Orifice flowbench project. - Project to winter 2005

[68Corvette]

Hello.

I am starting to build MSD style flowbench.
This flowbech is uset mostly for 4-banger heads and V8 SB and BB head (~100cmf-400cmf@28")

I allready contacted mercdog about "SET B", but i have been reading that all their parts arent as good as they should be.

Does someone have good photos and dimensions about wood parts?
Is the old HOT ROD "Build your own flow bech" still technically good at these days? Or should i make some changes to it to get better repeatability.

I HAVE been reading many nights this forum and finally getting some picture how flowbench works.
There haven't all tought been any actual dimensions about plenum sizes etc..

Lets see how this projekt starts with your help.
Thanks =)

Marko Pirkonen
Finland

[larrycavan]

Hi Marko,

Yes, there are some modifications you should consider before you begin assembling the bench. I'll pass along the mods I'd make.

First thing to consider is that design of the flowdisk as it is in the article makes it prone to leakage between ranges, especiall on exhaust flow. I'm uploading a picture of the flowdisk setup on a bench called a Clo-Flow. It has what I consider to be a setup that should seal the orifice ranges.

#2 - You'll want to install a baffel system to prevent direct blasts of air on the flowdisk. I'd do it above and below the disk if I was starting from scratch. There are drawings posted in the orifice bench section. Look for MSD or mods or design posts.

#3, I'd incorporate [already did on mine] a top section like the SF300/600 series units have on the top of the bench. The baffel would go between that top section and the flowdisk.

#4, decide up front how much air you're going to need to pull through the unit before you settle on flowdisk range sizes. In other words, don't make holes bigger than you need or have the vacuum power to use.

#5, the thickness of the board that your flow disk sets on can have a definite affect on your exhaust flow numbers. Look at the clo-flow photo closely. The guy that owns it had a problem with his exhaust numbers always being low on his bench. The board is too probably too thick.

#6, pretty much everything you need to make the project a success is here on Bruce's board [except the materials of course]. Need a calibration plate...talk to Bruce...want digital manometers....talk to John [aka Mouse]..FP1 setup.

Best Regards
Larry

[Terry_Zakis]

Hello Larry,

I don't think that the supporting board being too thick is root cause of the low readings, but rather that the hole cut in the supporting board looks like it's the same diameter as the larger range orifice. So when it's operated, it would almost be like having an orifice plate that was 1.5 inches thick. The opening in the supporting board for an orifice plate should always be larger than the biggest size orifice in the disc. Just something to consider.

Terry Terezakis
Western Massachusetts, USA

[larrycavan]

Hi Terry

Yes, I agree. In this case however, the intake flow was comparable with superflow units while the exhaust flow was down. Logically, the thickness of the orifice should impact both directions if the Cd on each side is equal. To an extent, the airflow is passing through two orifices on this unit.

I believe all properties of the airflow path to through the orifice are influenced by the ratio of the opening under the orifice to the orifice itself and the shape of the opening [especially on exhaust function with this type of bench].

Ideally, I'm beginning to think the flowdisk might be best located, sandwiched in between two equally thick boards with identical openings on both sides for both sealing purposes and flow Cd. That may be overstating the case somewhat. Only a beta build would yield the results.

Larry

[larrycavan]

Here's bit closer picture.

[Mousehouse1]

Marko if you decide to use the Mercdog plans send me an email. You can find it in my profile. I am in the process of finishing mine and there are several parts you should upgrade. I would buy the plans and software. You should be able to make everything else.

[gofaster]

Mousehouse,
I am also starting a project based on Mercdog plans. Any tips would be appreciated. I have ten ametek vac motors. I'm going to use a Dwyer 60" vertical manometer to monitor depression, Dwyer 246 Durablock inclined manometer, and another 60" vertical for pitot tube testing. The Dwyer items are a natural choice because I live a few miles from their Michigan City facility.
For depression control, data acquisition, and software, I'm using Audie's Flow Pro components.



I am currently running a SF 110, and I want to take my flow testing to a higher depression.

Any tips or suggestions?

[Maxflow]

Hi every one. I dug up this old thread, because I,m in the beginning stages of assembly of A mercdog design bench.
What needs to be changed or mod. from the original plans.

At this point I have all the details made. The flow disk is
already mounted to the board. The bottom, front & sides
are assembled. The baffles I read about at the begining of
the thread, where would they go and what size and shape should they be. The added top section how big should it be. What changes do I need to make to the flow disk set up.
I did not quite under stand what the pictures were showing. It looked like a fixed orfice plate. Would I be better of making it a single direction of flow rather than two direction. Any advise would be help full.
Thanks.

[68Corvette]

Seems like my winter project stretched a little.. maby that why its mentioned as project, as they allways do =)

I made a new topic to here:

as I did not realize this topic was still alive.. though no one has commented anything in one week.

Today I actually did something, I bought 2 meters of 3" pvc drainpipe for check valves

and 2 meters of 6.3" pvc pipe for connecting pressure side of motor chamber to MSD pressure chamber.
The idea is to get more volue to orifice chambers while keeping the box height reasonable by making motor box by the side of orifice & valve boxes.

I made some really initial draft drawings, they might still be a little confusing, as angles of orifice and valve plates need to be redefined (propably) and I don't yet have angle ruler for the purpose..
Also scale is from freehand, but I guess you get the idea.


3" cutted pieses are still waiting for rubber / pvc flaps as I am testing that the glue is really working.

Orifices... after reading forum a lot I still kinda like the rotating orifice type.
Maby I'm just slow learning.
I have been thinking about making three layer steel sandwitch where orifice plate would be middle and two steel plates would surround it with large enough hole to support largest orifice.. maby 4.5"?
Orifice sizes that I am thinking (currently)
1" for leak testing.
2" for most of the heads I test (flowing with 32" depression of h20) and keeping % in reasonable area.
2.5" for huge heads (flowing with 32")
4" for testing carbs & throttle bodies.

With this setup I could calibrate all four ranges to suck and 2" & 2.5" to blow.

..still thinking about motors, there are some good choices from europe and some good from US.
I'm waiting untill vacation time is over in here and then start calling dor prices from local markets.

Wood materials would propably be 1" thick MDF.
Is it too thick (heavy) for no purpose.

[SWR]

For leak cfm I'd run a smaller one.. I have a 10 cfm one,which is about 3/8" dia.. And,I'd go NO LESS than 1" thick on the MDF.. the pressures make considerable force when applied to any large area..

[68Corvette]

Thanks SWR.
I have been stuggling with the desing:
- Motor control vs. valve
- Rotating orifice vs. fixed
- Flow box overall desing

After buying the PTS plan set I am pretty confident that that is the proper way to proceed.. its just so plain and simple with big boxes around orifice plate etc.

So I better continue this topic on "PTS Flowbench Plans discussion area".

[106-1194218389]

I like the fixed plate design myself. I am trying to design a faster way to change the orifices. I am looking at a way similar to the flow direction plate in the motor side. Have each orifice a slider plate with an external control to clamp the orifice plate to seal it.

John

[Tony]

[jakesportingservice]