Thread: New 350sbc do i have a blow head gasket? Or something worse..

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Sorry for the book on this, seemed necessary.

CFM requires horse power, regardless wether driven by crank or electric (in our cars the electric is driven off the crank). Higher the CFM, higher the horse power required.

Electric fans use current to produce horse power. The more horse power (CFM) the circuit requires, the larger the load (current) demand will be on the circuit. If the load (current demand) is larger than the wire’s capacity or switch’s rating the circuit will fail at its weakest link. If the switch is the weakest link, the switch will burn up. If the wire is the weakest link, the wire will burn up and usually cause a fire. The circuit must be designed to accommodate the current demands of the appliance(s) operated.

The ignition switch or its wiring is NOT designed for high current loads such that cooling fans can apply. High load circuits such as cooling fans are usually sourced through a fuse rated at slightly above the appliances maximum current requirement, connected to a high current supply (directly to the battery or its main feed), using wiring sized larger than the maximum load the circuit requires and controlled (switched) by a relay rated higher than the maximum current demand of the appliance(s) attached to the circuit. The relay can by triggered (remotely switched) by the ignition switch or any other means as the relay's primary (trigger/switch) side is a very low current draw.

While electric fans can produce energy when they are free spun (windmill effect), seldom does this produce enough current to damage a circuit designed for its intentional load. Any effect caused by windmill would be negated by the switching device controlling such a circuit, as the circuit would be open (off) and would prevent any damage if it did occur (an open circuit applies no load).

Whenever the electric circuit is in demand (on) it applies a load to the circuit and requires horse power to operate it. In our cars the battery/alternator supplies the current required to supply the demand. The battery is the storage, the alternator replenishes the battery. High current demanding circuits will drop the batteries voltage as the demand is applied, the alternator applies the required addition to the circuit to maintain the required load that was designed into the original circuit (complete car). If the alternator can not keep up with the demand the weakest link will fail (usually alternator and battery damage results).

If a new load is attached to a source larger than the overall circuit(s) were originally designed for, the circuit and its sources will need to be redesigned to meet the load (current) demands. This can require a larger alternator, battery and wiring.

And yes, it require horse power from the crank to drive it. The only exception to this is a quarter mile race car that is driven off the battery only during its run down the strip and charged between runs. ONLY then (race situation) can there be a horse power gain to the motor by running electric fans and pumps as there is no connection to the crank.

Again sorry for the book, hope it helps....

Originally Posted by 36 sedan

Sorry for the book on this, seemed necessary.

CFM requires horse power, regardless wether driven by crank or electric (in our cars the electric is driven off the crank). Higher the CFM, higher the horse power required.

Electric fans use current to produce horse power. The more horse power (CFM) the circuit requires, the larger the load (current) demand will be on the circuit. If the load (current demand) is larger than the wire’s capacity or switch’s rating the circuit will fail at its weakest link. If the switch is the weakest link, the switch will burn up. If the wire is the weakest link, the wire will burn up and usually cause a fire. The circuit must be designed to accommodate the current demands of the appliance(s) operated.

The ignition switch or its wiring is NOT designed for high current loads such that cooling fans can apply. High load circuits such as cooling fans are usually sourced through a fuse rated at slightly above the appliances maximum current requirement, connected to a high current supply (directly to the battery or its main feed), using wiring sized larger than the maximum load the circuit requires and controlled (switched) by a relay rated higher than the maximum current demand of the appliance(s) attached to the circuit. The relay can by triggered (remotely switched) by the ignition switch or any other means as the relay's primary (trigger/switch) side is a very low current draw.

While electric fans can produce energy when they are free spun (windmill effect), seldom does this produce enough current to damage a circuit designed for its intentional load. Any effect caused by windmill would be negated by the switching device controlling such a circuit, as the circuit would be open (off) and would prevent any damage if it did occur (an open circuit applies no load).

Whenever the electric circuit is in demand (on) it applies a load to the circuit and requires horse power to operate it. In our cars the battery/alternator supplies the current required to supply the demand. The battery is the storage, the alternator replenishes the battery. High current demanding circuits will drop the batteries voltage as the demand is applied, the alternator applies the required addition to the circuit to maintain the required load that was designed into the original circuit (complete car). If the alternator can not keep up with the demand the weakest link will fail (usually alternator and battery damage results).

If a new load is attached to a source larger than the overall circuit(s) were originally designed for, the circuit and its sources will need to be redesigned to meet the load (current) demands. This can require a larger alternator, battery and wiring.

And yes, it require horse power from the crank to drive it. The only exception to this is a quarter mile race car that is driven off the battery only during its run down the strip and charged between runs. ONLY then (race situation) can there be a horse power gain to the motor by running electric fans and pumps as there is no connection to the crank.

Again sorry for the book, hope it helps....

Amen!! Your description is thorough and accurate in all respects, IMO.