I'll talk to my dad about it and see what he thinks, used to be a mechanic so he is really mechanically inclined and made me that way (why pay when u can do it yourself in a few hours). straight pipe? u mean, he's running the header and nothing else throughout the pipe till the tip? no cat or muffler? how does he pass inspection or is this a trail rig?

 

I pulled this from my website it is about making power etc.. (dealing with thermostats)


Will Switching To A colder Thermostat Increase Power


Like spark plugs available in varying heat ranges, many aftermarket auto parts manufactures offer replacement thermostats in a range of operating temperatures-most commonly, those that open at the OE-specified temperature and some that do so several degrees cooler-for those of us who live in hotter climates or stress the capacities of our cars systems. Thermostats that open earlier allow coolant to circulate sooner, ideally keeping engine temperatures lower. The debate occurs when certain aftermarket producers of cooler-temperature thermostats market them for "POWER INCREASING" benefits.... not naming names of course.
To test, we and out project miata visited MD Automotive, SoCal's premier two wheel drive dynamometer rental facility and hit the dynojet for back to back power testing with a 160-degree aftermarket replacement thermostat installed in the roadster, then again with it replaced by a 192-degree, OE specified unit. Temperature of coolant (50/05 glycol/water mix) was monitored at the radiator inlet throughout testing, to ensure dyno runs for each thermostat option were conducted at consistent starting points, once the engine had reached the base idle temperature for each given thermostat. Ambient temperature remained within 1-2 degrees throughout testing.


THE VERDICT

Hotter engines make more power. Sure cooler air and fuel is denser, meaning more of it can fill the combustion chambers to make more power, but once detonated, less energy (heat in the case) being absorbed by engine material and coolant means more of it can be put toward forward motion. Also many of today's knock-sensor-equipped cars are programmed to run optimally at a pre-set engine temperature; lowering that temperature might keep your engine from running on i ts optimal fuel/timing trims. "WRXs and STIs that aren't driven hard lose power with cooler thermostats," explains Tuning Technologies' Alfred Beltran, "usually as much as 10-15whp."



END RESULTS: FICTION

 

I don't know what thermostat is in my Jeep right now, but it gets up to around 210 at operating temp according to the gauge. I'm completely stock with AX15 and get 12.8 miles per gallon no matter how I drive it, babied or foot on the floor(which is most of the time). It also might not help that any time a Honda pulls next to me at a red light my tires "happen" to break loose and my right foot goes to the floor while the left is on the brake and somehow results in a smokeout. I don't care though, I'm happy with my XJ, whether is gets good mileage or not. And about 1/4 of that is highway driving.

 

Excellent data Spooled up!
No surprise there. Reinforces the need to run the 195 stat.

Mike

 

One question, i know you all said that it would go into open loop dumping twice as much gas in the motor, wouldn't "twice" as much gas make it raise rpms? mine are at a constant like uh idk 600 and never hesitate from there, when it firsts starts it runs at 1,000 or so for like the first 10 seconds then goes back to normal. dumping twice as much gas doesn't make much sense? the motor would react to twice as much gas.

 

But theres not enough incoming air for the rpms to rise, therefore you get a rich condition..

 

Not if it doesn't have enough air to burn all that gas, in which case you get an incomplete burn(running rich) and black sooty smoke coming out of the tail pipe.

 

Mine done the same when the AUX fan was not working, as long as your moving there's enough air flowing through the radiator. But at standstill / idle it would climb rapidly !

If yours seems more RPM related then look at the clutch fan ! And flush that radiator / cooling system out ...


Good Luck.............................

 

and if your fan clutch is busted, either get one from the JY or drill the clutch housing and use 3 grade 5 bolts to make it spin at a 1:1 ratio with the RPM of the engine

 

nothing is wrong with my jeep, just asking a question to see the correct answer is all. im changing the thermostat back to stock in a couple hours.

 

well new stat is in, and now back up to an estimated 15 miles per gallon. i will measure it at the next fill up. but so far it is a vast improvement over 7!

 

Good to hear! Anywhere near your estimated new mpg's is one heck of a gain! Better than I would have thought.
Mike

 

yea driving it to and from work today (about 30 or so miles) and it is more like 13...but that is cause i was going 75 mph @2800 rpms. so that is still pretty good, oh and did i mention a little more power as well...