High flow numbers

[Mousehouse1]

I haven't been able to get my bench to duplicate or flow a head that I know is in the 370cfm range. I can't get it to flow over 280 on my bench.

What would be some of the reasons for this? I know leaks would be one. What would some others be? I am going to have some time this week to mess with the bench and don't want to waste it looking in the wrong direction.

The low lift numbers (under 400) are close but after that they don't increase much no matter how far I open the valve on the head.

[Pesty]

Gday Mousehouse1,

By using Root Cause Analysis i would suggest
1. check orifice plate for blockage.
2. check that all motors required to get flow are functioning.
3. If possible remove duct work to ensure that nothing has been sucked into it and blocking the passage in some way.
For example there may have been a rag inside the port and has been sucked down into the ductwork.
4. check the location of your pressure sensors.
5. check the thread on the "bowls" that determine flow (inlet to outlet) as they may have seated in the holes and when you operate the handle to open them all you are doing is turning the thread and not moving the bowls off their seats.
6. Are the side ports of the bench open.
7. check the orifice plate for corerect flow numbers.

These are just some of the things i would check the other guys may have other ideas.

Pesty

[gofaster]

What I would try first is to make a 2.250" test orifice plate. Doesn't need to be fancy, just use a piece of 1/8 plate, cut a hole with a hole saw, and hit the faces on a belt sander (If you don't have a belt sander, just tack some sandpaper to a flat board and smooth the faces) and try to leave sharp square edges around the hole. Tape it over your bench opening so it doesn't leak around the edges. That test orifice should flow very close to 363.2 cfm @ 28" of depression.
If that proves out, then I would be suspect of the numbers that came with the head. (Maybe the original test on another bench was run with a spark plug left out, or some other oversight. It's happened often enough, people get in a hurry or are distracted by something.)
If it doesn't check out, then maybe there are internal leaks in your bench, or your bench just won't pull that much cfm at 28".
You could try to test your test orifice at a lower depression and convert the results to see if that is the issue.
Handy calculator link:


If it points to an internal leak, my only experience with that had me chasing my depression. It would not hold steady and I had to keep fiddling with the flow valves. In that case, the internal leak was getting worse the longer I played with it.
Hope some of this may help you

[larrycavan]

[Mousehouse1]

Thanks guys. I will make another test plate and flow it. I know the heads flow 370cfm but not on my bench. I have had them checked locally on a superflow 600 bench. I have 10 16-1234 motors in my bench. I don't see it being a problem flowing over 400cfm.

The bench holds 28" and doesn't move up or down more then +/- .1.

I know I have a leak between the head and the head fixture. I am trying to find a better way of sealing the head against the fixture. I also have a leak in the top of the side doors. That will be solved when I get the deck plates installed.

I will try and pull the valve out of the head and see what it does. I don't have a intake radius right now. I have been using clay and the bench keeps trying to pull it through the port. I need to finish the one I am making or buy one so I can rule that out.

Again I haven't had a lot of time to spend in front of the bench. I should be able to rule out a lot of this stuff when I get more time to mess with it.

What is everyone using to seal a cylinder head to the head fixture?

[Mousehouse1]

One more thing I thought of. When I made my orifice plate I cleaned up the inside of the holes and deburred the top edges. I wonder if that is part of my problem? I have since found out that I am suppose to leave the inside edges rough and just deburr the top and bottom of the orifice plate.

Is there a way of making a orifice plate type system? I would like to have several orifice plates that are 4x4, 5x5 or 6x6 in size (whatever it takes)with the hole in the middle. Make it to where the plates slide in and out of the bench to change ranges. Is this possible?

How would you do your orifice style bench if you were going to replace the orifice disk?

I am going to install another deck plate in the orifice disk area of the side panel. This should allow me to check and see if I have any leaks around the orifice disk. It would also allow me to change the orifice plates if I can figure out how to make it work.

[cspeier]

Martin

Make 100% sure your on the correct mode. I've done before. Been on the #8 orifice but had the FP on a different setting. I've found, the low numbers can be close, but the highs are in the weeds.

I put a head gasket centered over the fixture and tape it. I make sure the head bolt holes line up. I use three big C-clamps to hold it down. Then before I do anything, I put the FP to a small hole setting and check for leakage. I write this number down. If it's high, I re-adjust the clamps to get a better seal.

I turn the FP back to a large hole setting and flow the head. I then subtract the leaking from all the number. This is my actual flow.

What I do to see if my machine has leakage is put a no-hole plate on the bench. I have also c-clamped it to the head fixture. I also put clay around the lip of the plate. I turn the machine on and see what it shows.

As far as going over 28" you also might be sucking air from your fittings. I went thru that. It got worse as the cfm got higher. I put silicone on the brass and slipped the tubes on and wire tie it.

Chad

[larrycavan]

[gofaster]

[quote="Mousehouse1"]I know I have a leak between the head and the head fixture. I am trying to find a better way of sealing the head against the fixture

What is everyone using to seal a cylinder head to the head fixture?
.........................

I seal the head to the test cylinder with a head gasket RTV'ed to the cylinder and coated on top with vaseline. I also grease the valve stems with vaseline to prevent a leak there. I use a purpose built ratchet clamp to seat the head tightly against the gasket.
I hope you figure out what is going on with your bench, and that it's nothing critical.

P.S. At he expense of sounding foolish...How do you put your QUOTE from a previous post in the little white box?

[Mousehouse1]

See the little quote icon in the upper right corner of the post? That is how it is done.

Do you by chance have any pictures of your head fixture with the head attached gofaster?

I was told that the brass tubes going into the bench should have holes in them. What size and how many?

[Mousehouse1]

Just got a chance to play with the bench a little. I put duct tape around the orifice disk to rule it out if it had a leak. Then I made a 2.30" hole (it started as a 2.25" hole and measured 2.30 when I was finished cutting) and it flowed 295cfm with all 10 motors on at 28" using the biggest hole (3.068").

After that I decided to do a leak test. I taped off the 2.30" hole and moved the orifice disk to the 1.270" hole. At 28" the FP1 was reading 70-75cfm. The one thing I did notice was the plexi-glass piece that I made for the front of the bench was moving upwards toward the top of the bench as I turned on more motors. With 4 motors on I had 70-75cfm at 28" like stated above. I moved a candle around the front panel and it didn't seem to have any leaks but I don't think it should move like that.

Where else can I look for leaks?

I have ruled out the orifice plate, FP1 hoses connections, back panel and exhaust side door. Everything else is either glued or siliconed in place.

[gofaster]

Mousehouse1,
here's a picture of my clamping fixture.

[gofaster]

I tried again, and the file is too big.

[Mousehouse1]

Gofaster email it to me if you get a chance.

[Mouse]

Martin,

You may want to relocate your pressure taps. Their current location may be a bad place. If relocating your pressure taps changes things, you may have some turbulence problems internally.

John