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Discussion Starter #21
I'm just thinking here. Everything I've read and everybody here seems to agree that the blades of the fan should be 1/2 in 1/2 out of the shroud. I have a piece of 8" round duct that has a booster fan in it. It blows pretty hard for an 8" fan. It seems to me to be the same as a shroud. Why wouldn't the fan pull if it was completely inside this sleeve we're talking about?
 

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It all depends on the pitch and how "twisted" your blade tips are. As a general rule if your going to fully enclose the fan then it needs to be inside a "cone" shaped shroud

Here is my favorite shroud. Thing can hide a 7 blade fan, Encase a 4 core Big block radiatior, easy to remove the upper part for maintance, and it is fairly cheap.

But with applications like yours where there is no "cone" then you need to experiment to find what shroud depth works best with your fan and distance from the radiator, etc.
Start with 50% and play around to see what works best for your application.
 

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Those 6 blades fans kinda suck because they don't have enough pitch and the angle of the tips are supposed to supress air spillage but again, on those type, they just aren't that great of a design.
Air has mass and momentum so it doesn't really like having to change directions quickly. Shrouds with Cone shapes tend to be better than box shapes.
 

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Just guessing , ( or thinking out loud) I believe its the shape/ design of your fan shroud . There's no shape/ space to create a venturi effect ??? An other thing that comes to mind , when I installed my brodix aluminum heads , they were very specific about enlarging the coolant passages in the head gaskets ....
All hi-tech answers so far, but no one mentioned that you don't have enough fan belt wrap around the water pump pulley, to drive the fan, which means you have no air pulling through the radiator when the car is sitting still. You will get air at driving speed, so of course, the engine coolant temperature will go down driving, but go up when the car is sitting still. Get a double sheave pulley for the water pump, and rig an idler pulley, so that the new (second) fan belt has good wrap around the water pump pulley. Should fix your problem.
 

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Discussion Starter #26
Those 6 blades fans kinda suck because they don't have enough pitch and the angle of the tips are supposed to supress air spillage but again, on those type, they just aren't that great of a design.
Air has mass and momentum so it doesn't really like having to change directions quickly. Shrouds with Cone shapes tend to be better than box shapes.
Yeah, I agree with you. I went from a stock 57 chevy 4 blade fan to the 6 blade to see if there was any improvement. No difference at all between the 2. I always used that 4 blade fan in all my race cars. Worked great, but we were running alcohol. Can you suggest a better fan?
 

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Discussion Starter #27
All hi-tech answers so far, but no one mentioned that you don't have enough fan belt wrap around the water pump pulley, to drive the fan, which means you have no air pulling through the radiator when the car is sitting still. You will get air at driving speed, so of course, the engine coolant temperature will go down driving, but go up when the car is sitting still. Get a double sheave pulley for the water pump, and rig an idler pulley, so that the new (second) fan belt has good wrap around the water pump pulley. Should fix your problem.
I wondered how long it would be before someone noticed that :) . It actually does turn the fan at idle, but I know that it is not ideal. There just is no where else to put the alternator and it makes for the low wrap situation. I have looked into an idler, but everything I have read says not to put an idler on the back of the belt. An idler won't work to increase wrap used any where on the belt in this application. The double pulley would be pretty easy to do as I already have a 3 belt pulley on the crank for PS with the 2nd pulley unused. We always used to run the circle track cars with one belt, WP to Crank. You had to put the belt on the pulley then put the pulley on the WP. No idler. I would almost bet that is not the problem, but is real easy to try and can't hurt anything.
 

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I have aT bucket with a 160 thermostat and an 18" electric fan no shroud and it seems to be okay (hopped up 283). And 210 is not too hot especailly if you get a hi PSI cap like 25-45 LB. If your coolant is low the temp will climb and then come back down, up and down.
 
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I went to waterless coolant and just let the engines run 210 -230. The important thing is waterless doesn’t boil till 375 at atmospheric pressure. This keeps the jackets wet by suppressing nucleate boiling and doesn’t need to pressurize the cooling system to 18-20 psi to prevent boiling at 212 degrees.

Bogie
 

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I wondered how long it would be before someone noticed that :) . It actually does turn the fan at idle, but I know that it is not ideal. There just is no where else to put the alternator and it makes for the low wrap situation. I have looked into an idler, but everything I have read says not to put an idler on the back of the belt. An idler won't work to increase wrap used any where on the belt in this application. The double pulley would be pretty easy to do as I already have a 3 belt pulley on the crank for PS with the 2nd pulley unused. We always used to run the circle track cars with one belt, WP to Crank. You had to put the belt on the pulley then put the pulley on the WP. No idler. I would almost bet that is not the problem, but is real easy to try and can't hurt anything.
(1) Remembering back through my working career, fans seemed to need about an inch into the fan shroud, and the rest outside the shroud, and towards the engine. (2) Back in the 60's, there was really high octane fuels at the gas stations. The car manufacturers increased their engine's compression up to over eleven to one compression ratio. We thought one full point compression ratio increase raised the horse power by about 11%. But that compression ration and horse power makes some serious heat. So much so, you couldn't stand putting your hand under the hood of the late 50's and early 60's, high compression Pontiacs, and things like 1961 hot rod, 348" Chevies. As a tool, we would hang a fender cover in front of the radiator, to see how much air (draught?) the fan would pull through the radiator. It took every bit of what those six blade fans could to just to be able to drive the car as a grocery getter. And it took some serious belt wrap to pump that much air. My hot rod 1970 Corvette 9.3 to 1 compression 454" needed a solid fan hub, instead of fan clutch, and when driven sounded like an air plane coming. It was dangerous to drive, as we would lose fan blades occasionally. A GM six blade fan (from a fan clutch car) but driven directly with a solid hub, would cool those problem cars. We had to use solid fan drives at highway speeds as well as at idle, as the wind through the radiators just wasn't enough. We tore up belts because of the drag on the fan belts, from working to move air (airplanes used to call propellers: air screws). During a thrashing through the gears, a 1955-57, high winding, 283 Chevy would turn their fan belt up side down. Deeper pullies and more wrap around their pullies solved that flipping problem. The factories, developed dual fan belts, which helped a lot. Do not under-estimate how much "wrap around" a fan belt requires when you are trying to move a substantial amount of air through a radiator. I pretty much guarantee the pictured fan pulley ( with about ten degrees or so wrap around) is slipping compared to the crankshaft pulley (sheave), and the fact that the frontal radiator air blast cools the engine down when you drive at highway speed pretty much proves the point. (3) I have a 72" Ferris 33.5 Horse Power diesel lawn mower, that came with a 17 foot long belt that wrapped around the engine's PTO, then horizontally up to the zero-turn deck, then around all the mower blades and back again. The belt wraps at least150 degrees around each pulley with the aid of idler pullies, and does indeed run on both sides of the belt. My machine also has dual PTO belts that have a drive Vee at 6:00 and at 12: 00. So, the double PTO Vee belts run on pullies on both their tops and bottoms. The deck belts run on their single Vee bottoms on engine pullies, and their flat top sides around idler pullies. (4) Remember too, you are not only pumping air at and idle, you are pumping water as well. (5) Our first dynamometer was home made and consisted of a huge brake drum with an impellor inside. We would open a ordinary hardware store water faucet, and allow water into the spinning impellor inside the sealed up brake drum. The impellor drag through the water resisted enough to pull against a scale with which we calculated horse power and torque. Believe me when I tell you it takes some serious horsepower to turn a water pump and an air fan air at the same time.
 

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Running two v belts (going to accessories on either side of the block) with a dual pully will provide plenty of wrap.
Running crank, wp, alt with a tensioner on the alt then
Crank, wp, ps with a tensioner on the ps keeps the alternatior mostly wrapped to avoid slipping.

If you use a serpentine setup then running a idler and tensioner will provide 120 to 150 degrees of wrap.


Build some brackets for your accessories so that wp has sufficient wrap. Plywood at first then aluminum/steel can be cut on a 4x4 locally.
Run a 7 blade
Change your shroud to a cone style
Check your cap and system to ensure the system is pressurized.
Check for and eliminate air pockets.

This is one of those issues where if you dont have room you need to make room. If you can not move your radiatior forward then you may need to move the engine back.

One last thing to help shed heat is running thin walled aluminum or copper in place of the majority of hoses. You just run 4" sections of hose on the ends to allow for engine movement. This eliminates hoses collapsing and with copper/brass looks great polished up next to the accompanied brass/copper vacuum lines, nicopp fuel and brake lines.
It improves both the look while adding function. Bending the larger diameters of hard line can be done easily with sand after watching some videos.
 

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Discussion Starter #32
The only location for an idler would have to be on the outside of the belt between the WP and ALT. It would take a drastic turn in the belt to gain any significant pulley wrap. I am sure that would drastically reduce belt life. I have ordered a 2 groove pulley for the water pump. This will allow me to use a dedicated crank to WP belt. That will eliminate the possibility of a slipping belt not driving the WP. That should take care of 1 possible problem.
With the center of the fan blades being 2" from the radiator there is no room for "coning" the shroud. A 15" fan and a 16" core leaves no where to cone to. And no, I am not moving the engine or radiator.
This really is not a show stopper problem. I drive the car all the time. I can manage it. It is just annoying and only happens if the engine is idling for 15 or 20 minutes., which doesn't happen often.
I am trying to design a new shroud that addresses the issues discussed here, the "sleeve" and enclosing the bottom of the shroud.
I have thought about water wetters and waterless coolants. I don't really want to go there. My feeling is that my car/ engine/ cooling system is nothing out of the ordinary so shouldn't require extraordinary measures. I think that getting my basics correct will solve the problem. (Therein lies the problem!) :rolleyes:. But I will keep the waterless route in my back pocket for use if all else fails.
 

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New double groove waterpump pulley also going to speed the fan and pump up at idle, via smaller diameter than current pulley?
 

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Discussion Starter #34 (Edited)
New double groove waterpump pulley also going to speed the fan and pump up at idle, via smaller diameter than current pulley?
Yes. Old pulley = 6.75". New pulley = 5.813. So, 14% difference. Should help some. Champ Pans WP pulley JR 181. Kinda pricey, but the smallest I could find.
 

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Discussion Starter #35
Well the above mentioned WP pulley wouldn't line up with the stock 3 groove crank pulley. The new replacement just arrived. Crank pulley is 6.75". Old WP pulley was 7". New pulley is 6". So the pump was actually under driven a little bit. Now it will be overdriven about 12.5%. Should help and 2 belts on the WP should help also.
I am just finishing up the new shroud. The fan is now 360 degrees enclosed by the shroud. 1/2" clearance fan tip to shroud. I was also able to put a "sleeve" in it as discussed. The sleeve is only 1/2" wide though so we'll see what happens. Mounted the shroud to the radiator with weatherstrip. Should make a pretty tight seal. I think the new crank/WP ratio and the improved shroud will go a long way to solving the problem.
I am also installing a new ignition system with a better ignition curve. May help some.
I'm thinking the real test will be putting the hood sides on. With the tight packed engine bay, I am worried about air exiting. I haven't been running the hood sides due to the temperature problem. It might be time to lay the hood sides out for a bunch of louvers.
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That shroud was quite the project. Now that it is done I wish I had hammer formed that sleeve instead of adding it on. Might have been easier. Definitely would look better.
Now I have to start figuring out belt sizes for the alternator and WP. That'll take at least 2 trips to the parts store.
 

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Maximizing air flow is what you're trying to accomplish with the " sleeve / fan design. I wish I knew more about it . I believe you may find the sleeve needs to be wider & extend into the shroud further , & I'm admitting that its a " what looks right" guess ..even if the sleeve ends up being 1/2 -3/4" away from the core , it will still pull air from the whole radiator
 

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Discussion Starter #40
Maximizing air flow is what you're trying to accomplish with the " sleeve / fan design. I wish I knew more about it . I believe you may find the sleeve needs to be wider & extend into the shroud further , & I'm admitting that its a " what looks right" guess ..even if the sleeve ends up being 1/2 -3/4" away from the core , it will still pull air from the whole radiator
My thinking is that if that sleeve runs into the inside of the shroud it would block the air running down the wall of the shroud. I'm betting the changes I am making will fix it. The temp gauge will be the final judge.
 
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