NOW YOU'VE DONE IT

[RRBD]

Well Bruce & Mouse, now look what you've done! My curiousity of an annubar based bench has gotten the best of me, now I've put my orifice type bench project on the back burner(it will be killer when I get it finished). Anyway...A few nights ago I started on a small annubar bench, almost exactly like "Digs" picture. The annubar is per D.T. specs and it is in the middle of a 24" long piece of 1-1/4" pvc and it goes into a 18x12x12 box(lxwxh)made of 1/2" mdf with a 3" opening adapter plate on the top. Now for the questions:1) I placed my static tap (.06 dia) one inch below and 90-deg from the axis of the annubar, do you have any pointers/rules of thumb for the grasshopper ? 2) I have to make an inclined manometer yet
and my testing has shown that this flow element will pull about 4-1/2" h20, so can I make one say 20" in length w/ a rise of 4-1/2" and then make a percent of flow scale for it?
I know I've made you cringe atleast twice(box & percent of flow scale) but just bear with me. Can this be done and maintain a good level of accuracy? Lastly should I put my static tap for depression in the flow element or in the box and where do you think it will work the best? I have some other questions too, but will go a little further to see if the answers come to me after I get this manometer stuff figured out.
This bench is soley made for a Briggs Intek 206 cylinder heads.
No, not a kart guy, I'm a snowmobile guy, building a tube chassis, i.f.s. snowmobile to race in an outlaw class.

Thanks in advance

Scott
Rad Rides By Dad

[bruce]

Ok, on static pressure taps here is what I have found to work best for me. I placed my static tap for my vertical manometer under my test plate in the plenum area as close to the top as posible this elminates any static error from velocity pickup of moving air. My plenum area is 6" dia PVC with a 5" test hole on top.

The static pickup for the inclined manometer is located in the test pipe 1/2" in front of the annubar and is a #52 drilled hole that is flush with the inside surface. So as you can see I have two seperate static pickups. I have found that on my bench to work best for accurate readings. Others may have found different. If you happen to go back in the archives to the old old forums you will see some extensive discussion on the trials and tribulations of this setup and how much testing was actually done before settling on what I now have.

As for the inclined manometer refer to previous post last week on inclined manometer design that about covers all that you need to figureout what should work for you. Your inclined manometer should be made so it will handle flows at the static depression you will be testing at. So if you will be testing at 10" the inclined needs to be able to read 100% of what your flow element will flow at that depression.

If you make your flow element replaceable you will be able to handle various ranges of testing. I base the flow element dia on the max dia of the part I am testing. I am using a 1-1/2" flow element now since I am doing alot of testing on parts in the 1.380 range.

[RRBD]

Thanks for the info Bruce. I went through the old forums and read up a little. I've read those old forums a few times now, but its hard remembering what is over there. I have another question though.... When making my annubar, i made it so only one end stuck out of the pvc, (drilled through one wall and only .060" into the opposite wall and offset my annubar hole pattern .060"so it is centered as well) Now, do you think it would be better to have the annubar go through both sides and connect each end to a "T" which in turn will go back to the inclined manometer? Also, How did you come to choose the size of the hole for the static pressure taps? I havent came across any info like that on the net....

Scott