I remember a comparison Hot Rod mag (or maybe car craft) did a few years back with different kinds of fan setups. They tested a clutch fan, e-fan, and a non-clutch flex fan. They ran all three setups on the same car on a chassis dyno. All variables were the same throughout the test.

The flex fan came in last, making the least power. The e-fan came out ahead of the clutch fan, but only by a couple horsepower. So, technically, you will gain some power, I guess. But I wouldn't want to spend that much money for a couple horsepower that you won't be able to feel, anyway.

Now, if your fan clutch is all old and messed up, maybe it's costing you something. Maybe it's hooked up and blowing on the highway when it's supposed to be free-wheeling. I would still spend maybe $50 on a fan clutch than a couple hundred for an e-fan setup.

 

What about the flex a light fan?? Would it give me some power.
And a flowmaster 40 series?

 

The flex fan came in last

 

So I'm thinking about flowmaster 40 series? Does it have a loud interior sound?

 

The non-clutch flex fans were the worst. The engine is still having to turn them even at highway speeds. With a properly operating clutch fan, it will disengage at speed, since you have 60 mph wind blowing across your radiator while driving down the highway. The clutch should only be engaged at idle and slow speed driving.

If you do end up doing the e fan, at least document your mileage before and after, and do a good write up on here. That would be good, real world information that would benefit people thinking about doing the same thing.

Also, if you end up doing it, try and pull a set from a junk yard car. I've heard guys like (I think) Taurus fans, and possibly some Chrysler application, but I can't remember. They pull as much if not more cfm than some of the slick aftermarket ones, and are much cheaper used.

I have no clue about the flow master. If you do get some drone, some sound deadening material above the muffler might help?

 

The Taurus/sable fans and the Chrysler application (from the intrepid) are the ones I've seen used most for s10's in general. Really the most expensive part of an electric fan setup is the fan controller to set which temp the fans kick on at would be the most expensive part. Just source everything else from the junkyard. I've seen guys on other forums hook them up to a 3 way switch. Gives them an off, temp sensor only, and an always on option. If you spend 100 bucks, and get 1 more mpg, it'd pay for itself after like, 30 gallons of gas? Something like that anyway. Point is, buy **** at the junkyard.

 

Bigger tires also means a taller end gear ratio which results in less torque, and worse city fuel mileage because it requires more engine power to get the truck moving from a stop. The taller tires may help a bit on highway mileage because the taller end gear ratio will probably result in a lower RPM for a given cruising speed. This may be negated if you live in a hilly area and your transmission ends up shifting more often due to the loss in torque. That was certainly what happened to me with 3.42 gears and 31's. I swapped to 3.73 gears and it evened things out a lot, and my mileage went back up.

I'm now rolling on 32's with 3.73 gears, 3.5" lift, and I average 17mpg with 60%/40% highway/city driving. I do tend to have a heavy foot too, so I would probably be another 1-3mpg higher if I granny drove.

 

I barely average much higher than 17 mpg, and I'm on 235s, 3.73s, maybe a couple inches lift, over half highway driving, and I DO drive like a grandma! I figured 32"s, and the lift required to clear them would kill ones mileage. Guess what it takes away in town, it gives back on the highway from a lower cruise rpm.

 

will my blazer be better with 4.11 gears than stock?

 

It totally depends on your tire height and driving style. If you are running 31's then 4.11 gears will be too low, and will KILL your highway mileage. I'd suggest that the 3.73 gears that many S-series trucks come with from factory are very well matched to 31" tires, and will net the best mileage for both city & highway driving.