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Sun Feb 28, 2010 8:04 am

Does anyone here know the CFM rating of the blower motor for the heater from a Bay Bus? I am using one in an application not originally for the VW but none the less it is being used to cool a motor. I have an all electric VW Ghia and I use the heater blower from a bus to cool the motor. I is a perfect fit and seems to do a pretty good job. I was asked what the CFM rating was and I have no clue.

Can anyone here help me answer the question?

Thanks
Pete :)

Sun Feb 28, 2010 9:01 am

Hook it up to a giant garbage bag with known cubic foot capacity and time how long it takes to fill it, then multiply that to make 60.

Any links to your Ghia thread? sounds interesting.

Sun Feb 28, 2010 2:37 pm

busdaddy wrote: Hook it up to a giant garbage bag with known cubic foot capacity and time how long it takes to fill it, then multiply that to make 60.

Any links to your Ghia thread? sounds interesting.

http://greenev.zapto.org/electricvw

Sun Feb 28, 2010 7:02 pm

busdaddy wrote: Hook it up to a giant garbage bag with known cubic foot capacity and time how long it takes to fill it, then multiply that to make 60.

Any links to your Ghia thread? sounds interesting.

Well I don't have a huge bag with known cubic foot capacity. So that won't do at all.

Anyone else?

Sun Feb 28, 2010 7:08 pm

Usually the outside of the box says how big they are - 30 gallon, 33 gallon etc. That measurement can be converted to sq ft. It really is a clever way to determine that.

Sun Feb 28, 2010 9:39 pm

Actually I do have bags but that is the volume of an opened bag not a closed top bag. So the volume is actually smaller so an accurate measurement from that method is marginal at best. So I'd just like to know if anyone just knows the answer to the question. If I can find a good sized bag then I may give that a spin. But knowing the proper CFM would be best.

Pete :)

Some one should know some where out there in VW land.

Sun Feb 28, 2010 9:55 pm

Can't imagine why anyone out here would know, especially since these fans tend to run almost dead headed and never at zero back pressure unless the hoses have blown off. If you have a strobe tach available you should be able to figure out the operating RPM's and from there you compare these fans with other fans of the same size and rpm. There are a pile of 12V centrifugal bilge blowers out there that you can find fan curves for with a little searching.

The plastic bag test is a pretty good idea, it will give you a good idea of how the fan will perform under real world conditions with whatever ducting and stuff you have installed on it. You may not get three significant figure accuracy but I doubt you really need that either.

Mon Mar 01, 2010 6:51 am

I will try to remember to test one this evening. I have a digital anemometer I can hook up to one. The easiest thing to do would be to plug one outlet and test the other....then test both intermittantly. I'll have to dig out a fan. Ray

Mon Mar 01, 2010 7:33 am

well if you feel the need to really figure it out, pitot tubes are cheap and super easy to use. all you need to do is have an accurate pressure guage and a free afternoon.

Mon Mar 01, 2010 1:09 pm

fusername wrote: well if you feel the need to really figure it out, pitot tubes are cheap and super easy to use. all you need to do is have an accurate pressure guage and a free afternoon.

I have an Omega Vane type aneomometer that reads calculated static pressure, air temp, calculated density, velocity and CFM. Its pretty simple to duct it up to one end of the fan. I also have access to a hot-wire type sensor at work. Ray