Originally Posted by Tango
I am going with electric fans on my 4BT. A., to make room for all the other cooling crap I have to stuff in the buses narrow little nose...and B., I have been told it will save nearly 10 horsepower.
I am, however, going to use a two fan system instead of one. That way if one goes south, I will still have some measure of cooling. And these engines don't really need that much 90% of the time.
PS...the tranny will have it's own separate fan combined with some passive, radiant coolers.
There is a big difference between cooling a 4BT up front and any engine in the rear. Moving air through a radiator at the back of the bus has been a continual engineering problem for every bus OEM that builds a rear engine bus.
It is very difficult to move air into a radiator at the back of a bus and then out the back of the bus in large quantities. Kenworth Pacific buses used a scoop on the roof to help increase air volume, an option that became available on Gillig buses after Gillig purchased the KW Pacific Bus division.
Most rear engine Gillig buses have a problem with overheating when it gets hot outside and you start to push the speed. I honestly do not know if electric fans can move enough volume to keep things cool. The fans on most Gillig rear engine buses have blades that are 8"-12" long and at least six or seven blades.
Again, depending on what is wrong with the fan it might be a relatively easy fix or it could end up being an expensive fix.
One problem with the fans is some people insist on running the belt really tight. This tends to wear the bearing out on the fan shaft. If that bearing goes out that is not going to be cheap or easy to fix.