Fan cooling

car electric fan is 200 Wt maximum, and not so small, it is not enought for class 8 truck. Wanna save some fuel (1-3%) - switch to BW two speed fan, like used on Mercedes Actros ore electro-hydrolic fan clutch like on MAN TGA (PWM controlled), bit IMO, you will not save more 3% fuel.

As a good advice of electric fan use is to get fan for example from Audi A6 ore from Taurus and disable lining fan clutch with A/C (reprogramming ECM).

I did this way - if you turn A/C on lining fan is off, but electric fan runs at low speed, when lining fan is on, electric fan runs on full speed. We did this conversion on KW, I used '94 Ford Taurus relay with '99 Audi A6 fans (dual fan).

May be it does not save a lot of fuel, but saves lining fan clutch and beltd drive

 

When the fan is running mechanical is more efficient, only problem is they usually take some power when they are not used. You are right, there is no electric fans big enough and they would need a very big alternator. Biggest mechanical fans need about 75 hp at max rpm, that's about 55 kW, you can calculate how many amps is needed at 12 volts..

 

55 000/12= 4583A

OMG! wires of elephant's leg thik!

 

I concider that factory ECM programming when cooling fan is on every tome you turn A/c on is not optimal, becouse air flow is exessive!

That's why we used to add electric cooling fans to use with A/C only.

150-200 WT is more then enought for A/C condencer and no reason to use BIG LINING FAN.

 

i just looked at a 379 pete with 4 electric fans and the mechanical removed he has all 4 wired to the switch on dash. anyone seen this before? i checked the air clutch and it works ,never seen this before

 

as a good solution I'd prefere BW twin speed fans, like on Actros. ore PWM controlled MAN TGA fan...

unfortunatly US truck maker do not use this kind of fans.

 

I saw it on a 99' 379 Peterbilt that a friend used to own. Had its own dedicated switch on the dash.

KH

 

thats how this one is , i ended up buying the truck and will use a heavy duty relay that can handle the 4 fans. mainly because it will be a pain to remove them. i figure ill try it and see how well it works.