Fans and HP

[glemon]

This may seem like a goofy topic, but I went to the big red later fan from a TR6 on my TR250. It cooled pretty well with the regular fan, but does cool better with the big one.

However, I am thinking about going back to the yellow fan with a shroud like this.

https://www.speedwaymotors.com/Chrome-Fan-Shroud-3-Inch-Wide,844.html

I know we are probably talking 1-2 hp, but it seems like the better shrouding would be more efficient that just using a big old fan and that appeals to me (I like efficiency AND power).

I know somebody is going to say why don't you just get an electric fan, but I really don't want to add the expense or complexity, plus have read stories of them working better for idle, worse on the highway, don't really want to fiddle about finding the right set up.

Any thoughts, am I just goofy? (ok not me goofy, that is a whole nother conversation, but the idea)

 

[PeterK]

I think that's the reason later cars have a fan clutch. Even turning up the radio takes some horsepower though, the more the alternator has to put out the more drag on the engine. Yup, I'm goofy too. How much do your wheels and tires weigh?

 

[poolboy]

I have an indicator light in the cockpit so I know when my 16 inch Procomp fan comes on and it never comes on if I'm moving along. There seems to be enough outside air passing thru the radiator until I really slow down, then the temp gauge creeps up a hair past mid way and on comes the fan. Then the temp stabilizes and soon enough begins to drop.
So I'm not sure what you may have heard about "worse on the highway" because I wouldn't expect it to be running at all unless you developed a loss of coolant or a water pump failure or a broken "fan belt" to cause the coolant to rise above 185*F.

 

[Simon TR4a]

Unless you are in bumper to bumper traffic you absolutely do not need a fan on the highway- air is rushing through the radiator.
It is surprising how little use an electric fan actually gets, unless you live in a very warm climate.

 

[glemon]

I guess by saying I didn't want to talk about electric fans I started a conversation about electric fans

The phenomena of bad cooling at highway speeds especially with pusher fans are anectdotal stories I have heard about various cases, not necessarily tr250/6.

 

[TR3driver]

The trick is to mount the fan behind the radiator (puller).

And I agree, if you are looking for better efficiency, then the only way to go is to lose the mechanical fan (which sucks power all the time whether you need it or not) and go electric.

Even with prolonged idle or stop-and-go traffic, my 12" Hayden fan only runs for a few seconds and then shuts off again. On a hot day, it might reach 75% duty cycle (where it runs 3/4 of the time). But if I can hold 20mph or more, it never comes on at all.

 

[poolboy]

I guess by saying I didn't want to talk about electric fans I started a conversation about electric fans

The phenomena of bad cooling at highway speeds especially with pusher fans are anectdotal stories I have heard about various cases, not necessarily tr250/6.

Speaking for myself, I'm sorry for bringing up the electric fan subject. I didn't get the impression that you didn't even want to talk about an electric fan. However, even if I had I would have wanted to bring to light some facts based upon my actual experience with a properly mounted electric fan.

 

[glemon]

Not a problem, always good to look at all the alternatives, actually with some of what is said maybe an electric does make the most sense.

 

[FordFiesta]

But then again, if your generator gives up, the electric fan can drain down the battery very fast and as the battery runs low, the fan runs slower and the car overheats anyhow.

All of which can leave you stranded in a friend's car on a September day in Lakeport, California when it's 100 degrees and Saturday afternoon, so the auto parts places are about to close......

We did get back on the road (eventually) but thank goodness it was a friend's TR2 and not mine. I almost kissed the engine driven flex-fan in my TR3A when I got home. If all you have to do is run the ignition and no lights, a TR will go for a day or two with a dead generator.

 

[TR3driver]

But then again, if your generator gives up, the electric fan can drain down the battery very fast and as the battery runs low, the fan runs slower and the car overheats anyhow.

Unless of course, you can manage to stay over 20 mph or shut the engine off when you have to stop. Then the fan shouldn't be running at all, and the engine shouldn't overheat.

I once drove an entire Indiana summer with no fan at all. I wouldn't necessarily want to do that again today, but it is possible.

 

[FordFiesta]

Unless, of course, the bulky electric fan is blocking most of the airflow on Mike's highly-modified TR2, which puts out way more heat than a stock TR, and the car is being run very hard up the twisty back roads on a broiling day, alternating with idling through traffic in wine-country towns. A veritable vortex, it was......

 

[glemon]

The real question I had was whether anybody had an opinion as to whether the earlier smaller fan would cool as well with the add on shroud as the later red fan. But the discussion of the electrics has been interesting, the other thing I would worry about with the electric is drawing down the battery, I have the stock lucas alternator which only puts out 25 amps or so. But I guess if the fan doesn't need to run that much maybe not so much an issue.

 

[FordFiesta]

(end of thread hijack talking about electric fan pros and cons)

Has anyone out there measured the power draw of the red versus older fans?

 

[poolboy]

glemon, does your car have the radiator air duct ?
I tried running w/o one before I went electric and although it did just fine while the weather was cool, when the season changed I learned why it was a necessity. YMMV

 

[glemon]

It has the stock set up for a TR250, the TR4A had a shroud of sorts that went in front of the radiator to channel air in, the 250 has two simple side panels that go on either side of the radiator to force the air trhough the radiator, but no shroud of any sort.

When I was driving around today the temp guage went about a quarter past the cold end and stayed there, on a hot day with the red fan it still doesn't move much past the middle, so it runs pretty cool.