WyoCherokee Posted October 18, 2008 Share Posted October 18, 2008 I'm getttin tired of having to pull freeway hills in 3rd gear at 50. perhaps its cause its the summit of the highest point along I-80(8500 ft) but i would to at least like to pull it in 4th? ide like to keep my 26 mpg. I'm thinking rustys air tube, cut the cat converter out, and idk if i can get a bigger throttle body? any suggestions Link to comment Share on other sites More sharing options...
wolfpackjeeper Posted October 18, 2008 Share Posted October 18, 2008 air tube is crap, it will just pull hot air from the bay. The cat may or may not help, you would probably see the same benefit from a new one as from none at all. And depending on if you have tbi or mpi you could switch to a 4.0 throttle body for a bit of a boost. There used to be a "purple cam" made for the 2.5 but I do not remember by who. It is most likely the 8500 feet that hurts you the most, so the one thing that would really noticeably change it would be a turbo setup. Cram more air in there. you could also switch to the new MPI if you have tbi, just snag the harness/manifold/computer/ and wiring from a 94 or 95 2.5. that would let you go with the 4.0 throttle body as well. Whats gears/tranny do you have. Link to comment Share on other sites More sharing options...
Eagle Posted October 18, 2008 Share Posted October 18, 2008 I know someone who has (I think he still has it) a NIB factory Stage 3 cam kit for the 2.5L. I have no idea what he might want for it, if he still has it, but I believe his plans changed and he no longer has a need for it. Let me know if you'd like me to find out if it's available. Link to comment Share on other sites More sharing options...
jared Posted October 18, 2008 Share Posted October 18, 2008 turbo that b*@$£ Link to comment Share on other sites More sharing options...
WyoCherokee Posted October 18, 2008 Author Share Posted October 18, 2008 I'm pretty sure i have 3.55's. ive got the ax-4 speed. how bad would the 4.10's hurt my mileage? Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 18, 2008 Share Posted October 18, 2008 I'm pretty sure i have 3.55's. ive got the ax-4 speed. how bad would the 4.10's hurt my mileage? improved mileage if you also swap to a 5 speed. more balls too when downshifting...you'll run 4th on interstate when passing Link to comment Share on other sites More sharing options...
Pete M Posted October 18, 2008 Share Posted October 18, 2008 I'll bet you'll see improved mileage even without the 5th gear. I'd do it in a heartbeat! Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 18, 2008 Share Posted October 18, 2008 I'll bet you'll see improved mileage even without the 5th gear. I'd do it in a heartbeat! you'd lose top speed on the highway though. if not upgrading to a 5 speed, I'd say that 3.73 gears are the way to go. Link to comment Share on other sites More sharing options...
WyoCherokee Posted October 19, 2008 Author Share Posted October 19, 2008 soooo ax-5? Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 19, 2008 Share Posted October 19, 2008 the HP gains on an empty cat vs. a O.P. cat is like 2 or 3hp. its been proven on a dyno. pretty much, if you turbo it, yes it will go up hills better and so on. but it WILL affect your mpg's. so beware! i would suggest a good tune up that includes a complete cleaning of the throttle body and have you ever though of getting skinnier tires? same height just not as wide? id leave the engine stock personally, but i live at like 60 feet above sea level. you could try getting your injectors(i think its got 2) cleaned and run some mystery oil to help restore some power. you gotta remember, its only a 4 banger. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 19, 2008 Share Posted October 19, 2008 soooo ax-5? sure, but putting an AX-5 in is not going to help you until you regear the truck...it will simply add another gear that the engine is incapable of pushing enough power to use. regear to 4.10's, and then get an ax5. I have one ax5 from a 94 xj, one that's in my 86 mj but is coming out for an upgrade. I rebuilt the one that is in the 86 less than 1000 miles ago, and the only thing that needs to be done is reseal it (I used RTV black, not ultrablack... :oops: ), and enough parts to build yet another one in the 2wd or 4wd flavour (plus spare transfercases for the 4wd version). not sure on shipping, but we could work it out so the whole deal benefits you. Link to comment Share on other sites More sharing options...
WyoCherokee Posted October 19, 2008 Author Share Posted October 19, 2008 the HP gains on an empty cat vs. a O.P. cat is like 2 or 3hp. its been proven on a dyno. pretty much, if you turbo it, yes it will go up hills better and so on. but it WILL affect your mpg's. so beware! i would suggest a good tune up that includes a complete cleaning of the throttle body and have you ever though of getting skinnier tires? same height just not as wide? id leave the engine stock personally, but i live at like 60 feet above sea level. you could try getting your injectors(i think its got 2) cleaned and run some mystery oil to help restore some power. you gotta remember, its only a 4 banger. no injectors just a main throttle body and I'm runnin pretty much all stock. lt215/75/15's and i would cut the cat completely out since we don't have emisions here in wyoming Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 19, 2008 Share Posted October 19, 2008 the HP gains on an empty cat vs. a O.P. cat is like 2 or 3hp. its been proven on a dyno. pretty much, if you turbo it, yes it will go up hills better and so on. but it WILL affect your mpg's. so beware! i would suggest a good tune up that includes a complete cleaning of the throttle body and have you ever though of getting skinnier tires? same height just not as wide? id leave the engine stock personally, but i live at like 60 feet above sea level. you could try getting your injectors(i think its got 2) cleaned and run some mystery oil to help restore some power. you gotta remember, its only a 4 banger. no injectors just a main throttle body and I'm runnin pretty much all stock. lt215/75/15's and i would cut the cat completely out since we don't have emisions here in wyoming a throttle body has fuel injectors. but instead of having them near the end of the intake runners, its in the throttle body. i wanna say there is two but there may only be one. Link to comment Share on other sites More sharing options...
WyoCherokee Posted October 19, 2008 Author Share Posted October 19, 2008 ohh gotcha. yea theres just one main one. Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 19, 2008 Share Posted October 19, 2008 tune up includes cap, rotor, plugs, wires, tb cleaning and injector cleaner and some fuel additive that cleans valves or something. well at least thats what it is where i work. when y ou have the plugs out its a good time to check compression. disconnect the coil and hold the throttle to the floor and crank for 5 seconds. should be 120 and up. Link to comment Share on other sites More sharing options...
WyoCherokee Posted October 19, 2008 Author Share Posted October 19, 2008 i changed plugs cap rotor and wires this summer and did compression last winter. all were around 124 Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 19, 2008 Share Posted October 19, 2008 sounds like its time for a cold air intake WITH a sealed box. and a new cat back exhaust that will give it a bit more flow. anything 2 1/4-3'' will do fine. Link to comment Share on other sites More sharing options...
jteckmann Posted October 21, 2008 Share Posted October 21, 2008 no injectors just a main throttle body and I'm runnin pretty much all stock. lt215/75/15's and i would cut the cat completely out since we don't have emisions here in wyoming I have an '86, 2.5, 4sp, mostly stock. Same set-up as yours. Unfortunately, there just isn't much available for the old Renix TBI set-ups (I had to go on a wild goose chase just to get a replacement injector) My suggestions: 1. Ditch the mechanical fan for an electric one. Bang for your buck, that's probably the best upgrade. Makes a noticeable difference in power. 2. Sounds like your tire size might be big. Stock is 195/75R/15 - each P-metric step up from that adds about .5" to your overall tire diameter, affecting your final drive ratio. Smaller tires but will help maintain higher power at cruising speeds. If the truck sees mainly road use, consider dropping tire size. When I got my Comanche, it was fitted with 235's - and going back to the stock size made a big difference in drivability. 3. Free up the exhaust and let the engine breathe. Personally, I run 2.5" pipe w/ a Magnaflow hi-flow cat & Gibson oval-style (it was a tad more expensive than the Flowmaster, but IMO worth it because it isn't quite as loud and had a lower tone - so it doesn't sound like a ricer). You can cut the cat out if you want - but IMO it won't make much of a difference, and might even do more harm than good. Even if you free up the exhaust, you want to keep a little back-pressure in the system to maintain low end torque. You can pick up a quality hi-flow universal cat for about $50. After the exhaust, check your options for a better intake. IMO, cone filters & power tubes aren't worth the money, because you're limited by a relatively smaller throttle body anyways, and most of them just wind up sucking hot air in from the engine compartment. Just drop an AirHog or K&N in your stock airbox, and you're probably good to go. That's pretty much it as far as cheap, easy options go for the older 2.5 TBI's - and that's how I have my truck configured. I use mine as a daily driver and work truck. I drive like a grandma (don't have much of a choice), but I have plenty of power for my needs. I get low-to-mid 20's mpg in mixed driving and occasionally the high-20's when I have a lot of highway miles. I'm in Washington State so I deal with a lot of climbing/mountain passes. With the smaller tires and few power upgrades, I can usually maintain speed (60-65mph) on all but the steepest grades - but I still occasionally have to downshift to 3rd on a few. Like was said earlier - the 2.5 probably needs to be matched with the 5sp and a re-gear to have the best drivability. When I save up the money/parts, that's going to be my next (and final) upgrade to my truck. No matter what you do with the 2.5, "there's no replacement for displacement" It's always going to be a dog. The only thing appealing about it is the mpg - but even then, it's not like we're talking about a miserly +35mpg engine, it simply has to work too hard to put up great economy numbers. You start throwing big tires and a lot of weight on the rig, and suddenly the 2.5 is giving you mileage in the teens. I've known guys with stock XJ's & MJ's with 4.0's and manuals that drive them efficiently and get numbers that are only 2-3mpg's off what the 2.5's get. Link to comment Share on other sites More sharing options...
WyoCherokee Posted October 21, 2008 Author Share Posted October 21, 2008 thanks that was a really good write up. the 225's almost seem to small, but then again I'm used to 35" tires on my 67. ill be on the lookout for a electric fan. I'm runnin a 2 1/4 exhaust with a magnaflow. does anyone have a link to an electric fan setup on here? Link to comment Share on other sites More sharing options...
SoloCamo Posted October 21, 2008 Share Posted October 21, 2008 sounds like its time for a cold air intake WITH a sealed box. and a new cat back exhaust that will give it a bit more flow. anything 2 1/4-3'' will do fine. A 3" exhaust on a 2.5 4banger comanche? That's a huge waste and will do wayy more harm than good. 2 1/2 is even too much on a 2.5L Link to comment Share on other sites More sharing options...
wolfpackjeeper Posted October 21, 2008 Share Posted October 21, 2008 sounds like its time for a cold air intake WITH a sealed box. and a new cat back exhaust that will give it a bit more flow. anything 2 1/4-3'' will do fine. A 3" exhaust on a 2.5 4banger comanche? That's a huge waste and will do wayy more harm than good. 2 1/2 is even too much on a 2.5L ditto, 2 1/4 will be great if you get smooth bends on a 4.0, 2 on a 2.5 would be fine. At 3" you will get a lot of flow seperation in the tube and it will slow down the gas velocity. Link to comment Share on other sites More sharing options...
jteckmann Posted October 21, 2008 Share Posted October 21, 2008 thanks that was a really good write up. the 225's almost seem to small, but then again I'm used to 35" tires on my 67. ill be on the lookout for a electric fan. I'm runnin a 2 1/4 exhaust with a magnaflow. does anyone have a link to an electric fan setup on here? No probs, man. Glad to help. Here's a good electrical fan write up for the 4.0: http://comancheclub.com/forums/viewtopic.php?t=8342 On mine, I just picked up one of those Hayden universals from AutoZone when they were having a sale. 14" and came with all necessary hardware/wiring. IIRC, the set-up cost me about $60. I removed the 4 bolts to remove the old fan off the water pump pulley, and pulled out the old shroud. Mounted the new fan as a puller behind the radiator - plenty of space, no clearance issues with the 2.5. I have an aux fuseblock mounted under the hood, coming off the battery (I use it for the stereo amp & a few other accessories) so that's where I wired it for power & ground. Mine came with a thermostatic switch on/off that clamped into the radiator, and an optional wire turned the fan on whenever the A/C was running - no A/C on mine, so I ran that wire to a rocker switch on my dash to control the fan manually as well (usually just play it safe and run it full time if I'm in-town or stuck in traffic). Been running it for about a year now, and it's worked great. Also - I wanted to echo what the posters above me said about exhaust. 2.5" or more is probably way too big for the 4-banger. I made a typo in my previous post - my exhaust is 2.25" (2 1/4), NOT 2.5. Sounds like you have a good exhaust set-up on yours already. :cheers: Link to comment Share on other sites More sharing options...
Rockyrider367 Posted October 25, 2008 Share Posted October 25, 2008 Does anyone know if the swap to a 4.0 TB is an easy swap? Also is it really worth it? Link to comment Share on other sites More sharing options...
Pete M Posted October 25, 2008 Share Posted October 25, 2008 Does anyone know if the swap to a 4.0 TB is an easy swap? Also is it really worth it? I don't know if it's worth it, but I believe it only applies to 91+ mpi 2.5Ls. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now