Help Opinions Plans

[hdwgfx]

This is a great site! Hello to everyone.

I have read tons of stuff on this forum, time to plan.

So far I'll probably set up blower box (Audie/PTS style) with 8 motors and 4 extra holes for future use. I will also make the blower box bolt in to the plenum box . Nothing is set in stone yet. I already have a never used Meriam 8" DP 40" scale and 2 36" vert Dwyer manometers.

At this time I only need to flow test @ 200 cfm @28" Test Pressure. (I'm only going to be doing street Harley Twin Cam heads, some of the best heads like this flow @168cfm @28. In the future I want to test at higher test pressures and cfms.


1) Is a single SEO capable of the accuracy like those who tested the pass around plates using my manomters?

(Larrycavan is doing this and I'm not doubting it forgive me if I have misquoted this) BUT from all the reading here I have done on this I have questions, backed by several of the mentors here. There is that "sweet spot" concerning SEO and manometers. So I'm not sure

2) How to convert my Meriam 8" DP 40" scale to read %scale, this guage is very expensive and well built, it should be sensitive if setup right. ( In the future I would like to test at higer test pressures) I think I have the right spreadsheet but need a detailed explanation. (maybe not lol)

I have read numerous SEO post here that indicate there must be enough Diff. Pressure to get accurate readings so this is a design parameters concerning the SEO diameter and how the Inclined DP guage is set up ?

((If this won't work is it really worth the time to build a muptiple orifice bench vs. just getting a pilot type FP or Audie digital setup?)

Bottom line question is can I build this bench with my Meriam manometer and a single SEO and get accuracy, repeatability, and read small modifications to the port???

3) How are the digital setups (FP, Audie, , PT etc.) getting around the above mentioned issues (having one rage to read from) ? Elec. Sensors much more sensitive? (I'm sure they are) Or is it just in the math? Even so the above condition still exist?

4)I would like to see some pics or diagrams of a multiple orifice stopper bench with the orifices on the outside oft the bench aka SF style, have searched but haven't found any?

Hope all this makes sense?
???

[Tony]

I cannot answer all your questions, but will make a partial attempt some of them.

Any orifice develops a pressure drop that increases with the square of the flow.
If flow doubles, the orifice pressure drop rises four times. If flow triples, the pressure increases nine times.

If your flow manometer is forty inches long, and that corresponds to 100% flow, 50% flow will be at one quarter scale (40/4) or ten inches.
33% percent flow will be at (40/9) or 4.44 inches along the scale.

The problem, is that the % flow scale becomes increasingly cramped and more difficult to read towards the low flow end of the range. A longer manometer scale certainly helps here, but for ease of reading there is a definite limit to how low a flow can be accurately read with any particular orifice size.

By measuring the pressure electronically, it is possible to read down to much smaller pressure increments than would be convenient to read with a fluid manometer. This too has its limits, but a single orifice size flow bench becomes practical.

Another way is to just use a simple fluid manometer and have a range of orifice sizes arranged in maybe 2:1 flow ranges. That way only the top 75 percent of the manometer scale will be used (50% to 100% flow on the flow scale)

For 2:1 flow ranges, the orifice size needs to increase by x 1.414 each range.

A range of orifice hole sizes will go up:
1.000 (flow range x1.0 CFM)
1.414 (flow range x2.00 CFM)
2.000 (flow range x4.00 CFM)
2.828 (flow range x8.00 CFM)
4.000 (flow range x16.0 CFM) and so on...........

The choice is yours between an electronic bench, or a simple manometer bench with a suitable range of measurement orifices. Either type is capable of excellent results.

One thing to be aware of. The air in an orifice bench should ideally flow through the test piece, then the orifice, then through the suction blower. That way the air temperature through the test piece and orifice will always be the same. It is the same air at the same temperature, so no temperature compensation is required.

If the air flow path is, test piece, air suction blower, orifice, things change dramatically. The air is significantly heated, because the air is used to cool the blower motors. This is fundamentally a bad idea.
As far as I know, nobody here has copied this design, once the undesirable temperature rise problem with it are understood.

The air coming out of the blower will be hot expanded less dense air, so the flow through the measurement orifice will need to be corrected for this temperature rise. Superflow stopper benches are like this. While changing ranges with a few rubber stoppers on the outside of the bench may be cheap and convenient, correcting for temperature is a real nuisance and adds the possibility of introducing error into the measurements.

Much better to place the measurement orifice INSIDE the bench, located before the air blower, and arrange some convenient way to change orifice size. Bruce's bench is like this, and it is the preferred way for accuracy.

In blow mode the air will be heated, but both orifice and test piece will get the same heated air, so this is not a problem.

[106-1194218389]

I have a bench built after Bruce's plans, an orifice plate bench. I have a 36" inclined manometer at 12" dp. I also have a Performance Trends Black Box hooked up. The functions you get with it and the PT Port Flow Analyzer software are Great! You also could go with the FP unit and use Larry C's software with is also fabulous. Electronics are the way to go but I will always have my water manometer as a back up for verifying. I have been testing with a range of 4 orifices. It is a pain to change all the time. So going on what Tony said I left just my largest orifice in, my range 4, and did a flow test back to back with one where I used all four orifices. With the electronics it will repeat between 1 single orifice and all four. Using the manometer it will not. You have to change orifices when using the manometer but not with the electronics, at least the PT black box. I do not have the other to verify but feel confident it will also work that way. Thanks Tony for making me look at this. It will now save me a ton of time flowing.

John

[larrycavan]

Those flow numbers for twin cam heads sound more like 10" of test pressure and certainly not some of the best flowing twin cam heads available......You need to rethink your flowbench needs.

One of my friends was into porting HD heads and his SF110 bench wouldn't cut it once they were ported properly.

IMO you want something that can handle 350CFM @28" for serious HD efforts.....

The manometer vs digital setup has been discussed so much that I'm not going to go too far down that road again. I'll say thins much on that. Either method works and work well. Analog or Digital. $ to $, from the initial planning stages, that means nothing has been purchased yet, Digital is the only way to go IMO.

Anyone asking my input on a bench setup, my answers are always standard.......orifice bench w/ digital guages.

You can't beat Bruces orifices & pitots.
Working without a pitot is a waste of time.

Look at the hard work John's put into his heads recently and all the information he's gathered from his pitot testing and digital setup........speaks for itself.



Edited By larrycavan on 1207619586

[hdwgfx]

yes my bad on the flow numbers that is something @10wc tp, I never knew I was taking a test

larry did you notice how many motors I am planning to start my build with? way more than I need!

I didn't ask anything about pilot tubes or bruce's seo's

I'm not new to this stuff, but haven't worked with it since the 90's and I'm just trying to get back into it..........

did you address any question I asked???

[larrycavan]

[Tony]

[DWC]

There is just no pleasing some people!

I for one very much appreciate what Bruce has done here and to all you guys that are contributing with such valuable and intelligent information dont let one ungrateful individual get under your skin. One of the things great about this forum is the polite exchange of information between people with like interests.

DWC.

[hdwgfx]

Larry I'm sorry, I just felt you jumped on me. I have a lot of bad things going on in my life. (I know that's not an excuse)

I am not ungrateful for this site or for any of the very talented, tenacious people that are members here including you. I bought Bruce's plans as a donation knowing that I had already read on this site most of what could have even be in his plans....

To Larry and any others that may feel offended by my reply to you, I hope you can accept my apology. I was wrong......

[larrycavan]

David,

'nuff said. Move on with your support needs. You'll get the help you need if you're open to receiving it.

Larry C

[racehead-1]

[color=#000000]We all owe Bruce a HUGE..... without him there would be no FORUM. TRUE...

In my opinion Bruce has taken the black magic out of the flowbench. Like he says, his pitot bench is not one of the best looking benches but it works good. I think he was clever in making his bench that way, one of the reason is that you don

[bruce]

Ok, I'll admit that Bruce guy is alright I guess . . . BUT he can't run this forum without the help of "regulars" who take the time out of their schedules to answer the questions that get posted!!! I could in no way answer every question that gets posted, heck I can't answer half of them, I'm still learning myself. The "regulars" are the ones who need the credit, I just came up with the idea of having a forum many years ago.

The forum is made up of a "collective knowledge" and without that collective knowledge we'd all be going in different directions, we all come together to solve the problems, sometimes we do butt heads but that's life . . .

[racehead-1]

[color=#000000]That

[thomasvaught-1]

I personally post on several forums on the internet. This forum has to be one of the best as there is almost never any bickering going on. The members try and help each other understand basic flow bench construction for the different measurement types.

The members also identify the best places to get specific parts: Check valves, motors, relays, manometers, port holes, etc.

Some members come up with detailed spreadsheets to calculate orifice diameters, create manometer scales, properly wire the benches, etc.

Quite a TEAM EFFORT.

I am proud to be a part of this group and appreciate all of the information I have picked up over the time I have been here.

JMO

Tom Vaught

[hdwgfx]

Just for reference , some Harley Twin Cam flow #'s



Twin Cam Head Flow Characteristics
Unported Stock twin cam head 1.840 intake 186.2 cfm
Louthan ported stock twin with 1.90 intake 220.4 cfm
Louthan ported stock twin with 1.94 intake 226.7 cfm
Unported Screamin Eagle twin cam 218.8 cfm
Louthan ported Screamin Eagle twin cam 247.6 cfm
Jerry Branch ported stock twin with 1.94 intake 221.9 cfm
.500 valve lift CFM at 28 inches