Homemade Flowbench Idea!!( WILL IT WORK)???

cobrarwanab

cobrarwanab

Club Member
For a while now I have been thinking of this homemade flowbench idea for at home head porting. Here is a blueprint i made of it. The theory is listed below blueprint. Wondering What you guys think about it!

Homemadeflowbench.jpg


Here is the theory!
1. Get shop vac
2. Connect tube or pipe to suction port of a shop vac.
3. Using wood or plexi glass create 2 plates with a hole in the center.( Cut hole to the engine bore size the head will be installed on.)
4. Find a tube with a bore that matches your engine bore.
5. Sandwich bore tube between the 2 plates you made to create bore adapter.
6. Connect suction tube or hose to bore adapter.
7. 1/2 way between shop vac and bore adapter install vacuum gauge in-line with suction tube or hose.
8. Install Valves in head using cheep test springs that will over power the max vacuum pressure the shop vac can produce.
9. Using a square piece of card bord, cut a hole in the center of it the same size as the bore adapter.
10. Clamp head to bore adapter using cardboard as a "head gasket".
11. Clamp a dial indicator to the head with tip of indicator pushing on top of valve stem.

Now my theory is that with the head in stock condition, turn the shop vac on. using the dial indicator open the valve .100 and record the vacuum pressure the vac gague shows. Then open the valve .300 and record the data. Last, open the valve .500 and record the data.
Now port your head! Using the same valve opening steps you should get less vacuum pressure at the same amount of valve lift wright?

Example--

Before port job.
Valve open .100 = 4psi Vacuum
.300 = 3psi
.500 = 2psi

After port job
Valve open .100 = 3 1/2psi
.300 = 2 1/2psi
..500 = 1 1/2psi


Will it work?
 
I saw a guy do similar to see about air filters and his BMW...
sounds like it will work, I am a big fan of DIY/homemade tools
 
Here is the problem I see, big ports are lazy the increase of size can cause a loss of velocity.

Sorry, I am still tired and will think of more later. There is measuring equipment available to make the idea a little more plausable.

Here is a better design for you to look in to. http://www.diyporting.com/flowbench.html
 
Last edited:
cobrarwanab said:
For a while now I have been thinking of this homemade flowbench idea for at home head porting. Here is a blueprint i made of it. The theory is listed below blueprint. Wondering What you guys think about it!

Homemadeflowbench.jpg


Here is the theory!
1. Get shop vac
2. Connect tube or pipe to suction port of a shop vac.
3. Using wood or plexi glass create 2 plates with a hole in the center.( Cut hole to the engine bore size the head will be installed on.)
4. Find a tube with a bore that matches your engine bore.
5. Sandwich bore tube between the 2 plates you made to create bore adapter.
6. Connect suction tube or hose to bore adapter.
7. 1/2 way between shop vac and bore adapter install vacuum gauge in-line with suction tube or hose.
8. Install Valves in head using cheep test springs that will over power the max vacuum pressure the shop vac can produce.
9. Using a square piece of card bord, cut a hole in the center of it the same size as the bore adapter.
10. Clamp head to bore adapter using cardboard as a "head gasket".
11. Clamp a dial indicator to the head with tip of indicator pushing on top of valve stem.

Now my theory is that with the head in stock condition, turn the shop vac on. using the dial indicator open the valve .100 and record the vacuum pressure the vac gague shows. Then open the valve .300 and record the data. Last, open the valve .500 and record the data.
Now port your head! Using the same valve opening steps you should get less vacuum pressure at the same amount of valve lift wright?

Example--

Before port job.
Valve open .100 = 4psi Vacuum
.300 = 3psi
.500 = 2psi

After port job
Valve open .100 = 3 1/2psi
.300 = 2 1/2psi
..500 = 1 1/2psi


Will it work?
Click to expand...


In theory, yes it will. You'd need a pretty big shop vac to pull a reasonable CFM through there. If the flow is too low, the pressure variation might be hard to measure without a good manometer. If you wanted to get trick, use a MAP sensor to figure out the pressure, DIY EFI forums will have the pressure vs. voltage transfer function to make it useable. Two sensors will help you track port pressure depression vs. ambient pressure so your data is more useful in different climatic conditions.

If you want to get silly, then maybe some of the Megasquirt guys can help you instrument your setup... and datalog it. The electronics are easier to home-brew than the rest of it.

But that's getting ahead of the flow issue. If you are doing big heads, then 300+ cfm is required at ~28 in-Hg.. that's a lot of flow. You need a seriously big air mover to make that kind of flow.

I too am a big home-brew-tool kind of guy.. like my paint curing box.. :\

http://www.jalopyjournal.com/forum/showthread.php?t=156894

And my body swap apparatus. http://www.geocities.com/abbynrml94
 
I'd put a real flow meter in there. I don't know if a vaccuum gauge will really correlate to anything.

-Geoff
 
There are forums about making your own flowbench. Just type homemade flowbench into a search. And yes they can work very well too!
 
beertestr said:
I too am a big home-brew-tool kind of guy.. like my paint curing box.. :\

http://www.jalopyjournal.com/forum/showthread.php?t=156894

And my body swap apparatus. http://www.geocities.com/abbynrml94
Click to expand...

I like it!

And You guys convinced me! I am going to order kit B from www.mercdog.com for x-mas! When I receive the kit i will definitely post copies of the plans up for all motownens to see. $30.00 value for free!!! I learned to flow heads on a very similar machine. It was a superflow SF-600 at my collage. The one on mercdog.com is very similar. I will be sure to post when i receive the plans if anybody wants copies.
 

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Go for it man!
I guess a shop vac CAN pull the CFM required to get reasonable flow data.. ya learn something new everyday.

Personally I like the one on the DIY porting site, as it's solid state, and lets you export the data to Excel. But that's just me. If I can get the data into the laptop, I can plot, hmmm and hawww while sitting in a meeting.... it's easier to explain that having a web browser open to MM on your laptop in the conference room.... like well.. now. ;)

Great one more tool for me to think about buying. First, is the electrolytic de-rusting process for cleaning rusty old parts. That's another post.
 
I'm making one with a 10-71 superharger off an old detroit motor and a 8 hp ele motor, we are going to see how it works @ 68 inches of water wich will be around 13-18 lbs of vac !!
I think it will give a real time head flow number like if it was on a motor.
 
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