PTS Flowbench Forum

hello all

New member from the UK. well Wales but close enough to be part of it.

Ordered plans from bruce but so recently they haven't arrived as yet. Did a load of research and loved this forum and hopefully the help it will provide when I get into difficulty's.

Am going to build a bench so I can flow test lots of ports on some alfa V6 heads im building for the 3.7 bottom end I,ve nearly finished.

Hope to get some decent results once it built and working.

first issue is deciding on motors here in the UK. Did read some posts about European motors that flowed 130cfm but efficiency seemed low at around 40% tops. or is this around the average efficiency for such motors.

looking forward to getting started.

Welcome to the Forum.

Someone in the UK can probably give you advice on motor choice and availability. There are bargains that come and go, and knowledge of what is out there can date pretty rapidly.
Most of us are spread out around the world and have no idea about motor availability in the UK, so cannot really help.

yeah looked around the forum found 240v motors types and dome suppliers just awaiting prices now..

thanks for the reply

plans arrived today busy evening reading i think. thanks Bruce

found some uk spec motors

I can get Ametek 119996 for 130 pounds each in 240v

or

I can get Ametek 115923 for 80 pounds each in 110v

is there a huge difference in performance for the extra 600 pounds if i get the 119996 motors

I could find nothing on the internet about either motor, and as nobody else has responded there is probably no quick answer.

That leaves you with the only option of testing a sample motor of each type to determine which is better.
You may be able to turn on the charm and arrange to return an unused motor, on the understanding that if it does the required job, you plan to buy several more. Worst case, just buy one of each.

Anyhow, there are two figures you need to test for to make the final choice.
The first is CFM per amp at 44 inches of back pressure.
The most efficient motor will provide the most air for the available electrical power that is available to you.
This is usually the most important consideration for a flow bench for most of us.

The other figure might be CFM versus initial cost.
That might be a consideration if you have unlimited available electrical power, or the bench is only for very infrequent use, and running costs are of no importance.

Here are the datasheets for those two motors:
http://dev.ametekfsm.com/Bulletins/115923.pdf
http://dev.ametekfsm.com/Bulletins/119996-00.pdf

Performance wise, those motors are quite similar, the 115923 has a slight edge, So, I'm not sure of the implications of running two 120V motors in series on a 240v supply but if there are no issues in that regard, I'd go with the 115923s

Both motors are excellent for efficiency, the usual range is from about 8CFM per amp to 16CFM per amp (at 230 volts).
Most common motors are around 12CFM per amp.

The 115923 (two motors) 168CFM at 10.5A = 16CFM per amp.
One 119996 motor 82.9CFM at 5.3A = 15.6 CFM per amp.

These figures are approximate, because the test pressures are not at exactly at 44 inches, but both motors are very good with nothing much between them to choose for efficiency.

So as the 115923 is cheaper it may (?) be a better buy.

A word of caution though.
Running two motors in series is not good practice. They will work fine when brand new, but over time the motor voltages will not remain equal. One motor will gradually draw more power than the other, and eventually self destruct usually always taking its partner with it.
All these motors are mass produced and built down to a price, and will eventually wear out and fail.
Running two in series will almost guarantee that problems will occur sooner than otherwise, and involve a motor pair.

Another consideration is that with a motor speed control, the motors will very rarely be run flat out for any length of time, so motor lifetime will be greatly extended from what it might be in a real vacuum cleaner.

So the answer is, I really do not know which is the better choice when everything is taken into account.

Thanks for me it would be the single motor options as i can get one cheaper than two of the others and no need to run is series


think i will start with four and see how i get on.. first heads will only flow 200cfm max but will machine it for 8 so i can add four later on if and when required.

thanks Tony and 86rocco