{"id":1130,"date":"2013-04-28T16:48:47","date_gmt":"2013-04-28T20:48:47","guid":{"rendered":"http:\/\/mewagner.com\/?page_id=1130"},"modified":"2025-06-01T13:30:06","modified_gmt":"2025-06-01T17:30:06","slug":"pcv-valve-flow-test-shootout","status":"publish","type":"post","link":"https:\/\/mewagner.com\/?p=1130","title":{"rendered":"High Performance PCV Valve Shootout – Flow Test Results"},"content":{"rendered":"

M\/E Wagner recently developed a data acquisition system that logs realtime crankcase pressure measurements, enabling us to do a comparison of several stock PCV valves with our Dual Flow\u00ae<\/sup> PCV valve.<\/p>\n

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All data was logged with a laptop during actual on-highway driving.\u00a0 Driving conditions were varied from light, moderate to heavy throttle identically for each test.\u00a0 The test route was a 17 mile round trip consisting of uphill, downhill and flat sections of road.\u00a0 The same test was performed twice for each valve, and the results averaged.\u00a0 Each valve showed excellent consistency from Test 1 to Test 2, validating the accuracy of the testing method.\u00a0 Full testing details can be seen below.<\/p>\n

TESTING RESULTS – SUMMARY
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The most basic metric of evaluating a PCV valve’s performance is how effectively it evacuates the crankcase of blowby under a variety of driving conditions.\u00a0 When a PCV valve flows the proper amount of air, it will evacuate blowby from the crankcase and draw fresh air into the crankcase through the valve cover breather\u00a0 During this condition, a slight vacuum is present in the crankcase.<\/strong><\/em>\u00a0 This slight vacuum is also helpful in preventing oil leaks.<\/p>\n

When the engine produces more blowby than the PCV valve can handle, the blowby gasses find their way out through the valve cover breather.\u00a0 In this condition, the crankcase is under a slight amount of pressure<\/strong><\/em>,<\/strong> and no fresh air is drawn into the crankcase.\u00a0 This pressure is detrimental for oil leaks, but also indicates a more serious problem is present, the crankcase is not being properly evacuated.<\/em><\/strong>\u00a0 The acids and moisture present in the blowby are not being cleaned from your crankcase under this condition.<\/p>\n

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Our data acquisition system logged crankcase pressure vs. engine vacuum while driving using high precision pressure transducers.\u00a0 The table and graph above shows an average of how often the crankcase was under pressure (not effectively ventilated) vs. under vacuum (properly ventilated).\u00a0 As expected, running only breathers yielded a crankcase that was under pressure 100% of the time.\u00a0 Selecting a dress-up valve or a stock valve not specifically intended for the vehicle yielded mixed results.\u00a0 The M\/E Wagner Dual Flow PCV Valve far outperformed any other valve tested, since it was properly tuned to the specific vehicle.<\/em><\/strong>\u00a0 (The 1% of the time the Dual Flow valve left the crankcase under pressure was under full throttle conditions where manifold vacuum is zero, this limitation is inherent to any PCV system.)<\/p>\n

We won’t name names with the competitor’s dress-up valve<\/strong><\/em> we tested, however we will mention that we have observed this particular valve on a number of cars at car shows.\u00a0 It isn’t a coincidence that many of these vehicles had a pool of oil or a towel around the opposite valve cover breather to mop up the excess blowby being constantly forced out.<\/p>\n

An interesting note is that all three stock valves tested had exactly the same physical outer dimensions!<\/strong><\/em>\u00a0 All valves were listed as compatible with one or more V8 applications from the manufacturer, we did not test with 4 or 6 cylinder only valves to make the results fair.\u00a0 As can be seen from the results, the flow performance can vary greatly <\/strong><\/em>depending on which stock valve you happen to pick, as well as which valve happens to be compatible with your engine’s vacuum profile.<\/p>\n

TESTING RESULTS – DETAILS
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The chart above shows the average over both tests for the integral (or area) under the pressure vs. time curve.\u00a0 The curve was split into areas that were above zero and below zero and integrated separately, so the pressure integrals did not cancel out the vacuum integrals.<\/p>\n

This information can be used to determine to what degree the crankcase was under pressure or vacuum.\u00a0 For example, a valve that kept the crankcase under a low amount of pressure would have a low pressure integral (undesirable).\u00a0 A valve that kept the crankcase under a high amount of pressure would have a high pressure integral (even more undesirable).\u00a0 A valve that only moderately kept the crankcase under vacuum would have a low vacuum integral.\u00a0 A valve that kept the crankcase well under vacuum would have a higher vacuum integral (desirable, indicates proper ventilation).<\/p>\n

The “under pressure” integral is proportional to how much blowby was forced out of the breather during the drive cycle, while the “under vacuum” integral is proportional to how much fresh air was drawn through the crankcase during the drive cycle.<\/p>\n

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The chart above shows full details of the testing data.\u00a0 This data was used to generate the averages displayed in the color coded graphs above.\u00a0 It can be observed from this data that over multiple tests, the same valve produced very similar results from test to test.\u00a0 This validates the consistency of the testing methods.<\/p>\n

EXPERIMENTAL SETUP<\/span><\/p>\n

Test Route<\/strong><\/p>\n