Blue fan clutch mod...Thread has gone to hell, read at your own risk

[landtank]

You get to be the Ref....

That's no bargain, Sumotoy tends to throw a little wild.

 

[SUMOTOY]

I have read most of you "data" and have no need to reread it. In a dynamic environment things flex and move, when offroad frames flex, body mounts flex, the body flexes, motor mounts flex, etc. The radiator is mounted to a different structure from the fan and the flex can and will change the available clearance.

Ok, agreement

I am very happy for you having that nice "data". I can clamp a fan in the vice, grab a blade with a wrench and get more flex than that, but what does mechanical flexing have to do with a discussion on aerodynamic load flexing to determine clearance?

None. The data I posted was aero load only, up to the point of mechanical interference that is. Then it became a exercise in measurements and conclusions as to the exact aero flex involved.

SJ

 

[SUMOTOY]

That's no bargain, Sumotoy tends to throw a little wild.

Someone has to figure out what my problem is! I had a lot of coaches early on, that didn't give me the right moves. I figured them out on my own, but they hurt my backside a bit each time I had to throw another 50 to the radiator guy.

Scott Justusson

 

[Tools R Us]

... It looked a little bent. Well, it was about 1.5" bent upwards. ..

That would qualify as a little bent, why change it, think of the extra clearance!

 

[cruiserdan]

Some VERY interesting observations this afternoon.

Today was the first "warm" day we have had since my 10,000 change and perhaps this belongs in Sumo's hood vent deal.

I deliberately left the truck idling, with the A/C on and the aux fan off and I watched the gauge. 200, 205, 210, 215, 218....Kicked the rpm up to 1,800 and held it. 215, 210...hold. Kicked the aux fan on, ....hold.


Opened the hood.........210, 205, 200, 195, 190, 185.......
















Time to cut some holes.

 

[landtank]

what is considered a warm day in NM?

 

[cruiserdan]

over 90 and a parked 80 that might as well be black, with a huge heat-sink bolted to the head and a non-stock fan blade.

 

[landtank]

The idea of a SC has been kicking around in my head for quite a while. It would be nice to see a solution to the hot running temps that seems to go hand in hand with it's install.

 

[turbocruiser]

Some VERY interesting observations this afternoon.

Today was the first "warm" day we have had since my 10,000 change and perhaps this belongs in Sumo's hood vent deal.

I deliberately left the truck idling, with the A/C on and the aux fan off and I watched the gauge. 200, 205, 210, 215, 218....Kicked the rpm up to 1,800 and held it. 215, 210...hold. Kicked the aux fan on, ....hold.


Opened the hood.........210, 205, 200, 195, 190, 185.......










Time to cut some holes.

Sheesh, to think that I was all worried about 94 degrees celcius with my AC on and 96 degree farenheit ambient temperatures. I've never gone above 98 degrees celcius and that was just the other day with the cruiser loaded with about 700 pounds of people, my boat on the roof, 300 more pounds of gear, going up a super steep super long mountain road at about 12,000 ft altitude at a super slow rate behind some flatlander with the AC on until just past the point of 98 degrees and then the AC off (by my switching). I really think that the intercooler must be helping a huge amount as there is no other factor to explain this effect. Ohh, brand new blue fan clutch that must have been the only friggin one from the factory that works although I almost never hear the thing roar??? If I saw anything above 102 celcius I'd crap my pants, pull over with the heaters on full force, stand up on the ARB bull bar and start pissing all over the radiator for liquid to vapor heat dissipation! One more vote for the turbo system!!!

 

[landtank]

I think Dan's biggest issues are the SC blocking the air flow and th eneed to run something other than the stock fan.

Next step might be to remove the rear seal on the hood. This might give some idea if vents would help with the idling issue. You would hate to cut into the hood with little or no positive results.

 

[SWCruiser]

Washers

How about adding the washers? Has anyone tried that yet?

 

[turbocruiser]

I think Dan's biggest issues are the SC blocking the air flow and th eneed to run something other than the stock fan.

Next step might be to remove the rear seal on the hood. This might give some idea if vents would help with the idling issue. You would hate to cut into the hood with little or no positive results.

Well, one thing that ST stated that I tend to totally agree with is you want to keep whatever is under the hood, out of the HVAC system. Years and years of living overseas and working with extra risky embassies and consulates taught me that anything that is toxic, harsh or hot should stay out of the cabin of cars - the first thing you learn on the State Department's "Crash and Burn" courses is should your rig get riddled with molotof cocktails, mace, or other toxic things turn OFF your HVAC system and DO NOT TURN ON THE WINDSHIELD WIPERS no matter how tempting - as soon as the HVAC is on you introduce and inhale all sorts of stuff into the cabin and as soon as the wipers are on you just smeared melting rubber from the wipers all around the windshield - NOT GOOD!!! Not practicing these precautions will turn the toughest of armored vehicles into a dead still deathtrap. In the context of this topic, however you allow any heat to exit the engine bay, you do not want to reintroduce this to the cabin. Find some other way such as louvers mid-hood and DONT remove that rubber seal end-hood. HTH.

 

[landtank]

I wasn't advocating the seal removal as a solution but as a next step in determining if opening the hood would help with a truck stationary and idling. I'd also try and determine how much he would have to open the hood to get the relief he needs to maintain the truck's temp. This might be done by just spacing the rear of the hood up.

I'd want to know how big the holes need to be before hacking in some louvers to be sure they will get the job done. Once you know the size then figuring out the placement would be next.

 

[SUMOTOY]

I wasn't advocating the seal removal as a solution but as a next step in determining if opening the hood would help with a truck stationary and idling. I'd also try and determine how much he would have to open the hood to get the relief he needs to maintain the truck's temp. This might be done by just spacing the rear of the hood up.

I'd want to know how big the holes need to be before hacking in some louvers to be sure they will get the job done. Once you know the size then figuring out the placement would be next.

Rear hood raising will work at low speeds, *for testing purposes only* please.

LT, I used pretty small vents on the audis, because I was addressing radiant heat, not really convective heat. IOW, the small ones sit above turbos, manifolds, SC's, and other heat sinks for 'free convection'.

For 'forced convection', for a maximum vent area rule of thumb, 4:1 is usually the guideline for maximum practical airflow.
Air shroud opening area * .25 / n (number of vents) = vent area

I haven't done this math, but that sounds like it's gonna be a pretty high number. However, this also changes based on vehicle, placement of vents, aero pressure changes etc. So the practical application is much more a what fits with the most consistent low pressure zone. Any reduction in temps is good, and even in production cars, secondary goal, so I say grab whatever ones fit your fancy.

Some of the semi trucks have the best air vents IMO. I've used several of these (side quarter panel vents) on various applications and they look good. Rover uses a lot of vents (defender), pontiac supercharged and chevy Z34 (these are my personal favorites, they are huge and open). Then it's back to datalogging temps to find the efficiency rating of the vents.

My best hope, if I can survive the technical terminology critiques, is to actually get a bunch of data that points us to the best placement and efficiency rate of any given vent install. We are a ways away, since there seems to be an aversion to cutting the hood, regardess of temperature dictators.

One of my favorite hood vent stories was speaking to the Audi engineers on the Pikes Peak Quattro sport winner during an outing in '99. Seeing a 100 drilled holes up the PS of the hood, I asked what was used to make them. Thinking of course, on a 1mmUSD race car, they must have laser cut them in Germany. Nope: Hole saw and chicken wire.

Form follows function?

SJ

 

[landtank]

Rear hood raising will work at low speeds, *for testing purposes only* please.

I might be off here but his issue is when he's parked, doesn't get that much lower in speeds.

Before I started to carve up my hood I'd do what I could to address my issue. All this talk about louvers and where they need to go as far as when the truck is in motion is all well and good but if your problem is when your stationary the parameters of where the holes need to go might be different.

One thought I had was since his fan sits 3/4" further in the cowling that maybe some trimming on the cowling to allow a more open exit for escaping air might be the ticket.

 

[SUMOTOY]

I might be off here but his issue is when he's parked, doesn't get that much lower in speeds.

Not sure I understand. Raising the hood at low speeds/parked means that the high pressure boundary layer from the windshield cowl induction is no longer present. So the high pressure zone is at the rear of the hood, and the low pressure zone is the HVAC vent. Turn off the Climate control fan, and test away.

Again, not sure the reason for 'testing', but cutting hoods is high stress for some. I suppose you could gather some decent data as to rise of hood (vent surface area) vs temp effect.

Before I started to carve up my hood I'd do what I could to address my issue. All this talk about louvers and where they need to go as far as when the truck is in motion is all well and good but if your problem is when your stationary the parameters of where the holes need to go might be different.

LT, stationary engine running, the pressure in the engine bay is higher than the ambient pressure in the atmosphere Peng>Po (foced convection by the engine fan). At that point, it really doesn't matter where you put the vents, they will vent air. I don't see that as being critical, place them for high vehicle speed low pressure zones (ram forced convection air and 80 areodynamics), they will work for low vehicle speeds (fan convectoin air no 80 aerodynamics). The critical differences are really with the engine off, Peng=Po, then free convection is most efficient above the radiant heat source.

One thought I had was since his fan sits 3/4" further in the cowling that maybe some trimming on the cowling to allow a more open exit for escaping air might be the ticket.

Shroud you mean? As I read current application the deeper you can put the fan into the cowling the more efficient it is (up to a point where shroud vortex interferes). I popped a hood on a new F150 about a week ago. That fan sits much further into the shroud than the 80. And a really deep shroud to boot.

If you are really averse to putting vents in, I would be going after ducting/scoops in front of the condenser. A lot of air escapes around the condenser/radiator that can be directed through it. IOW, decrease the pressure before the radiator (velocity stack theory) at low speeds, and increase the ram air pressure at higher speeds.

That will work, but I've found that without increasing the pressure drop on the back side of the radiator, the gains won't be optimized. Back to vents....

Scott Justusson

 

[Tools R Us]

...
Shroud you mean? As I read current application the deeper you can put the fan into the cowling the more efficient it is (up to a point where shroud vortex interferes). I popped a hood on a new F150 about a week ago. That fan sits much further into the shroud than the 80. And a really deep shroud to boot.
....

Scott Justusson

For our mostly thin edge shrouds the fan is best placed with less than half in the shroud. A shroud with a longer "stovepipe" would be more efficient, ideally the stovepipe would be at least as long as the fan is thick with the fan centered in it. Using a piece of plastic about 2.5" wide bending it around and screwing it into the fan opening would probably be a good mod, making the fan a ducted setup.

On the 80 the fan is almost too close to the radiator, the S/C spacer makes it worse. A powerful large cord fan needs to have room on the front side for the air to flow smoothly into it, the closer it's moved to a surface (the radiator) the narrower the blades need to be. The 80 fan is sized to pull all of the air that can flow through the coolers, so air from the corners is rushing to the front side of the fan and has to make a tight turn, air doesn't like to make tight turns and it becomes turbulent the blades don't deal with turbulent air well and can stall the same way an airplane wing does.

So yes a deeper shroud with a longer stovepipe area is much more efficient, unfortunately the long motor and short snout on the 80 make it difficult to achieve.

 

[SUMOTOY]

For our mostly thin edge shrouds the fan is best placed with less than half in the shroud. A shroud with a longer "stovepipe" would be more efficient, ideally the stovepipe would be at least as long as the fan is thick with the fan centered in it. Using a piece of plastic about 2.5" wide bending it around and screwing it into the fan opening would probably be a good mod, making the fan a ducted setup.

On the 80 the fan is almost too close to the radiator, the S/C spacer makes it worse. A powerful large cord fan needs to have room on the front side for the air to flow smoothly into it, the closer it's moved to a surface (the radiator) the narrower the blades need to be. The 80 fan is sized to pull all of the air that can flow through the coolers, so air from the corners is rushing to the front side of the fan and has to make a tight turn, air doesn't like to make tight turns and it becomes turbulent the blades don't deal with turbulent air well and can stall the same way an airplane wing does.

So yes a deeper shroud with a longer stovepipe area is much more efficient, unfortunately the long motor and short snout on the 80 make it difficult to achieve.

Kevin, I suggest that some optimization in front of the radiator could change that. I believe some of that turbulence in front of the radiator can be addressed with honeycomb ducting. Research has shown that getting laminar airflow on the intake side of radiators increases the efficiency on the snout side. It could cause more vortex in the shroud, but if it's efficient enough, then the shroud can be removed

I also would suspect the reason I experience very little overheat problems with my shroudless carnage, is that ram air gets more efficient at a lower vehicle speed the less depth of the shroud. Add to that, there is a lot of vortex in that shroud to begin with, I suggest some data might be collected from a shroudless setup.

My experience hasn't shown the shroud to increase effectiveness noticeably. I should rephrase though. At low speeds the airflow thru the radiator fan is enough to cool the engine properly. My empirical data shows that without a fan shroud I can still make fan blades aero flex as far as with the fan shroud. And high speed cooling is already documented to be more efficient without shroud.

My conclusion has always been that really narrow depth shrouds/intake rams are probably a wash to most radiator fan efficiency numbers.

I like the idea of adding a collar to the shroud, but as you note, my spacer dictates that's not a practical mod.

Scott Justusson

 

[Tools R Us]

Kevin, I suggest that some optimization in front of the radiator could change that. I believe some of that turbulence in front of the radiator can be addressed with honeycomb ducting.

Honeycomb or vane ducting is neat stuff and in some applications can yield positive results. What we are talking about here it would have no effect. Look at the blade depth and pitch of the stock fan, compare it to a contact type, like an electric.

The contact type has narrow blades and a small motor, sized to pull the amount of air that can flow through the cooler in the diameter of the blade. For the sake of argument lets say that an 18" contact fan can pull 1000 cfm through the coolers. Now the stock fan is pulling from what 16" x 28"? area and lets call that 4000 cfm.

As the stock fan is moved closer to the radiator it reaches a point where it starts to operate like a contact fan pulling the 1000 cfm that the coolers can flow in an 18" circle. But the fan is trying to pull the extra 3000 cfm that its sized for and that much airflow wont physically fit in the space between the cooler and the fan. So now the fan is pulling a bigger vacuum than it's designed for and the in rushing air from the edges mixed with the air through the cooler and the close spinning blades combine to make a more turbulent environment than the fan is designed for, the airflow breaks down, blades stall and the cfm delivery goes to almost nothing.

My experience hasn't shown the shroud to increase effectiveness noticeably. I should rephrase though. At low speeds the airflow thru the radiator fan is enough to cool the engine properly.

The big thing that you don't know/ignore/forget (circle your choice) is that the 80 is designed as a heavy duty offroad vehicle and some here use them as designed. There are some here that are trying to convert them to sports cars, but I don't think that they are the majority.

From your above statement the first thing that needs to be defined is "low speed", your definition and mine are probably very different. I am willing bet that the highest total loads that my truck ever sees are at ~.5 mph. In this environment it's common to have 2 or more tires climbing vertical rocks and another descending, so you have one foot hard on the throttle to provide power and the other modulating the brake sometimes hard to keep speed control and prevent overshoot damage. So now we have the motor at near or full power, the trany working hard, the torque converter slipping like mad, the brakes working hard, the power steering sawing back and forth sometimes pushing rocks out of the way, its 110F, the A/C is going full blast and the window is down so I can see where to steer. This will be repeated many times in a row, our last trip it took about 6 hours to go 3.5 miles up a creek bed!

That's one of the great things about the 80 is it's fan dependent full load, zero speed cooling system, is it perfect, no but it only needs a few tweaks to be very robust. Once you make that design compromise for a fan dependent full load, zero speed cooling system most of the aero dependent aides become useless or a liability. A system designed to provide full cooling at zero mph generally has no problem cooling at speed and is probably overkill.

I have no problem with data, other than data incorrectly applied is worse than touching and feeling. If you want to test that no shroud and clipped fan is better theory, load your rig and come on out, we will hit Florence Junction on a 110f+ day and see who's junk can hang! I bet that shroud less theory goes up in a cloud of steam on the dirt road on the way to Ajax trail.

 

[Tools R Us]

Rick, the light came on today at 227 miles. Hard to tell if there is any change, this tank has the wheeling and 90 mile highway trip home from last weekend on it.