[EFI] Re: [EFI] Re: Building a Flow bench

[The Dupuis]

> As far as a flow bench is concerned... I did a quick calculation, and it
> seems that if you took a 20 gallon tank, pressurized it to 120 psi
> (assuming you do it slowly or let it cool), then could somehow release
> it very quickly, you could achieve your 25" water column pressure at 200
> cfm for like 6-7 seconds.  The numbers are approximate, and the valving
> would probably be really tough, but it would let you take your time
> building up the air mass with any old compressor and then let it go in a
> hurry.  I've also completely avoided the temperature / condensation
> issue.  But hey, it's a shot.  I'm sure someone's tried it and failed.
>
> Brian

Well, since I started this thread, I guess I should add something here.
First off, between 6 second bursts of flow, 20 gallon drums(at 120 psig!)
and my Turbo Volvo on jackstands, sixteen vacuum cleaner motors are sounding
better and better!!! ;-)  Actually, after reading the PHR article on
http://www.spiritone.com/~eoa/Cars/Flow_Bench/Flow_Bench.htm, it seems like
4 good sized motors will do fine.  The article stated that 16 motors were
good for 100 CFM each at 28", and I'm looking for max 400 cfm to test a
cylinder head.  The bench is pretty impressive too, allowing blow-thru and
draw-thru testing.  If it weren't for the thousand other projects I'm
currently crying in my sleep over, I might start this one too.  At the start
of this, I was looking for advise on how to use a MAF as a flow tester, and
I got pointed towards the archives (where I found nothing...), and somehow
it evolved into this.  Oh well - the article showed me how to build what I
need, so thanks everyone.

To someone who has the article - the airflow manometer has a special scale
that is linear and inclined.  The orifice plate is designed to flow a
certain amount of air based on a certain amount of water column depression
across the orifice.  The article gives an example of what the scale looks
like and gives a slope of the manometer, but without the length of the scale
mentioned or the actual amount of WCD known, I can't estimate the airflow.
I could still use this as a relative comparison between modifications, but
I'd prefer to have a formula that will allow me to calculate airflow
desired, WCD, orifice area, and operating pressure.  That way I could design
my own orifice meter and my own percentage manometer.  If anyone has this
formula, I'd appreciate it if they could forward it to me.
dupuis10 at telusplanet.net

Thanks.
Matt

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