard fan with one that was recommended by someone. It fans out the higher the speed, thus reducing the load on the engine at highway speeds anyway.

[JeepNmpg2]

Originally Posted by FastPlastic

I'm afraid I'm probably not up to the challenge of putting in the Taurus electric fan. I was however looking at the possibility of replacing the standard fan with one that was recommended by someone. It fans out the higher the speed, thus reducing the load on the engine at highway speeds anyway.

What's the information on that fan you're looking at? Maybe that will be an easier/cheaper method for me as well. Right now, I can get a brand new fan/motor/shroud assembly for $108 (add another probably $60-100 for wiring, two way electronic thermostat switch and relays).

[FastPlastic]

Originally Posted by JeepNmpg2

What's the information on that fan you're looking at? Maybe that will be an easier/cheaper method for me as well. Right now, I can get a brand new fan/motor/shroud assembly for $108 (add another probably $60-100 for wiring, two way electronic thermostat switch and relays).

Never fails the second you say something about it you can't find it anymore. I could swear I found one for my 1998 Cherokee. Anyway, it's made by a company called Flex-a-lite. I found the one for the 1984-1995 here. I guess it's designed in such a way that the faster it go's it feathers out some how reducing load on the engine. They seems to have a lot of different models listed on their website, so who knows maybe one could be modified if they don't actually carry one for the newer Cherokee's.

[JeepNmpg2]

Wow.... 95 taurus fan at $108 = great deal!
PWM (Pulse Wave Modulation) Fan Controller at $240 = holy crap!

I guess the big question is how much do I REALLY want to put in to have an all electric setup. I have to say that fan controller I found is outstanding as it actually runs the fan anywhere from 20-100% speed depending on engine temp threshholds versus 100% everytime the engine gets over a certain temp. I'm still waiting on a reply from the technicians that designed the device to find out if it can handle the 85 amp peak startup draw this fan has (33 amps continouos at full blast). I'm leary about just buying it otherwise (isn't ecomodding supposed to be economical to my wallet as well) I know that it will eventually pay for itself... but it might be quite a while...