Has anyone designed/built a positive pressure ...

[thomasvaught-1]

Quote by me:

"With the "High Dollar" bench we now just program in all of the test pressures mentioned above and it runs a sweep of all of them for each valve lift point. LOL!"

We also do the L/D and the .050" incremental test points. Trying to make everybody happy.


The 25" test pressure mentioned is for the SF 300, 600, and 1200 benches. I do not know the number for the variable floating orifice in the 1020 bench.

Tom V.

[bruce]

[86rocco1]

With big pressure like that, I'd suggest anything with flat sides is out. All of the bits and pieces should probably look like either pipes or pressure vessels. And maybe instead of orifices, something with a higher cd like nozzles. The advantages of that being less total pressure drop through the device, this bench is going to consume MASSIVE amounts of power, every little bit helps. And a nozzle could be made more structurally stable and less prone to wear than an orifice in a plate.

[thomasvaught-1]

I agree with 86rocco1, Our Thick 3/8" plate orifice tank is made in a tube shape with an entrance cone on the front of the tank and a rounded dome shape on the rear. The "access hole" to change the orifices resembles a Submarine Hatch you see in all of the movies.

This is a Nozzle Bench built by a friend of mine but Very Low test pressures involves.



Look under design concept.

You would have to make the tank much stronger. You would mount the head or tested part on the right side of the bench.
The blower would be a very high capacity supercharger with a lot of horsepower to drive it, Like an automobile engine.

Just giving you ideas vs telling you your idea is a bad one.

Tom V.

[larrycavan]

[thomasvaught-1]

Well, Larry, the benches we have are typically in a sound proof room with an air lock so that should tell you something. Our bench is automated so once the head is on the test stand and the actuators for valve lift are correctly installed and calibrated, the Test Engineer/ technicial running the test programs the test points, pushes the button, and can walk out of the room. The data is recorded and can be analysed when the Technician returns.

I personally have seen no differences between the 10 inch point and the 67-68" test point for comparing numbers.

At one time we had a situation where when we would switch from one range to another range, they would not match perfectly (highest number on the low range vs lowest number on the high range) but I suggested that we check all of the pneumatic connections for the sensors and once
that was done the numbers were right on line.

I would suggest the same for our members with their benches.
Super Flow uses a rotating disc to switch from intake to exhaust flow for the manometers. This disc can wear over time and the readings can vary as the leakage gets larger. Most would never notice the change unless they had a "Standard Head" that that they used over a period of years for quality checks. You need to do a full head sweep vs checking one point as the multiple point sweep will pick out the leakage change.

Tom V.

[Farrell Vaughan]

Well guys, after reading some of your responces to my post it became really apparent that the current state of "mind reading" in our world is not up to snuff. In all honesty, it was my fault for the lack of info provided. At no time did I envision this as being a particle board type enclosre, rather it will most probably be a series of food grade stainless conduits and chambers. The only wood used would be for the "bench" aspect of this flow bench.

It seems that my air source is a tad suspect though. It being a screw blower off of a Mustang Cobra. On a running engine, it would produce just around 20 psi boost. It was easy to turn unlike our old stripped 14-71's, so I figured it wouldn't take too much power to drive. The idea of a motorcycle engine did come up, but we do have neighbors in the complex. I've found a 20 hp electric motor that will spin 3600 rpm, so pulleying the blower to give us 20 psi to one steady state cylinder, doesn't seem to unrealistic.

Recently I've discovered a line of insertable hot wire flow meters that could possibly do away with the orifice plates. I don''t really know how finite, accurate or repeatable these instruments are. Anyone know?

One last thing, it seems alot of you got a chuckle out of my 20 to 30 psi for saftey reasons comment. Laugh at me , laugh with me, at least I made you laugh. I to was snickering to myself at your responces. I remember preasure testing the first intake manifold I built for a drag race Cummins motor. Long story short, I lost a seam at 85 psi. Too bad, it had to live with 130 psi. I don't hear as well on the right side anymore.

thanks for your indulgence,
Farrell

[bruce]

[bruce]

::liability mode on::

Also let me add . . . this posting is in the general area and as such is open for anyone who surfs in here (the general area is open to the public) so that being said I would not want someone with zero knowledge to go out and start playing with high pressures and not know the seriousness of what could happen! I am not inferring your post was taken that way by myself. I'm merely making a post (hijacking) here as it presents a good opportunity for me to show why the lurkers should join this forum to see the rest of the forum information which the general public can not see.

We have had forum members implode/explode benches at far lower levels and I for one would not want someone to "assume" a partical board bench could be used for serious pressure testing.

::liability mode off::

[Tony]

Bruce is right about safety.

Someone just starting out building their very first flow bench may have no natural intuitive fear of how very powerful even quite low air pressure can be when acting over a very large surface area. This not only applies to the bench itself, but also the whole room or building in which the bench is located.

If you are drawing or venting air from outside the test room, (to reduce noise) only a very few inches of air pressure difference can be enough to burst a wall or rupture a ceiling fairly readily. Take care guys.

Most people only need to have this danger pointed out to them once, then they go "oh shit, you are right". And forever more, they respect the problem. But it is something we should keep repeating here on the Forum to save newcomers from an unexpected disaster.

I could tell you about a guy that exploded the side out of a freshly built race engine when he decided to pressure test the whole cooling system with over 100 psi of shop air. The newly replaced welsh plugs did not leak, but it blew a large hole right out of the side of the cast iron engine block. He was leaning right over the engine at the time, looking for leaks when it blew, but was lucky to avoid serious injury. It gave him one heck of a fright and cost him an engine. He was lucky.

[thomasvaught-1]

Welcome Farrell Vaughan, my name is Tom VAUGHT (pretty close on the spelling).

I do Boosting for a living for the Ford Motor Company at their Research Center. I have been playing with boosted engines for 34 years now, 30 years at Ford.

I believe your 20 psi number on the Mustang Cobra. That was one of the projects I worked on. I assume you are talking about the 2003 Cobra that originally had the Eaton unit on it. So who made the screw blower you want to use?

My comments in previous posts were based on actual equipment we have used at Ford. I would like to understand more about what you feel the benefits of testing a single cylinder at 20 psi when as you know we rarely run single cylinder engines in competition vs multi-cylinder engines. I do a lot of single cylinder work at Ford but it is to design and refine combustion events.

As far as your Hot Wire question goes. I have built Hot wire benches in the past and the current distribution bench I use at Ford uses that technology. You need to get a really solid Transfer Function, based on bench data, and potentially inter-cooling for the test pipe as the curve is only good for a given amount of heat. This is why most Hot Wire mass air meters are on the inlet side of the system.

I too have ripped an intake manifold open but it was only at 44 psi of boost on a 200+ mph Pro Mod GTO. Not a good situation.

Please continue posting and we will enjoy your comments.

Tom Vaught

ps Here is a link to a little 2071 HP dyno test (With a Carb)

[Farrell Vaughan]

Tom, that is some serious power that motor makes. I would love to see the metering blocks and discharge nozzles on that carb. Hilborn style fuel pump with a bypass? I would have never have thought to use a carb in an application requiring 8-900 lbs of fuel an hour. On to the bench though. I've decided to use an Eaton blower not the Whipple I had originally intended to use. Cost cutting measures. My reason for wanting to test at boost are this. Many of the two valve heads we work on are of the high swirl variety. I first saw these in the mid eighties on Japanese gas engines. To get these ports to flow any air you need to take as much of the spiral out of the bowl as possible without hitting water. Since the boost levels are much higher than intended from the factory, lack of swirl doesn't seem to be an issue. I've also played with biasing the Heron style chamber to produce piston induced charge motion. I didn't understand your coment on needing to get a really "solid transfer function" when using hot wire flow sensors. If your interested I could send you some pictures of the turbo system I built for the race truck that I exploded the manifold on. You might find it interesting. Thanks for taking the time to comment on my post.

[FPV_GTp]

There is a wealth of information in this thread AND a vast amount of knowledgeable people.

Einstein was thought to be a crazy scientist and not to mention many other great thinkers of the past and present world.

One mans testing method is another mans learn curve , there is no right or wrong it is all about science.

Guys great postings and good to see it shared with other people on the forum.

Farrell Vaughan can I get a copy of those pictures please.

And that 2000 HP Blow Through Carb Testing youtube clip awesome vision.

Steve Morris http://au.youtube.com/watch?v=ZtaYdzoCz ... re=related