[RocktimusPryme]

This was posted on my FE Facebook group. Its been discussed on here though so I thought I would cross post the info. Not my test, Im sure some of you can dispute the method. But its better than nothing.

Basically this dude tested a factory Mark VIII fan against two Rock Auto type re-pops. I know I have wondered how the re-pops actually perform. Pleasantly surprised if these numbers are to be trusted.

Writeup below is copy/pasted with some bolding to make it easier to read.

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Did some simple flow testing on the 2 speed Lincoln Mark VIII style fan I run on the Dart to see which is the best. Never had heating issues with these 2 speed fans but with new brushless technology out I'm sure there's a ton better out there now.

I used the old radiator from the Dart in front of them to get true flow numbers with the pressure drop of a core in front.
Made sure the testing voltages were the same, and needed a battery to calm the inrush current and maintain current. These pull huge (50+ amps) on high speed when starting.

The stock Ford OEM fan flowed the most, followed very closely with the Dorman 620-118 then the TYC-620950.
Between the Dorman and TYC, the Dorman is made in Thailand and the TYC in China. Thailand seems superior as they revamped the fan blade design and flowed closest to the stock design.

With a higher voltage on high speed I can see these fans getting close to 3800-4000CFM at 14.4V.

Without a radiator in front the low speed amperage dropped 3-5 amps and the full speed only about an amp or so.

Results were as follows


Stock Ford fan :
High speed
3415 CFM
22 amps @ 12.7 Volts
Low speed
2800 CFM
18 amps @ 13.7 Volts

Dorman :
High speed
3355 CFM
22 amps @ 12.7 volts
Low speed
2578 CFM
16 amps @ 13.7 volts

TYC :
High speed
3116 CFM
22 amps @ 12.7 volts
Low speed
2578 CFM
17 amps @ 13.7 Volts