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 calibration problems 
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Joined: Sun Feb 02, 2014 10:57 pm
Posts: 14
Location: iva sc
I got a set of cal plates from mr. bruce, put,em on my bench, here is what I found, 50cfm plate is low by 8.4 cfm the 300 plate reads high by 43 cfm, I put them on top of my head adapter (4.150" bore) 50 plate read 57 no change @ 300, but the kicker is my bench is stingy with a head?? I have flow #'s for sevral heads and compared to most published #'s im pretty close, I fully relize this is not the rite way to go about it but something is a mis with the cal plates, (not that thay are wrong) but with my pitot tube its doing something funny to the air???? talked with bruce a couple times ( very helpful!!) but we could come to no sensible conclusion to solve the problem with the cal plates. there may not be a problem @ all but I would like to no for sure, as I am building a pts bench and will sell this one and I want it to be accurate, it is super repetable, day to day week to week, I get the same #'s within 1-2 cfm ...its a jkm 600 purchased new around 98-99,

any ideas??


Sun Mar 30, 2014 9:10 pm
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Joined: Fri Feb 19, 2010 7:36 pm
Posts: 1628
Location: Grantsville, Utah 45 min west of Salt Lake City
Do you have any pictures and specs of you bench you can post? Need to see bends, tubing size, how much tubing length before and after the pitot itself.

John


Mon Mar 31, 2014 1:43 am
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Joined: Fri Jan 08, 2010 3:35 pm
Posts: 1664
Location: Pennsylvania
John, It's a JKM flowbench pretty much straight runs of pipe up and down.

We've run through a bunch of ideas, moved the pitot probe location, used the plates on and off the head adapter.

I think our next step that we discussed is to have Daniel send a head to me and flow it on my bench and see what numbers I get and then go from there.

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Bruce

Who . . . me? I stayed at a Holiday in Express . . .


Mon Mar 31, 2014 6:44 am
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Joined: Fri Feb 19, 2010 7:36 pm
Posts: 1628
Location: Grantsville, Utah 45 min west of Salt Lake City
Brucepts wrote:
John, It's a JKM flowbench pretty much straight runs of pipe up and down.

We've run through a bunch of ideas, moved the pitot probe location, used the plates on and off the head adapter.

I think our next step that we discussed is to have Daniel send a head to me and flow it on my bench and see what numbers I get and then go from there.


Probably the best idea, Bruce. Good luck. I hate chasing gremlins ;-)


Mon Mar 31, 2014 2:10 pm
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Joined: Sat Apr 26, 2014 11:49 am
Posts: 1
Just wondering if there are any updates on this, I am going through the same thing with my JKM 600, not sure what to do.


Wed Jul 16, 2014 10:01 pm
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Joined: Sun Feb 02, 2014 10:57 pm
Posts: 14
Location: iva sc
what I have found is my bench is good with a head (what I mean is my #S are close to what other are getting and its dead nuts repeatable), it must be straighting out the air, I notice when I have a bad port design and the air is turbulent it does the same thing and the test pressure is very jumpy, kinda a good feature, u no u have a turbulent port right away, one thing I can say is if my bench shows improvements the clock at the end of the track and the gage on the dyno are in agreement , I think at some point im going to put a flow straightner in the pipe between the pitots (waffle cone) I think this may help,


Tue Sep 16, 2014 9:59 pm
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