It's finally working! - Details of new bench

[115-1172523331]

[color=#000000]This is a lengthy submission, but I hope it is worthwhile to some other

[bruce]

Doug,

Excellent writeup!!

Any chance of getting some closeup pics of how you built your inclined and vertical manometers?

[larrycavan]

Nice job on the bench.

[49-1183904562]

Doug,

Great to see you are up and running, it looks great.

Rick

[115-1172523331]

[color=#000000]Hi Bruce and Larry, Thanks for the kind words! I was going to post this in the Spreadsheet Section as I have some issues with the corrections required on the inclined manometer, but it works here as well. I

[bruce]

Doug, thanks for the extra info!!

[larrycavan]

Doug,

Generally, the inclined is a fixed position setup. That's quite the slick way you did yours but I'm not sure why you made it adjustable. What's the thinking behind that?

Larry

[ThomasVaught]

Typically when you have different angled inclined manometers you get more sensitivity out of the lower "rise over run" positions for the same scale length. Once the scale relationship is determined for any given "rise" you can use the same scale and a computer to figure out the actual reading. A good example would be the approximate 13.5" of water giving 50% more "range" vs the same length scale at the 6" "range." By the way, as I looked at how you did the well mounting, that is a slick piece of engineering.

Just my thoughts, Larry

Tom V.

[115-1172523331]

Tom, Thanks for the description and the engineering comment!

Larry, Rick Szajna (aka 1960fhl) and I spent some time communicating about this aspect of my bench. Since my engines are so small (100cc, 50-60 cfm@max valve lift of 0.250 inches), what a "normal" inclined might see as noise level could be a significant change. In looking for maximum sensitivity, I opted to go variable. Notice also that I am able to change from the 1-1/2 inch flow element to 1-1/4 or even 1 to further push this area if needed. I had started with a 2 inch (I was using a friend's AudieTech unit previously), but when I did the numbers, I realized that 2 in was too big.

Also, once I made the variable commitment, it was almost as easy to higher and build future capability into the bench (with added motors). When I post the spreadsheet, it may give you a better feel for my problem. Hopefully, that will be tomorrow. Thanks for the interest! -- Doug

PS - Since I am posting anyway, I've added a detail of the upper end of the inclined and the adjusting "mechanism" as described in the initial post.

[bruce]

Doug, I can understand your plight on low flow. Most of my testing is done on valve diameters less than 1.375" with a limit of .330 lift on the cam. I run one of my 1.5" flow elements on my bench with the FP1. I ran into the same thing you did with the water gage. I had one that was 36" long to give me a finer resolution.

It has now been hacked up to use as a 24" long incline manometer for prototyping on my PTS Flowbench build.

I like the idea of the moving well!



Edited By bruce on 1200446422

[115-1172523331]

Just so you know, most of the people here have valves bigger than my bore. With a 3mm overbore, I am at 52mm (2.047in) and my valves are 27mm (1.063 inches) and 24mm (.945 inches) (again oversize). The engine is a HEMI and at 27.5mm, the valves bump during overlap. The cam was .150 inches max lift but has been builtup and reground to .200 (which required relieving the case). Rocker arm ratio is 1.25. It all sounds small, but falls right into the Chrysler hemi specs, just scale it up and add 7 more like it. The best thing about it (other than the minimal cost of racing) is: "You meet the nicest people on a Honda!" -- Doug

Again adding a detail pic, here is the vertical manometer showing the 28" depression at the flow showing on the earlier pic. The small piece of blue tape shows me where 28" is in cm.

[blown alcohol]

Very nice job on the bench...your craftsmanship is superb!!!

Enjoy your new machine!

Jeff

[115-1172523331]

Here's one of the latest "lessons Learned". While working on the spreadsheet for this bench, I discovered that there were a couple of geometry corrections to be incorporated for the actual "rise" on the Variable Inclined Manometer. This is due to the placement of the scale and locating pin relative to the pivot. Although the math to complete these corrections is straight forward, I am in the process of revising the manometer to eliminate them.

In the current configuration, the lower end of the scale is raised when the incline (rise) is changed due to the offset from the pivot. This is a simple ratio of offset to scale length correction.

At the other end, I can best explain it as a "virtual" change in offset with change in rise. As the angle (or rise) is increased, the offset is not vertical and, therefore, the reference point on the scale does not rise as far as the locating pin (the way I set up my locating holes). Again it's a (fairly) simple geometry correction.

Simple as they are, I am going to change the design to eliminate them. To get rid of the lower end correction, the Zero point on the scale will be moved to the center of the pivot. This will require a "cut and paste" on the well mount, but it was easy on paper. On the other end, I will also get rid of the offset, and put the locating pin on the upper edge of the scale "reference line". This may require that I buy another metric ruler to cut up, but they were less than $4. That should make the geometry "problem" go-away and simplify setup (and the spreadsheet). For those of you who are interested, the spreadsheet (as is) is posted in the section for spreadsheets. -- Doug

Pics / sketches are available if so desired.

[larrycavan]

Doug,

Makes perfect sense. Electronics tends to be more sensative and eliminates that problem. At least my FP1 is like that. I can get numbers at low lifts through a 2" orifice that are dam near identical to an SF110 on the low range. I was quite impressed with that when I first began testing using electronics. Now I'm spoiled and take it for granted.

Larry

[86rocco1]

Hi Doug,
If you want to try electronic pressure measurement, let me know. I've got a nice that I'm not using for anything, it's + 5" wc range, 0-5 vdc output.