Electric fan for cooling? Options

[teamgravy]

We are building a track car for endurance racing in Lemons/Chump Car series from a 74 914-4 1.8/carb converted. Rules state we have to spend no more than $500 on the car minus the safety equipment (seat, cage, tires, wheels, brakes, etc..)

I am thinking of leaving off the 914 cooling system and much of the engine tins and running a electric fan to cool the motor. The fans are cheap $70 for 2100 CFM fan and I can also use some big ducting to cool motor at speed. Elec is free (no night racing) right and no HP drain. Just loosing the 50lbs of fan/ducting on the front of the motor seems worth it.

I would build a shroud and use some of the existing tins push air across the jugs and heads. I would relocate the alternator above the oil fill/breather and run it off the small AC pulley that was behind the fan. Would love to buy a DTM or Fat 911 conversion kit but not allowed in budget.

I was wondering what the peanut gallery thinks of this.

Is this going to give me cooling issues?
Will ALT function from smaller pulley?

Thanks!

[teamgravy]

I agree. The benefits you're looking for don't exist and you're adding more risk of unreliability in exchange for dubious benefits. Bad tradeoff in a racecar.

But it sounds like you've decided to go this direction and you just wanted us to pat you on the back. :(

Give it a go and report back. We learn from success as much as failure. And I mean that in an honestly respectful way. Try it out, and let us know what you find so we can all learn. :beer2:

Guess the admin role and 16K in posts means you have seen it all and type people pretty quick. I was actually asking since I have the motor torn down and deciding if going a different route is worth it. The benefits I see (still haven't been convinced they aren't there) are worth exploring so exploring.

1. Room to work on the motor in the car. From experience I assume we will be dealing with oil pumps failing, valve adjustment, Ign/electrical issues so room around the motor without removing it would be huge.

2. If the belt to run Alt takes 5HP to run from the motor and a fan (5LB of spinning mass + air resistance) takes another 3HP, wouldn't getting that 3HP back since I have to run ALT to keep batt charged for coil regardless of the elec fan or not.

3. Stock air shroud is 40-50lbs with all that heater hardware maybe more. Putting the air box back on may be only adding 30lbs back so maybe I close up the heater ports and use it with stock fan

#1 is probably most important to us in the long run.

...The fans are cheap $70 for 2100 CFM fan and I can also use some big ducting to cool motor at speed.

...Will ALT function from smaller pulley?

The Little Spec Book rates the stock coaxial fan at 800 liters/sec at 4600 rpm which is 1695 cubic_feet_per_minute - so you're in the ballpark on airflow.

But - how many amps does it take to make 2100 cfm, and Watts (pardon the pun...) that in HP ?

Keeping in mind that there are coupling loses in the alternator drive the coaxial fan doesn't have. The alternator will run with any size pulley, and it's a common racer's trick to run them with small(er) pulleys on high-revving engines. But it's gotta rev fast enough to make the power you need (plus stuff like ignition, fuel pump, cool suits? Helmet blowers? ...).

You may be able to pick up some airflow efficiency with an external oil cooler, at some cost in drag. And weight, due to the hoses and fittings, although the tradeoff is you can move the weight to where it helps you. And the downside is more risk of damage due to contact or debris.

The upside of the coaxial fan is it only draws power (roughly) proportional to your need for cooling.

Fan is 8-9 amps so should be plenty left over to charge batt and power coil. I was thinking of external oil cooler in back window or below mesh above motor. May plumb it further if we can get more air to it.

Adding to the e-fan we would put ducting into the motor for additional airflow at speed tho not sure how to run this with the fan, into same fan opening?