View Full Version : Horsepower Sucking Fan
OK, for those in the know, I had complained previously about a gutless upshift from my 700R4. I blamed it on shifting at too high an RPM. I stated that after modifying the governor, it seemed to be an 80% solution. I noticed fan roar corresponding with the drop off in engine power right before upshifting, and had commented that the engine felt much better after modifying the governor to shift at lower RPM. I eliminated the monster fan today, and installed a ginormous electric fan from an Olds Silhouette Minivan with dual AC (a high heat load application). I wired it up with a redundant heat control and separate circuit for the A/C. The results were phenomenal! The fan kicks in at 195 degrees (a secondary "backup" temp switch calibrated to 210 degrees also works as a backup), and cools the engine to 185 degrees before shutting down. The fan also runs continuously with the A/C on. The result? On a 95 degree day, the engine never broke 200 degrees, whether driving or sitting in gear with the A/C blasting. I simulated the worst case scenario by parking nose first into the sun in the local Walmart parking lot between two parked vehicles with another one directly in front of me (to limit air circulation), and idled in gear with both A/C units blasting for 15 minutes, and the temperature hovered at 185 degrees. In driving without the A/C on the fan doesn't even need to run, and the temperature seldom rises to 195 with the fan off at a red light, unless it is a very long one. One of the best features, however, is the fact that I picked up 5.4 seconds 0-60. I ran three back to back 0-60 runs of 17.4, 17.8, and 17.5 seconds for an average of 17.6 seconds 0-60. The previous best time was 23 seconds flat. The engine seems so much more responsive, even while cruising in overdrive. I can't wait to calculate my fuel mileage now, with the electric fan setup. Also, A/C temperatures are much cooler now, with a vent temperature of 38 degrees at idle in gear (during the 15 minute "Walmart" test). The A/C would only approach those temperatures previously when cruising at 35 MPH or better before the electric fan swap. I know this might not be the ticket for everyone, especially those of you who tow heavy loads up steep grades. But for those of you who are only using your rig to commute, travel, or do light hauling work, this might be a setup worth trying. I am only into the experiment for about $65, and that includes the fan ($10.00 at the local wrecker), $38.59 for the Hayden adjustable thermostatic control, $15.00 for the non-adjustable temperature switch (200 degrees on 185 degrees off) from Summit, and some solder, heat shrink, wire (22 gauge for the sensing and relay control, 10 gauge for the high current circuitry) and two automotive relays (swiped from a Ford Crown Victoria during a junk yard raid some months back). The wire and supplies were already things I had on hand. I have heard the horror stories of insufficient cooling with electric fans, and that may hold true for heavy tow applications, but for me, it seems to have addressed the heating issues at idle, and the mid to high RPM sluggishness I had been experiencing.
convert2diesel
07-31-2010, 06:13
Those tests seem to correspond to my experiences. As I have said before, I can't speak to the effectiveness when used in a turbo application, but for a NA engine they are more then sufficient, even when used to tow a 3,000 lbs. camper up long hills.
Careful with the Hayden controller. The one I had to buy in Georgia one year (the sender unit I had used died on me on vacation) only lasted a few months before the internal electronics failed. Better to use specific temperature senders. Check your local parts store and ask for their Standard Motor Parts catalogue. There a section in there listing all the temp senders, their thread size and electrical specs.
From what you are saying, it would appear that your mechanical fan's clutch was toast. If working right, everything except the low speed AC would have been acceptable. I too experienced much better AC with electric fans.
Bill
Great to hear that you have things working to your likeing.
The electric fan for slow speed running with the AC on is a real plus.
This is an area that has always anoyed me. The fans used on these engines really hogs down some HP when it hooks up.
The electrics are great with an engine thats not worked too hard.
The 6.2 NA engine in an application such as yours should be fine.
Obviously you have done some realtime seat of the pants testing of the application and it works.
Several of the older GM pickups with Big Blocks, had an auxilliary electric fan mounted up front of the Radiator to help during slow speed driving.
This was mostly to maintain the AC function.
As far as the power goes, the 6.2 in heavy duty applications (J CODE) was rated at 160 HP, this is no rocketship for sure but, will deliver some good mileage.
The issue you had with the tranny is a common one and has played out countless times over the years. The owner or tranny shop does an overhaul of a used box and does not research the differences in the various applications.
Next thing you know there are issues with shifting and such, as you experienced.
Many times the torque converters get mixed up or the wrong one used and the troubles really get going.
The 700 converter is very small anyway and then when you get a gasser unit behind a diesel its a real mess.
Have fun and keep us posted on the MPG's
Missy
Careful with the Hayden controller. The one I had to buy in Georgia one year (the sender unit I had used died on me on vacation) only lasted a few months before the internal electronics failed. Better to use specific temperature senders. Check your local parts store and ask for their Standard Motor Parts catalogue. There a section in there listing all the temp senders, their thread size and electrical specs.
Bill
I know. They are hit or miss. I have one that's 8 years old in my F-150 and it is great. My friend had one on his '68 Mustang and it kept dying. I always use the Hayden controller to activate a separate relay to drive the fan. Also, I have a 200 degree on 185 degree off thermal switch wired into the same relay as a backup. I unhooked the Hayden unit to test it and it works. It actually kicks in closer to 210, but if the Hayden unit should fail, the thermal switch will back it up, and my tip off will be elevated (but still safe) operating temperature.
More Power
08-01-2010, 13:44
It's been said that the 6.5 or Duramax engine-driven fan can absorb up to as much as 20-hp in a worst-case situation (high engine speed). We've discussed before that if I were building a fuel economy rig used for commuting or traveling - or a dedicated race truck, I would use an electric fan or fan pair. The big Flex-a-Lite aftermarket electric fan pairs made for the Duramax is advertised at pulling about 5500-6000 CFM. The stock engine-driven fan can pull up to about 10K in a high rpm situation, so it remains the best choice when hauling heavy loads in high temps.
Another consideration is current draw. A fan system will draw 30-40 amps (or more) when running. This'll push a stock alternator to its limit on a good day, and will overstress it at night (with lights, A/C and the fan). So, a good high-output single or dual alternators might be a good choice.
Jim
I tested the fan with an inductive pickup, and while it spikes 34 amps on start-up, it runs at 15.1 after it reaches full speed.If you factor that into the blower fans (both on high) figure another 30 amps, the lighting system another 30 amps, and the wipers, 10 amps, and the electric fuel pump, 5 amps, then we have a total of 90 amps under a worst case scenario, which while not great, is still withing the load range of the stock alternator. I am all about electrical upgrades, however, and plan to soon install a 180 A rated CS-144 unit to give the old CS-130 a break. I am very happy with the CS-144 alternator I have on my Ford F-150 (what can I say? I like GM alternators better, regardless of the badge on the grille).
I was interested in replacing my OEM fan/clutch system with a dual fan set up by flexalite. My problem is that on my 1991 Chevy Suburban 6.2L with auto transmission there are two transmission cooling lines that run from left to right across the middle of the radiator just behind the radiator core which would interfere with the electric fan blades. I suppose I could try and reroute the two cooling lines so that I could accomodate the flexalite fan. Anyone else ever run into this problem before and how did you make clearance for the electric fan setup? Thanks.
DmaxMaverick
08-13-2010, 01:19
I was interested in replacing my OEM fan/clutch system with a dual fan set up by flexalite. My problem is that on my 1991 Chevy Suburban 6.2L with auto transmission there are two transmission cooling lines that run from left to right across the middle of the radiator just behind the radiator core which would interfere with the electric fan blades. I suppose I could try and reroute the two cooling lines so that I could accomodate the flexalite fan. Anyone else ever run into this problem before and how did you make clearance for the electric fan setup? Thanks.
Those aren't tranny lines. They are engine oil cooling lines, and need to be there for the extra cooling capacity, and the assist to engage the fan clutch when the oil is extremely hot. The bare aluminum lines shed quite a bit of heat.
If you have ANY engine cooling issues, at all, electric fans will be a step backward, especially if you tow. However, auxiliary electric fan(s) are beneficial.
Thanks for the correction on the cooling lines. I rarely tow anything and when I do it's just a utility trailer loaded with a golf cart. Where would one place an auxiliary electric fan?
Thanks for the correction on the cooling lines. I rarely tow anything and when I do it's just a utility trailer loaded with a golf cart. Where would one place an auxiliary electric fan?
Whenever possible, place an electric fan behind the radiator. All fans (electric or mechanical) are most efficient when used to provide suction (I.E. a "puller") as opposed to blowing through a radiator (I.E. a "pusher"). If running large electric fans, placing them side by side may not work, in which case you would want to make one a pusher and one a puller, and stagger them so that between the two fans you have 100% coverage of your core. This is the setup I have used on my 1996 F-150, with a 300 six. It has always kept the engine cool even when towing upwards of 8,500 lbs. Even under those conditions pulling the trailer up hills in the Pocono mountains in the summer heat with the A/C on, The temperature never broke 210* (I run a 195* thermostat in the F-150). The fans are from two Olds Cutlass Cieras, that I swiped from the junkyard for $5.00 each, 8 years ago. I am not advocating using this setup as a cure all, as has been stated previously.
If you have ANY engine cooling issues, at all, electric fans will be a step backward, especially if you tow. However, auxiliary electric fan(s) are beneficial.
An engine driven fan is most likely needed when towing 3/4 ton or 1 ton truck loads up steep hills. An electric auxiliary fan to provide additional low speed cooling in this case would be a benefit. However, in my application (Back to the Suburban, not the F-150), what I needed was more low speed cooling, as my temperatures and air conditioner were both fine above 15 MPH. I was having trouble at idle in traffic with the A/C on, as the temperature would slowly creep past 210, then drop almost instantly once moving, even slowly. My electric fan rarely runs without the A/C on, even climbing hills. The temperature stays nice and cool without ever breaking 195* (I have a 180* Thermostat). Do I plan to tow with this rig? Nothing more than a 2,500lb pop up camper or a jet ski. I have my F-150 for heavy hauling. However, I must say that in this application, it improved the performance of the cooling system and the truck dramatically. It possibly is why I was able to achieve 27 MPG. The only way to know for sure though is to try it out and see what works for you. Don't buy the expensive aftermarket fans, though. There are good reliable units ripe for the picking under the hoods of most FWD cars at the local pick a part for nearly free. Get a couple, slap them in, and hard wire them to see if it works for you. If it does, then mount them properly (no plastic fan zip ties! Fabricate some brackets out of metal and bolt them in) get a thermostatic controller and wire them up through two relays (FOR EACH FAN; one for A/C the other for thermostatic, hey I like redundancy) and you are set.
The vehicle itself seems to keep cool enough under loads but I suffer A/C cooling while in town stop and go driving. Seems like not enough airflow. So would a pusher electric fan in front of the radiator help in that area?
The vehicle itself seems to keep cool enough under loads but I suffer A/C cooling while in town stop and go driving. Seems like not enough airflow. So would a pusher electric fan in front of the radiator help in that area?
Absolutely. I typically install GM or Ford FWD car fans when space permits. Honda and Toyota fans will fit ins tighter spots as well. If you do it though, you may as well install a thermal switch and relay combination so if the engine is working hard and getting hot, the electric fan can supplement the engine driven fan (if you leave it in place). Just to note, however, you will have to wire it backwards, I.E. the wire that used to be positive will now be negative and visa/versa, because the fan will have to spin the opposite direction. Also, the fan will only be about 2/3 it's efficiency as a pusher.
PREFERRED METHOD: If you have room, you can install the auxiliary electric fan behind the fan shroud between the engine driven fan and the radiator. This has the added benefit of coaxing the engine driven fan to engage sooner, since the electric fan will put more heat into the clutch assembly. It would be better to use a smaller electric fan between the engine driven unit and the radiator as a puller than a larger one in front of the condenser as a pusher, because of the efficiency loss using a pusher configuration.
I'm a little confused. If a OEM fan is installed behind the radiator and is pulling air thru the radiator and you install it in front of the radiator isn't it now pushing air thru the radiator or does the fan have to be reversed when installing it in front of the radiator hence you have to wire it in reverse to push the air thru the radiator? Are there any suggestions on what type thermal switch/relay combinations to use and where would a good place to install the thermal switch. Would the thermal switch be adjustable? Thanks.
I'm a little confused. If a OEM fan is installed behind the radiator and is pulling air thru the radiator and you install it in front of the radiator isn't it now pushing air thru the radiator or does the fan have to be reversed when installing it in front of the radiator hence you have to wire it in reverse to push the air thru the radiator? Are there any suggestions on what type thermal switch/relay combinations to use and where would a good place to install the thermal switch. Would the thermal switch be adjustable? Thanks.
You would have to wire an OEM fan to run backwards in a pusher setup, because (almost without exception) the OEMs install electric fans as pullers. As for relays and thermostatic switches, using a typical 30A automotive relay works fine. Provide fused constant power to Terminal 30 and power your fan from terminal 87. There are adjustable and non-adjustable thermostatic switches. An example of an adjustable controller is available here (http://www.summitracing.com/parts/HDA-3651/). Non-adjustable switches come in two types. Some have a single terminal, and are used to ground the relay, as seen here (http://www.summitracing.com/parts/BCI-75030/). Some have two terminals, and are used to power the relay, as seen here (http://www.summitracing.com/parts/PRF-30111/). NONE are meant to directly power or ground a fan, even if they say they are.
Wiring:
If you have an adjustable unit, hook it up as per the manufacturer's directions, EXCEPT do not power the fan directly from the unit. Instead, run the fan output to a 30 amp relay, terminal 86. Ground terminal 85. Provide fused (30A) power to terminal 30 on the relay. Hook up fan positive to terminal 87.
If you have a TWO TERMINAL non-adjustable unit, hook up ignition on power to one of the terminals on the switch. Run a lead from the other terminal on the switch to a 30 amp relay, terminal 86. Ground terminal 85. Provide fused (30A) power to terminal 30 on the relay. Hook up fan positive to terminal 87.
If you have a SINGLE TERMINAL non-adjustable unit, hook up ignition power to a 30 amp automotive relay, terminal 86. run terminal 85 to the terminal on the thermostatic switch. The switch will ground the relay when it reaches it's turn on temperature. Provide fused (30A) power to terminal 30 on the relay. Hook up fan positive to terminal 87.
To wire up an A/C turn on relay, hook up A/C request power (positive power to the low pressure switch from the A/C control head) to a 30 amp automotive relay, terminal 86. Ground terminal 85. Provide fused (30A) power to terminal 30 on the relay. Hook up fan positive to terminal 87. Note that some adjustable thermostatic controls will automatically turn on the fan for you with the A/C on, so you can skip this step if yours is set up this way.
Thanks argo for sharing your info on the electric fans. It will become very useful when I get time to try it out on my Suburban.
I was interested in replacing my OEM fan/clutch system with a dual fan set up by flexalite. My problem is that on my 1991 Chevy Suburban 6.2L with auto transmission there are two transmission cooling lines that run from left to right across the middle of the radiator just behind the radiator core which would interfere with the electric fan blades. I suppose I could try and reroute the two cooling lines so that I could accomodate the flexalite fan. Anyone else ever run into this problem before and how did you make clearance for the electric fan setup? Thanks.
Bump.
I was just rereading my quote above and realized that I made a mistake in describing the two lines running across the back side of the radiator as transmission fluid cooler lines when they are actually the engine oil cooler lines.
It's been a few years since I thought about installing the double electric fan set up. I just recently installed a pulled 6.2L HUMVEE engine into my rig and will now be installing the two electric fan set up. I will be installing a remote engine oil cooler with electric fan along with relocating the engine oil cooler lines that run directly behind the radiator so that the new two electric fan set up can rest directly on the back side of the radiator. Does anyone know what type connections are used for the engine oil cooler at the radiator? Need to know what type of caps I will need to plug up those ports.
Thanks.
Merrill
Dvldog8793
08-31-2015, 06:07
Howdy
IMHO...if possible get a radiator without the oil cooler if you are not going to use it. It will add to cooling capacity of the radiator.
If you are going with JUST the external oil cooler get the biggest baddest one you can find...jegs list several. Stacked plate style is typically better than tube/fin type. Try to mount it with as much space as possible between it and the AC.
FYI...I have a blazer with out AC and a HEAVY duty radiator. That truck has pulled some mild loads and NEVER gets above 185*. The AC really blocks a ton of airflow and adds a bunch of heat into the system. make sure and clean between radiator and AC and make sure the AC is clean and open to pass air.
Good luck!
Howdy
IMHO...if possible get a radiator without the oil cooler if you are not going to use it. It will add to cooling capacity of the radiator.
If you are going with JUST the external oil cooler get the biggest baddest one you can find...jegs list several. Stacked plate style is typically better than tube/fin type. Try to mount it with as much space as possible between it and the AC.
FYI...I have a blazer with out AC and a HEAVY duty radiator. That truck has pulled some mild loads and NEVER gets above 185*. The AC really blocks a ton of airflow and adds a bunch of heat into the system. make sure and clean between radiator and AC and make sure the AC is clean and open to pass air.
Good luck!
I'll will use the same radiator only because I recently replaced the OEM one with an aluminum one. Funds are minimal at the moment. Thanks for your suggestions and good luck. Take care.
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