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

[Daniel Houlton]

[Admin: tone this down or it won't be approved in the future]

Greg Hermann wrote:
> 
> 
> >
> >If it's 25 in/Hg you need, that's around 12.5 psi/1.8:1
> >pressure ratio.
> 
> It;s not.

Yes, it is.


> >
> >If it's 25 in/water, that's absurdly less, less than 1 psi.
> 
> That IS what is used. And it IS an appropriate pressure level for an intake
> port test. You DO want some oxoygen to get into an engine, don't you ??

Rather than answering with a "because it just is" type answer,
why don't you tell me *why* less than 1 psi of pressure is 
used to flow test a head.

I never said it wasn't what's used.  If you care to re-read
my initial post, I was asking what I'm missing on how a flow
bench works.

Yes, I would want some oxygen to get into the engine.  Which is
why I'm questioning why you'd use less than 1 psi to flow test
a head when there's in the order of 14 psi (on a NA motor) 
pushing through the intake valve at WOT?


> >
> >If you're flowing a head that typically has engine vacuum
> >inside, and atmospheric pressure outside, why is 25 in/water
> >even remotely enough pressure.  And if it is enough, why is
> >is so hard for a leaf blower to do?  It is, after all, less
> >than 1 psi.
> 
> Most centrifigal fans can only make about 5 or 6 in H2O static pressure
> before you "stall" the fan blades !! As I said before, TRY looking at some
> commercial fan curves before you run your mouth !!!

Oh gee, let me just grab those commercial fan curves from my
filing cabinet.  After all, everyone has them just lying around.
So, what you're saying, is that if I were to completely plug 
up the outlet from one of these leaf blowers, it'd only make
about 1/5 of 1 psi (5 - 6 in/h2o) static pressure?  I guess I can't 
contradict that as I've never tried it, but I'll take your 
word for it.  All you've got to do is say it.  No need to be
rude about it.


> What might ""SEEM" intuitively reasonable just ain't necessarily so , not
> even because you can type it !!
> 
> Greg


Is there a reason you're being an ass?  I'm not implying anything,
nor have I said you are wrong in anything.  I asked a few simple
questions about a flow bench.  If you can't answer them, fine.  But
you don't need to be such a rude prick either.


--Dan
houlster at inficad.com

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