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Wet Flow Test Pic...................AFR Chevy 235

General engine tech -- Drag Racing to Circle Track

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GregGood
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by GregGood »

Yeah, reversion could be aggravating it. These circle track engines usually have a tight lobe separation and are installed pretty far advanced, so reversion at the crack of the intake valve is a factor here probably.
ProPower engines
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by ProPower engines »

So all that said for the guys that wet flow test when the tests are done at varied valve lifts how does the full cycle compare to just opening the valve. The real world events the engine see's are much faster when the valves open and close. This has to create a different swirl efect in the chamber.

Can this be tested like a spintron checks valve train parts? When the valve is first opened the velosity is geater then at higher lifts creating different swirl patterns so would that not change the test as the valve is opened then closed and what is seen during these events as opossed to just having the valve open and looking at steady flow?
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by Cylinder Head Works Inc. »

Ha Greg , how are things in Texas??? Dave (ProPower)...........Spintron I have a story. People bar with me.......1993 I was attending Northern Alberta Statute of Technology (N.A.I.T.) for my 2 year out of 4 for Automotive Technician, the teacher we had was a Hot Rodder, Gear Head not your standard suit bow-tie teacher. The school made there own Spintron just to show student valve events, pushrods, lifter rotation, it was crude had its own oiling system and only ran at 1000 rpm but it worked for years. One day the teacher said " can you write your name on top of a piston??? with the engine rpm at 1000??? Well the first thing that came to everybody's mind was " are you NUTS" how are you going to do that??? The impact came out and the heads and valve train were gone.. flick the switch there is your piston at 1000 rpm.......who's first??? Nobody volunteered!!! He pasted around a new Sharpie marker with a fine tip just so we all could see the condition , and wrote" COOL" on top of the piston, that marker still had a sharp tip shape!!!!! When my turn was up, I was shocked......... like I wrote my name on a table, that piston had the effect of not even moving!!! 1000 rpm..... what about 8000rpm??

Having that experience..... what is the Air doing ????? The teacher described the inside of the cylinder as a Scientific Black Hole, something out of Star Trek with the RPM as its only governing Law to the intensity of the low pressure area created, he just wished it was big enough to suck in his Ex-Wife....

Having experienced that and trying to relate it to Air does the valve events play a role from off idle to 3000rpm yes............what about 7000 to 10000 or 22000 rpm in a F1 ??? do all the moving events even have a bearing in the air stream or is it just a column of Air with Weight ramming that Black Hole???

John Yelich
GregGood
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by GregGood »

Wished it was big enough to suck in his ex-wife. Ha Ha! Funny post.

There was a guy at one of the Superflow Conventions years ago that described in-cylinder mixture motion as *Chaos*. Very true.
ProPower engines
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by ProPower engines »

Well with all that said does anyone test this with the power stroke eliminated form the cycle?
It seems possible to better understand what all the port work is really doing.
By this I mean the ports are opened up to the point where we feel we get the best flow of air/fuel by the wet flow simulation but there is no testing done at any engine speed.
I think there is some bearing on the chaos in the cylinder that we may be overlooking. When the cam/valve actions are put in to the test does this not change what the engine really sees. By this I am saying the air/fuel that falls out of suspension during a wet flow test has to be way different then what happens when the engine is at a given speed.
Just trying to better understand why heads are ported the way they are when what apears to be a "good port design"
makes less power then what is said to be unconventional port shapes
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by GregGood »

There are guys that know what is really happening inside a cylinder, how the flow shears off the short turn, etc. OEM's and well funded teams with high speed cameras. Of course, those guys can't post it on the internet, otherwise.....you guessed it, their toolboxes get rolled out into the parking lot and they sued for breech of contract.

In that arena there is no marketing hype.
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by blaktopr »

With all being said which are only a few parts of the equasion, there are answers to all the questions. Each new discovery helps put the puzzle together. Even though there is "chaos", these events are not random. Everything follows one form or another of physics, no matter how fast or slow. Uncovering every variable helps to link everything together. Unfortunately for some of us, the ability to test on motors with multiple cars and dynos are not at our disposal. So instead we try to piece the physics together using steady state means and invision a 3D model to apply to the one shot deal. I find it fun and facinating.
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by eric's 327 »

I have tried to visualize the movement of air inside the port and its like the air is 'quivering' - at a very high frequency. When I read about pressure waves and wave tuning it is amazing that pressure waves can be reflecting back and forth so much in so little time. Then I wonder if the frequency, or vibration, is so fast that it could be helping keep fuel in suspension. I am reminded of what happens to water on an ultrasound transducer, the type they use for athletic injuries, sprained ankles and such. The water dances at lower settings and as the frequency is increased it breaks up as though it is beginning to boil and will vaporize at high enough frequencies. These units work in the .7-3.3 mega/hertz range. Someone who knows the math equations better may be able to calculate the frequency of the pressure waves in a port at various rpms.

Just a thought. This may be another way that port shape, obstructions, etc. may affect fuel atomization or separation.

Eric
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by Ron E »

eric's 327 wrote:I have tried to visualize the movement of air inside the port and its like the air is 'quivering' - at a very high frequency. When I read about pressure waves and wave tuning it is amazing that pressure waves can be reflecting back and forth so much in so little time. Then I wonder if the frequency, or vibration, is so fast that it could be helping keep fuel in suspension. I am reminded of what happens to water on an ultrasound transducer, the type they use for athletic injuries, sprained ankles and such. The water dances at lower settings and as the frequency is increased it breaks up as though it is beginning to boil and will vaporize at high enough frequencies. These units work in the .7-3.3 mega/hertz range. Someone who knows the math equations better may be able to calculate the frequency of the pressure waves in a port at various rpms.

Just a thought. This may be another way that port shape, obstructions, etc. may affect fuel atomization or separation.

Eric

So true. It can be overwhelming just entertaining what could be going on in there. Many of our methods seem hopelessly crude when put in such a context. They no doubt are. When our methods no longer make positive on-track results, we will know they're too crude.
I've been blown away just watching valve events happen in real time. I wonder how any of what we do can possibly matter.
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by Lockwire »

[quote="eric's 327"]I have tried to visualize the movement of air inside the port and its like the air is 'quivering' - at a very high frequency. When I read about pressure waves and wave tuning it is amazing that pressure waves can be reflecting back and forth so much in so little time. Then I wonder if the frequency, or vibration, is so fast that it could be helping keep fuel in suspension. I am reminded of what happens to water on an ultrasound transducer, the type they use for athletic injuries, sprained ankles and such. The water dances at lower settings and as the frequency is increased it breaks up as though it is beginning to boil and will vaporize at high enough frequencies. These units work in the .7-3.3 mega/hertz range. Someone who knows the math equations better may be able to calculate the frequency of the pressure waves in a port at various rpms.

Just a thought. This may be another way that port shape, obstructions, etc. may affect fuel atomization or separation.

The event to atomize is caused by Relitive shock and I think the Normal shock also has effect. I am not sure if the Oblique shock is there but it should be with the shape changes. These are caused by camshaft events and do move the fluid off of the runner walls and do help, it is not that easy to do effectively. The program I am familiar with worked pretty damn good. Stuart. :)
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by FastFourierTransportation »

Ron E wrote:So true. It can be overwhelming just entertaining what could be going on in there. Many of our methods seem hopelessly crude when put in such a context. They no doubt are. When our methods no longer make positive on-track results, we will know they're too crude.
I've been blown away just watching valve events happen in real time. I wonder how any of what we do can possibly matter.
I'm not nearly to the point of giving up just yet. While conventional modeling isn't bad, the latest modeling with compressibility effects factored into the CFD formula, even an F1's exhaust became predictable to within less than 5%. We've just gotta keep on learning. :)

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A theory without experiment is like a painter without sight, but an experiment with no theory is just a 4 year old with paint.

Practical Engineering is finding new and better ways to copy other people's designs.
Stuart lush
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by Stuart lush »

John,
I know this post is now 10 years old but wondered whether you had done any further development.
I am running 220 AFR Eliminator heads on a F5000 engine with Lucas mechanical injection and have found that I have very poor combustion, based on the burn pattern on the Pistons. Have built a spintron to test the Lucas metering units and although the uneven fuel distribution accounts for some of the problem it by no means explains the total situation.
My only conclusion is that the fuel dams on the Eliminator ports don't suit the 200 micron type fuel particle size typical of a Lucas injector running at about 150 psi.
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Re: Wet Flow Test Pic...................AFR Chevy 235

Post by BILL-C »

Stuart lush wrote: Wed Jan 06, 2021 3:39 pm John,
I know this post is now 10 years old but wondered whether you had done any further development.
I am running 220 AFR Eliminator heads on a F5000 engine with Lucas mechanical injection and have found that I have very poor combustion, based on the burn pattern on the Pistons. Have built a spintron to test the Lucas metering units and although the uneven fuel distribution accounts for some of the problem it by no means explains the total situation.
My only conclusion is that the fuel dams on the Eliminator ports don't suit the 200 micron type fuel particle size typical of a Lucas injector running at about 150 psi.
Have you installed lambda sensors in exhaust to monitor A/F ratio curve? It can be very difficult to achieve a linear fuel curve with mechanical stack injection over a broad rpm range. This is one of the reasons why methanol and it's wide tuning window is so popular with these systems.
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