engine power killers

[Gary68]

motor trend engine masters=playing around with a dyno

this episode,cooling fans


chevy 350
horsepower torque
baseline no fan 349 406
modern clutch 335 400
flex 325 388
old fixed steel 318 388

looks like a electric fan is a good investment

 

[highdesertranger]

what about the drag the alternator is putting on the engine running the fan. electric fans draw some serious amps. highdesertranger

 

[Gary68]

Amps x Volts = Watts
Watts / 745.7 (one HP) = Electrical HP Produced by the Alternator
HP x 15% Efficiency Loss = HP Loss
HP + HP Loss = Total HP Used


Example:
57A x 14.9V = 849.3 Watts
849.3 Watts / 745.7 = 1.14 HP
1.14 HP x 15% = 0.17 HP
1.14 + 0.17 = 1.31 HP Total

the best i could find was between 2-5 hp for the alternator

 

[Gary68]

and you have to realize thats a max output dyno pull so naturally the more rpm the more drag and hp loss from the fan so at 1500-3500 rpm that we most drive at the power loss will be about half of the max at 6500rpm or whatever they took it to

but yea,no more old steel fans for me,find a clutch type

 

[highdesertranger]

I agree there, clutch fan is the way to go. electronics have a habit of failing at the worse possible times. highdesertranger

 

[Spaceman Spiff]

 . . .
HP x 15% Efficiency Loss = HP Loss
HP + HP Loss = Total HP Used
 . . .

A good first order approximation for alternator efficiency is 50%, although it is all over the map based on (alternator) speed, temperature and load:  https://www.intechopen.com/source/html/38166/media/image3_w.png 

The big efficiency gain with electric fan is the ability to turn off when not needed.

 -- Spiff

 

[SternWake]

https://alternatorparts.com/how-much-horse-power-does-an-alternator-make.html

^^that site claims each 25 amps the alternator makes consumes about 1 engine HP.

I can easily tell when my alternator is making 65 amps vs 12 amps by the throttle pedal on my 318 V8 engine.

I love electric fans, but am not screwing with my fan clutch. It works reliably.