Newb with 8/71 based bench needs some help!

[thomasvaught-1]

I have a friend who years ago made a nice Flow bench using a roots supercharger with a 3 phase motor to drive it. His bench was similar to a Blue bench except that he had external plumbing to be able to locate the supercharger and motor in a enclosure outside his working area of his shop. He used adjustable valving to control intake or exhaust flow from the supercharger as well as test pressure (bleed valve) strategy.
It was very quiet.

I see you have made venturis like a very old Flow bench article recommended. Those actually work pretty well. The multi-million dollar Ford Flow Bench uses a similar bi-directional venturi system. Calibration is everything. Get some of Bruce's plates for that when you are ready to test. How many venturis did you make? Still have the old plans??

Tom Vaught

[TK]

Yep, still got the old plans somewhere - 'hyperflow'? I think.

If you guys want them I can scan them & post em up - may take a while tho.

I've got 50cfm, 100, 200 & 300 venturi's - I'll have to make a 400 as well.

I was intending to calibrate using a head tested on a mates SF600 as a benchmark & also getting him to flow the ventui's for me to know exactly where they're at - that way I get figures that are directly compareable to the 100's of old sheets I have from tests on his bench.

[thomasvaught-1]

What I have found from Venturi benches is that the piping upstream and downstream of the venturi makes a big difference in the flow number. Again, I would install the venturi arrays using an arrangement resembling a group of straws bundled together loosely with a head plenum on one end and a motor plenum on the other end. Valving would turn on each branch as required. The calibration plates tested on your friend's bench and then your system would allow "in place" venturi calibration.

JMO

Tom Vaught

[hdwgfx]

Tony ( and all others), I have the same 3 lobe blower as TK ( we have spoke ) and a GE 10 hp 3500 rpm 230v 40 amp ele. motor, I bought this new in the 80s @ $600, still like new . The blower was rebuilt by a local diesel shop. The blower and ele. motor are all set up to work together.

I have this due to building a LFE 1000 cfm bench and the 10 hp motor was not up to the task, it has been way to long to give you any data on that project.

Can you provide any input about using the GE 10 hp motor, if this motor is a good choice then I want to do something SIMPLE to use it right away with minimum work. All I need is 28" TP and 400 cfms right now, Actually if I can read positive/negative changes without cfms and do velocity
readings in the ports I would be happy for the moment

I also have -->

1 Meriam inclined mano. 40" long scale 0-8" dp
2 Dwyer 36 " vert. manos.
2 Dyer magnehelic guages 25" and 50"
1 Dwyer 90 degree pilot tube

If I can just see this work even in a crude fashion then I will build according to PTS plans ( I have them).

I posted this here not to hijack TK's thead but to share any info that may help TK or any others...

Thanks ahead of time

[Tony]

[hdwgfx]

Thanks Tony... Are VFDs only for 3- phase motors?

[hdwgfx]

ok, sorry I don't know ;-(

[Tony]

[TK]

hdwgfx - I'm not 100% sure who you are?, you wouldn't happen to be machining a couple of sets of subaru cases for me would you?

Anyway, long time between updates from me, been busy again.

I've got a 15kw VFD on it's way - a real good quality second hand unit from a mate of a mate for $200 (bargain!).
I'm also probably going to be using digital manometers with the ability to hook to a computer, for now there will be no huge advantage other than more being more compact & easier to maintain - they may be a little faster to use, but the main thing is if I get excited I can look at computer controlled flow testing in the future with motor speed & logging controlled.
Going to be switching to oriface plates - seems much simpler.

Hopefully I'll get back to actually working on the thing in a few weeks once I've cleared out some of the backlog of actual work (bloody customers actually forcing me to work LOL).

Tony - What do you think my chances are of being able to test up to 400cfm @ 50" with this setup? - I don't need to for now, but it would be nice to be able to test at higher pressure drops.

[TK]

Another question for Tony - reading a post of yours on VFD's it seems that I may be able to set mine up to automatically adjust test pressure to 28", meaning I could just set the bench going & wind open the valve without shutting the bench down, the VFD would keep test pressure at 28" & I could log almost infinate lift points very, very quickly.
Mine is an industrial Danfos controller - do most controllers have this feature?, I don't have the controller here yet to suss it out but it's something to think on.

Also - what sort of rpm range would you expect me to need to drive the blower at & how much can I safely overspeed the motor? - would 100% faster be pushing it?.
If I could run the motor faster it would mean I don't have to gear it up as much in the belt drive so there would be less chance of belt slip etc. I also believe that underspeeding the motor can be harmfull, so running it in the range of 50-150% of it's regular speed should be better for it than running from 20-120% - yeah?

[Greg]

Hey Tony,

no, it's me with your Subaru's. They will hopefully be running through the mill late this week so the other has a chance to turn up first.

Cheers,
Greg

PS Can you get any more of those VFD's?

[TK]

Sweet cheers!

Ok then, who is the other guy.....

VFD - dunno, maybe, I'll find out next time I'm talking to the guy - probably won't be exactly the same even if he can get another.
I may see how many he can get - would be nice to hook one up to my seat machine so I can slow it down for large dia seats.

[Tony]

[hdwgfx]

TK, I had PMed you concerning your progress on your 8-71 blower project. I am doing the same but with a single phase 10 hp ele. motor. I am now thinking that once I get pulleys close I can add or build in to begin with 2 (or more) good regular vac. motors and speed control them.

[TK]

Aha!

Why use vac motors as well? - even without a VSD you should be able to control the testing pressure pretty well with a bleed - that's what I was originally going to do.