xj_dummy Posted September 25, 2008 Share Posted September 25, 2008 What can I do to my 86 comanche 2.5 to get better fuel millage? Besides droping a 4.0 in it. Do they make aftermarket headers for it? What have YOU 2.5 owners done to yours? Link to comment Share on other sites More sharing options...
Pete M Posted September 25, 2008 Share Posted September 25, 2008 What size tires do you have? Link to comment Share on other sites More sharing options...
mjtjnj Posted September 25, 2008 Share Posted September 25, 2008 What can I do to my 86 comanche 2.5 to get better fuel millage?Besides droping a 4.0 in it. Do they make aftermarket headers for it? What have YOU 2.5 owners done to yours? Pretty sure the 4.0 won't get you better gas mileage, but to answer your question, I had my 2.5 bored out and bigger pistons put in, used Yella Terra roller 1.5:1 roller rockers, K&N filter with Rusty's cone adapter, I have a header made by Clifford performance and cherry bomb muffler. You're still limited by the throttle body/injector, and I haven't heard of anything that can be done to improve fuel delivery. Mine isn't a whole lot faster than it was. It's better just by virtue of being rebuilt, but I'm not pouring any more money into it to try and gain HP/torque. It is what it is -- 151 cubes. Link to comment Share on other sites More sharing options...
Mitch Posted September 25, 2008 Share Posted September 25, 2008 Push it half way to your destination, drive it the rest of the way. Link to comment Share on other sites More sharing options...
Pete M Posted September 25, 2008 Share Posted September 25, 2008 A basic tuneup is the best medicine for improving MPGs. Beyond that, you can remove the mechanical fan for an electric. That'll free up a couple horsepower. Link to comment Share on other sites More sharing options...
jteckmann Posted September 26, 2008 Share Posted September 26, 2008 +1 on the electric fan. Bang for the buck, that's probably the easiest way to squeeze extra power/economy out of the 2.5. Letting the engine breathe better with a hi-flow exhaust and/or intake helps out. Best millage out of the 2.5 is relative, and depends on what you want to use the truck for. Running the stock tire size (205/75/15) doesn't look nearly as cool but will increase your mpg and give the truck the guts it needs at highway speeds, and to keep from having to downshift on any hill you approach. So for a truck that sees mainly highway miles, the 2.5 is going to be economical. But for building a trail rig, the 2.5 isn't going to give you significant savings over a 4.0 (maybe 2-3mpg) because it simply has to work to hard to turn the gears & taller tires. The best thing you can do with a 2.5 is just keep it well tuned & maintained with quality stock parts. Make sure the MAP & O2 sensors are good and that you're getting the right fuel mix. Check the vacuum lines for any leaks. The Renix ignition system works best with standard copper plugs, a set of quality wires, and brass terminal cap & rotor. Spending the extra for platinum plugs or performance wires doesn't make much of a difference, and some people have reported that it can slightly decrease economy I use my '86 2.5, 4spd as a DD, so have it close to stock. I run an electric fan, 205/75/15 tires, 2.5" exhaust with a hi-flow cat & oval Gibson muffler (tad loud but not ricey), good cap & rotor with a premium wire set from NAPA. No AC or Power steering. I've averaged high 20's (25-28mpg) with mixed driving/more highway miles. But honestly, I drive like a Grandma. If you really want to squeeze every mpg out of your truck - a good trick is to T a cheap vacuum gauge into the pcv system and mount it on your steering column. The engine generates higher vac pressure at lighter loads, so by watching the gauge, you get a feel for the most "economical" way to drive it. Link to comment Share on other sites More sharing options...
jaekl Posted September 26, 2008 Share Posted September 26, 2008 That's what the old vacuum wipers were good for, a heads up vacuum gage. You even kinda instinctively back off the throttle to make the wipers move. Link to comment Share on other sites More sharing options...
Redramman Posted September 28, 2008 Share Posted September 28, 2008 How many mpg gained with electric fan? How much of a differance will 215's be than 205's? (2.5L 2wd). Link to comment Share on other sites More sharing options...
Pete M Posted September 28, 2008 Share Posted September 28, 2008 Probably enough to balance each other out. Your driving habits will have more of an effect that either mod. Link to comment Share on other sites More sharing options...
Redramman Posted September 28, 2008 Share Posted September 28, 2008 :smart: Thanks Pete. sombody told me the best MPG mod is a clean air filter and proper tire psi.Synthetic lube might also be worth it. Link to comment Share on other sites More sharing options...
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