TRS Technical Staff
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V8 Engine Swap
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- Aug 9, 2007
- Reaction score
- woodhaven mi
- Vehicle Year
- Make / Model
- FORD mostly
- Engine Type
- Engine Size
- 2WD / 4WD
- Total Lift
- Tire Size
- My credo
- it is easier to fix and understand than "her"
yes...With no belt you aren't spining an alternator, power steering pump, and water pump either so that accounts for your power loss.
that is and was always completely understood.
only regret was not draining the block to see what just that system did under spin up with no pump load.....and then we would know exactly what the water pump was costing....
i had a hard time believing that a serp system....especially in that particular configuration with no load could produce that much drag....i mean 3 v belts and big body steering pump and alternator and ac compressor.....sure...and maybe a direct drive fan....
never would i have suspected a clutch fan would use much power...it was quite a let down.
i was totally wrong. and i am wrong alot....just not now.
the question is whether a ranger mechanical fan is more efficient then an electric fan swap...
as you stated....once something is turning and up to speed it does not use any serious power.......but it is using power. and it is detectable in many cases....thus the clutch fan is regarded from idle to cruise simply as 1hp as a rule of thumb when it is off...and direct mount fans around 8 or so for that range. as that is the data for systems this size account for.
that said...i used a flex fan...17 inch when i originally swapped to a v8 back in 95 for my application because it was the most trustworthy setup as i had seen it for a truck. we built 3 trucks at pretty much the same time...two cobras and a 351 ho....the 351 truck was a rebuild from its first 302 swap...and converted from 2wd to 4x4.
the flex fan i chose seemed like it worked much better at idle then the mustang mechanical.. on paper it was a no brainer.. the goal was low speed airflow when wheeling in the woods...
we had the trucks side by side and did the rag test.....i was running a re-necked dakota v8 radiator and a 3 in body lift and the setup was perfect....and the sister truck to mine was running a 304 v8 jeep radiator.....so that test was apple to oranges literally...and the 351 truck was running a 25x19 aluminum unit...previously had an aa unit and a ho truck fan d/d initially.
i preferred efi and i thought what i had was perfect. i had worked on a few dozen various swaps in one form or another at that point... so i had high confidence in my thoughts...
but it did not take long to get sick of the c4....fuel economy was relatively non existent compared to the 12-14 i was getting with the previous 2.9... and i was sick of going 70-75 mph turning 34-3600 rpm and overheating all of the time.. after busting a few c4's in short order, i knew i needed to upgrade...and a c6 was not the answer.
so in with the aod.... totally happy with that setup initially. i was able to go to work in shorter periods of time...fuel economy was increased to par with the 2.9..so that was good..plus it did not bog down to 55 or less on hills....and could pass on two lanes with 33 in tires instead of bogging out.
.but my totally awesome flex fan was eating my 40 dollar belts and tearing up water pumps.... plus now it was noisy as hell and starting to drive me crazy...something it never did before because of my drive cycle at that time.....
this fan was howling at my new 24-2600 rpm cruise speed where that particular fan was full glory in its ability to pull air. turns out...with a lifted ranger the ram air effect is minimized and drag is maximized by the dirty air that goes under the rig....this is serious drag...i went to the mark 7 clutch fan to quiet things down and on the road it was awesome....picked up a point of mpg and was ecstatic..still was getting cruise oscillation on temperature but that is another issue with increased atf temp load....
but that was all it was good for....flat ground......
off road.....it was causing fitment issues while 4 wheeling....like totaling radiators when i was twisted up climbing hills.....it did ok on the street.....but my favorite thing to do....off roading....was not good.
i did not like electric fans for my particular use scenario...i was convinced they were not as reliable for a truck that had to travel down harsh lease roads to get to job sights in the middle of no where and i had evidence that they were not reliable....i just did not really properly vet the evidence.
long story short....i gave in and started using electric...mpg went up again....reliability went up...belt life went up.....noise and vibration went down... waterpump life went way up... best thing i ever did was install the electric fan...the amount of experimentation from there went 15 years.
by definition....a properly sized and installed clutch fan can not be more efficient then a properly installed electric fan...
the key is in the definition.
can the mechanical fan pull more air? fawk yeah it can....it has a 100 hp to work with.... not 1 or 2 horsepower... but that engine will be revving to pull that air.......because the amount of air it pulls, just like any fixed blade.... has a specific rpm where it is max..
but with a fixed nylon blade there is also a cavitation point...when over speed...
for sure a stock ranger fan can pull more air then the engine needs...and can beat most small electric fans in actual max cfm and any of the shelf junk at the parts store....
but it sure as fawk wont do it at idle.
because they are not more efficient. they are a compromise.....better then a direct drive. and that is about all one can say.