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Discussion Starter · #1 ·
Hell all, first time post. BLUF: I have a 120 round trip commute everyday, and I want to increase the performance and gas mileage of my compass. The only thing I have right now is a K&N rechargable air filter. I have 130k+ on her right now, bearings have been changed, brakes last year.

Any suggestions?

Thanks.
 

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There is not much you can do to the motor itself its already squeezing out a big peak HP number for its size/displacement, there is no magic 30 HP waiting to be unlocked by throwing a couple of bolt-ons at it. Just making sure its in peak condition (ie, if its never had spark plugs before now is the time), basic things to keep it at its original peak power, if you've lost 20 HP from age and mileage do what you can to get that back basically.

You'll want to run small, lightweight tires with low rolling resistance to get the most out of it on the highway and for all around performance. You lose a lot twisting tires that are larger and heavier than stock.
 

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Discussion Starter · #3 ·
There is not much you can do to the motor itself its already squeezing out a big peak HP number for its size/displacement, there is no magic 30 HP waiting to be unlocked by throwing a couple of bolt-ons at it. Just making sure its in peak condition (ie, if its never had spark plugs before now is the time), basic things to keep it at its original peak power, if you've lost 20 HP from age and mileage do what you can to get that back basically.

You'll want to run small, lightweight tires with low rolling resistance to get the most out of it on the highway and for all around performance. You lose a lot twisting tires that are larger and heavier than stock.
Roger, thanks for the reply. Regarding the 20 that is lost with age, how can I get that back?
 

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Nothing major but if it has a fuel filter it should be changed (most stuff that new doesn't have a replaceable fuel filter), maybe run a bottle of injector cleaner through it (but follow directions and use properly, its not a "if one is good then dumping in three bottles should be great!" kind of thing), maybe spray-clean the throttle body, nice synthetic oil in the engine and quality oil filter, maybe a transmission fluid flush assuming its a 6 speed (and change transmission filter if serviceable, many are not), new rear diff fluid if 4x4 just to keep everything rolling good back there, spark plugs and wires/coils as applicable, sounds like you got a good air filter already, maybe consider an alignment at this point and if they ask how you want it (most don't) you can tell them its a lot of highway miles and maybe they will straighten it up more than stock for best straight-line performance and longest tire life. Won't gain you any power or economy but if the belt and tensioner are old those should be changed, any loose idler bearings, etc. Coolant should be flushed if its never been done (again, not an item that will reclaim any power just standard maintenance). If the OEM thermostat is still hanging in there maybe just let it ride, replacement ones never seem to last like OEM. Or change it, either way.

None of that stuff is real exciting but its a better use of money than buying a $200 intake and $400 exhaust, if you want it to run many more smooth miles.
 

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Basically I agree with @arudlang post #3 above. Engineers with college degrees are working tirelessly to squeeze every last HP/FP and every last MPG out of these tiny engines. Consider my first car was a 6-cyl Ford with the same displacement as our Compass but only generated exactly half the HP, and fuel economy was a little less, too. The engineers didn't neglect anything. There's no tweaking you can do, nothing you can pour into your fuel tank, nor any aftermarket gizmo that's going to make much of a difference. If K&N really made a difference they'd either install them at the factory or develop a mopar equivalent. You might get a nice placebo effect with some fancy decals, however.

Others will disagree but premium fuel may make a slight difference. I didn't say dramatic, but slight. It's been quite a few years since I experimented with this, but I did a few MPG checks back in the 1970s and decided the improved fuel economy wasn't worth the 4c/gallon difference. That was with a carburated 6-cyl. Maybe I should try again. I will say premium fuel made a huge difference in my 225CID Volares, not so much in fuel economy, but it solved the stalling problem with my '77 Volare and solve the pre-ignition problem in my '78 Volare. The '78 got premium fuel after I burned out the valves. :( No problems after that. Coulda been the gasahol I tried running during the second fuel shortage.

I think LRR tires make a slight difference, but I only run them in the summer. Weather makes a huge difference, too. Last weekend was quite warm and on a lark I filled up with Premium, then made a long trip (200 miles) and got 35MPG and that was with my snow tires still on. See my post here: Humor me

I made the same trip this weekend in 40 degree rain and buffeted by high winds and only got 30MPG. That's a 15% decrease in MPG. Because of the weather I was even driving a little slower, particularly on the turnpike where 70MPH = hydroplaning.
 
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