Electric radiator fans for the stepdown

bob ward

I'm thinking of replacing my belt drive radiator fan with an electric fan set up. The stepdown radiator is 24" wide and rather than 1 large fan I'm looking to use a pair of say 10" fans mounted side by side. And I'm also hoping to find a ready made 2 fan arrangement from a small Japanese or Korean car.

One option of course is to go to the wrecking yard and peer under hoods at various fan set ups, but if someone on here has already been through that exercise and can share the knowledge that will be useful.

[Deleted User]

Interesting idea. You won't gain much more cooling capacity, though. If my math is right, two 10" fans have an area of 628 square inches compared to 615.5 square inches of a single 14" (pretty standard size) fan like the one I have on my Hornet.

dougson

I to have to discourage the use of two small fans. I tried this on another resto. and they failed to keep the temperature down, they simply can't move enough air. Go with as large a single fan as you can with at least 2000 cfm. I went with a 16" 3000 cfm unit (that I will post picture of later) made by Derale (?).

Hudson Grandpa

Heres where I got mine.


http://scottscoolingfans.com/

Unknown

When we put A/C on the 49 Super Eight at Vintage Coach, we put a 12" I believe electric fan in front of the radiator to supplement the engine fan on hot days with the A/C/ on. It works fine but I wouldn't rely on it alone to cool the engine. It works great as a backup though.

[Deleted User]

Walt here. Get a 6 or 7 blade fan from a Lincoln or an AMC to replace the 4 blade you have now. This is what I have in my 53 with air and a 12 inch in front of the radiator for when I turn the air on. Never had a problem traveling across this country in over 100 degree weather. Just don't install one of those plastic fans. The 12 inch fan is in front of the air condenser, which is a must. Walt.

kamzack

I'm intending to use an electirc fan on my H.C. 8. I'm gonna have a guy fab an aluminium shroud to fit, which will pull air from the whole core. Also, there's an outfit that makes 6 volt fans. I got thier name here from the Hudson family, although I can't remember the name. I think it's "just Fans" .
I sure appreciate all of the contributors here, Would be much more of a challenge to bring a Hudson back to life without everytone here.
Thanks again,
Kim

mikeyb

I have a setup similar to what you are thinking of (see pic): two electric fans in front of the radiator, in addition to the regular belt-driven four-blade. During normal highway speeds I do not need the extra fans, not even in hot weather. But as soon as I´m moving in stop-and-go traffic I switch them on and they keep the temp at the normal (slightly higher than half the range of the gauge) setting. Without the electrics, in stop-and-go traffic my temp will move up within a few minutes, especially when standing still after a longer highway ride.

Mike

bob ward

Thanks for the photo Mikeyb, that's a neat installation.

I'm thinking, and a little research also shows, that for a front radiator car, whether the fan is belt driven or electric, the fan becomes redundant once the car is traveling over 10 to 20mph. Belt driven fans are mainly designed for slow traffic conditions (even there they can be marginal), at highway speeds they just consume HP and create noise.

Assuming 100% fan efficiency, a standard stepdown 4 blade 18" x 1" fan running at 1000RPM (roughly 500 RPM idle speed) will draw 600cfm through the radiator, but in real terms its probably closer to 300 to 400cfm.

Idling along in top gear in a stepdown at 10mph (roughly 500 RPM) a theoretical 2900cfm will pass through a stepdown's radiator core, nearly 5 times better than what the fan can do. Which explains why, when you are stuck in sphincter tightening traffic with the temperature gauge creeping upwards, a few 100 yards of movement quickly drops the needle back to normal.

The advantage of the electric fan, whether you switch it manually or have a temperature switch installed in the radiator, is that when it comes on it is going flat out, just what you need in low speed conditions. A pair of 10" fans, according to the manufacturers data, (take with a pinch of salt) will pass a total of 1600cfm, a single 16" fan will produce 2100cfm. Both of those options produce far more air than the factory belt driven fan.

First experiment I think is to do some highway driving with and without the engine fan and see what the temperature gauge tells me. Its starting to warm up around here, 90°F days, so that will be a fair test.

mikeyb

Bob, actually my two fans are 6 volt units. I just let them untouched after converting the car to 12 volts 5 years ago and they simply turn double speed since
Another idea for additional cooling might be a "fan shroud" like almost all modern cars have. Obviously the manufacturers do not just rely on the radiator for cooling but also try to get additional air cooling on the block by guiding the air there. If you eliminate the belt driven fan you could shape the fan shroud outlet in a way that it has a rectangular outlet of identical shape like the Hudson flathead has, thus guiding the air very close to/around the block?

Mike

Walt-LA

What has been tried on the '54s which have far less room in front of the radiator because of the grille arrangement? Need more cooling with A/C on at low speed in Louisiana summers (when temp x humidity = T squared :woohoo:).
Walt-LA

Hudson Grandpa

Walt: The pic you see of the fan & rad up above is going into my 54 cpe. I have measured a thousand times, and it fits, however I should have been just about 1/4" higher, as the back of the fan motor may touch the back of the big stainless. If so we will have to bend the stainless just a little in the back to fit the fan.
Shoudn't be noticeable. On my rad the bolts that secure the rad to the frame, are in back. Otherwise I could shim the radiator forward towards the motor to get the clearance I need. Engine going back in the car sometime this week and when all is said and done I will post some pics. 6 volt system with Alternator, and Optima Battery

Dave

kamzack

Wanted to stick my nose into this topic again. I was into street rods some years back before they evolved beyond the back yard builder into a high end business and not much fun any longer.
That to say that above 30 mph a mechanical fan isn't needed as there is enough ram air across the core to bring to normal temp. Mechanical fan takes somewhere in the area 10 to 18 horse power to turn and as stated above, isn't efficient in slow moving traffic, and by removing it the chance of a blade going through the hood is gone. Also makes sense to conclude that ram air at speed will not be impeaded by the mechanical fan. Air can free flow through the engine compartment and add to the cooling effiency. Another advantage is if fan is connected to a fused constant power source and is thermostatically controlled fan will run until water temp goes down to set temp and shut down. I'm not concerned about authenicity at all, but want to make cooling system as effient as possible. Another reason to be glad to a part of the Hudson family, ya don't get critized for not having everything correct and no points deducted at a meet. No Judging. Drive your Hudson and enjoy.
Thanks for letting me share,
Kim