Generator fan box sizing

richard5933 · February 12, 2020, 08:50:57 AM

Quote from: Knuckles on February 12, 2020, 07:03:04 AM
Re: using squirrel cage fans for generator radiator. Why wouldn't you try some of the fantastic 12v electric fans used for automobile radiators...

From what I'm seeing online, the blower (squirrel fan) is going to move more air than an electric radiator fan. If those electric radiator fans were capable of moving as much air, the HVAC units would be using them in the air handlers.

The fan on a generator is usually also being called on to cool the generator head itself, in addition to the radiator.

luvrbus · February 12, 2020, 10:05:39 AM

Electric cooling fans have came a long way in the last few years though,Prevost buses are now using those for engine cooling saving on fuel and hp,the low amp fans you buy at autozone and other places I argree they are not much for moving air

chessie4905 · February 12, 2020, 12:37:20 PM

My Cutlass Ciera 4.3 diesel used electric cooling fans only from the factory. Never had overheating problems. It had high and low speeds controlled by thermostat. It may have had one large fan and a smaller one along side. Details are fuzzy anymore.

dtcerrato · February 12, 2020, 01:32:52 PM

An option not mentioned is hydraulic driven fan. The 5.7L Hemi in our Grand Cherokee toad has a hydraulic driven radiator fan powered by the power steering pump thermostatically. Was surprised to see that setup... I think that kind of setup in a bus could eliminate belts & right angled fan drives.

luvrbus · February 12, 2020, 01:48:03 PM

Quote from: dtcerrato on February 12, 2020, 01:32:52 PM
An option not mentioned is hydraulic driven fan. The 5.7L Hemi in our Grand Cherokee toad has a hydraulic driven radiator fan powered by the power steering pump thermostatically. Was surprised to see that setup... I think that kind of setup in a bus could eliminate belts & right angled fan drives.

Just about all the diesel pusher RV's have a hydraulic fan mine does to cool the monster Cummins engine it and it stays around 180 degrees even on long grades

richard5933 · February 12, 2020, 09:11:36 PM

Remember guys - the OP is asking about the fan to cool his generator radiator and bay, not the main engine.

luvrbus · February 13, 2020, 05:42:57 AM

That is a option for him Richard there many buses are using the engine cooling system with the generator tied into it and they work very well,I prefer 2 systems myself $:-\$

Knuckles · February 13, 2020, 06:57:04 AM

Re : electric fans for radiator cooling. Both my brothers are heavy duty mechanics for coast mountain bus that operate all city buses in the Vancouver BC area. They informed me all new buses have electric cooling fans now. They have come a long ways in the last few years and move so much air that cooling issues are a thing of the past. I am installing one on my 4107 this spring on their advice and I'll let you know how good it works

chessie4905 · February 13, 2020, 08:48:11 AM

They aren't running two cycle engines. Also city busses have fewer shorter hills to deal with along with many cool down stops. Make sure you don't overheat and damage your engine with this experiment.

luvrbus · February 13, 2020, 10:14:00 AM

Diesel and gasoline engines I believe have reached their peak in design and fuel economy, they are using electric fans for more performance and economy a fan driven by the engine uses a lot of HP from 25 to 50 hp lol on a 4104 with a N/A -6-71 that doesn't leave much,but his little 4 stroke generator doesn't take much to cool because tops under a load he will only burn 1 GPH tops,so it is only the enclosed heat you worry about.My 12.5 Onan in the quite box the radiator lays flat inside the box and vents out the bottom and only uses 1 fan it doesn't have all the extra squirrel cage blowers and works great

richard5933 · February 13, 2020, 12:01:02 PM

Quote from: luvrbus on February 13, 2020, 05:42:57 AM
That is a option for him Richard there many buses are using the engine cooling system with the generator tied into it and they work very well,I prefer 2 systems myself $:-\$

Our 4106 had that setup - the coolant of the generator was sent through the bus's main radiator, and there was an electric fan strapped on that could come on with a thermostat.

BUT (and a big one at that)...

There was still a squirrel fan in the generator bay to cool the generator head and peripheral parts. Especially if the coolant is going through a remote radiator, there has to be something installed to cool the other parts of the genset.

luvrbus · February 13, 2020, 02:16:14 PM

Quote from: richard5933 on February 13, 2020, 12:01:02 PM
Our 4106 had that setup - the coolant of the generator was sent through the bus's main radiator, and there was an electric fan strapped on that could come on with a thermostat.

BUT (and a big one at that)...

There was still a squirrel fan in the generator bay to cool the generator head and peripheral parts. Especially if the coolant is going through a remote radiator, there has to be something installed to cool the other parts of the genset.

I don't know what generator you had but all the generators have a cooling fan between the engine and the generator some have 2 to draw cool air into the head ,my Eagle with a 12.5 only had 2- 3x12 inch holes in the floor 1 to pickup cool air at generator fan and the other at the front let the hot air out plus it was in a insulated foam quite box and never gave a problem with overheating,generators use the same principal as a alternator on your car does for cooling fwiw

richard5933 · February 13, 2020, 09:34:46 PM

Quote from: luvrbus on February 13, 2020, 02:16:14 PM

I don't know what generator you had but all the generators have a cooling fan between the engine and the generator some have 2 to draw cool air into the head ,my Eagle with a 12.5 only had 2- 3x12 inch holes in the floor 1 to pickup cool air at generator fan and the other at the front let the hot air out plus it was in a insulated foam quite box and never gave a problem with overheating,generators use the same principal as a alternator on your car does for cooling fwiw

I've also seen units like yours, but I thought we were talking about an Isuzu diesel with a 20kw head. Sounded more similar to what I had (Perkins diesel with 12.5kw head) than a modern Quiet Diesel. Whole lot of heat was thrown off both the generator head and the engine/exhaust in the bay on mine, and the airflow was needed. If there is something built-in to the unit that would be different.

chessie4905 · February 14, 2020, 04:32:56 AM

The end of the generator head on ours had large cast cooling fins at engine end as part of the rotor. Saw those when I attempted to replace rear main seal due to a slow drip. Couldn't get the rotor to disconnect from the crankshaft. Appeared to be a tapered shaft connection. I didn't want to risk damaging rotor, so left it as it was.