One end of the hose is open to atmosphere and the other is taken down into the cabinet plenum below the test piece. The clear presence of furniture because an area, along with assortment is dominated by it may significantly influence the feeling that in with a furniture. The pressure ratio of a single fan blade is too low and cannot be used. It was 50 years since I performed my first cylinder-head flow test. Engine simulation applications each require their own specification. If you are building an engine for this or a similar class of racing, you have to ask yourself: Just how much money can I afford to give away to be competitive? If flow doubles, pressure goes up 4 times, therefore the scale on the inclined manometer must follow this non-linear rule, the scale is logarithmic. The curves starting high on the left and dropping toward the right show the test depression used for each of the two flow tests.
The bottom line is: Most racers have far more surplus expendable time than surplus expendable income! It comes fully instrumented with the Audie Technology electronics and computer software. Step 3: Open the 5-cfm orifice and note the depression when I was talking about machining this plate they were referred to as holes—now that we are flowing through them they are orifices. Exhaust port designs can either aid or hinder this. We hope this two-part article has helped in the understanding of flow bench testing and that the resources named herein will be useful, should you decide to test for airflow in your Pontiac. Here is a deeper look into flow bench testing and what you really need to know to have the right cylinder head and induction system set up for your engine. This was not because I had, even at the tender age of 15, figured out that a floating pressure drop was better; it was because I had no idea how else to do the job. The result is an engine that can achieve a volumetric efficiency well in excess of 100 percent.
The voltage input to the motor influences the amount of suction a vacuum cleaner or any electric air mover can produce. The valve heights are usually set in increments of. Using these tools, the velocity profile throughout the port can be mapped which gives insight into what the port is doing and what might be done to improve it. Correction factors are then applied during flow calculations. You will see why some heads make more power than others. Establishing the Numbers Okay, so you have built a budget flow bench. An uncontrolled vacuum source, such as a shop vac, pulls a large vacuum when the intake valve is closed and a progressively lesser vacuum as the intake is opened.
Just how this is done is our next subject. The head was equipped with a way to precisely open the valves. Step 7: When you have a curve for the intake, repeat the test but use the blower side of the vacuum cleaner and reverse the plate. For the most part, we flow the exhaust at 28 inches and live with the fact that it is not the best way to do things. One end of each manometer is connected to its respective plenum chamber while the other is open to the atmosphere. The coefficient may be based on the inner valve seat diameter, the outer valve head diameter, the port throat area or the valve open curtain area.
Not only can you use this plate to figure out how much flow is passing through a head on a floating depression bench, but you can also use it as a reference tool for a regular bench, such as a Superflow. As you can see from Figure 3. So what are the advantages? You must monitor the voltage at the motor input and make sure you test at the same voltage each time. Also we can see that it does not test the head at a standard pressure drop, as does almost every pro-built bench. Here is how it works.
The wooden blocks on the back wall are what the laminar flow grid rests on. Despite this ease, the majority of flow benches have never been calibrated and it throws data way off. Looking back on it many years later, I realized I should have continued flowing heads using this original method, instead of being swayed by convention. The inside edge of the fan holes and the main box holes are chamfered for maximum air flow I used a router, but could be filed by hand easily. In fact, SuperFlow resells Port Flow Analyzer software, Pitot tubes, swirl meter, and other accessories with its flow benches. Please see the page for some research reading, also keep an eye out for future products and tech articles with additional measurement tools and information. Regardless of the big difference between the red and green test depression curves, the Flow Quik still corrected the flow numbers to generate the nearly identical red and green flow curves seen here.
Several tests run under identical conditions showed readings spanning less than 1 percent. Temperature is measured at the test piece plenum and at the metering element plenum. Using this reading, correct the numbers up or down by whatever percentage of error is seen. The Port Flow Analyzer Pro version can combine cylinder head flow data with basic engine and cam specs to make Performance Estimates. This Tech Tip is From the Full Book,. Step 6: Get a couple of large sheets of graph paper, the larger the better.
Since the point was to see if a typical vacuum cleaner could be used, it was not part of the plan to get the biggest one we could find. Head Setup Although installing the test head on this bench was the same as with any other bench, there was a difference from, say, a SuperFlow bench: The Flow Quik does not directly sense and compensate for any extraneous leakage. Instead, I invested a lot of hours building my monster British Standards bench with all the corrections then known to man. Most flow testing is done at 10 and 28 inches of water pressure 2. Flow Performance flow bench kits employ the power of a personal computer to give the operator instant flow rate readings while flow testing. This is only an issue to the head designer, because my data has to be dead set accurate or otherwise all my other equations are in error. Pneumatic quick release fittings blue pipes in photo are used, but simple push in hose fittings would be fine.
Running the flow bench tests and conducting high-to-low floating pressure-drop tests creates the same pattern of flow-reducing portto-wall separations that occur during real-world running conditions. Overly large ports also contribute to fuel fall out. The average difference from 0. Such things as valve discharge coefficient and port velocities at various pre-determined points are calculated and displayed. For flows up to about 150 cfm, the 4-inch system works fine. Testing tips are beyond the scope of this paper! The only difference between what I do on this bench and what most others do is that I use a sliding scale of pressure drop, the same floating pressure drop I described earlier in this chapter. If you want to do more, consider purchasing the SuperFlow manual for a complete listing of flow bench math.