Jeep Cherokee Aeromods

[JeepNmpg2]

Originally Posted by Christ

It's a net waste of energy in any sense.

Again, hence the mod. It won't net a huge about of MPG improvement directly, but with quicker warmups and less fan usage overall should net better MPG in the end. This is also due to the fact that I think my current fan is in a state of constant lockup most of the time (clutch is failing to dissengage). On a non-eco note, lack of the chattering clutch and roaring fan on acceleration will make the vehicle a lot quieter... well, at least the engine compartment , I still have my exhaust system!

[Christ]

I wasn't arguing, I was noting the reason that the clutch fan wasted energy. Many people don't know, thinking that it's a "great" upgrade... while it is a decent upgrade, the e-fan is a more proper solution.

[Nerys]

hmmm actually jeepnmp2 that is not how they usually fail (unless rusted or something) they usually fail where they DO NOT lock up ie you start to overheat more because the fan clutch is NOT engaging so you get less airflow at least thats how mine failed on me.

[Christ]

The seals corrode and leak the viscous fluid. Without viscous fluid, your clutch fan has no "clutch".

[winkosmosis]

Originally Posted by eco_generator

That clutch may get "loose", but it is still drawing loads of parasitic power. It can soak up 5hp before the fan even begins to turn. I got rid of one on my Subaru wagon, with 95 hp and loaded with work equipment there was not a whole lot of extra horsepower to just lose in a fan. I took it off (it also has an electric fan) and the extra power was immediately noticeable.

So losing the clutch fan is a win/win. You will save gas just from not turning that clutch all the time.

5hp? Really? That is a huge amount of energy to constantly be turning into heat... 3000W!

The engine is making about 60hp to keep an XJ going at 70mph.

[Christ]

FAN TYPE IDLE (800) IDLE (1600) HP LOSS (4500) TIME LOSS %
__________________________________________________ ___________________

BB18 1680 2355 40.8 8%

BB18C(heat) 1580 2205 35.6 13%

BB18C(COOL) 1104 1400 19.3 11%

SKIPPER 1503 2020 31.5 7%

FLEX 17 1420 1814 20.2 5%

__________________________________________________ ____________________


Dyno testing on fans, alternators and oil.....all here!

We want to pay specific attention to the BB18C figures, which show an expenditure of more than 5HP between cool and hot situations, but an expenditure of at least 19 horsepower to keep the cool fan spinning. That entire loss could be mitigated with an electric fan, minus the energy cost of conversion from mechanical to electrical to mechanical energy, and the energy required to run the fan when necessary.

The net after conversion losses and all, is still a gain in efficiency, I'd say.

Of course, lots of magazine articles (who advertise for Flex-A-Lite) would disagree with me on this.

[Christ]

Also of interest, but not specifically to this discussion, from the same link:

Last but not least.....is the oil change out. I did a series of pulls after all the testing that we had done and got a reading of 360.4 hp, a slight and expected increase due to friction loss improvements and ring sealing (compression improvements)! I changed to Valvoline Synthetic 10W30 and did it all over again. The test revealed a 363.5, a slight improvement. But there is one other thing that I noticed that I can't explain. The regular oil was measured at a temperature during these testing cycles consistently. The synthetic showed a reduction of 9 degrees??? What?.......the thermostat was the same...the water temperature was the same. My estimation of this is that the surface/friction loss reduction diminishes the heat production and therefore the oil is cooler? Hmmmmmmmmm? I have to think on this some more. Anybody got an answer to this?

[JeepNmpg2]

Originally Posted by Christ

an expenditure of at least 19 horsepower to keep the cool fan spinning

- Screw that! ten percent of my hp to spin a nearly useless fan (ok, it is cooling some, but not enough to be worth 19 hp)

Christ - Sorry for seeming argumentative, it was unintentional. Thanks for the massive info dump! Unfortunately for my wallet, I think I'm going to take the plunge with the electric fan and controller I was looking at.

winkosmosis - Where did you get that info on the Cherokee? If you don't mind, could you pass any other Cherokee baselines along? (Cd, etc)

And lastly...

FastPlastic - Sorry for taking over your thread, I didn't mean for this to spin out of control like it has. I promise to get my own build thread once I get started .

[Christ]

You have to remember that the testing laid out there wasn't scientific at all, and it's probably not wholly accurate, but it still makes a decent baseline to provide an idea of how much power it really takes.

FastPlastic -

Apparently, we did jump on your tailgate here a little bit... my apologies.

[FastPlastic]

Originally Posted by Christ

FastPlastic -

Apparently, we did jump on your tailgate here a little bit... my apologies.

No big deal guys, It's all about learning what works best for what car. As long as it relates to the Cherokee's I don't mind. Now for my two cent's worth. Has anyone ever thought about several smaller electric fans? Place 4-6 smaller fans on the radiator and set them up to kick in at different temps. Just a crazy idea.

Ok, for those of you following my Cherokee. The Partial-WAI looks to be a success. Outside temp of 24F, traveling across town with a mostly warm engine I managed to pull 20MPG's. Once warmed up she was purring like a kitten and was sucking in 60F air.